Chapter 12-13 Review Questions
1
1
The average number of muscle cells in a motor unit is about 5 23 200 2000
200
an ECG tracing of someone with a third degree AV block is best described as a tracing with a ______
2:1 ratio of P waves to QRS complexes
The region of the sarcomere that contains both actin and myosin myofilaments is called the I band. A band. Z disk. H zone. M line.
A band.
The myosin head is bound to _________ when it is in the extended, high energy conformation.
ADP and Pi
Energy is released when
ATP is broken down into ADP and phosphate.
Energy is released when...
ATP is broken down into ADP and phosphate.
S1
AV valves close
What is the name of the neurotransmitter used at a skeletal neuromuscular junction?
Acetylcholine
Which of the following statements is correct?
Actin filaments slide along myosin filaments.
sarceolemma
At each end of the fiber, myofibrils are anchored to the inner surface of the WHAT?
The semilunar valves are the valves that prevent the blood from flowing back into the atria when the ventricles contract. A) True B) False
B. FALSE
electrodes of the EKG detect the
electrical current in the hearts' cells
raises eyebrows
epicranius
perimysium
fibrous connective tissue: the WHAT that bundles muscle fibers together in fasicles; collagent elastic fibers
epimysium
fibrous connective tissue: the WHAT that encloses the entire muscle; dense regular
the beginning o the muscle that typically does not move when a muscle contracts is called the
fibrous joint
abducts thigh; flexes and medially rotates leg
gracilis
flexes leg and rotates it medially; abducts thigh
gracilis
systolic pressure
high pressure measured on artery wall when heart ventricles contract
Shin splints are caused by __________. rupturing of the calcaneal tendon tearing of the hamstring muscles inflammation of the tibialis anterior inflammation of the gastrocnemius
inflammation of the tibialis anterior
The structures that connect cardiac muscle cells are
intercalated discs.
example first-class lever
lifting your head off your chest
leaky heart valve causes
murmur
myalgia
muscle pain resulting from any muscle disorder
An example of a partial but sustained contraction is
muscle tone.
The neuron releases acetyl choline causing a muscle potential to run down the innervated muscle cell
neural excitation phase
area on the surface of a muscle cell where the axon foot of the nerve meets the muscle cell it will stimulate
neuromuscular junction
Which of the following best describes the role of Ca2+ in muscle contraction?
It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
cardionatrin
potent natriuretic and diuretic hormone
Fast glycolytic
quick contracting-fatigue easily in biggest motor neuron
Too much acetylcholinesterase causes
rapid degradation of acetycholine.
the successive activation of the same and additional motor units with increasing strength of voluntary muscle contraction
recruitment
tropomyosin
Part of actin filaments. A thin filament also has molecules of protein called WHAT (an elongated protein winds along the groove of the F actin). When a muscle fiber is relaxed, tropomyosin blocks the active sites of six or seven actins and prevents myosin from binding to them.
Phase 1
Partial Repolarization - Na+ channel closes and K+ begins to flow out due to the depolarization which stops the obstacle for K diffusion
Pacemaker Action Potential phases
Phase 0 - depolarization skips 1&2 Phase 3 - repolarization Phase 4 - slow depolarization
What is released when myosin heads attach to actin filaments?
Phosphate.
Trained sprinters have high levels of phosphocreatine in the muscles. Explain the advantage of this. (4)
Phosphocreatine stores phosphate; Used to generate ATP from ADP in anaerobic conditions; Sprinter's muscles often work strenuously and so oxygen supply is short; Phosphocreatine allows for production of ATP to continue when anaerobic respiration is not possible
Responsiveness
Placing a muscle in a solution containing Ca and ATP.
PVC stands for
Premature Ventricular Contractions
What receptor does Ca+ bind to?
RyR - Ryanodine receptors - causes more Ca+ to be released from SR
What are the sounds of Korotkoff
Sounds that can be auscultated over a partially occluded artery
Unflexing of the myosin head requires ATP. True False
TRUE
sacroplasm
The cytoplasm of a muscle fiber is called the WHAT.
Negative inotropic agents
reduce contractility
What happens to A band during sarcomere contraction?
remains unchanged
epimysium
The fibrous connective tissue sheath, which encloses a whole muscle
myofibrils
The sacroplasm is occupied mainly by long protein bundles called WHAT- not to be confused with myofibers, the muscle cells themselves.
How does summation occur? Why is the second peak higher than the first peak when two AP are stimulated close to one another? What is tetanized muscle?
The slack is out of the system, so the second action potential doesn't have to waste any energy and can get a larger force for APs. Also bc the two APs were so close to one and another, more Ca channels were opened, stimulating more muscle contraction. At tetanus-either we have released as much Ca as we possible could or that all the cross bridges are used up, either way it is the maximum amount of tension a muscle can generate. A tetanized muscle is often 3-4 times more tension than a single twitch.
What is the purpose of the triad?
The triad allows for Ca2+ release when a muscle fiber is excited.
What structures do the calcium ions bind to when muscle contraction is initiated?
The troponin molecule
Which structure do the calcium ions bind to when muscle contraction is initiated? The actin myofilament The troponin molecule The tropomyosin molecule The sarcoplasmic reticulum The sarcolemma
The troponin molecule
Which structure do the calcium ions bind to when muscle contraction is initiated? (11)
The troponin molecule
What is not true about ventricular systole?
The ventricles relax
In a relaxed muscle, the H zone is at its widest width.
True
Unflexing of the myosin head requires ATP (T/F)
True
Stroke Volume
Ventricular ejection
What event causes the semilunar valves to close?
Ventricular pressure<pressure in the great arteries
T wave
Ventricular repolarization
An action potential reaches the axon terminal causing ____________ to open.
Voltage-gated Ca2+ channels
A motor unit is
a motor neuron and the muscle fibers connected to it.
What is myosin?
a protein of the microfibril, most common protein in muscle cells
abducts and extends thumb
abductor pollicis longus
elasticity
ability of a muscle to return to its resting length after being stretched
extensibility
ability to be stretched or extended
excitability
ability to receive and respond to a stimulus
contractility
ability to shorten forcibly when adequately stimulated
toxins from drugs or medications can cause
abnormal heart rate
According to your data, a single contraction produced maximum tension when the muscle was held at
about 28 mm.
Maximum tension is achieved when the muscle is at resting length. According to your data, the resting length of the muscle was:
about 28 mm.
The chemical used at the junction with a skeletal muscle is _______.
acetycholine
Which one of the following is a typical component of striated muscle thin filaments? (p. 5)
actin, troponin, tropomyosin
Myasthenia gravis is
an autoimmune disorder.
At what we did you record a maximum amount of muscle shortening?
Between 20 to 60 grams.
There is an increase in the activity of the enzyme ATPase during muscle contraction. An investigation into muscle contraction involved measuring the activity of ATPase in solutions containing ATP, myosin and different muscle components. The table shows the results. (Refer to exam q) Explain the importance of ATPase during muscle contraction. (2)
Breaks down ATP, yielding energy; Used to break actomyosin bridges
How do snails travel?
By a strong muscular foot along a trail of mucus.
The point where the axon terminal synapses with the muscle fiber sarcolemma is called the _____________. A sarcolemma junction B active site C neuromuscular junction D membrane receptor
C
The primary neurotransmitter at the neuromuscular junction is A dopamine. B adrenaline. C acetylcholine. D histamine. E serotonin.
C
Large motor units
Climbing stairs, Moving a piano and Sitting upright.
A muscle shortens forcefully.
Contractility
In a fully contracted sarcomere, the H zone
Disappears.
What is effective refractory period?
During phase 0, 1, 2, and part of 3, the cell is refractory to the initiation of new action potentials (allows time for each action potential to complete and re-fill. Prevents sustained contractions
As actin and myosin filaments slide past each other during muscle contraction, A actin filaments shorten, while myosin filaments do not. B myosin filaments shorten, while actin filaments do not. C either actin or myosin filaments shorten, but not both at the same time. D both actin and myosin filaments shorten. E neither actin nor myosin filaments shorten.
E
Phase 4
at resting potential
During twitch summation (a.k.a. temporal or wave summation) A a muscle fiber under continuous stimulation and contraction becomes unable to contract at all until it has rested. b muscle fiber stimulations are such that muscle fibers are able to contract and then completely relax before the next contraction. c the stimuli arrive at the muscle fiber so rapidly that there is no muscle relaxation between stimuli, but rather, a continuous contraction of the muscle fiber. d the stimuli arrive at the muscle fiber at such a rate that the muscle fiber is unable to completely relax between stimuli, and sequential contractions exhibit an equal contractive force that is greater than when the muscle fiber is allowed to rest completely. e a second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
E
Conductivity
Electrically stimulating a muscle, Action potentials in the center of the fiber radiating to the ends and Depolarization of a single muscle fiber causing Depolarization of adjacent muscle fibers.
The connective tissue that surrounds each muscle fiber is called the _____________.
Endomysium
In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm. True False
False
What are the areas in the center of the A bands containing only thick filaments?
H zones
In smooth muscle calcium ions binds to?
In smooth muscle it binds with calmodulin
Which of the following valves keeps blood from backing up into the left ventricle? A) pulmonary valve B) bicuspid valve C) aortic valve D) tricuspid valve
c. aortic valve
Which mineral is most important throughout life to assist in maintaining strong bone?
calcium
What is the cause of rigor mortis? high levels of sodium in the cell after death diffusion of potassium out of the cell after death calcium influx into the sarcoplasm after death breakdown of protein in the cell after death
calcium influx into the sarcoplasm after death
circular
close body opening shy contracting
myofibril
composed of actin and myosin filaments.
Tendons:
connect a skeletal muscle to a bone.
What is a twitch?
contraction produced by one action potential
What are the three types of muscle contraction?
Isotonic, Eccentric, Isometric
P wave
depolarization in the atrial tissue - positive deflection
maintaining posture
development of tension to prevent movement, as in keeping the vertebral column upright
When are the AV valves closed
during ventricular systole
When are the AV valves closed?
during ventricular systole
Rest
At rest, total (blood) flow is quite constant, and is equal to the cardiac output (5.25 L/min)
Phase 4
At the end of repolarization, when the membrane potential is very negative (about -60 mV), ion channels open that conduct slow, inward (depolarizing) Na+ currents. These currents are called "funny" currents and abbreviated as "If". These depolarizing currents cause the membrane potential to begin to spontaneously depolarize, thereby initiating Phase 4.
An action potential enters a neuron... a by diffusion. B by the T-tubules. C by the sarcolemma. D by the sarcoplasmic reticulum. E by the actin myofilament.
B
An isotonic contraction is described as A action potential frequency is high enough that no relaxation of muscle fibers occurs. B a muscle produces constant tension during contraction. C a muscle produces an increasing tension during contraction. D a muscle produces increasing tension as it shortens. E a muscle produces tension, but the length of the muscle is increasing.
B
During contraction of a muscle, calcium ions bind to... A the actin myofilament. B the troponin molecule. C the tropomyosin molecule. D the sarcoplasmic reticulum. E the sarcolemma.
B
Each actin filament is composed of A a single strand of actin molecules. B two strands of actin molecules wrapped together. C three strands of actin molecules wrapped together. D four strands of actin molecules wrapped together. E hundreds of strands of actin molecules wrapped together.
B
The amount of additional oxygen that must be inhaled following exercise to restore pre-exercise conditions is called _______ _________. A Creatine phosphate B Oxygen debt C Lactic acid D Glycogen replenishment
B
Which of the following structures allow one cardiac cell to electronically stimulate another by allowing ion flow across the intercalated disk? A) fascia adherens B) gap junctions C) desmosomes D) intercellular folds
B) gap junctions
The valve that lies between the right atrium and the right ventricle is the: A) aortic semilunar valve B) tricuspid valve C) mitral valve D) bicuspid valve
B) tricuspid valve
The maximum amount of work done by the weight 120 grams. When compared with the response for a lighter weight like 40 gram, the response for the 120 gram weight:
Both of the above statements are true.
When _________ causes more motor units to contract in a whole muscle as the stimulus strength increases, the relationship between increased stimulus strength and increased number of motor units contracting is called ___________. A summation, tetanus B recruitment, treppe C recruitment, multiple motor unit summation D summation, recruitment
C
Calcium's role in action potential
Ca+ channels open allowing influx into cytoplasm and this triggers the SR to release Ca+ to activate the actin-myosin complex and myofibril contraction. During phase 3 and 4, Ca+ is pumped out of the cell or into the SR
Phase 2
Ca+ moves in slowly along concentration gradient with K going out
What is the role of Ca2+ in muscle contration
Ca2+ (Calcium) binds to troponin, moving tropomyosin, so that myosin heads can bind to actin
What is the effect of the presence of calcium ions inside the axon terminal?
Calcium ions inside the axion terminal cause several Synaptic Vesicles to FUSE w/ the membrane of the axon terminal.
What evidence is there that muscle contraction is caused by actin and myosin filaments sliding past one another? (1)
Changes seen in the band patterns on myofibrils
A concentric contraction is described as A action potential frequency is high enough that no relaxation of muscle fibers occurs. B a muscle produces constant tension during contraction. C a muscle produces an increasing tension during contraction. D a muscle produces increasing tension as it shortens. E a muscle produces tension, but the length of the muscle is increasing.
D
A myofibril is the A cell membrane of a muscle fiber. B cytoplasm of muscle cells. C structural and functional unit of the skeletal muscle cell. D contractile thread that extends the length of the muscle fiber. E protein strand composed of actin.
D
A single motor neuron and the muscle fibers that it innervates is called a ___________. A neuronal unit B active unit C postsynaptic unit D motor unit
D
electrocardiogram
ECG/EKG: electrodes attached to ankles, wrists and 6 locations on chest. It's a composite recording of all action potentials produced by nodal and myocardial cells Electrocardiogram (ECG or EKG) - Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs, and chest
A skeletal muscle fiber (cell) contains a single nucleus.
False.
endomysium
Fibrous connective tissue: the WHAT that surrounds each muscle fiber; loose reticular fibers
For an isometric muscle fiber contraction...
For isotonic contractions, the shortening velocity of a muscle fiber is inversely proportional to the mass of the load.
What changes occur to a sarcomere when a muscle contracts? (3)
I-band becomes narrower; Z-lines move closer together (sarcomere shortens); H-zone becomes narrower
The training regimen of a competitive weight lifter is designed partly to
Increase the average number of myofibrils per muscle fiber.
Left atrioventricular valve
Mitral
How is the motor unit appear in a muscle?
Motor units are spread out a little bit in the muscle fiber.
Why is energy needed for muscle contraction? (2)
Movement of myosin heads; Reabsorption of calcium ions into endoplasmic reticulum by active transport
contractility
Muscle fibers are unique in their ability to shorten sustainability when stimulated. This enables them to pull on bones and other tissues and create movements of the body and its parts.
parallel
strap like with an extended belly; great ability to shorten but not usually very powerful
Arrangement of fibers in muscle in which fibers are combined into parallel fibers
striated
chief medial rotator of arm
subscapularis
Afterload
sum of all forces opposing ejection of blood from ventricle. Anything that impedes arterial circulation can also increase afterload - Lung diseases that restrict pulmonary circulation - Cor pulmonale: right ventricular failure due to obstructed pulmonary circulation • Largest part of afterload is blood pressure in aorta and pulmonary trunk - Opposes the opening of semilunar valves - Limits stroke volume • Hypertension increases afterload and opposes ventricular ejection
The functional connection between a neuron and a skeletal muscle fiber is a
synapse
The space between the neuron and the muscle is the ___________. synaptic knob motor unit motor end plate synaptic cleft M line
synaptic cleft
These chemicals diffuse across a small gap between the neuron and muscle fiber called the _______ _______.
synaptic cleft
the space between the neuron and the muscle is the what?
synaptic cleft
The attachment of calcium to the syptic vesicles causes the calcium ions enter the axon terminal. action potential to propagate along the sarcolemma and down the T Tubules. synaptic vesicles to fuse to the membrane of axon terminal, allowing release of acetylcholine. action potential to be initiated on the sarcolemma. Calcium ions to be released from the terminal cisternae. acetylcholine to bind to receptor sites on the motor end plate.
synaptic vesicles to fuse to the membrane of axon terminal, allowing release of acetylcholine.
A muscle that assists the agonist is a(n)
synergist
A muscle that assists the muscle primarily responsible for a given action is a(n) __________. levator primary antagonist originator synergist antagonist
synergist
muscles that help the prime mover my interacting at the same time to assist in the movement so that the movement is more effective
synergists
effort
the applied force
AV node
the atrioventricular node is located at lower end of the interatrial septum near right AV valve. -acts as an electrical gateway to the ventricles -the fibrous skeleton acts as an insulator to prevent currents from getting to the ventricles by any other route.
Ventricular systole causes
the atrioventricular valves to close, and then the semilunar valves to open.
z line
the border of a sarcomere. where actin is anchored by titin
sarcolemma
the cell membrane of a muscle fiber
M line
the center of the A band
Blood Pressure
the force that blood exerts against a vessel wall • Measured at brachial artery of arm using sphygmomanometer - A close approximation of pressure at exit of left ventricle • Two pressures are recorded - Systolic pressure: peak arterial BP taken during ventricular contraction (ventricular systole) - Diastolic pressure: minimum arterial BP taken during ventricular relaxation (diastole) between heart beats • Normal value, young adult: 120/75 mm Hg
During fused tetanus...
the stimuli arrive at the muscle fiber so rapidly that there is no muscle relaxation between stimuli, but rather, a continuous contraction of the muscle fiber.
In the sarcomere of skeletal muscle, myosin is found in:
the thick filaments
contraction period
the time in which the muscle is shortening
What structures do the calcium ions bind to when muscle contraction is initiated?
the troponin molecule
During contraction of a muscle, calcium ions bind to
the troponin molecule.
dorsiflexes foot and inverts foot
tibialis anterior
ST segment
time when ventricles are ejecting blood
What is the main function of heart valves?
to prevent backward flow of blood. Heart valves are one-way valves that prevent blood from flowing backward. For example, the AV valves only allow blood to flow from the atria to the ventricles. And the semilunar valves only allow blood to flow from the ventricles to the aorta and pulmonary trunk. When valves do not completely close, blood flows backward through the heart, creating an abnormal "sloshing" sound known as a heart murmur.
The term that means a continued mild or partial contraction of a muscle that keeps it healthy and ready to respond is muscle ___________. tetanus summation tone stimulation twitch
tone
muscle name that describes direction of fibers
transverse abdominis
In order for a skeletal muscle fiber to contract, calcium must bind to:
troponin
a complex of muscle proteins which, when combined with Ca2+, influence tropomyosin to initiate contraction
troponin
Action potentials are carried by the Purkinje fibers from the bundle branches to the ventricular walls.
true
After cross-bridges form, phosphate is released, followed by ADP.
true
After the passage of the action potential, the sodium-potassium pump reestablishes the resting membrane potential.
true
An action potential causes depolarization of the T tubule membrane.
true
An action potential causes depolarization of the T tubule membrane. True or False
true
Bones act as levers for movement.
true
Both smooth muscle contractions and skeletal muscle contractions involve thin (actin) filaments sliding over the thick (myosin) filaments. True or False
true
The semimembranosus muscle belongs to the group known as the "hamstrings."
true
The sliding of the myofilaments past each other cause the sarcomere to shorten
true
Unflexing of the myosin head requires ATP.
true
muscles are only able to pull, they never push
true
When an action potential arrives at the axon terminal of a motor neuron, which ion channels open?
voltage-gated calcium channels
QRS Complex
when signal from AV node spreads through ventricular myocardium and depolarizes
Isotonic contraction
when the muscle is stimulated it is capable of holding the weight, but also shortens as well. l
m line
where myosin is attached
Bundle Branch Block (BBB)
wide QRS, ventricular depolarization is taking longer
A band
width remains constant during muscle contraction
the sides that delineate one sarcomere from another
z lines/discs
(i) What is at the centre of each anisotropic band? (ii) What is at the centre of each isotropic band? (2)
(i) H-zone (ii) Z-line
L type channel
(long) Ca+ channel
Left side of heart
- Fully oxygenated blood arrives from lungs via pulmonary veins - Blood sent to all organs of the body via aorta
EKG deviations indicate
- Myocardial infarction (MI) - Abnormalities in conduction pathways - Heart enlargement - Electrolyte and hormone imbalances
Right side of heart
- Oxygen-poor blood arrives from inferior and superior venae cavae - Blood sent to lungs via pulmonary trunk
Arrange the following in the proper order in which they occur at the pre-synaptic side of a neuromuscular junction. 1. Calcium ions are released 2. Action potential arrives at the presynaptic terminal 3. Neurotransmitter is released
2, 1, 3 2. Action potential arrives at the presynaptic terminal 1. Calcium ions are released 3. Neurotransmitter is released
List the following structures in order from smallest to largest. 1. muscle fiber 2. myofilament 3. myofibril 4. muscle fasciculus 4, 2, 3, 1 2, 1, 4, 3 3, 1, 4, 2 2, 3, 1, 4 1, 2, 3, 4
2, 3, 1, 4
Which chambers of the heart are at the base of the heart? A) atria B) ventricles
...
Arrange the following list of biochemical events in the correct sequence. 1. An action potential is conducted deep into the muscle fiber by the T tubule. 2. Calcium ions bind to troponin. 3. The membranes of the sarcoplasmic reticulum become more permeable to calcium ions. 4. Calcium ions diffuse into the sarcoplasm around the myofibril. 5. The troponin-tropomyosin complex moves exposing active sites. 1, 5, 2, 3, 4 1, 3, 4, 2, 5 1, 2, 3, 4, 5 1, 3, 2, 5, 4 1, 4, 3, 2, 5
1, 3, 4, 2, 5
List 3 factors that decrease contractility
1. Acidosis 2. Increased extracellular K 3. Calcium channel blockers
What are the steps of excitation-contraction coupling?
1. Calcium diffuses throughout the muscle cell and binds to troponin 2. Troponin changes conformation, moving tropmyosin off the myosin binding site of actin 4. Myosin binds to actin-corss bridge formation 5. ADP and Pi are released and power stroke ensures 6. ATP binds to myosin 7. Myosin release from Actin 8. ATP is hydrolyzed 9. Myosin changes conformation rebinds to actin, ADP and Pi are released and power stroke. 11. Next DHP receptor closes, blocking the exit of Ca from the sarcoplasmic reticulum 12. Remaining calcium is pumped back into the SR by active transport 13. Troponin returns to its non calcium bound conformation, moving tropomyosin back on the actin myosin binding site 14. Muscle is now relaxed.
Cardiac muscle depends almost entirely on aerobic respiration to make ATP. A) True B) False
A. TRUE
The chordae tendineae are connected to the walls of the ventricle via the papillary muscles. A) True B) False
A. TRUE
The primary neurotransmitter at the neuromuscular junction is
ACh
The neurotransmitter in the neuromuscular junction.... What is the neurotransmitter?
ACh causes ligand gated sodium channels in the muscle fiber to increase their permeability to sodium, which depolarizes the postsynaptic membrane
What happens to ACh after it's RELEASED into the synaptic cleft?
ACh binds to ACh RECEPTOR sites of CHEMICALLY-GATED ion channels on the "MOTOR END PLATE"
In the neuromuscular junction, acetylchoine ... (what happens)
ACh diffuses across the synaptic cleft and binds to ACh receptors on the postsynaptic muscle fiber
Acetylcholine is broken down into acetic acid and choinesterase by choline (T/F)
ACh is broken down into acetic acid and choline by acetylchoine-asterase
What happens to the ACh after it DIFFUSES away from its receptor on the motor end plate?
ACh is then BROKEN DOWN by the enzyme: Acetyl-cholines-ter-ase
The primary neurotransmitter at the neuromuscular junction is
Acetylchoine
If we cut across a myofibril at certain points, we see only thick myosin filaments. Cut at a different point we see only thin actin filaments. At yet other points we see both types of filament. Explain why (2)
Actin and myosin filaments lie side by side in a myofibril; and overlap at the edges where they meet
Muscle contraction is caused by
Actin filaments sliding past myosin filaments.
The movement of the sodium ions throughout the Chemically gated ion channel initiates a Depolarization of the motor end plate. What happens after this depolarization is generated?
An ACTION POTENTIAL which propagates along the sarcolemma in all directions and down the T-tubules.
Correct sequence of smooth muscle contraction
An increase in cytosolic calcium binds to calmodulin in the cytosol. This complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to the actin filaments' active sites, resulting in contraction.
Correct sequence for skeletal muscle contraction
An increase in cytosolic calcium binds to troponin, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin, forming cross-bridges, resulting in contraction.
At rest, the active sites on actin molecules care covered by ________ and ___________, two contractile proteins that inhibit contraction.
Tropomyosin and Troponin
Outline how a muscle contracts. (6)
Tropomyosin molecule prevents myosin head from attaching to the binding site on the actin molecule; Calcium ions released from the endoplasmic reticulum cause the tropomyosin molecule to pull away away from the binding sites on the actin molecule; Myosin head now attaches to the binding site on the actin molecule; Head of myosin changes angle, moving the actin filament along. ADP molecule is released; ATP molecule fixes to the myosin head, causing it to detach from binding site; Hydrolysis of ATP to ADP by ATPase provides the energy for the myosin head to resume its normal position. This process is repeated further along the actin filaments
During muscle contraction, binding sites for myosin are uncovered by the movement of
Tropomyosin.
In a relaxed muscle fiber, the active sites of actin are blocked by
Tropomyosin.
During muscle contraction, calcium ions bind to
Troponin.
T-tubules are invaginations of the sarcolemma of a muscle cell. T/F
True
T/F? Each myosin protein has a globular head that extends outward from the myosin filament.
True
T/F? In a relaxed muscle, the H zone is at its narrowest width.
True
T/F? Once threshold is reached on the post synaptic membrane, an action potential is generated and propagated over the muscle cell membrane.
True
T/F? The area between the pre-synaptic nerve cell and the post-synaptic muscle cell is termed the synaptic cleft.
True
The calcium involved in muscle contraction ultimately comes from extra cellular fluid , true or false?
True
The muscle fiber length and the amount of force exhibited by the muscle fiber are directly proportional when the muscle fiber is shorter than its relaxed length.
True
Unflexing of the myosin head requires ATP.
True
When cross bridge form and the muscle fibers contract, the actin myofilament slides past the myosin myofilament (T/F)
True
cardiac cycle
a. Ventricular filling i. End-diastolic volume (EDV) b. Isovolumetric contraction c. Ventricular ejection i. Stroke volume(SV) ii. Ejection fraction iii. End-systolic volume(ESV) d. Isovolumetric relaxation
It is essential that both ventricles eject the same amount of blood even though the pressure in the right ventricle is much less than the pressure in the left ventricle. A) True B) False
a. true
When the ventricles relax blood in the aorta flows back toward the heart filling the coronary arteries. A) True B) False
a. true
The first event in muscle fiber contraction is that
acetylcholine is released from the end of the motor neuron.
People with myasthenia gravis have a deficiency of
acetylcholine receptors
Synaptic vesicles found at the synaptic terminal of a nuromuscular junction contain acetylcholine. acetylcholinesterase. sodium. calcium.
acetylcholine.
The primary neurotransmitter at the neuromuscular junction is
acetylcholine.
has binding sites for myosin heads and slides past the myosin when the head goes through its pull stroke during contraction
actin
Myofibrils are composed primarily of
actin and myosin
The sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated is known as the ___________. action potential resting potential membrane repolarization membrane hyperpolarization motor end plate potential
action potential
All or None Response
all action potentials are all or none the response of an excitable cell to stimulation. It either happens or it doesn't Individual muscle cells are all or none Muscle as a whole is a graded response.
Electric signals called action potentials cause a muscle cell to contract. transfer information from cell to cell. make complex mental processes possible. send information to the brain. all are true
all are true
Factor/s which affect muscle tension in a whole muscle include Frequency of Stimulation Number of motor units recruited Degree of muscle stretch all are true
all are true
Which of the following is true during the resting membrane potential? More positive charges outside the cell. More sodium outside the cell. More negative charges inside the cell. Less sodium inside the cell. all are true
all are true
in order for a muscle to contract properly, it requires
all of the above
Cardiac muscle
all of the above.
Functions of muscles include
all of the above.
Two factors that promote movement of blood through the heart
alternate contraction and relaxation of the myocardium and opening and closing of the heart valves
What is tension?
amount of contraction per fiber, number of muscle fibers contracting
stroke volume
another factor in cardiac output, besides heart rate, • Three variables govern stroke volume - Preload - Contractility - Afterload • Examples - Increased preload or contractility increases stroke volume - Increased afterload decreases stroke volume
The muscle that opposes a particular action is called the
antagonist
muscles that relax when the prime mover and synergist are contacting
antagonists
dense body
any of the small regions of increased density in the sarcoplasm of muscles to which myofilaments seem to attach, attachment plaques in smooth muscle cells are believed to be analogous to Z lines, contain alpha-actinin and function as myofilament attachment sites, actin, myosin and intermediate filaments are also present in nonvascular smooth muscle cells (majority), intermediate filaments are desmin, in vascular smooth muscle intermediate filaments are vimentin
neural stimulation
at presynaptic terminal, stimulates influx of Ca 2+ ions, causes synaptic vesicles to cluster and release contents along specialized linear sites (active zones) in the presynaptic membrane, acetylcholine release from vesicles--> bind to acetylcholine receptors in sarcolemma of muscle cell, cause transient increase in sodium ions, depolarizes muscle cell membrane, generates action potential action potential propagated over sarcolemma into T tubules, activate release of calcium-->contraction acetylcholinesterase in basal lamina lining secondary clefts of motor end plate limits response to neurotransmitter by breaking down acetylcholine
Maximum tension is produced in a skeletal muscle fiber when it is:
at resting length.
The chambers that have just been emptied are the
atria
Immediately after the second heart sound, the ___ and ___ fill with blood
atria and ventricles
S4
atrial contraction (not normal)
P wave
atrial contraction - atrial depolarization
Blood pressure (BP)
Normal value: 120/75 the force that blood exerts against a vessel wall two pressures recorded: Systolic pressure Diastolic pressure
ECG waveforms
P wave QRS complex T wave
Calcium Ions return to the sarcoplasmic reticulum, detaching the cross-bridges so the sarcomere can lengthen, during the ____________ phase.
Relaxation
Extensibility
Stretching a muscle, Increasing I-band length and Increasing sarcomere length.
In skeletal muscle, alternating light and dark bands are termed
Striations
Acetylcholine diffuses across the ___________ before binding to its receptor located on the _____________.
Synaptic Cleft; Motor end plate
Heart: two cycles
Systole: contraction Diastole: relaxation
An action potential enters the depths of a muscle fiber by way of __________. (11)
T tubules
Invaginations of the sarcolemma that projecting deep into the cell are called Sarcolemma Triad Terminal cisternae Sarcoplasmic reticulum T tubules
T tubules
Isovolumetric relaxation
T wave ends, ventricles expand, ventricles not taking in blood because both semilunar and AV valves are closed
Structures to create Muscles Contractions
T-Tubule -Invaginations of the sarcolemma penetrating deep into the interior of the muscle cell. Synaptic Cleft -the space between the axon terminal and the motor end plate. Axon Terminal -the swollen distal end of the motor neuron axon. Sarcolemma -the muscle cell membrane. Synaptic Vesicles -structures within the axon terminal that contain the neurotransmitter acetylcholine (ACh). Terminal Cisternae & Sarcoplasmic Reticulum (SR) -structures within skeletal muscle cells that serve as reservoirs of calcium ions. Motor End Plate -a folded region of the sarcolemma at the neuromuscular junction.
An action potential enters a neuron by
T-Tubules
Energy is needed to make muscles relax.
TRUE
What is a Action Potential?
The ELECTRICAL SIGNAL consisting of the DEPOLARIZATION & subsequent REPOLARIZATION of a nerve or muscle cell membrane.
Which of the following statements about the "heads" of the myosin molecules is TRUE?
They can attach to different sites on the actin filament.
How are fast-twitch fibres adapted for their function? (4)
Thicker and more numerous myosin filaments; High concentration of enzymes involved in anaerobic respiration; Store of phosphocreatine, which generates ATP from ADP in anaerobic conditions; So adapted for anaerobic respiration due to a build-up of lactic acid and more intense exercise
F actin, tropomyosin, troponin
Thin filament is composed of 3 major proteins?
What happens after the ACh BINDS to the ACh receptor on the motor end plate?
This causes the channels to OPEN permitting an INflux of Sodium Na+ ions and a small EFlux (out) of Potassium K+ ions. This ion EXCHANGE causes a local Depolarization of the "MOTOR END PLATE"
What makes the mucus of a snail so interesting as an area of study?
This fluid changes its properties when subjected to stress.
In contracting muscle the what lines come closer together?
Z lines
During crossbridge cycling, tension is created by:
a change in the shape of the myosin head.
myofilament
a contractile protein found in myofibrils
During twitch summation...
a second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
aponeurosis
a sheet of ct. that may attach muscle to bone, fascia, or to other muscles.
Muscle fibers are made up of ______ and _______
a single cell and many nuclei (results from cell fusion)
fascicle
a small bundle of m. fibers
tendon
a structure that connects muscles to bones. A ligament attaches bones to bones.
myosin
a thick protein that contracts and relaxes the m. fibers
Two strands of actin and one strand of regulatory protein coiled together is _____
a thin filament
What is an ACE inhibitor
a type of drug the blocks an enyme that raises blood pressure
The first three branches off the aorta are the right, left, and middle coronary arteries. A) True B) False
b. false
ACE inhibitor allows
blood vessels to enlarge and dilate to reduce blood pressure
powerful flexor of forearm
brachialis
cardiac muscle cells
branching chains of cells, uni- or binucleate striations; intercalated discs
An action potential enters a muscle cell ______________________.
by the T-tubules
I band and Z line contains what kind of protein?
connectin
cardiovascular system
consists of the heart and blood vessels has two major divisions: pulmonary circuit and systemic circuit
Muscle myofibrils are found in the sarcolemma. extend from the sarcolemma to the T-tubule. contain myosin and actin myofilaments. hold muscle cells together. do not appear striated.
contain myosin and actin myofilaments.
muscle myofibrils
contain myosin and actin myofilaments.
Systole
contraction of the ventricles
isometric contraction
contraction without a change in length
What indirectly provides most of the energy for muscle contraction?
creatine phosphate
Myosin heads
cross bridges
Rigor mortis occurs after death because cross-bridges form but can't release. calcium is actively transported back to the sarcoplasmic reticulum. anaerobic respiration is occurring. myosin levels decline at death. cross-bridges never form.
cross-bridges form but can't release.
Acetylcholine binds to a membrane bound receptor and causes ligand-gated sodium channels to open and results in
depolarization
Pulse pressure
difference between systolic and diastolic pressure
H zone
disappears during muscle contraction
I band also contains?
elastic filaments
MI
elevated ST segment
The layer of connective tissue that closely surrounds a skeletal muscle is called the ________.
epimysium
Acetylcholine is released from the presynaptic terminal by the process of exocytosis. endocytosis. diffussion. active transport.
exocytosis.
extends fingers and hand
extensor digitorum
The binding of ATP immeditely initiates the sliding of muscle filaments past one another.
false
True or False: There is a minimum amount of mineral in bone necessary to maintain appropriate strength, but typically no upper limit on the amount of mineral that can be present. (p. 4)
false
cardiac muscle control is voluntary
false
The audible heart sounds are caused by the contraction of the atria and ventricles.
false Audible heart sounds are caused by the closing of the valves.
Within a muscle, the fibers are divided into larger bundles called _____, each surrounded by its own connective tissue sheath.
fascicles
flexes wrist; aids abduction of hand
flexor carpi radialis
Blood supply to a tissue can be expressed in terms of ______ and ________
flow and perfusion
The _______ nerve innervates all of the extrinsic tongue muscles. vagus hypoglossal facial trigeminal
hypoglossal
where is the SA node located
in the right atrium
If the amount of tension produced by the muscle depends upon the number of crossbridges, according to your data the number of crossbridges:
increase as the muscle was lengthened to about 28 mm.
A child ingested an organophosphate poison used to kill insects. Soon the child's muscles began tetanic contractions. Predict what occurred at the synaptic cleft. increased accumulation of acetylcholine in the synapse increased release of acetylcholine from presynaptic neurons the poison binds to acetycholine receptors and stimulates them increased breakdown of acetylcholine in the synaptic cleft.
increased accumulation of acetylcholine in the synapse
Which of the following helps explain the increased tension seen in multiple wave summation? increased motor unit recruitment increased concentration of calcium ions around the myofibrils exposure of more active sites on myosin myofilaments the breakdown of elastic elements in the cell decreased stimulus frequency
increased concentration of calcium ions around the myofibrils
The sequence for smooth muscle contraction is...
increased cytosolic calcium, which binds to calmodulin in cytosol, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to actin filaments, resulting in contraction.
The sequence for skeletal muscle contraction is...
increased cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross bridges, resulting in contraction.
The sequence for skeletal muscle contraction is...
increased cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross-bridges, resulting in contraction
The sequence for skeletal muscle contraction is...
increased cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross-bridges, resulting in contraction.
propagation of the action potential
increased positive charge inside sarcolemma changes permeability of adjacent areas, opening voltage-regulated Na+ channels
Hypocalcemia
increases heart rate - low Ca+
The duration of the latency period:
increases with weight.
What are multiunit summation or recruitment?
increasing the number of motor units contracting at the same time. Generally, the samller motor units which are more sensitive are activated first, followed by progressively larger motor units. Activation of more motor units will increase the greater the number of cross bridges formed and therefore produce more tension.
fibromyositis
inflammation of a muscle, its connective tissue coverings and tendons, and capsules of nearby joints
after the meal the _________ receive priority and the skeletal muscles receive very little flow
intestines
cardiac muscle
involuntary intrinsic system regulation, hormones, and autonomic nervous system controls
Which of the following is NOT a characteristic of skeletal muscle contraction? It is voluntary. It contracts rapidly. It can exert tremendous power. It can contract for long periods of time without tiring.
it can contract for long periods of time without tiring
What happens to the H band during muscle relaxation?
it lengthens
The concentric rings of bone produced are...
lamellae
mitral regurgitation
leaky valve sometimes called a heart murmur
elevates mandible
masseter
The names of the muscles can indicate all of the following, EXCEPT ___________. the region of the body where the muscle is located the direction of the muscle relative to the long axis of the body myofibril composition of the muscle structural characteristics of the muscle action of the muscle
myofibril composition of the muscle
Which of the following is the site of ATP binding and hydrolysis?
myosin
Is a polarized membrane more positive or negative?
negative
myoneural junction (motor end plate)
nerve terminal, contains many mitochondria and small vesicles (storage sites of the neurotransmitter acetycholine)
H band is what kind of filament?
none, lighter color
smooth muscle
nonstriated, involuntary, found on the wall of hollow organs and tracts
Sinus rhythm
normal heartbeat triggered by the SA node - Adult at rest is typically 70 to 80 bpm (vagal tone)
Cardiac cycle
one complete heartbeat, both atria and ventricles contract and relax
epimysium
outermost layer. encircling the whole muscle.
Thick filaments of muscles in clams contain _________ which allows muscles to stay in a fixed state of contraction for up to a month
paramyosin
Muscles extend ________
passively
sarcolemma
plasma membrane of skeletal muscle fiber
Each of the following terms is used to describe the shape of a muscle, EXCEPT ____________. piriformis pollicis trapezius rhomboid quadratus
pollicis
Is a depolarized membrane more positive or negative?
positive
Ventricular ejection
pressure in ventricles exceeds arterial pressure, semilunar valves open, blood leaves ventricles, T wave occurs late in this phase 1. Stroke volume (SV): amount of blood ejected by ventricles 2. Ejection fraction: percentage of blood ejected from ventricle (what percentage of EDV was ejected?) usually about 54% 3. End-systolic volume (ESV): blood left behind that is not ejected (EDV-SV=ESV)
blood pressure
pressure on the walls when blood moves through the blood vessels
slow-oxidative
prolonged, long term action
lever
radius
Muscle fibers are basically a collection of
sarcomeres
hinge
shaking your head no
Both acetylcholine and norepinephrine can affect (which muscle)
smooth muscle contraction
Both acetylcholine and norepinephrine can affect
smooth muscle contraction.
Short muscle cells with centrally located nuclei are
smooth muscle fibers.
Which causes:
sodium ions to diffuse through and enter the cell.
Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of sodium ions. calcium ions. potassium ions. chloride ions.
sodium ions.
plantar flexes foot; important in posture
soleus
synaptic cleft
space between the neuron and and the muscle membrane
broad two-part muscle that lies on the back of the neck between base of skull and upper thorax
splenius capitis, and cervicis
Fibers in cardiac muscle are ________
striated
abducts arm; stabilizes shoulder joint
supraspinatus
endomysium
surrounds individual muscle fibers
I
the ____ band contain only actin
calcium, troponin
the _____ ion binds with the protein _____ during m. contraction
Blood flow
the amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min.)
SR
the cisternae are enlarged portions of the ____
sacroplasma
the cytoplasm of a muscle fiber
A band
the dark area of a sarcomere. Mostly thick filaments
tendon or aponeuroses
the deep fascia extending beyond the length of the muscle and attach the muscle to bone, cartilage, or muscle.
The amount of work done by a skeletal muscle is:
the distance the weight is lifted multiplied by the weight.
For every cross-bridge formed...
the energy from the same ATP molecule that detaches the cross-bridge also forms the next one.
cisternae
the enlarged portions of the SR near the TT of the sarcolemma
fulcrum
the fixed point upon which a lever moves
ACE inhibitor can improve
the function of a failing heart and slow progression of kidney disease due to high blood pressure or diabetes
Hyperpolarization, or afterpotential occurs because
the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
resting potential
the initial polarized state of the membrane
Sphygmomanometer
the instrument used to compress the artery and record pressures in the auscultatory method of determining blood pressure
H zone
the lighter central region of the A band that contains only myosin
SR
the loose network of flattened tubules that surrounds the myofibrils in muscle fiber is referred to as
fibers
the m. cells w/in a grp. such as teh biceps braccii are ind. called ____. A m. ____ is a multinucleated cell.
the P wave represents
the start of the electrical journey as the impulse spreads from the SA node downward from the atria through the AV node to the ventricles
a very large fibrous protein that connects thick myosin filaments to z discs in the sarcomere
titin
A muscle whose name ends in the suffix -glossus would be found attached to the ___________. chin tongue lips jaw cheek
tongue
End-diastolic volume (EDV)
total amount of blood in ventricles
The triangle of auscultation, commonly used to hear sounds of respiratory organs, is located near the border of the
trapezius and latissimus dorsi.
Each of the following terms is a descriptive term for a muscle's action, EXCEPT ____________. levator tensor pronator trapezius adductor
trapizius
Calcium ions bind to ______ in order to initiate a muscle contraction.
troponin
Ca++ is essential for skeletal muscle contraction
true
Calcium ion is released from the sarcoplasmic reticulum. True or False
true
Communication between neurons and skeletal muscle fibers occurs at specialized junctions called neuromuscular junctions.
true
During contraction, the myosin myofilaments shorten.
true
Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions. True or False
true
T tubules are invaginations of the sarcolemma of a muscle cell. True or False
true
T-tubules are invaginations of the sarcolemma of a muscle cell.
true
The end of the muscle, attached to the point that moves when the muscle contracts, is called the insertion.
true
The muscle that inserts on the acromion and scapular spine is the trapezius.
true
True or False The ventricles begin to fill during ventricular diastole.
true
true or false? Ventricular contraction begins at the AV valves and progresses downward toward the apex of the heart.
true
At what point in the cardiac cycle is the pressure in the heart the lowest
ventricular diastole
At what point in the cardiac cycle is the pressure in the heart the lowest?
ventricular diastole
QRS wave
ventricular muscle depolarization - positive deflection
What point in the cardiac cycle is the pressure in the heart highest?
ventricular systole
When the semilunar valves are open, what is occurring?
(2) AV valves are closed (3) ventricles are in systole (5) blood enters aorta (6) blood enters pulmonary arteries
sarcoplasmic reticulum
(SR) Most other organelles of the cell, such as mitochondria, are packed into the spaces between the myofibrils. The smooth endoplasmic reticulum, here called the WHAT, forms a network around each myofibril. (It runs longitudinally and surrounds each myofibril. Form chambers called terminal cisternae on either side of T-tubles.)
The activity of the heart depends on intrinsic properties of cardiac muscle and on neural factors. Thus,
(a) vagus nerve stimulation of the heart reduces heart rate (b) sympathetic nerve stimulation of the heart decreases time available for ventricular filling, (c) sympathetic stimulation of the heart increases its force of contraction
Freshly oxygenated blood is first received by the
(b) left atrium
The fact that the left ventricular wall is thicker than the right reveals that it
(b) pumps blood against greater resistance
The sequence of contraction of the heart chambers is
(c) both atria followed by both ventricles
(Refer to June 2013 paper) The table shows features of fast and slow muscle fibres. Use information from the table to suggest and explain one advantage of: (i) the high glycogen content of fast muscle fibres (ii) the number of capillaries supplying slow muscle fibres (many).
(i) Glycogen broken down gives lots of glucose for anaerobic respiration; Anaerobic respiration is not very efficient; (ii) Many capillaries give large surface area for oxygen diffusion; Allows high rate of aerobic respiration
Myofibrils appear striped due to their alternating light-coloured and dark-coloured bands. (i) What makes up the light coloured bands? (ii) What makes up the dark coloured bands? (2)
(i) Isotropic bands - actin and myosin filaments do not overlap (ii) Anisotropic bands - actin and myosin filaments overlap
Describe the part played by each of the following in myofibril contraction. (i) Tropomyosin (ii) Myosin (4)
(i) Moves out of the way when calcium ions bind; Allowing myosin to bind to actin; (ii) Head of myosin binds to actin and pulls actin past; Myosin detaches from actin and moves further along actin
Use your knowledge of the processes occurring at a neuromuscular junction to explain each of the following. (i) The cobra is a very poisonous snake. The molecular structure of cobra toxin is similar to the molecular structure of acetylcholine. The toxin permanently prevents muscle contraction. (2) (ii) The insecticide DFP combines with the active site of the enzyme acetylcholinesterase. The muscles stay contracted until the insecticide is lost from the neuromuscular junction. (2)
(i) toxin binds to the acetylcholine receptors; acetylcholine can not depolarise the membrane (ii) acetylcholinesterase is unable to breakdown acetylcholine; acetylcholine still available to depolarise the membrane
excitability
(responsiveness) This is a property of all living cells. When stimulated by chemical signals (neurotransmitters), stretch, and other stimuli, muscle cells respond with electrical changes across the plasma membrane.
Isovolumetric relaxation
- T wave ends and ventricles begin to expand - Blood from aorta and pulmonary trunk briefly flows backward filling cusps and closing semilunar valves • Creates pressure rebound that appears as dicrotic notch in graph of artery pressure • Heart sound S2 occurs • When AV valves open, ventricular filling begins again
Ventricular filling
- Ventricles expand and their pressure drops below that of the atria - AV valves open and blood flows into the ventricles - Filling occurs in three phases: • Rapid ventricular filling: first one-third • Diastasis: second one-third; slower filling - P wave occurs at the end of diastasis Atrial systole: final one-third; atria contract - End-diastolic volume (EDV) achieved in each ventricle (about 130 mL of blood)
QRS complex
- Ventricular depolarization - Complex shape of spike due to different thickness and shape of the two ventricles
ST segment
- ventricular systole - Corresponds to plateau in myocardial action potential
Check all those that are characteristic of cardiac muscle.
-Cells are striated -Gap junctions join adjacent cells
Which of the following statements are true about the "heads" of the myosin molecules is TRUE? -they form permanent links with actin filaments correct -they can attach to different sites on the actin filament -they straighten the myosin filaments -they allow the myosin filaments to wrap around each other -none of the above
-they can attach to different sites on the actin filamen
the beginning of the muscle that typically does not move when a muscle contracts is called the what?
...
what is the most distinguishing characteristic of muscle tissue?
...
The time interval of atrial systole
0.1 sec
The ventricular contraction period
0.3 sec
The quiescent period, or pause
0.4 sec
The length of a normal cardiac cycle
0.8 sec
What is the role of troponin and tropomyosin?
1. cross bridge-binding of actin and myosin 2. Roles are to regulate formation of cross bridges this regulation is done using Ca, in absence of Ca, tropomyosin blocks the actin myosin binding sites 3. When Ca is present it binds to TnC, causing a conformational change to the troponin complex that forces torpomyosin to move away from the actin myosin binding iste thus allowing actin to bind to myosin and form the cross bridge.
Arrange the following in the proper order in which they occur at the post-synaptic side of a neuromuscular junction. 1. Action potential is propagated over the muscle cell membrane 2. Depolarization of the post-synaptic membrane 3. Sodium ions move into muscle cell
3, 2, 1 3. Sodium ions move into muscle cell 2. Depolarization of the post-synaptic membrane 1. Action potential is propagated over the muscle cell membrane
An action potential A occurs when the local potential reaches threshold level. B is not propagated. C has no repolarization phase. D is an example of negative feedback. E can be of varying strengths depending on strength of the stimulus.
A
Cardiac muscle cells are like skeletal muscle cells in that they both A have striations. B depolarize as a result of sodium and calcium influxes. C possess intercalated disks. D lack sarcomeres. E are multinucleated.
A
During exercise, an individual experiences ____________ due to aerobic respiration, and after exercise, this oxygen is replenished with ________________. A oxygen deficit, recovery oxygen consumption B recovery oxygen consumption, oxygen deficit C fatigue, anaerobic respiration D physiological contracture, creatine phosphate
A
During the ___________ phase, the inside of the cell becomes positively charged, and during the _________ phase, the membrane potential returns to its resting value. A depolarization, repolarization B polarization, resting C repolarization, depolarization D active, resting
A
If the resting membrane potential becomes more negative, which of the following has occurred? A hyperpolarization B repolarization C depolarization D isopolarization E hypopolarization
A
Movement of the myosin head while the cross-bridge is attached is called the ________, and the return of the head to its original position after releasing from the cross-bridge is called the __________. A power stroke, recovery stroke B recovery stroke, power stroke C active movement, resting phase D active movement, potential movement
A
Rigor mortis occurs after death because A cross-bridges form but can't release. B calcium is actively transported back to the sarcoplasmic reticulum. C anaerobic respiration is occurring. D myosin levels decline at death. E cross-bridges never form.
A
Smooth muscle and cardiac muscle are similar in that they both A are under involuntary control. B are striated. C are widely distributed in the body. D have multiple nuclei. E are under voluntary control.
A
Tetanus of muscles is described as A action potential frequency is high enough that no relaxation of muscle fibers occurs. B a muscle produces constant tension during contraction. C a muscle produces an increasing tension during contraction. D a muscle produces increasing tension as it shortens. E a muscle produces tension, but the length of the muscle is increasing.
A
The bond between the actin and myosin head is broken when... A an ATP molecule binds to the myosin head. B an ATP molecule binds to the actin molecule. C an ATP molecule breaks down on the myosin head. D an ATP molecule breaks down on the actin molecule. E ADP and phosphate bind to the myosin head.
A
The condition of painful, spasmodic contractions of muscles is referred to as A cramps. B fibrositis. C fibromyalgia. D muscular dystrophy. E paralysis.
A
The force of a contraction can be increased with _________, which involves increasing the force of contraction of the muscle fibers, as well as with __________, which involves increasing the number of muscle fibers contracting. A summation, recruitment B gradient change, summation C recruitment, communal change D reinforcement, gradient change
A
The outside of the resting plasma membrane is __________ relative to the inside of the resting plasma membrane. A positively charged B negatively charged C electrically neutral D recharged E None of these choices is correct.
A
The sarcolemma is the A cell membrane of a muscle fiber. B cytoplasm of muscle cells. C structural and functional unit of the skeletal muscle cell. D contractile thread that extends the length of the muscle fiber. E protein strand composed of actin.
A
Thin myofilaments are _______ myofilaments, and thick myofilaments are _________ myofilaments. A actin, myosin B tryptin, actin C myosin, sarcomere D myofibril, globular
A
What is the role of pacemaker cells? A can rapidly develop action potentials B shallow invaginations of cell membrane C relatively constant tension maintained for a period of time D intracellular cytoskeleton E enzyme that removes phosphate from myosin
A
The area of the muscle fiber where the actin and myosin myofilaments overlap is the...
A Band
triad
A T tubule and the two terminal cisternae associated with it constitute a WHAT?
The area of the muscle fiber where the actin and myosin myofilaments overlap is the
A band
The area of the muscle fiber where the actin and myosin myofilaments overlap is the...
A band
During muscle contraction, what happens with the A & I band?
A band remains the same and the I band narrows
Which region of the sarcomere does not change length between muscle relaxation and muscle contraction?
A band.
How do you produce smooth contractions at different tensions?
A combination of motor units recruited and stimulation rate provide for smooth contractions at different tensions..
Elasticity
A stretched muscle returning to its original length, Spring-like effect of muscle and Passively resisting the separation of two bones.
Which of the following is true? Muscle fatigue has no influence on the force of contractions. A threshold stimulus will cause contraction of a muscle fiber. A subthreshold stimulus causes a muscle contraction. Motor units do not obey the "all or none" law. A threshold stimulus will not affect motor units.
A threshold stimulus will cause contraction of a muscle fiber.
actin filaments
A type of myofilaments. Composed primarily of two intertwined strands of a protein called fibrous (F) actin. Each F actin is like a bead necklace- a string of subunits called globular (G) actin. Each G actin has an active site that can bind to the head of a myosin molecule. A thin filament also has molecules of protein called tropomyosin (an elongated protein winds along the groove of the F actin). When a muscle fiber is relaxed, tropomyosin blocks the active sites of six or seven actins and prevents myosin from binding to them. Each tropomyosin molecule has a smaller calcium-binding protein called troponin bound to it.
diffusion
ACh moves across the synaptic cleft by _____
When the myosin head physically pulls the actin past the myosin toward the center of the sarcomere, what part of the ATP molecule is still attached?
ADP
During skeletal muscle contraction, if the myosin head group is attached to the thin filament, but the power stroke has not occurred, what is likely to be found in the nucleotide binding site of the myosin head? (p. 8)
ADP + Pi
Cross-bridge formation occurs when the myosin head is bound to __________.
ADP and Pi
What regulated the release of Calcium?
AP travels down the axon ACh is released at nerve terminal, ACh binds to its receptor on the postynaptic cell muscle cell. End plate potential develops depolarizing area above threshold for voltage gated Na channel rapid depolarization spread over entire muscle. SP travels down the T tubes where the Dihydropyridine receptor is activated DHP receptor then activates the Ryanodyne recpetor-found in the sacroplasmic reticulum Ca exits the sarcoplasmic reticulum, down its concentration gradient Immediately Ca pumps begin returning Ca back to the sarcoplasmic reticulum
Tawanda finishes a sprint and suffers great pain in her calf muscles. Her muscle cramps are most likely due to a temporary deficit of
ATP
The absence of ___________ would prevent the myosin head from detaching from the thin filament.
ATP
The myosin head is bound to ________ when it is in the low energy conformation and is not bound to the thin filament.
ATP
Skeletal muscle is made of bundles of fibres. Describe the role of ATP and phosphocreatine in producing contraction of a muscle fibre. (3)
ATP allows myosin to detach from actin; Phosphocreatine allows regeneration of ATP under anaerobic conditions; Phosphocreatine releases Pi to join ADP
Dead cells can no longer produce ATP. Soon after death, muscles contract, making the body stiff. From your knowledge of muscle contraction, explain why this happens. (3)
ATP attaches to myosin heads and detaches them from binding sites on the actin filament, making muscle relax; As no ATP is produced after death, none attaches to myosin heads; Remain attached to actin, leaving the muscle in a contracted state
Energy is released when... (relates to ATP and ADP)
ATP is broken down into ADP and phospate
Energy is released when...
ATP is broken down into ADP and phosphate
People who have McArdle's disease produce less ATP than healthy people. As a result, they are not able to maintain strong muscle contraction during exercise. Use your knowledge of the sliding filament theory to suggest why. (3)
ATP is needed for attachment between actin and myosin; And the movement of myosin heads, which pulls actin along; Myosin heads need to move back to original position
The bond between the active site on actin and the myosin head is broken when an __________.
ATP molecule binds to the myosin head
The actin-myosin bond is broken by the attachment of
ATP.
The first heart sound is a result of the closure of the
AV valves
When the pressure in the ventricles becomes lower than the pressure in the atria... A) the ventricles contract. B) blood flows into the pulmonary trunk. C) blood flows into the aorta. D) the atrioventricular valves open. E) the semilunar valves open.
AV valves open
At what length do you think this muscle would be able to lift the heaviest weight?
About 28 mm
What chemical, released by the nerve, is involved in stimulating the muscle?
Acetyl Choline
ACh is broken done into acetic acid and choline by what enzyme
Acetyl-choline-sterase
The neurotransmitter at the neuromuscular junction is
Acetylcholine.
The thin filaments of the sarcomere are made up mostly of the protein _____________.
Actin
Which of the following is not a filamentous protein?
Actin Myosin Troponin Tropomyosin Toponi
Describe the two types of protein filaments. (2)
Actin - thinner and consists of two strands twisted around one another Myosin - thicker and consists of long rod-shaped fibres with bulbous heads
Which of the following statements is correct? -Tropomyosin molecules move and expose specific sites on myosin filaments. correct -Actin filaments slide along myosin filaments. -Cross-bridges form between actin and sarcolemma filaments. -Filaments of troponin and tropomyosin slide past one another. -Myosin and actin alternate to form filaments.
Actin filaments slide along myosin filaments
Muscle contraction is caused by:
Actin filaments sliding past myosin filaments.
Thin Filaments
Actin, Active sites, Troponin, Tropomyosin and I band.
Increased calcium ion permeability of the presynaptic terminal cell membrane is caused by an
Action potential.
Which is true about the heart conduction system?
Action potentials pass slowly through the atrioventricular node
Which of the following is true concerning the heart's conduction system?
Action potentials pass slowly through the atrioventricular node.
Inotropic
Affecting the force of muscle contraction. An inotropic heart drug is one that affects the force with which the heart muscle contracts.
When does the CHEMICALLY-GATED ion channel on the motor end plate close?
After a brief period, ACh DIFFUSES away fm its Receptor site (ion channel Closes).
2,1,3
Arrange the following in the proper order in which they occur at the pre-synaptic side of a neuromuscular junction: 1. Calcium ions are released 2. Action potential arrives at the presynaptic terminal 3. Neurotransmitter is released
Arrange the following in the proper order in which they occur at the pre-synaptic side of a neuromuscular junction. 1 Calcium ions enter presynaptic terminal and cause release of acetylcholine. 2 An action potential arrives at the presynaptic terminal. 3 Diffusion of acetylcholine across the synaptic cleft and binding of acetylcholine to acetylcholine receptors. A 1, 2, 3 B 2, 1, 3 C 2, 3, 1 D 3, 2, 1 E 3, 1, 2
B
Each presynaptic terminal contains ___________, which contain the neurotransmitter __________ that, when released, cause ligand-gated Na+ channels to open in the postsynaptic membrane. This causes __________ in the muscle cell. A ACh receptors, acetylcholinesterase, repolarization B synaptic vesicles, acetylcholine, depolarization C proteins, acetylcholine, repolarization D mitochondria, acetylcholinesterase, depolarization
B
Energy is released when... A ADP is broken down into ATP and phosphate. B ATP is broken down into ADP and phosphate. C ADP and phosphate combine to form ATP. D ATP and phosphate combine to form ADP. E AMP and two phosphates combine to form ATP.
B
In ___________, muscle fibers partially relax between contractions, and in ___________, no relaxation occurs between contractions. A complete tetanus, rigor mortis B incomplete tetanus, complete tetanus C stretching, incomplete tetanus D rigor mortis, hypotonia
B
Muscle atrophy A involves an increase in the number of muscle fibers. B is characterized by a decrease in muscle size. C results from aerobic exercise. D causes an increase in blood flow to the affected muscle. E is characterized by an increase in muscle size.
B
Sarcoplasm is the A cell membrane of a muscle fiber. B cytoplasm of muscle cells. C structural and functional unit of the skeletal muscle cell. D contractile thread that extends the length of the muscle fiber. E protein strand composed of actin or myosin.
B
The active sites to which cross-bridges attach are found on the A sarcoplasmic reticulum. B actin myofilaments. C Z disks. D T tubules. E myosin myofilaments.
B
The charge difference across the plasma membrane of an unstimulated cell is called the __________. A plasma membrane potential B resting membrane potential C sarcomere potential D charge potential
B
The region of the sarcomere that contains both actin and myosin myofilaments is called the A I band. B A band. C Z disk. D H zone. E M line.
B
What is a triad? A a protein found along the groove of the F-actin double helix B a T tubule and two adjacent terminal cistern C the combination of myosin heads with active sites on actin molecules D the movement of myosin head while attached to actin myofilament E after exercise, the oxygen taken in that exceeds the oxygen required for resting metabolism
B
What structures do the calcium ions bind to when muscle contraction is initiated? A the actin myofilament. B the troponin molecule. C the tropomyosin molecule. D the sarcoplasmic reticulum. E the sarcolemma.
B
Which of the following statements about the "heads" of the myosin molecules is TRUE? A they form permanent links with actin filaments B they can attach to different sites on the actin filament C they straighten the myosin filaments D they allow the myosin filaments to wrap around each other E none of these choices are correct
B
________ occurs when a rested muscle is stimulated repeatedly, at low frequencies, allowing relaxation between contractions. This causes each contraction to be stronger than the previous one until the levels of tension are equal between contractions. A Summation B Treppe C Tensile strength D Complete tetanus
B
This chamber has to work harder than the others, so it has the thickest myocardium: A) right ventricle B) left ventricle C) right atrium D) left atrium
B) left ventricle
Which of the following refers to the cardiac muscle tissue? A) pericardium B) myocardium C) endocardium D) epicardium
B) myocardium
Which of the following is associated with the atria? A) trabeculae carneae B) pectinate muscles C) chordae tendineae D) papillary muscles
B) pectinate muscles
Atrial pressure is at its highest when: A) the AV valve is closed B) the AV valves are open C) the semilunar valves are closed D) the valves have no influence on atrial pressure
B) the AV valves are open
The semilunar valves close during... A) ventricular systole. B) ventricular diastole. C) atrial systole. D) atrial diastole. E) both atrial and ventricular systole.
B) ventricular diastole
The atrioventricular valves open during... A) ventricular systole. B) ventricular diastole. C) atrial systole. D) atrial diastole. E) both atrial and ventricular systole.
B) ventricular diastole.
Closure of the AV valves occurs when: A) the second heart sound is heard B) ventricular pressure exceeds atrial pressure C) atrial pressure exceeds ventricular pressure D) ventricular pressure and atrial pressure are equal E) blood is ejected from the ventricles
B) ventricular pressure exceeds atrial pressure
What is Exocytosis?
Bulk transport of material OUT of cell by 1st FUSEing a membrane-bound vesicle, ( 0 ), w/ plasma membrane . When membrane ruptures , the contents of the vesicle are RELEASED into the extracellular space (or synaptic cleft)
A sarcomere is the A cell membrane of a muscle fiber. B cytoplasm of muscle cells. C structural and functional unit of the skeletal muscle cell. D contractile thread that extends the length of the muscle fiber. E protein strand composed of actin or myosin.
C
An isometric contraction is described as A action potential frequency is high enough that no relaxation of muscle fibers occurs. B muscle produces constant tension during contraction. C a muscle produces an increasing tension as the length remains constant. D a muscle produces increasing tension as it shortens. E a muscle produces tension, but the length of the muscle is increasing.
C
Calcium ions bind to ___________, which is bound to the thin filaments.
Troponin
During contraction of a muscle, calcium ions bind to the __________.
Troponin
Which of the following is not a filamentous protein? Actin Myosin Troponin Tropomyosin
Troponin
Which of the following isn't a filamentous protein? -actin -myosin -troponin -tropomyosin -troponin and tropomyosin
Troponin "Globular troponin protein"
During contraction of a muscle, calcium ions bind to ...
Troponin Molecule
What structures do the calcium ions bind to when muscle contraction is initiated?
Troponin Molecule
The protein that acts as a calcium receptor in skeletal muscle is
Troponin.
Action potential are carried by the Purkinje fibers from the bundle branches to the ventricular walls. True or false
True
After cross-bridges form, phosphate is released and then ADP follows (T/F)
True
An action potential causes depolarization of the T tubule membrane (T/F)
True
An action potential causes depolarization of the T tubule membrane.
True
An action potential causes depolarization of the T tubule membrane. True False
True
Both smooth muscle contractions and skeletal muscle contractions involve thin (actin) filaments sliding over the thick (myosin) filaments.
True
Both smooth muscle contractions and skeletal muscle contractions involve thin (actin) filaments sliding over the thick (myosin) filaments. True False
True
Each myosin protein has a globular head that extends outward from the myosin filament.
True
Each myosin protein has a globular head that extends outward from the myosin filaments (T/F)
True
For isotonic contractions, the distance that the muscle fiber shortens is inversely proportional to the mass of the load.
True
In a contracting muscle the Z lines come closer together (T/F)
True
In a contracting muscle the Z lines come closer together.
True
In the ventricles , the action potential travels along the Interventricular septum to the apex of the heart, where it spreads superiorly along the ventricular walls . True or false
True
Once threshold is reached on the postsynaptic membrane, an action potential is generated and propagated over the muscle cell membrane (T/F)
True
Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions.
True
Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions. True False
True
T tubules are invaginations of the sarcolemma of a muscle cell.
True
T tubules are invaginations of the sarcolemma of a muscle cell. True False
True
T-Tubules are invaginations of the sarcolemma of a muscle cell (T/F)
True
T/F? The sodium channels in the cell membrane have receptor sites for acetylcholine.
True
T/F? This channel is formed by a channel protein.
True
T/F? Unflexing of the myosin head requires ATP.
True
The are between the pre-synaptic nerve cell and the post-synaptic muscle cell is termed the synaptic cleft (T/F)
True
The area between the pre-synaptic nerve cell and the post-synaptic muscle cell is termed the synaptic cleft. True False
True
The area between the presynaptic nerve cell and postsynaptic muscle cell is termed the synaptic cleft (T/F)
True
The muscle fiber length and the amount of force exhibited by the muscle fiber are inversely proportional when the muscle fiber is longer than its relaxed length.
True
The p wave of the ECG coincides with ventricular filling. True or false
True
The sequence of cross bridge formation and myofilament movement will be repeated as long as calcium ions are present (T/F)
True
The sequence of cross bridge formation and myofilament movement will be repeated as long as calcium ions are present.
True
The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions and ATP are present.
True
The sequence of crossbridge formation and myofilament movement will be repeated as long as calcium ions are present. T/F
True
The thin filament consists of actin, troponin, and tropomyosin molecules.
True
The ventricles begin to fill during ventricular diastole? True or false
True
Transverse (T) tubules are invaginations of the sarcolemma of a muscle cell.
True
True or False: One adaptation to endurance training is that the muscles increase the number of mitochondria
True
True or False: The lactate threshold is the % O2max where a significant rise in the concentration of lactate in the blood occurs
True
When cross bridges form and the muscle fibers contract, the actin myofilament slides past the myosin myofilament.
True
When cross-bridges form, and the muscle fibers contract, the actin myofilament slides past the myosin myofilament.
True
nflexing of the myosin head requires ATP.
True
the active transport of Ca2+ into the sarcoplasmic reticulum requires ATP
True
Myofibrils are composed of protein filaments called actin and myosin.
True.
The I-band of a sarcomere is widest when a muscle is relaxed.
True.
myosin filaments
Type of myofilaments. Each is made of several hundred molecules of a protein called myosin. A myosin molecule is shaped like a golf club, with two chains intertwined to form a shaftlike tail and a double globular head projecting from it at an angle.
During fused tetanus A a muscle fiber under continuous stimulation and contraction becomes unable to contract at all until it has rested. B muscle fiber stimulations are such that muscle fibers are able to contract and then completely relax before the next contraction. C the stimuli arrive at the muscle fiber so rapidly that there is no muscle relaxation between stimuli, but rather, a continuous contraction of the muscle fiber. D the stimuli arrive at the muscle fiber at such a rate that the muscle fiber is unable to completely relax between stimuli, and sequential contractions exhibit an equal contractive force that is greater than when the muscle fiber is allowed to rest completely. E a second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
C
One cause of spastic paralysis might be A inhibition of acetylcholine molecules. B blockage of acetylcholine receptors. C inhibition of acetylcholinesterase. D destruction of synaptic vesicles. E increase in the amount of acetylcholinesterase.
C
The constant tension produced by muscles for long periods of time is ___________. A muscle energy B potential energy C muscle tone D myofibril energy
C
The cycle of a mysosin molecule forming cross-bridges, moving, then releasing and returning to its original position is called _____________. A sliding filament model B contraction cycle C cross-bridge movement D myosin exchange
C
The myofilaments that contain two strands of F actin coiled together to form a double helix are ________ myofilaments, and the myofilaments that are composed of molecules that are shaped like golf clubs are _________ myofilaments. A myosin, actin B myosin, myosin C actin, myosin D actin, actin
C
Which of the following occurs during recovery from oxygen deficit? A an elevated level of anaerobic metabolism B depletion of reserves of creatine phosphate C conversion of excess lactic acid to glucose D glycogen degradation to provide creatine E depressed level of aerobic respiration
C
What happens when the calcium ion is present in the cytosol of the muscle cell?
CONTRACTION of the muscle cell / fiber (only one cell)
What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in the formation of cross bridges? acetylcholine troponin myosin Ca2+ calmodulin
Ca2+
Which of the following does NOT occur during skeletal muscle contraction? ATP is hydrolyzed. Calcium binds to myosin heads. Myosin heads bind to actin. Calcium concentration in the sarcoplasm increases. The I bands shorten and H zones disappear.
Calcium binds to myosin head
What happens as the action potential moves down the T-tubules?
Calcium ions are released from the TERMINAL-CISTERNAE into the CYTOSOL.
Tropomyosin shifts off of the moyosin-binding sites of the actin protein during the ______________ phase.
Contraction
Increased calcium concentrates in the cytosol causes?
Contraction of sacromeres
The step in which the action potential depolarizes the T tubules is called ___________.
Coupling
Contractility
Creation of force, Pulling two bones close together and Actively resisting the separation of two bones.
myofibril
Cylindrical structures within muscle fiber. They are bundles of myofilaments (protein filaments). There are two kinds of myofilaments: myosin and actin filaments
Arrange the following in the proper order in which they occur at the post-synaptic side of a neuromuscular junction. 1 Calcium ions enter presynaptic terminal and cause release of Acetylcholine. 2 An action potential arrives at the presynaptic terminal 3 Diffusion of acetylcholine across the synaptic cleft and binding of acetylcholine to acetylcholine receptors A 1, 2, 3 B 2, 1, 3 C 2, 3, 1 D 3, 2, 1 E 3, 1, 2
D
As a result of extreme muscular fatigue, muscles can become incapable of relaxing or contracting, which is called _____________. Similarly, several hours after death, ATP levels decline, causing muscle muscle rigidity, known as ____________. A rigor mortis, physiological contracture B stiffness, physiological contracture C psychological fatigue, rigor mortis D physiological contracture, rigor mortis
D
Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called A ligand-gated ion channels. B non-gated ion channels. C relegated ion channels. D voltage-gated ion channels. E obligated ion channels.
D
Curare blocks acetylcholine receptors at the motor end plate. This would result in A increased stimulation of the muscle. B more acetylcholinesterase production. C lack of calcium uptake by the muscle fiber. D inability of the muscle fiber to respond to nervous stimulation. E sustained contraction of the muscle.
D
Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of A potassium ions. B chloride ions. C calcium ions. D sodium ions. E amino acids.
D
During unfused tetanus A a muscle fiber under continuous stimulation and contraction becomes unable to contract at all until it has rested. B muscle fiber stimulations are such that muscle fibers are able to contract and then completely relax before the next contraction. C the stimuli arrive at the muscle fiber so rapidly that there is no muscle relaxation between stimuli, but rather, a continuous contraction of the muscle fiber. D the stimuli arrive at the muscle fiber at such a rate that the muscle fiber is unable to completely relax between stimuli, and sequential contractions exhibit an equal contractive force that is greater than when the muscle fiber is allowed to rest completely. E a second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
D
Hypertrophy means that there is a(n) ______________ in the size of the muscle fibers, and there is usually _________ muscle fibers. A decrease, an increased number of B increase, an increased number of C decrease, a decreased number of D increase, no change in the number of
D
Muscles exhibit the property of excitability. This means that the muscle A shortens its length. B recoils to its original resting length. C stretches beyond its normal length. D responds to stimulation by the nervous system. E excites itself.
D
Muscular dystrophy is characterized by A chronic muscle pain. B decreased size of muscle fibers. C spastic contractions of muscles. D replacement of muscle cells by connective tissue. E hypertrophy of muscle tissue.
D
The elevated oxygen consumption relative to activity level after exercise has ended is called A oxygen deficit. B oxygen debt. C oxygen repayment. D recovery oxygen consumption. E anaerobic recovery.
D
Troponin A has two subunits. B is part of the myosin myofilament. C is a long, flexible protein. D has a calcium-binding site. E binds to ATP
D
Which of the following changes have the potential to dramatically affect the potential difference across the plasma membrane? A increased permeability of the membrane to sodium ions B increased intracellular concentration of potassium ions C any change in the rate at which the sodium-potassium pump works D increased permeability of the membrane to sodium ions and increased intracellular concentration of potassium ions E increased permeability of the membrane to sodium ions, increased intracellular concentration of potassium ions and any change in the rate at which the sodium-potassium pump works
D
Which of the following is NOT a function of skeletal muscle? A body movement B maintenance of posture c respiration D constriction of organs E production of heat
D
Which of the following is NOT a known effect of illegal use of anabolic steroids in large dosages? A increased muscle size B kidney damage C diminished testosterone secretion D increased cardiovascular fitness E sterility
D
Which of the following is NOT an age related change in skeletal muscle? A loss of muscle strength B loss of synapse surface area C loss of fast-twitch fibers D decreased recovery time E decrease in motor units
D
Which of the following is mismatched? A I band - contains only actin B M line - middle of the H zone C Z disk - structure between adjacent sarcomeres D myosin myofilaments - thin myofilaments E actin myofilaments - thin myofilaments
D
(Refer to exam q) The diagram shows the banding pattern observed in part of a relaxed muscle fibril. Describe what causes the different bands seen in the muscle fibril. (2)
Darker band has both types of filament; Light band has only actin filaments
Phase 0 - Action Potential in Cardiac muscle cells
Depolarization - Na+ flows in and causes inside of the cell to become positive for short period of time
Cross bridges form between... A troponin and tropomyosin. B calcium and sodium. C the sarcolemma and the sarcoplasmic reticulum. D the T-tubules and the sarcolemma. E the actin filaments and the myosin heads.
E
Which of the following is NOT a function of the muscular system? A Maintenance of posture B Constriction of organs and vessels C Respiration D Production of body heat E Immune system support F Production of body heat
E
Unlike skeletal muscles, cardiac muscle has this feature: A) larger cisternae B) smaller T tubules C) several nuclei D) long, slender, unbranched cells E) calcium ions can come from ECF
E) calcium ions can come from ECF
Which of the following is the connective tissue layer that surrounds the internal surface of each chamber of the heart? A) pericardium B) myocardium C) endocardium D) epicardium
ENDOCARDIUM
Which of the following is the connective tissue layer that covers the external surface of the heart? A) pericardium B) myocardium C) endocardium D) epicardium
EPICARDIUM (D)
Z disk
Each light I band is bisected by a dark narrow WHAT which provides anchorage for the thin filaments and elastic filaments. (A protein disc to which thin filaments and elastic filaments are anchored at each end of a sarcomere; appears as a narrow dark line in the middle of the I band)
skeletal muscle structure
Each muscle is an organ composed of muscle cells (fibers), connective tissue, blood vessels, nerves
Endomysium
How are skeletal muscle cells electrically insulated from each other?
Fascicles are bundles of muscle fibers made up of all the following except ___________.
Epithelial Tissue
Which muscle group is composed of mainly slow-twitch (type I) fibers?
Erector spinae muscles of the back
capillary beds
Every muscle fiber is served by WHAT that surrounds muscle fibers. Extensive vascular network.
A muscle responds to a stimulus.
Excitability
Which of the following is the correct sequence of steps involved in a muscle contraction?
Excitation, Coupling, Contraction, and Relaxation
Exercise and Cardiac Output
Exercise makes the heart work harder and increases cardiac output • Proprioceptors signal cardiac center - At beginning of exercise, signals from joints and muscles reach the cardiac center of brain - Sympathetic output from cardiac center increases cardiac output • Increased muscular activity increases venous return - Increases preload and ultimately cardiac output • Increases in heart rate and stroke volume cause an increase in cardiac output • Exercise produces ventricular hypertrophy - Increased stroke volume allows heart to beat more slowly at rest - Athletes with increased cardiac reserve can tolerate more exertion than a sedentary person
A muscle can stretch beyond its normal resting length and still contract.
Extensibility
A complete muscle contraction is called a muscle twitch.
FALSE
A short rest period after a muscle fiber experiences fatigue will allow that muscle fiber to contract again equally as long as it did before the fatigue.
FALSE
An action potential introduced at the neuromuscular junction is propagated along the sarcoplasmic reticulum. True False
FALSE
Atrial contraction accounts for most of the ventricular filling. A) True B) False
FALSE
During contraction, the actin myofilaments shorten. T OR F
FALSE
In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm. True False
FALSE
It takes about twice as long for a muscle to contract as it does to relax.
FALSE
TRUE OR FALSE? in relaxed muscle the H zone is at its narrowest width?
FASLE
A complete muscle contraction is called a muscle twitch. True or False?
False
An action potential introduced at the neuromuscular junction is propagated along the sarcoplasmic reticulum. True False
False
An action potential introduced at the neuromuscular junction is propagated along the sarcoplasmic reticulum. (11)
False
Atrial contraction accounts for most of the ventricular filling? True or false
False
Bone building cells beneath the endosteum lay down bone to form ridges around a blood vessel.
False
In a relaxed muscle, the H zone is at its narrowest width.
False
In a relaxed muscle, the ends of the actin filaments overlap.
False
In a relaxed muscle, the ends of the actin filaments overlap. T/F
False
In fully contracted muscles, the actin filaments lie side-by-side.
False
In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm. (11)
False
Once a tunnel of bone is formed around a blood vessel, the bone building cells of the periosteum lay down bone in concentric circles that fill in the tunnel.
False
Re polarization of the cardiac muscle fiber is termed excitation
False
Receptors that bind the neurotransmitter at the postsynaptic cell membrane are voltage-gated. T/F
False
T/F? Acetylcholine is broken down into acetic acid and cholinesterase by choline.
False
T/F? In a contracting muscle the Z lines come closer together:
False
T/F? Receptors that bind the neurotransmitter at the post-synaptic cell membrane are voltage-gated.
False
The audible heart sounds are caused by the contraction of the atria and ventricles. True or false
False
The beginning of ventricular systole is when the blood flowing back toward the relaxed ventricles causes semilunar valves to close. True or false
False
The distance from one sarcomere to another is called the Z-line.
False
The voltage-gated potassium channels close before the membrane potential is brought back to its resting level.
False
True or False Anna Garcia was taking her blood pressure medication at the time of her death
False
True or False: Calcium couples the neural excitation to the contraction of the muscle by binding the tropomyosin which causes the troponin to move off the actin binding sites
False
True or false. An action potential in a cardiac muscle fiber is identical to an action potential in a skeletal muscle fiber
False
An action potential introduced at the neuromuscular junction is propagated along the sarcoplasmic reticulum (T/F)
False An action potential introduced at the neuromuscular junction is propagated along the SARCOLEMMA of the skeletal muscle
In a relaxed muscle, the H zone is at its narrowest width (T/F)
False H zone is at its WIDEST width when relaxed
A dark band formed by parallel thick filaments that partly overlap the thin filaments is known as an H band. (T/F)
False I Band?
In fully contracted muscles, the actin filaments lie side-by-side. (T/F)
False In RELAXED muscles, the actin filaments lie side-by-side
In a relaxed muscle, the ends of the actin filaments overlap. (T/F)
False In a FULLY CONTRACTED, the ends of the actin filaments overlap.
In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm (T/F)
False In response to an action potential entering the neuron, calcium ions diffuse from the SARCOPLASMIC RETICULUM into the sarcoplasm
The binding of ATP allows the muscle filaments to slide past one another (T/F)
False The binding of ADP + Phosphate
Receptors that bind the neurotransmitter at the post-synaptic cell membrane are voltage gated (T/F)
False Ligand-gated
A bundle of muscle fibers is known as a
Fascicle.
Order Largest to Smallest
Fascicle>Fibers>Myofibril>Sarcomere>Myofilament>F-actin>Tropomyosin>Troponin>Ca2+.
Perimysium covers
Fasciculi
How is the shape of the myosin molecule adapted to its role in muscle contraction? (4)
Fibrous protein long and thin; provides surface area for which actin can move along; Globular proteins form bulbous structures; Allows it to exactly fit the binding sites of the actin filament
During contraction, the actin myofilaments slide toward the...
H zone
Describe how the banding pattern will be different when the muscle fibril is contracted. (2)
H zone narrows; Light band narrows
What do H zones and I Bands contain?
H zones contain only myosin I bands contain only actin
What happens to the tension of a muscle during an isometeric twitch when you vary the frequency of APs?
Isometeric contraction, trying to lift something but can't. You contract but muscle does not shorten. Then you give up and relax. Sorta what we are seeing here. If you hit it with an AP, you get at twitch, hit it with another one get a twitch. If you hit it twice with 2 APs, you will see. The first part is exactly like the twitch you have seen, but when we hit it again it goes up higher. If we hit it with a bunch of forces then we see maximal contractability and it is Tetanized. Treppe-a rockier road going up, until you get tetanuization. At this point either fatigue sets in or we stop stimulating and and it goes back into relaxation.
How do we get the graph?
Isometric tension developed depends on the length of the muscle. If a muscle or muscle fiber was clamped between two fixed ends, stimulated electrically to contract and the resulting tension measure and this was repeated as the distance between the fixed clamps (note: affects muscle length) was progressively increased (i.e., the muscle is stretched) in small increments, then the relationship between muscle (sarcomere) length and isometric developed tension could be plotted.
During which complete phase of the cardiac cycle do both the atria and ventricles relax?
Isovolumetric - ventricles relax Immediately after the ventricular systole, the ventricles and atria are relaxed while all of the valves remain closed. Therefore, the volume of blood inside the ventricles remains the same.
During what phase of the cardiac cycle does aortic pressure reach its maximum?
Ventricular ejection
During which complete phase of the cardiac cycle do the atria both relax and contract?
Ventricular filling
(Refer to exam q) Figure 1 shows a diagram of part of a muscle myofibril. Name the protein present in the filaments labelled W and X. (1)
W: myosin X: actin
skeletal muscle
WHAT may be defined as voluntary striated muscle that is usually attached to one or more bones.
thin filaments
WHAT slide past the thick ones so that the actin and myosin filaments overlap to a greater degree. In the relaxed state, thin and thick filaments overlap only slightly. Upon stimulation, myosin heads bind to actin and sliding begins.
Neuromuscular Junction
What is the place called where a motor neuron stimulates a muscle cell?
What is a motor unit? Why are they important?
What percent you decide to use to get a graded response. Motor unit is a single alpha motor neuron and all the muscle fibers that it innervates. don't have to contract all, they can passively contract not due to a AP due to another motor unit contracting It is important bc a single tetanized muscle fiber only increases tension 3 fold due to APs. Using the motor unit, now the body has the ability to increase tension by a lot. Size can vary from very small to large ones size correlates with precision of control need for a particular muscle-smaller units are for fine, precise movements or adjustments like eyeball, large motor units are not very precise -gastronemius for example. works in an all or nothing fashion smaller motor units are activated first, as more tension is need to be generated then more motor units are added-motor units are progressively bigger and produce much more tension per motor unit than the initial ones activated
What is a neuromuscular junction? (1)
Where a motor neurone meets a skeletal muscle fibre
Small motor units
Writing a note, Playing a piano and Following words on a page with your eyes.
Are both sets of valves closed during any part of the cycle?
Yes, momentarily after atrial systole and ventricular systole
What are the borders of the sarcomere?
Z lines
troponin
a 3 unit protein. functions to bind to actin, binds to tropomyosin and bind to calcium
Isometric contraction
a contraction where the length of the muscle stays the same we generate tension, not shortening
In this lab, an electrical shock stimulates the muscle, which contracts and lifts the weight. The distance the weight is lifted is measured using:
a displacement transducer.
perimysium
a fasciculus is surrounded by what type of CT
What is a sarcomere?
a functional unit of skeletal muscle.
Elastic filaments contain titin which is?
a huge springy protein
I bands
a light band; from Z disks to ends of thick filaments
sarcoplasmic reticulum of skeletal muscle fibers
a modification of the smooth endoplasmic reticulum, surrounds myofilaments and forms a meshwork around each myofibril at the junction of A and I bands, it forms a pair of dilated terminal cisternae which pass around the myofibrils regulates muscle contraction by sequestering calcium ions (leading to relaxation) of releasing calcium ions (leading to contraction)
A motor unit is a motor neuron and all of the muscle fibers it stimulates. a motor neuron and one muscle fiber. all motor neurons in the body. all the muscle fibers in the body.
a motor neuron and all of the muscle fibers it stimulates.
unfused or incomplete tetanus
a muscle stimulated at high-frequency with some short relaxation time between, such that sustained but quivering contractions occur
fused or complete tetanus
a muscle that is stimulated so frequently that the relaxation phase is completely eliminated and smooth, sustained contraction results
actin
a protein in a m. fiber that forms filaments that slide between filaments of myosin, contracting m. fibers
Ectopic focus
a region of spontaneous firing other than the SA node - May govern heart rhythm if SA node is damaged
PVC on the EKG is
a relatively common event where the heart beat is initiated by Purkinje heartbeat initiator (pace maker) The ventricles contract first before the atria have optimally filled the ventricles with blood, which means the circulation is inefficient with low oxygen to the heart
lever
a rigid bar that moves on a fixed point
define pulse
a ryhthmetic pushing of the blood by the heart which can be measured by the movement of an artery
During twitch summation (aka temporal or wave summation)
a second stimulus arrives at the muscle before complete relaxation of the first contraction, causing the second contraction to have greater tension than the first one.
The strength of a muscle contraction is determined by the size of motor units being stimulated. the number of motor units being stimulated. the strength of the action potential. a&b are true.
a&b are true.
Which of the following is the correct sequence of events regarding the cardiac cycle?
Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling When the ventricles begin to contract, the volume of blood remains the same because the atrioventricular and semilunar valves are closed at the same time. This is isovolumetric contraction. Once the pressure opens the semilunar valves, blood is ejected. When the contraction ceases, the semilunar valves close and the atrioventricular remain closed, so the blood volume doesn't change. This is isovolumetric relaxation. At full relaxation, the atrioventricular valves open and blood passively travels from the atria to the ventricles. Finally, the atria contract and actively force the remaining atrial blood into the ventricles.
Which of the following best describes the role of Ca2+ in muscle contraction? -It binds to tropomyosin, moving troponin, so that myosin heads can bind to actin. -It binds to tropomyosin, moving troponin, so that actin heads can bind to myosin. -It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin. -It binds to troponin, moving tropomyosin, so that actin heads can bind to myosin. -It binds to actin, moving myosin, so that troponin can bind to tropomyosin.
It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
Which of the following best describes the role of calcium in muscle contraction?
It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
Electrolytes and HR
K (potassium) has greatest effect 1. Excess = lowered HR 2. Deficiency = requires more stimulation 3. Both are NEGATIVE chronotropic factors Calcium 1. Excess = decreased HR (negative factor) 2. Deficiency= raises HR (positive factor)
How are slow-twitch fibres adapted for their function? (4)
Large store of myoglobin to store large amounts of oxygen; Rich supply of blood vessels to deliver oxygen and glucose; Numerous mitochondria to produce ATP; So adapted for aerobic respiration to avoid a build-up of lactic acid
Acetylcholine receptors function as ___________.
Ligand-gated ion channels
Where is myosin's ATPase activity?
Located in myosin heads-globular part, by hydrolyzing ATP myosin can alter its conformation by pivoting around the hinge region of the molecule. So the energy supplied by the hydrolysis of the ATP causes a change in the 2 dimensional structure of the myosin molecule
Suggest a reason why there are numerous mitochondria in the sarcoplasm. (3)
Muscles require much energy from ATP for contractions; This energy from ATP is released during the Krebs cycle and ETC in respiration; Both of these processes take place in the mitochondria
During embryonic development multiple stem cells called ___________ fuse together to form each muscle fiber.
Myoblasts
The characteristic reddish brown color of skeletal muscle comes from which substance?
Myoglobin
The thick filaments of the sarcomere are made up mostly of the protein ____________.
Myosin
What is the site of ATP binding and hydrolysis? -Troponin -Tropomysin -Actin -Myosin
Myosin
contractile proteins
Myosin and actin are called WHAT because they do the work of shortening the muscle fibers. When myofibrils shorten, muscle shortens (contracts)
How is an action potential created across a neuromuscular junction? (6)
Nerve impulse received at neuromuscular junction; Synaptic vesicles fuse with presynaptic membrane; Release acetylcholine which diffuses to receptors on postsynaptic membrane; Alters its permeability to sodium ions; Sodium ions diffuse in and cause depolarisation; Acetylcholine broken down by acetylcholinesterase
Outline how a muscle relaxes. (3)
Nervous stimulation ceases; Calcium ions actively transported back into endoplasmic reticulum using energy from the hydrolysis of ATP; Absense of calcium ions allows tropomyosin to block binding sites on actin filaments again
Are both sets of valves open during any part of the cycle?
No
The myosin head is bound to __________ during the power stroke.
No Nucleotide
The myosin head is bound to ___________ when it is in the low energy conformation, and it is bound to the thin filament.
No Nucleotide
In the ventricles, the action potential travels along the interventricular septum to the apex of the heart, where it then spreads superiorly along the ventricle walls. A) True B) False
TRUE
Relaxation occurs when Ca2+ is transported back into the sarcoplasmic reticulum.
TRUE
The active transport of Ca2+ into the sarcoplasmic reticulum requires ATP.
TRUE
2nd degree Heart Block Type 2
P with no R, much more serious, purkinje dx - electrical impulses cannot reach the ventricles, pacemaker may be needed
The sequence of cross bridge formation and myofilament movement will be repeated as long as calcium ions are present. TRUE FALSE
TRUE
The sliding filament model explains how myofilaments slide past each other. T OR F
TRUE
The sliding of the myofilaments past each other cause the sarcomere to shorten. T OR F
TRUE
The ventricles begin to fill during ventricular diastole. A) True B) False
TRUE
When cross bridges form and the muscle fibers contract, the actin myofilament slides past the myosin myofilament. TRUE FALSE
TRUE
Calcium channels in the ______________ open and release calcium ions into the sarcoplasm.
Terminal Cisternae
The sac-like regions of the sarcoplasmic reticulum that contain calcium ions are called the Sarcolemma Triad Terminal cisternae Sarcoplasmic reticulum T tubules
Terminal cisternae
What is tatanus and how can it generate muscle fatigue? What is Treppe
Tetanus is a sustained maxium contracton of muscle fiber that results from stimulation of a muscle fiber at a high rate. If the frequency of stimulation incresaes, the more and more calcium accumulates within the cell. This permits contraction to continue without relaxation until the maximum number of cross bridges are formed. Tension remains at a plateau. Treppe-observed at high but some what lower rates of stimulation, a rise and small fall in tension may be observed which produces what looks like a staircase phenomenon. Max tension is mantained until the supply of ATP is impaired and the muscle then begins to fatigue. Muscle fatigue results in decrease in the strength of contraction, despite a high stimulation rate due to decrease in concentration of ATP. ATP supply depends on availability of substrates. Different types of muscle fibers vary in their susceptibility to fatigue.
pulse
Pulse: surge of pressure produced by heart beat that can be felt by palpating a superficial artery i. High in babies: 120bpm or more ii. Young adults: 64-80bpm, lower in males iii. Raises in the elderly
AV sends impulse to specialized muscle fibers called
Purkinje fibers
heart rate
Raised by positive chronotropic factors Lowered by negative chronotropic factors • Pulse - surge of pressure produced by heart beat that can be felt by palpating a superficial artery - Young adult females average 72 to 80 bpm - Young adult males average 64 to 72 bpm
Choline formed from the breakdown of acetylcholine in the synaptic cleft is
Reabsorbed by the presynaptic terminal membrane.
Ryanodyne
Receptor foundi n the sarcoplasmic reticulm that is activated by DHP, helps release Ca from Sarcoplasmic reticulum down it concentration gradient.
Which of the following is not true?
Red fibers have fewer mitochondria than white.
Elasticity
Refers to this tendency of a muscle cell to return to the original length when tension is released
Phase 3
Repolarization occurs (Phase 3) as K+ channels open thereby increasing the outward, hyperpolarizing K+ currents. At the same time, the L-type Ca+ channels become inactivated and close, which decreases gCa+ and the inward depolarizing Ca+ currents.
What is Titan?
Responsible for the resting tension. As you keep stretching the muscle, Titan want to resist that stretch. The primary thing for range of motion after ligament and bone problems is probably going to be do to Titan. The amount of expression of titan can cause pathologies. Largest protein attaches to Z line and goes out to H band.
Pacemaker Physiology
SA node does not have a stable resting membrane potential - Starts at −60 mV and drifts upward due to slow Na+ inflow - When it reaches threshold of −40 mV, voltage-gated fast Ca2+ and Na+ channels open • Faster depolarization occurs peaking at 0 mV - K+ channels then open and K+ leaves the cell • When SA node fires it sets off heartbeat - As the internal pacemaker, it typically fires every 0.8 seconds, setting the resting rate at 75 bpm
An action potential causes calcium ions to diffuse from the ____ into the ____
Sarcoplasmic reticulum; sarcoplasm
Which of the following statements about second-class levers is correct? Second-class levers work at a mechanical disadvantage. Second-class levers have a wide range of motion. Second-class levers have great strength but are slow and have little range of motion. Second-class levers are speed levers.
Second-class levers have great strength but are slow and have little range of motion.
Why does the structure of muscle allow it to perform its function of contraction efficiently? (1)
Separate muscle cells are fused into muscle fibres; so there are no points of weakness
Ca+ channel dependent
Sinus node (SA) and AV node with a slow conduction and fast automaticity
What is the type of muscle that is used consciously? (1)
Skeletal muscle
What is the Length-Tension Relationship in Muscle Isometerically? Describe it in a graph length vs tension.
Skeletal muscle->is ideally at the top of the curve. When completely extended it is at the descending part D, When in the curl it is in the Ascending part B. This is most important for the heart. It you fill it too much you will be on the descending part of curve, if you fill too little it will be on the ascending.. Tension developed depends on the length of the muscle. The more you stretch the muscle fiber and increase the length, the greater the tension until a certain point where there is no substantially tension bc the sacromere has been pushed too far.
Which of the following statements is INCORRECT? Skeletal muscles are responsible for the pumping action of the heart. Skeletal muscle contractions help maintain body temperature. Skeletal muscles form valves regulating the passage of substances through internal openings of the digestive and urinary tracts. Skeletal muscles support the weight of some internal organs. The contractions of skeletal muscles pull on tendons and move elements of the skeleton.
Skeletal muscles are responsible for the pumping action of the heart.
motor neurons
Skeletal muscles are served by nerve cels called WHAT, whose cell bodies are in the brainstem and spinal cord. Each nerve fiber branches out to a number of muscle fibers, but each muscle fiber is supplied by only one motor neuron. (Stimulate muscle fibers to contract; axons branch to innervate many fibers; neuromuscular junction)
During muscle contraction
The A band remains the same and the I band narrows.
During muscle contraction:
The A band remains the same and the I band narrows.
Which of the following is true during ventricular systole?
The AV valves are closed. At the beginning of ventricular systole, the one-way AV valves are forced shut. The AV valves remain shut throughout ventricular systole. This prevents blood from flowing back into the atria when the ventricles contract.
What about H zones and I bands is TRUE:
The H zones contain only myosin, while the I bands contain only actin.
Which of the following statements about H zones and I bands is TRUE?
The H zones contain only myosin, while the I bands contain only actin.
calcium ions
The SR is a reservoir of WHAT; it has gated channels in its membrane that open at the right times to release a flood of calcium ions into the cytosol, where the calcium activates the muscle contraction process. The T tubule signals the SR when to release the calcium bursts.
terminal cisternae
The SR periodically exhibits dilated end-sacs called WHAT, which cross the muscle fiber from side to the other.
What happens at the NM Junciton when the AP arrives at the axon terminal?
The VOLTAGE change of the membrane OPENS VOLTAGE-GATED CALCIUM CHANNELS, allowing Calcium ions to enter the axon terminal.
Cross bridges are formed between
The actin filaments and myosin heads
Describe the Sliding Filament Theory
The length of muscle determines the relationship between the thick and thin filaments. The amount of overlap determines the number of potential cross bridges that may be formed A short L, there is overlap of thin filament into the region of the thick filament with no myosin head or cross bridges. As the length is increased towards Lo more and more possible cross bridges may be formed , when Lo is exceed then there will be mysoin heads in the center of the sarcomere that can't bind to actin sites and the number of potential cross bridges are reduced.
Look at your graph showing muscle shortening against weight. With the trend in mind, predict the amount of isotonic contraction with the weight of 300 grams.
The muscle would not shortening, because the isometric contraction could not overcome such a heavy weight.
A bands
Striated muscle has dark WHAT? A dark band; full length of thick (myosin) filament. Each A band consists of thick filaments lying side by side. Part of the A band, where thick and thin filaments overlap, is especially dark. In this region, each thick filament is surrounded by thin filaments. (Dark band formed by parallel thick filaments that partly overlap the thin filaments)
Cardiac Myocytes
Striated myofibril bundles that have the intrinsic ability to "beat" or contract on their own without stimulation
Why does the unstretched muscle produces a relatively weak contraction? The overlapping thin filaments from opposite ends of the sarcomere, interfere and conflict with each other. This restricts productive cross bridge building and less tension develops. The thin filaments are pulled almost to the ends of the thick filaments where little tension can be developed. There is an optimum overlap of thin and thick filaments so that all cross bridges can participate in the contraction.
The overlapping thin filaments from opposite ends of the sarcomere, interfere and conflict with each other. This restricts productive cross bridge building and less tension develops.
sarcolemma
The plasma membrane of a muscle fiber is called the WHAT? Cell membrane that surrounds the sarcoplasm (cytoplasm). Contains many organelles, abundance of myoglobin, filled with intracellular fluid, storage of glycogen, forms openings which dip down into the cell.
transverse tubules
The sarcolemma has tubular infoldings called WHAT, which penetrate through the cell and emerge on the other side. Each T tubule is closely associated with two terminal cisternae, running alongside it on each side. (Narrow tubes extend into the sarcoplasm. Filled with extracellular fluid. Close contact with the SR)
Since muscle fibers are composed of a series of sarcomeres laid down next to one another, then what happens to the length of the sarcomeres when muscle fibers are stretched?
The sarcomeres get longer.
M line
The thick filaments originate at a dark WHAT in the middle of the H band. Protein to which myosins attach. Origin of the thick filaments.
Why does the overstretched muscle produces a little muscle tone? The overlapping thin filaments from opposite ends of the sarcomere, interfere and conflict with each other. This restricts productive cross bridge building and less tension develops. The thin filaments are pulled almost to the ends of the thick filaments where little tension can be developed. There is an optimum overlap of thin and thick filaments so that all cross bridges can participate in the contraction.
The thin filaments are pulled almost to the ends of the thick filaments where little tension can be developed.
When the atria contract, which of the following is true?
The ventricles are in diastole. Atrial contraction fills each of the ventricles to their maximum capacity−the end diastolic volume (EDV). This occurs towards the end of ventricular diastole while the ventricles are still relaxed.
Click on the "Work amp * wt" button in the Journal to display a graph of your data. Look at your graph and determine the relationship between work and weight.
The work done by the contraction increased to a maximum value and then decreased.
Why does the moderatly stretched muscle produces maximal tension and contraction? The overlapping thin filaments from opposite ends of the sarcomere, interfere and conflict with each other. This restricts productive cross bridge building and less tension develops. The thin filaments are pulled almost to the ends of the thick filaments where little tension can be developed. There is an optimum overlap of thin and thick filaments so that all cross bridges can participate in the contraction.
There is an optimum overlap of thin and thick filaments so that all cross bridges can participate in the contraction.
contracts
These connective tissues (endomysium, perimysium, epimysium) are continuous with the collagen fibers of tendons. Thus, when a muscle fiber WHAT, it pulls on these collagen fibers and usually moves a bone.
Duchenne's Muscular Dystrophy
This is a common (one male in 3500), sex-linked recessive trait. One third of cases are new mutations, and no population group is without these people. The fundamental lesion is a lack of dystrophin, an inner-sarcolemmal cytoskeletal component homologous to spectrin and actin, which appears to strengthen muscle cells and keep them from popping when overworked (Nature 349: 69 & 243, 1991; Proc. Nat. Acad. Sci. 90: 3710, 1993). The gene's on Xp21. Although the children appear normal at birth, the muscle is already abnormal, and the problem becomes obvious in early childhood. These boys have symmetric weakness, and must resort to unusual methods to stand up ("Gower's sign"). Fatty growth produces the characteristic "pseudohypertrophy of the calves". Boys become wheelchair-bound by their early teens
Myotonic Dystrophy
This is an autosomal dominant (* chromosome 19: q13.2-13.3, cloned: Science 255: 1253 & 1256, 1992; protein is "myotonin" Science 260: 235, 1993), variably expressed because of other genes, affecting several systems. In some communities, it is as common as Duchenne's. Patients have: weakness, starting in the facial muscles (tiny chins and temples, etc.), eventually atrophy of most muscle groups grip myotonia, with difficulty letting go of keys, handshakes, etc. percussion myotonia (muscles tighten when you rub then) frontal baldness and testicular atrophy (men) a distinctive face ("carp mouth") heart disease early dementia (sometimes) cataracts cardiomyopathy
The first event in muscle fiber contraction is that -the muscle fiber membrane is stimulated and a muscle impulse travels deep into the fiber through transverse tubules. -acetylcholine diffuses across a gap at a neuromuscular junction. -acetylcholine is released from the end of the motor neuron. -calcium ions diffuse from sarcoplasmic reticulum into the sarcoplasm and bind to troponin molecules. -morphine is released from the end of the motor neuron.
acetylcholine is released from the end of the motor neuron
When acetylcholine is released into the synaptic cleft, it causes calcium ions enter the axon terminal. causes an action potential to propagate along the sarcolemma and down the T Tubules. causes synaptic vesicles to fuse to the membrane of axon terminal, allowing release of acetylcholine. causes an action potential to be initiated on the sarcolemma. causes calcium ions to be released from the terminal cisternae. acetylcholine to bind to receptor sites on the motor end plate.
acetylcholine to bind to receptor sites on the motor end plate.
after nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?
acetylcholinesterase destroying the ACh
End-diastolic volume (EDV)
achieved in each ventricle (about 130 mL of blood)
Myofibrils are composed primarily of
actin and myosin.
Muscle contraction is caused by
actin filaments sliding past myosin filaments
Muscle contraction is caused by?
actin filaments sliding past myosin filaments
Muscle contraction is caused by
actin filaments sliding past myosin filaments.
Cross-bridges form between the __________ and the __________. (11)
actin filaments; myosin head
Cross-bridges form between the __________ and the __________. troponin; tropomyosin calcium; sodium sarcolemma ; sarcoplasmic reticulum T tubules; sarcolemma actin filaments; myosin heads
actin filaments; myosin heads
The active sites to which cross-bridges attach are found on the sarcoplasmic reticulum. actin myofilaments. Z disks. T tubules. myosin myofilaments.
actin myofilaments.
During the contraction phase of a muscle twitch, acetylcholine stimulates the pre-synaptic terminal. sodium ions diffuse into the muscle fiber. actin-myosin cross-bridges form. calcium ions are transported back to the sarcoplasmic reticulum. the action potential travels down the T tubule.
actin-myosin cross-bridges form.
What is the third step of muscle contraction?
action potential travels down t-tubules, which are adjacent to terminal cisternae; causes the release of Ca from cisternae; Ca then binds to troponin, causing shape change and because troponin is attached to tropomyosin, the shape change causes displacement of trypomyosin, revealing binding sites on the actin
Dihydropyridine receptor
activated via AP that travels down T tubes
Muscles contract _______
actively
Short-term intense movements
activities best suited for fast-glycolytic fibers
sprinting/ walking
activities best suited for fast-oxidative fibers
endurance type activities
activities best suited for slow-oxidative fibers
muscle name that describes action
adductor longus
Where does 95% of the energy needed for contraction come from during moderate exercise? anaerobic glycolysis lactic acid aerobic respiration creatine phosphate
aerobic respiration
Chronotropic
affecting the rate or timing of a physiologic process, as the heart rate.
Stroke Volume
affects CO (cardiac output) 1. Preload- - the amount of tension in ventricular myocardium immediately before it begins to contract 2. Contractility- refers to how hard the myocardium contracts for a given preload 3. Afterload - sum of all forces opposing ejection of blood from ventricle
Physical activity
affects heart rate
The muscle that causes an action is the
agonist
the muscles that perform most of the action in producing the movement
agonists
Which of the following is/are true of temporal summation? Temoral summation occurs when a second stimulus of the same intensity is applied to a muscle before the completion of the relaxation period of the first stimulus. In temporal summation, the second peak is higher than the first because the additional influx of calcium ion promotes a second contraction, which is added to the first contraction. If you wait until relaxation is complete from the first stimulus, then give a second stimulus to the same muscle, temporal summation will not occur. Temporal summation results in increased muscle tension. all are true
all are true
The bond between the action and myosin head is broken when
an ATP molecule binds to the myosin head
The bond between the actin and myosin head is broken when
an ATP molecule binds to the myosin head.
The bond between the actin and myosin head is broken when...
an ATP molecule binds to the myosin head.
A stimulus either causes an action potential or it doesn't. This is called
an all-or-none response.
A stimulus either causes an action potential or it doesn't. This is called an all-or-none response. a graded response. a latent period response. a relative refractory response. arbitrary response.
an all-or-none response.
According to the sliding filament theory for skeletal muscle contraction, a shortening of the sarcomere is produced by:
an increase in the amount of overlap between the thick and thin filaments.
Graded response
an intermediate response not all or none ability to lift something smoothly regardless of weight.
may control ulnar abduction during forearm pronation
anconeous
The _______________ assists the triceps brachii in forearm extension. brachialis pronator teres palmaris longus anconeus
anconeus
Smooth muscle and cardiac muscle are similar in that they both are under involuntary control. are striated. are widely distributed in the body. have multiple nuclei. are under voluntary control.
are under involuntary control.
H band
area in the center of the A band containing only thick filament
I band
area of sarcomere containing only thin filaments
A band
area of the sarcomere with overlapping thick and thin filaments
most of the redirection will occur in the ________
arterioles
A motor unit is a motor neuron and all the muscle cells it innervates. So when lifting a heavy weight...
as the muscle works harder to lift the weight more motor units are recruited
What do asynchronous alternate firing and relaxation of different motor units cause vs simultaneous firing ?
asynchronous alternate firing and relaxation of different motor units which result in a smooth contraction. Simultaneous firing tends to produce jerky motion
Muscle tone is maintained by synchronous stimulation of predetermined motor units. asynchronous stimulation of random motor units. stimulation of random motor units by large action potentials. stimulation of random motor units by small action potentials.
asynchronous stimulation of random motor units.
The force of contraction is greatest for a muscle fiber...
at 100% of its relaxed length.
Bones in the legs, arms, spine and pelvis grow
at different rates.
What event within the heart causes the AV valves to open
atrial pressure > ventricular pressure
T wave
atrial/ventricular muscle repolarization - positive deflection for ventricles, atrial repolarization is obscured by the QRS complex and it is so small it cannot be seen
3rd degree Heart Block
atrium and ventricles beating independently of each other, dissociation of P waves or no normal relationship b/w P and QRS waves
stabilizing joints
attaching to bones and keeping them in close proximity to one another
heart rate equation
beats/minutes
pivot
bending your elbow
effort
biceps brachil
flexes forearm at elbow joint; supinates forearm
biceps brachil
flexes and laterally rotates leg at knee
biceps femoris
Which valve is heard most clearly when the apical heartbeat is auscultated
bicuspid valve
troponin
binds Ca2+ and starts the contraction cycle
deep fascia
binds muscles to other muscles
how do skeletal and muscular systems work together for their role in body support and movement?
blah blah blah
BP across the cardiac cycle
blood flow in arteries is pulsatile - Speed surges from 40 cm/s to 120 cm/s - Blood spurts intermittently from an open artery • In capillaries and veins, blood flows at steady speed - Bleeding from veins tends to be slow and steady • BP tends to rise with age - Arteriosclerosis - Atherosclerosis
In the intact frog, muscles are held close to their resting length so that maximum tension can be achieved. Excessive shortening and lengthening of the muscle is prevented by:
bones and joints.
Atherosclerosis
build up of lipid deposits that become plaques
An electrical impulse travels into the interior of a muscle fiber:
by way of the transverse tubules.
What happens at the terminal cisternae when the action potential reaches it? Acetyl choline is released into the synaptic cleft. Action potential propagates along the sarcolemma and down the T Tubules. Synaptic vesicles fuse to membrane of axon terminal. Action potential is initiated on the sarcolemma. Calcium ions are released from the terminal cisternae. Acetylcholine binds to receptor sites on the motor end plate. Calcium ions enter the axon terminal.
calcium ions are released from the terminal cisternae.
(Refer to exam q) The diagram shows the stages in one cycle that results in movement of an actin filament in a muscle sarcomere. Describe how stimulation of a muscle by a nerve impulse starts the cycle shown in the diagram. (3)
calcium ions interact with the tropomyosin molecule; to reveal binding sites on actin; allowing myosin heads to bind to exposed sites on actin filament
Using your knowledge of muscle contraction, explain the difference in the results between B and C. (2)
calcium ions remove tropomyosin; to allow binding of myosin heads and actin, increasing ATPase activity
An action potential arriving at the pre-synaptic terminal causes...
calcium ions to diffuse into the cell
Muscle contractions are initiated by binding of ...
calcium ions to troponin
Muscle contractions are initiated by the binding of __________ to __________.
calcium ions, troponin
Which one of the following binds calcium ions in a smooth muscle, causing contraction? troponin tropomyosin myosin actin calmodulin
calmodulin
"systole" and "diastole"
can refer to contraction and relaxation of either type of chamber, they usually refer to the action of the ventricles
Cross-channel swimmers may suffer from muscle fatigue during which the contraction mechanism is disrupted. One factor thought to contribute to muscle fatigue is a decrease in the availability of calcium ions within muscle fibres. Explain how a decrease in the availability of calcium ions could disrupt the contraction mechanism in muscles. (3)
cannot move tropomyosin; from binding sites on actin; myosin heads do not bind
Nanotubes are made of
carbon atoms linked to each other to resemble collagen
BP determined by
cardiac output, blood volume, and resistance to flow - Blood volume regulated mainly by kidneys
Pressure point on the side of the neck
carotid
The binding of acetylcholine allows sodium gates to open, changing the inside of the cell to positive, which causes calcium ions enter the axon terminal. causes an action potential to propagate along the sarcolemma and down the T Tubules. causes synaptic vesicles to fuse to the membrane of axon terminal, allowing release of acetylcholine. causes an action potential to be initiated on the sarcolemma. causes calcium ions to be released from the terminal cisternae. acetylcholine to bind to receptor sites on the motor end plate.
causes an action potential to be initiated on the sarcolemma.
When enough positive ions enter the cell to bring the cell to threashold, this causes calcium ions enter the axon terminal. causes an action potential to propagate along the sarcolemma and down the T Tubules. causes synaptic vesicles to fuse to the membrane of axon terminal, allowing release of acetylcholine. causes an action potential to be initiated on the sarcolemma. causes calcium ions to be released from the terminal cisternae. acetylcholine to bind to receptor sites on the motor end plate.
causes an action potential to propagate along the sarcolemma and down the T Tubules.
repolarization
change in sarcolemma after the wave of depolarization; Na+ channels close and K+ channels open, allowing K+ to create a positive charge outside the membrane
myosin
changes shape during the contraction cycle
triads
characteristic feature of skeletal muscle, located at the A-I junction in mammalian tissue, each consists of narrow transverse tubule (T-tubule) between two terminal cisternae of sarcoplasmic reticulum
A muscle that is inserted on the mandible is probably involved in ____________. frowning chewing wrinkling the forehead kissing blowing
chewing
Hypotension
chronic low resting BP - Caused by blood loss, dehydration, anemia
Hypotension
chronic low resting BP Caused by blood loss, dehydration, anemia
The anterior end of an earthworm is moved forward when: (p. 2)
circular muscles contract and longitudinal muscles relax.
Diastole
complete relaxation of the ventricles
A muscle fiber exposed to a series of stimuli of increasing frequency combines individual twitches (summation) which results in
complete sustained contraction.
A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called
complete tetanus
A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called complete tetanus. incomplete tetanus. involuntary paralysis. all or none tetanus. treppe.
complete tetanus.
troponin
complex consisting of three subunits: TnC-binds calcium ions TnT-binds tropomyosin TnL-prevents the interaction between actin and myosin along with tropomysin involved in calcium regulation of contraction in striated muscle
thick myofilaments
composed of many myosin molecules arranged together to form a rod-like structure, measure 12 to 13 nm in diameter, 1.5 um in length, each myosin molecule appears similar to a double-headed golf club, with two globular projections, or heads, that possess a specific ATP-binding site, ATP hydrolysis occurs at the heads, also the location of the actin-binding site remain constant in length as the sarcomere shortens
T tubules provide nutrients to the muscle fiber. generate new muscle fibers. conduct action potentials deep into the muscle cell. release acetylcholine. store calcium ions.
conduct action potentials deep into the muscle cell.
the chief function of the T tubules is to
conduct the signal for contraction deeper into the muscle cell
Therefore, layers of _______ ________ enclose and separate all parts of a skeletal muscle
connective tissue
What does titin connect?
connects thick filament to Z structure
myofibrils
consists of longitudinally arranged cylindrical bundles of thick and thin myofilaments, lie parallel to the long axis of cell and extend for its entire length, display crossbanding characteristic of striated muscle, held in alignment by intermediate filaments composed of the proteins desmin and vimentin, individually surrounded by the sarcoplasmic reticulum
thin myofilaments
consists primarily of F actin, formed by polymerization of G (globular) actin monomers, 5 nm in diameter, 1.0 um in length, each actin filament consists of two such strands in the form of a double helix, troponins distributed along the thin filaments at 40-nm intervals, linear tropomyosin molecule lies within the groove of the actin double helix thin (actin) filaments and thick (myosin) filaments overlap for some distance within the A band
A proper definition of muscle tone is
constant tension produced by muscles for long periods of time.
A proper definition of muscle tone is constant tension produced by muscles for long periods of time. a feeling of well-being following exercise. the ability of a muscle to maintain a contraction against an outside force. muscles contracting together. warm-up of muscle tissue.
constant tension produced by muscles for long periods of time.
Actin myofilaments resemble bundles of minute golf clubs. contain both myosin and tropomyosin. are held in place by the M line. contain strands of fibrous actin. are the thickest proteins in muscle.
contain strands of fibrous actin.
sarcoma of neuromuscular junction
contains receptors for acetylcholine
axon terminal
contains vesicles filled with acetylcholine
Lack of acetylcholinesterase in the synaptic cleft would result in
continuous stimulation of the postsynaptic membrane.
Lack of acetylcholinesterase in the synaptic cleft would result in continuous stimulation of the postsynaptic membrane. decreased stimulation of the muscle. more acetylcholinesterase production. rapid degradation of acetylcholine.
continuous stimulation of the postsynaptic membrane.
Slow oxidative muscle fibers
contract slower but very hard to fatigue smaller axons bind to the muscle fibers but they are slower
myofibrils
contractile fibers within m. cells
All of the following terms refer to the ability to receive and respond to a stimulus, EXCEPT ___________. irritability contractility responsiveness excitability
contractility
when an external tension moves a load, this is called the ______ phase.
contraction
What is the fifth step of muscle contraction?
contraction is terminated when Ca is pumped back into sarcoplasmic reticulum
isotonic contraction
contraction of muscle during which the muscle changes length and the tension remains constant through most of the contractile period
isometric contraction
contraction of muscle during which the tension continues to increase but the muscle neither shortens nor lengthens
eccentric contraction
contraction of muscle in which the muscle contracts as it lengthens
concentric contraction
contraction of the muscle in which the muscle shortens and does work
Troponin pulls tropomyosin away from the binding sites on the actin filament. Myosin heads bind and sliding of filaments takes place using up ATP
contraction or sliding filament phase
isotonic contraction
contraction with a change in length, but not in tension
A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in
contraction with no relaxation.
Muscle Twitch
contraction/relaxation of muscle fiber in response to a single action potential (stimulus)
Cardiac muscle contracts the heart. moves the skeletal system. controls the automatic movements in our bodies.
contracts the heart.
ACE inhibitor are used for
controlling high blood pressure treating heart failure preventing strokes and kidney damage in people with hypertension/diabetes
Smooth muscle contracts the heart. moves the skeletal system. controls the automatic movements in our bodies.
controls the automatic movements in our bodies.
Conduction system
coordinates heartbeat. stimulates contraction and relaxation of atria and ventricles throughout cardiac cycle. composed of internal pacemaker and nerve like conduction pathways through myocardium.
The muscle that adducts and flexes the arm is the
coracobrachialis.
The relationship between ATP and creatine phosphate is that
creatine phosphate supplies energy to regenerate ATP from ADP and phosphate.
sarcoplasm
cytoplasm of skeletal muscle fiber
calmodulin
cytoplasmic, calcium-binding protein
If maximum tension indicates that the thick and thin filaments are set at optimal overlap to produce a maximum number of crossbridges, further stretching of the muscle will:
decrease the amount of thick and thin filament overlap.
Since the tension produced by a contracting muscle fiber depends upon the number of crossbridges between the thick and thin filaments, stretching the muscle beyond 28 mm:
decreases the amount of overlap and decreases the amount of tension produced by a single contraction
T-tubule
deep invagination of the sarcolemma (plasma membrane) into the muscle cell, rapidly conduct impulses from the exterior of the fiber to deeper regions, where they trigger release of calcium from the terminal cisternae, release of calcium into the myofibrils facilitates contraction
One of the key age related diseases facing the baby boomers generation is:
degeneration of bone integrity
a first degree block is caused by
delay of the action potential between the SA and AV nodes
cardiac cycle purpose
deliver adequate blood flow to pulmonary and systemic circulatory systems
The major abductor muscle of the upper arm is the ___________. coracobrachialis subscapularis supraspinatus teres major deltoid
deltoid
Which of the following is NOT a rotator cuff muscle? subscapularis infraspinatus deltoid teres minor
deltoid
abducts arm; anterior part flexes and rotates arm medially
deltoid
muscle name that describes shape
deltoid
the part of the neuron that normally receives stimuli is called what?
dendrite
fascia
dense CT that separates an ind skeletal muscle from adjacent muscles
Phase 0
depolarization is primarily caused by increased Ca+ through the L-type Ca+ channels that began to open toward the end of Phase 4. The "funny" currents, and Ca+ currents through the T-type Ca++ channels, decline during this phase as their respective channels close. Because the movement of Ca+ through these channels into the cell is not rapid, the rate of depolarization (slope of Phase 0) is much slower than found in other cardiac cells
end plate potential
depolarization occurring only at neuromuscular junction
Acetylcholine binds to a membrane bound receptor and causes ligand-gated (that means CHEMICALLY GATED)sodium channels to open and results in depolarization. hyperpolarization. repolarization.
depolarization.
Isovolumetric contraction
depolarizing ventricles (QRS complex) and begin to contract, AV valves close, no ejection of blood yet
depresses lower lip
depressor labil inferioris
EKG are used to
diagnose heart abnormalities such as irregular heartbeat irregular speed of contractions, angina (chest pain that can indicate tissue damage or even tissue death( (myocardial infarction, also known as a heart attack)
When are the semilunar valves closed?
diastole of heart as a whole and during atria systole
What can influence Blood pressure
diet weight age genetics stress smoking alcohol physical activity drugs/medications
Pulse pressure
difference between systolic and diastolic pressure Mean arterial pressure (MAP) - the mean pressure one would obtain by taking measurements at several intervals throughout the cardiac cycle - Diastolic pressure + (one-third of pulse pressure) - Average blood pressure that most influences risk level for edema, fainting (syncope), atherosclerosis, kidney failure, and aneurysm
load
distal end of forearm, hand
Each cycle requires hydrolysis of one molecule of ATP and moves one actin filament 40nm. During contraction of a muscle sarcomere, a single actin filament moves 0.6μm. Calculate how many molecules of ATP are required to produce this movement. (2)
distance single actin filament moves divided by distance moved using 1 ATP; 15 ATP
Pressure point on the dorsum of the foot
dorsalis pedis
What is the second step of muscle contraction?
due to the occurrences in the first step, action potential is triggered across the entire skeletal muscle membrane (sarcolema)
QT wave
duration of ventricular depolarization and repolarization
When are the AV valves open?
during atrial systole and ventricular diastole
Ventricular filling
during diastole, ventricles expand and pressure drops, AV valves open, blood flows into ventricles
When are the semi lunar valves closed
during the period of relaxation of the heart as a whole during atrial contraction
When are the semilunar valves open?
during ventricular systole
myofibril
each m. fiber is composed of ____
active contraction of a muscle occurring simultaneously with lengthening of the muscle
eccentric contraction
second-class lever
effort applied at one end of the lever; the fulcrum located at the other; load between them
third-class lever
effort applied between the load and the fulcrum
first-class lever
effort is applied at one end of the lever; the load at the other; fulcrum somewhere in between
sarcoplasmic reticulum (smooth ER)
elaborate smooth endoplasmic reticulum tubules that run longitudinally a log the myofibrils and surround each myofibril
Which of the following allows recoil of the muscle fiber when contraction ends? actin elastic filaments myosin troponin tropomyosin
elastic filaments
fulcrum
elbow joint
__________ ___________ directs and choreographs the rhythmic beating of your heart
electrical energy
what is the heart beat caused by?
electrical impulses that control SA node
Purkinje fibers conduct
electrical signal to apex of heart and induce ventricles to contract at the same time to pump blood to out aorta to body and out pulmonary artery to the lungs
Which of the following is equivalent to the ventricular volume during isovolumetric relaxation?
end systolic volume (ESV). Isovolumetric relaxation occurs at the beginning of ventricular diastole when the ventricular volume is at its minimum value−the end systolic volume (ESV). Because no volume changes occur during isovolumetric relaxation, ventricular volume remains at this value throughout the phase.
Each muscle fiber within a fascicle lies within a layer of connective tissue in the form of a thin covering called _______.
endomysium
Vertebrates are known to display which one of the following types of skeletons? (p. 1)
endoskeleton
terminal cisternae
enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules, discrete regions within the muscle cell, stores calcium (increasing the capacity of the sarcoplasmic reticulum to release calcium) and releases when an action potential courses down the transverse tubules-->elicit muscle contraction
acetylcholinesterase
enzyme release into neuromuscular junction to break down acetlycholine
An entire skeletal muscle is surrounded by ___________. epimysium perimysium endomysium. sarcolemma tendon sheath
epimysium
The dense layer of collagen fibers that surround an entire skeletal muscle is the ___________. fascicle tendon perimysium epimysium endomysium
epimysium
Which of the following connective tissue layers is outside all the others? perimysium endomysium epimysium paramysium sarcolemma
epimysium
the dense layer of collagen fibers that surround an entire skeletal muscle is the what?
epimysium
strain
excessive strain and possible tearing of a muscle caused by muscle overuse or abuse
muscle potential causes Ca2+ gates to open on the sarcoplasmic reticulum, Ca2+ flows out and binds troponin
excitation-contraction coupling phase
perimysium
extends inward from epimysium and sep. m. into sm. sections. surrounds bundles of 10 - 100 ind. m. fibers. Sep. each muscle into fascles.
Damage to which of the following muscles would aid inspiration? sacrospinalis rectus abdominis platysma quadratus lumborum external intercostals
external intercostals
The muscular wall of the abdomen is composed of ____________. glossal muscles spinal erector muscles muscles of mastication digastric muscles external oblique and rectus muscles
external oblique and rectus muscles
a baseball player was hit on the left side of his head in the temporomandibular area. He cannot close his eyes and the corner of the mouth droops. Which cranial nerve was damaged?
facial
negative chronotropic agents
factors that lower the heart rate
positive chronotropic agents
factors that raise the heart rate
A complete muscle contraction is called a muscle twitch.
false
A muscle that assists the muscle primarily responsible for a given action is called an agonist.
false
A short rest period after a muscle fiber experiences fatigue will allow that muscle fiber to contract again equally as long as it did before the fatigue.
false
Acetylcholine is actively transported from the pre-synaptic membrane to the post-synaptic membrane.
false
An example of a second-class lever is when you lift your head off your chest after a nap.
false
Calcium ion is released from the transverse tubule. True or False
false
During contraction, the actin myofilaments shorten.
false
If you bruised your gluteus maximus, you would expect to experience discomfort when flexing your leg.
false
In a relaxed muscle, the H zone is at its narrowest width.
false
In a relaxed muscle, the ends of the actin filaments overlap.
false
In fully contracted muscles, the actin filaments lie side-by-side.
false
Some muscles are named for the type of metabolism they generally use.
false
The anterior interventricular artery and the circumflex artery are the main branches of the right coronary artery. A) True B) False
false
The atria never need to contract due to passive ventricular filling. A) True B) False
false
The beginning of ventricular systole is when blood flowing back toward the relaxed ventricles causes the semilunar valves to close. A) True B) False
false
The degree of relative movement is greater in the pelvic girdle than in the pectoral girdle.
false
The end of a muscle that usually remains stationary when the muscle contracts is called the insertion.
false
The muscular arrangement that is the most advantageous when lifting a heavy load is parallel.
false
The pectoralis major originates on the scapula.
false
The pulmonary valve has string-like chordae tendineae and papillary muscles that prevent the valve cusps from prolapsing during right ventricular contraction. A) True B) False
false
The sternothyroid muscle originates on the hyoid bone.
false
The trapezius muscle is named for its location.
false
True or False Atrial contraction accounts for most of the ventricular filling.
false
True or False The atria never need to contract due to passive ventricular filling.
false
True or False The beginning of ventricular systole is when blood flowing back toward the relaxed ventricles causes the semilunar valves to close.
false
cross bridge attachment to actin requires K+
false
cross bridges are formed by the actin molecules
false
in the initial stages of repolarization, the ionic conditions are restored, returning the membrane to its resting potential
false
muscles that exert very fine control (such as the muscles controlling movements of the fingers and eyes) have large motor units
false
one of the functions of the smooth muscle tissue is to force blood from the heart into the major arteries
false
subthreshold stimuli result in only a small amount of muscle response movement
false
the space between he neuron and the muscle is the axon terminal
false
the type of muscle fiber that is most resistant to fatigue is the fast fiber
false
thick filaments consist mainly of the protein actin
false
Atrial contraction accounts for most of the ventricular filling.
false Most ventricular filling happens passively while the atrioventricular valves remain open in between ventricular contractions. Atrial contraction plays a small role in ventricular filling.
The atria never contract due to passive ventricular filling.
false The atria contract and are responsible for the active filling that takes place just before the ventricular contraction.
The beginning of ventricular systole is when blood flowing back toward the relaxed ventricles causes the semilunar valves to close.
false Ventricular systole begins when the ventricles begin to contract.
In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm. True or False
false Ca2+ diffuse from the sarcoplasmic reticulum into the sarcolasm
pennate
fascicles are short and attach obliquely to a central tendon that runs the length of the muscle; do NOT shorten as much but are more powerful
type of muscle fiber that responds quickly but also fatigues quickly
fast twitch fiber
tachycardia
faster than 100 beats per minute
Which of the following statements about smooth muscle is true? Nuclei are peripherally located in the fibers. Fibers are small and spindle-shaped. It has branching fibers. Smooth muscle is striated and involuntary. Contractions are rapid and forceful.
fibers are small and spindle-shaped
everts foot; plantar flexes foot
fibularis (peroneus) longus and brevis
which type of lever is demonstrated by using scissors?
first-class lever
flexes wrist and abducts hand
flexar carpi ulnaris
example third-class lever
flexing the forearm with the biceps brachil
Which of the following adducts the fingers and wrist? extensor digitorum extensor carpi radialis longus flexor carpi ulnaris flexor carpi radialis
flexor carpi ulnaris
flexes the four fingers and wrist
flexor digitorium superficialis
flexes fingers and assists in flexing wrist
flexor digitorum profundus
periaxial space
fluid-filled cavity that exists between the connective tissue capsule and intrafusal fibers
Reduced blood pressure makes it easier
for the heart to pump blood`
One ATP molecule is required for
formation of the cross-bridge, for movement of the cross-bridge, and for release of the cross-bridge.
Where is a sarcomere found?
from z line to z line
sarcomere
functional unit of a skeletal muscle fiber
plantar flexes foot; flex leg at knee
gastrocnemius
What happens to H zone during sarcomere contraction?
gets shorter
What happens to I band during sarcomere contraction?
gets shorter
Actin
globular actin naturally polymerizes into fibers in the presence of Mg and ATP the functional unit of the think filament is composed of two strand of F-actin that forms a double stranded alpha helix-looks like DNA but uses actin molecules instead of nucleotides bases.
"Cross bridges" that link between the thick and thin filaments are formed by the ___________. tails of myosin filaments globular head of thick filaments globular actin F actin
globular head of thick filaments
extends and laterally rotates thigh; extends hip against resistance
gluteous maximus
muscle name that describes size
gluteus maximus
A gluteal gait, in which a person walks with a waddling limp, is usually caused by a disorder of the
gluteus medius and gluteus minimus.
an anaerobic metabolic pathway that results in the product of two net ATP's per glucose plus two pyretic acid molecules is what?
glycolysis
Pacemaker Potential
gradual depolarization, SA node resting potential start at -60mV and then drifts spontaneously upwards
electrocardiogram
graph that monitors and records electrical activity abbreviated as EKG and ECG
antagonists
groups of muscles that produce oppositely directed movements
A current research alternative to knee replacement involves
growing new bone that is both fibrous and strong.
convergent
has a broad origin; single tendon of insertion
Troponin has two subunits. is part of the myosin myofilament. is a long, flexible protein. has a calcium-binding site. binds to ATP.
has a calcium-binding site.
During the ventricular ejection phase of the cardiac cycle, which of the following is true?
he semilunar valves are open.. During ventricular ejection, blood flows from the ventricles into the arteries. To do so, the blood must pass through the semilunar valves, which must be open during this phase. Narrowing of the left semilunar valve reduces blood flow out of the heart, a disease condition known as aortic stenosis.
circulatory system
heart, blood vessels, blood, some include lymphatic system
bradycardia
heartbeat slower than 60 beats per minute
Hypertension
high blood pressure - Chronic resting BP > 140/90 - Consequences • Can weaken arteries, cause aneurysms, promote atherosclerosis
Hypertension
high blood pressure Chronic resting BP > 140/90 Consequences: Can weaken arteries, cause aneurysms, promote atherosclerosis
In Anna's cardiac workup Anna had
high blood pressure her values averaged 142/85
Tetanus of a muscle is thought to be caused by
high calcium ion concentrations in the sarcoplasm.
creatine phosphate
high-energy compound in muscle
Contractility
how hard the myocardium contracts for a given preload • Positive inotropic agents increase contractility • Negative inotropic agents reduce contractility
The prime mover for flexion of the thigh is the __________ muscle. sartorius iliopsoas quadratus lumborum psoas minor
iliopsoas
Paralysis of which of the following would make an individual unable to flex the thigh?
iliopsoas and rectus femoris
Z
in a contracting muscle, the ___ lines come closer tog.
Which of the following statements is true concerning calcium ions?
in smooth muscle it binds with calmodulin.
relaxed
in this state, actin and myosin myofilaments lie side by side and the H zones and I band are at a max. width.
where is blood pressure taken
in upper arm on level with the heart over an artery in joint
AV node (atrioventrical node) is located
in wall between right atrium and right ventricle
Curare blocks acetylcholine receptors at the motor end plate. This would result in inability of the muscle fiber to respond to nervous stimulation. increased stimulation of the muscle. more acetylcholinesterase production. sustained contraction of the muscle.
inability of the muscle fiber to respond to nervous stimulation.
Initially, you applied a shock to the shortened muscle and measured the tension. You then stretched the muscle and repeated the experiment. After repeating the amount of tension:
increase as the muscle was stretched to about 28 mm
Positive inotropic agents
increase contractility
Sympathetic nerves
increase heart rate and contraction strength - Sympathetic pathway to heart originates in the lower cervical to upper thoracic segments of the spinal cord
The sequence for smooth muscle contraction is...
increased cytosolic calcium, which binds to calmodulin in cytosol, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to actin filaments, resulting in contraction.
The sequence for smooth muscle contraction is...
increased cytosolic calcium, which binds to calmodulin in cytosol, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross bridges, which bind to actin filaments, resulting in contraction.
What are spatial or temporal wave summations?
increasing the number of stimuli delivered to a given motor unit per time. Results in increased Ca concentration which then causes more tension/shortening. Activation of more cross bridges per period of time will generate more tension per time.
skeletal/cardiac muscle contraction
initiated by the binding of Ca2+ to the TnC unit of troponin, exposes the myosin binding site on actin (cross-hatched area), myosin head binds to actin, ATP breaks down into ADP-->energy, produces movement of the myosin head-->bound thin filaments slide over the thick filaments, process repeats many times during a single contraction, leads to a complete overlapping of the actin and myosin and a resultant shortening of the whole muscle fiber
number of muscle cells per motor neuron
innervation ratio
The attachment site of the muscle tendon to the more-movable bone is called the ___________. proximal end distal end origin belly insertion
insertion
Where would you expect to find numerous gap junctions in muscular tissue?
intercalated discs of cardiac muscle
the force generated during this time is called ______ tension
internal
low blood volume could indicate
internal bleeding
smooth muscle
involuntary, automatic nerves, hormones, local chemicals
The electrical properties of cells are the result of ion concentration differences across the plasma membrane. receptor sites that are present on the plasma membrane. phosphorylation reactions within the cytoplasm. phospholipids in the cell membrane
ion concentration differences across the plasma membrane.
toxins from disease could indicate
irregular beat
stress can cause
irregular heart rate
Sinoatrial node
is a pace maker that sets timing and rhythm of heart beat Brain signals it to send electrical impulses to both atria of heart to contract in unison
Treppe
is achieved during warm-up exercises. is an example of a graded response. may be due to an increase in the level of calcium ions around the myofibril. can contribute to improved muscle efficiency.
In the neuromuscular junction, acetylcholine:
is actively transported across the synaptic cleft and binds to acetylcholine receptors on the postsynaptic muscle fiber.
Treppe can contribute to improved muscle efficiency. may be due to an increase in the level of calcium ions around the myofibril. is an example of a graded response. is achieved during warm-up exercises. is all of the above.
is all of the above.
A fasciculus is a bundle of reticular fibers. is surrounded by perimysium. is only found in smooth muscle. possesses an external lamina. is a bundle of collagen fibers.
is surrounded by perimysium.
incomplete tetanus
is the condition in which the muscle fiber only partially relaxes between contractions.
the refractory period
is the time during which the tissue cannot respond again.
Cardiac muscle is under involuntary control. is under voluntary control.
is under involuntary control.
Smooth muscle is under involuntary control. is under voluntary control.
is under involuntary control.
Skeletal muscle is under involuntary control. is under voluntary control.
is under voluntary control.
The type of muscle contraction in which the muscle fibers produce increased tension, but the muscle neither shortens nor lengthens, is called _____________. treppe isotonic isometric concentric tetany
isometric
muscle is under tension (contracting but no noticeable movement is noted)
isometric contraction
muscle shortens during contraction
isotonic contraction
Phases of the Cardiac Cycle stages
isovolumetric contraction ventricular ejection isovolumetric relaxation
The steps of the cardiac cycle in sequence are...
isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.
How does the presence of the GLUT-4 carrier protein in the sarcolemma affect muscle metabolism
it increases muscle metabolism by allowing the cellular uptake of glucose for ATP production
What happens to the I band during muscle relaxation?
it lengthens
What happens to the sarcomere during muscle relaxation?
it lengthens
What happens to the I band during muscle contraction?
it shortens
What happens to the sarcomere during muscle contraction?
it shortens
What happens to the H band during muscle contraction?
it shortens and disappears
What happens to the A band during muscle contraction?
it stays the same
What happens to the A band during muscle relaxation?
it stays the same
Increasing the weight increased the latency period because:
it takes time to build up tension in the muscle and tendon to overcome the weight.
The deltoid is a muscle named according to ___________. its shape the direction of its fibers its location the number of its origins
its shape
fascicles
join tog. to form a muscle. a group of skeletal m. fibers is _
The chordae tendineae
keep the AV valves from everting during ventricular systole
Anna had a pace maker implanted to
keep the heart rhythmn constant. This is necessary because the SA node is not functioning properly
Functions of titin/ elastic filaments?
keep thick and thin filaments aligned with each other, resist over stretching, helps with elasticity
Which of the following substances increases in quantity during repetitive muscle contraction during oxygen deficit? adenosine triphosphate (ATP) glucose lactic acid oxygen creatine phosphate
lactic acid
during vigorous exercise, there may be insufficient oxygen available to completely break down pyretic acid for energy. As a result, the pyruvic aced is converted to what?
lactic acid
myosin
large molecular protein complex composed of two identical heavy chains and two pairs of light chains, heavy chains are enzymatically cleaved to form two fragments, light and heavy meromyosin, light meromyosin makes up most of the rod-like portion of the molecule, whereas heavy meromyosin represents the globular head and a small part of the rod, cross bridges seen between the thick and thin filaments are formed by the heads of the myosin molecules plus a small part of its rod-like portion has enzymatic activity and ability to bind to actin to produce shortening of the sarcomere and myofibril ATPase required for contraction is localized in the myosin heads or crossbridges
How many proteins does the thick filament have once made
largest subunit-heavy chain-so myosin is the heavy chain, ELC and RLC are the light chains, the total complex is considered a hexamere-6 proteins, or 2 trimers These hexameric myosin complex then further assemble into a much larger thick filament the thick filament is a bi polar structure growing out form a core
The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase. contraction relaxation latent or lag refractory threshold
latent or lag
the short delay between the stimulus and the onset of the twitch is called the?
latent period
In a recording of a muscle twitch, the delay between the time a stimulus is applied and the time the muscle responds is called the
latent period.
protracts mandible and moves side to side
lateral pterygoid
extends, abducts, and rotates arm medially
latissimus dorsi
Systemic Circuit
left side of the heart, carries blood to body (all tissues), carries oxygen RICH blood.
The force of contraction is lowest for a muscle fiber...
less than 100% of its relaxed length., greater than 100% of its relaxed length.
elevates, abducts, retracts, and steadies the scapula; flexes neck to the same side when the scapula is fixed
levator scapulae
I band
light area of a sarcomere. only actin
2nd degree Heart Block Type 1
long PR, longer PR, then P and no R complex, AV node dx - electrical impulses are delayed more and more until a beat is skipped/dropped
diastolic pressure
low pressure on artery wall when ventricles relax between contractions
dehydration could indicate
low water concentration in your blood
The monosyllables describing the heart sounds are
lub - dup
Which of the following muscles of the face is NOT innervated by the facial nerve? zygomaticus orbicularis oculi masseter mentalis
masseter
smooth muscle contraction
may be initiated by nerve impulses, stretching within the muscle itself or via hormones vascular smooth muscle contraction usually initiated by nerve impulse, there is little spread of conduction from cell to cell visceral smooth muscle contraction is myogenic (stretch) and signal spreads from cell to cell via gap junctions in uterus, during terminal stages of pregnancy, smooth muscle cells contract in response to oxytocin elsewhere in body smooth muscle cells responsive only to epinephrine smooth muscle cells lack troponin but require calcium for their contractile activity, calcium activate enzyme which phosphorylates light chain of myosin allowing myosin to bind to actin and hydrolyze ATP
Fibers of muscles whose motor neurons are severed
may be replaced by fat or fibrous connective tissue.
when one-third of the pulse pressure is added to the diastolic pressure a good estimate of the ___________ is obtained
mean arterial pressure
elevates mandible and moves side to side
medial pterygoid
diastolic pressure
minimum arterial BP taken during ventricular relaxation (diastole) between heart beats
Threshold stimulus is the
minimum strength of stimulation required to contract a muscle fiber
blood pressure in measured in
mm of mercury (Hg) the measurement of force/pressure that supports a column of mercury that many mm high
What category below do snails best fit into?
mollusks
What event results in dicrotic notch
momentary increase in aortic pressure that occurs when the semi lunar valves snap shut
during exercise the skeletal muscles receive ______ blood flow
more
The outside of the resting plasma membrane is __________ relative to the inside of the resting plasma membrane. more postively charged. more negatively charged. neutral. recharged.
more postively charged.
Depolarization occurs because
more sodium ions diffuse into the cell than potassium ions diffuse out of it.
The chemicals then bind to receptors located on the _____ ______ ______, a specialized area of the sarcolemma.
motor end plate
At a neuromuscular junction, the muscle fiber membrane folds, forming a
motor end plate.
At this junction, the ________ _______ releases a type of chemical called a ________.
motor neuron; neurotransmitter
A motor neuron and all the muscle fibers it supplies is called a(n) ____________. axon terminal motor unit motor end plate synaptic cleft neuromuscular junction
motor unit
Each somatic motor neuron, together with all of the muscle fibers it innervates, is called a ____________.
motor unit
a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axon terminal
motor unit
What is the main function of skeletal muscles? energy consumption pumping of blood through the body movement destruction of foreign chemicals
movement
Acetylcholine is the neurotransmitter at neuromuscular junctions. Describe how the release of acetylcholine into a neuromuscular junction causes the cell membrane of a muscle fibre to depolarise. (3)
movement of acetylcholine by diffusion; binding to receptors on post-synaptic membrane; causing sodium channels to open
Skeletal muscle contracts the heart. moves the skeletal system. controls the automatic movements in our bodies.
moves the skeletal system.
Which of the following actions is caused by contraction of skeletal muscle? contraction of the heart moving your feet in walking movement of food through the G.I. tract emptying of the urinary bladder vasoconstriction
moving your feet in walking
ball and socket joint
moving your leg at the hip
What is a sarcomere contraction?
muscle cells shorten becasue their individual sarcomeres shorten
sarcomeres
muscle fibers (myofibrils) are collections of these. p. 287
A weightlifter uses muscles so the muscles exert more than 75% of their maximum tension, This stimulates
muscle fibers developing new filaments of actin and myosin.
flexors
muscles that bend a limb at a joint
extensors
muscles that straighten a limb
Which of the following is thought to be an autoimmune disease of acetylcholine receptors? fibromyalgia myotonic dystrophy muscular dysthrophy myasthenia gravis
myasthenia gravis
Which one of the following is most accurately referred to as an autoimmune disease? (p. 17)
myasthenia gravis
A sarcomere is part of a(n) ___________. perimysium myofibril myofilament endomysium
myofibril
Figure 2 shows the cut ends of the protein filaments when the myofibril was cut at position Y. Figure 3 shows the protein filaments when the myofibril was cut at the same distance from a Z line at a different stage of contraction. Explain why the pattern of protein filaments differs in Figure 2 and Figure 3. (2)
myofibril is contracting in Figure 3 and relaxing in Figure 2; figure 3 shows movement of actin fibres between myosin fibres
Arrange the following structures from smallest to largest. (p. 5)
myofibril, muscle fiber, muscle bundle, muscle
one of the slender threads of a muscle fiber, composed of numerous myofilaments; composed of repeating units of sarcomeres
myofibrils
During muscle contraction ATP supplies energy for
myofilament movement.
In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and _________. myosin thin filaments troponin actin tropomyosin
myosin
a fibrous protein that attaches to actin through head like structures; it is the contractile filament of muscle cells
myosin
In order for muscle contraction to occur, cross-bridges form between:
myosin and actin.
Which of the following is not a part of the relaxation phase of a muscle twitch? muscle to return to its original length cross bridge cycling decreases and end calcium ions are actively transported back into the terminal cisternae myosin cross bridge cycling causes sarcomeres to shorten
myosin cross bridge cycling causes sarcomeres to shorten
As actin and myosin filaments slide past each other during muscle contraction:
myosin filaments shorten, while actin filaments do not.
During muscle contractions, cross-bridges form between
myosin heads and actin filaments
What is the fourth step of muscle contraction?
myosin heads bind to the binding sites exposed by the displacement of trypmyosin and pull actin toward the midline, shortening the sarcomere
ATPase is found in F-actin strands. G-actin globular units. myosin heads. tropomyosin grooves. troponin molecules.
myosin heads.
During muscle contractions, cross-bridges form between the _________ and the __________.
myosin heads; actin filaments
Which of the following is mismatched? I band - contains only actin M line - middle of the H zone Z disk - structure between adjacent sarcomeres myosin myofilaments - thin myofilaments actin myofilaments - thin myofilaments
myosin myofilaments - thin myofilaments
I band
narrows during muscle contraction
As actin and myosin filaments slide past each other during muscle contraction,
neither actin nor myosin filaments shorten.
Which of the following happens as actin and myosin filaments slide past each other during muscle contraction?
neither action or myosin shorten
Purkinje fibers
nervelike processes that arise from the lower end of the bundle branches and turn upward to spread through the ventricular myocardium. Purkinje fibers distribute the electrical excitation to the cardiocytes of ventricles. they form a more elaborate network in the left ventricle than in the right.
Each skeletal muscle fiber is controlled by a neuron at a single ___________. synaptic cleft transverse tubule sarcomere synaptic knob neuromuscular junction
neuromuscular junction
The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called neuromuscular junctions. sarcomeres. myofilaments. Z disks.
neuromuscular junctions.
acetylcholine
neurotransmitter at the neuromuscular junction
acetylcholine
neurotransmitter released into the neuromuscular junction
What part of the muscle does the chemical, released by the nerve, act on?
nicotinic protein channel receptor
After death, cross bridges between actin and myosin remain firmly bound resulting in rigor mortis. Using information in the diagram, explain what causes the cross bridges to remain firmly bound. (2)
no ATP produced; ATP required for separation of actin and myosin
Isovolumetric contraction of ventricles
occurs after the ventricles depolarize. The AV valves close as ventricular blood surges back against the cusps. Ventricles do not yet eject blood and there is no change in their volume even though they are contracting
A sarcomere extends from one Z disk to an adjacent Z disk. one T tubule to the next T tubule. the middle of the I band to the middle of the A band. the H zone to the I band. M line to the next M line.
one Z disk to an adjacent Z disk.
sphincter muscles of the eyelids; permits squinting and blinking
orbicularis oculi
Bone producing cells are...
osteoblasts
The combination of all of the concentric rings of bone built around a single blood vessel is called a(n)...
osteon.
electrical conditions of a resting sarcolemma
outside positive relative to the inside
tropomyosin
overs thin filament-binding areas
myoglobin
oxygen storage molecules in skeletal muscle
What is the downside to knee replacement surgery?
pain and discomfort in bending the joint across the skin
sinoatrial (SA) node
patch of modified cardiocytes in the right atrium, just under epicardium near the base of the superior vena cava. This is the pacemaker that initiates each heartbeat and determines the heart rate
AV bundle or bundle of His
pathway by which signals leave the AV node. Bundle forks into right and left bundle branches, which enter the interventricular septum and descent toward the apex
Systolic pressure
peak arterial BP taken during ventricular contraction (ventricular systole)
flexes and abducts thigh
pectineus
The extensor digitorum muscle is an example of a ____________ muscle. fusiform muscle convergent circular pennate
pennate
Another layer of connective tissue, called the _______, extends inward from the epimysium and separates the muscle tissue into small sections. These sections contain bundles of skeletal muscle fibers called _______.
perimysium; fascicles
The latency period is the time:
period between stimulation and the shortening of the skeletal muscle.
The alternating contraction and relaxation of opposing layers of smooth muscle is referred to as ___________. isotonic contraction peristalsis automatic contraction isometric contraction
peristalsis
bradycardia
persistent resting adult heart rate below 60 bpm. common in endurance trained athletes, in rest/sleep. endurance training enlarges the heart and increases stroke volume, enabling it to maintain same output with fewer beats
tachycardia
persisting resting adult heart rate above 100 bpm causes: stress, anxiety, stimulants, heart disease, fever heart rate rises to compensate for drop in stroke volume; heart races when body loses significant quantity of blood/when there's damage to myocardium
What is the role of phosphocreatine in the muscle cell?
phosphocreatine rapidly creates ATP by phosphorylating ADP in the cell
Repolarization occurs because
potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
myofilaments
precisely arranged in the myofibril, for the crossbanding in the sarcomere I band contains only thin filaments, which anchor at the dense Z line, A band consists of both thick and thin filaments (making this band birefringment, or anisotropic), ratio of thin to thick is 6 to 1, M line is formed by cross connections at the midpoints of the thick filaments, H band consists of thick filaments only
Which of the following statements describe histological characteristics of skeletal muscle? presence of visible striations & single, centrally-located nuclei presence of visible striations & multiple peripheral nuclei absence of visible striations & single, centrally-located nuclei number of nuclei
presence of visible striations & multiple peripheral nuclei
Which of the following statements describe histological characteristics of cardiac muscle? presence of visible striations & single, centrally-located nuclei presence of visible striations & multiple peripheral nuclei absence of visible striations & single, centrally-located nuclei number of nuclei
presence of visible striations & single, centrally-located nuclei
What can high blood pressure cause
pressure can cause damage to blood vessels which bleed and clot vessels damaged areas are more likely to accumulate plaque a substance which contains cholesterol
Blood pressure
pressure exerted by blood against the walls of blood vessels
hydrostatic pressure
pressure exerted on the wall of the of the "pipe" or "hose" as fluids move through them
Pulse
pressure surges in an artery occurring during each contraction and relaxation of the left ventricle
Describe the thick filament
primarily composed of the protein mysoin. Contains a tail region and globular head-looks like a golf club connected together by a hinge. Mammalian mysoin dimerizes through inter twining of their tails.
Athletes usually experience muscle fatigue less quickly than nonathletes because they
produce less lactic acid.
P wave
produced from signal from SA node (depolarizing atria) - SA node fires, atria depolarize and contract - Atrial systole begins 100 ms after SA signal
lactic acid
product of anaerobic glycolysis
depolarization and generation of action potential
production of an end plate potential at the motor end plate and consequent depolarization of adjacent areas
pronates forearm and hand
pronator quadratus
pronates forearm and is a flexor of the elbow
pronator teres
action potential
propagation of an electrical current along the sarcolemma
Sliding Filament Hypothesis (of Huxley)
proposes that during muscle contraction, filaments themselves do not change in length but slide past one another to increase the amount of overlap between them, sliding action results from repeated "make and break" attachments between the heads of the myosin molecules and neighboring actin filaments-->length of the sarcomere shortened in contraction, thin filaments slide to penetrate more deeply into the A band, A band remains constant in length, I band and H band both decreases in size, Z lines drawn closer to the ends of the A bands
tropomyosin
protein that blocks m. contraction until Ca++ is present
troponin
protein that functions with tropomyosin to block m. contraction until Ca++ is present
producing movement
pulling on something to change its position
subtracting the SBP from the DBP results in _________ which is directly proportional to the overall strength of one's pulse
pulse pressure
All of the following muscles are innervated by the sciatic nerve, EXCEPT the ___________. biceps femoris quadratus femoris semitendinosus semimembranosus
quadratus femoris
rotates thigh laterally; stabilizes hip joint
quatratus femoris
Fast oxidative/glycolytic
quick contracting, a little resistant to fatigue but fatigue in bigger motor neuron coming to it
Pressure point of the wrist
radial
fast-oxidative
rapid, long term action
fast-glycolytic
rapid, short term action
Elasticity refers to the ability of a muscle fiber to ___________. recoil and resume its resting length after being stretched shorten forcibly when adequately stimulated receive and respond to a stimulus be stretched
recoil and resume its resting place after being stretched
As you are lifting a box someone places extra weight on top of it. For your muscle to continue contracting and lifting the box, the muscle must
recruit more muscle fibers
Muscles with fibers that run parallel an imaginary line such as the long axis of the body are called ____________. lateralis rectus transversus medialis obliques
rectus
During abdominal surgery, the surgeon makes a cut through the muscle directly to the right of the linea alba. The muscle that is being cut is the ___________. splenius diaphragm scalenes digastric rectus abdominis
rectus abdominis
Which muscle flexes and rotates the lumbar region of the vertebral column? transversus abdominis internal oblique external oblique rectus scaliness
rectus abdominis
extends leg at knee and flexes thigh at hip
rectus femoris
blood flow is _____ to meet metabolic needs
redirected
Hypercalcemia
reduces heart rate - high Ca+
Which of the following would contribute to muscular fatigue in the muscle fiber? the emotional state of an individual relative depletion of ATP reserves inability of the motor neuron to produce sufficient quantities of acetylcholine depletion of neurotransmitter blocked receptors in the postsynaptic membrane
relative depletion of ATP reserves
generation of heat
release of energy during metabolism
Ca2+
released by terminal cisterna into the sarcoplasm to bind with troponin
A person continues breathing heavily for some time after exercising in order to repay an oxygen "debt". This oxygen debt allows for which of the following to occur:
replenish oxygen stored in the myoglobin of the muscle cell
The refractory period in which the muscle will NOT contract if stimulated occurs during __________ of the muscle cell. repolarization polarization depolarization hyperpolarization
repolarization
arrhythmia
resting heart that beats slower than 60 beats per minute or faster than 100 beats per minute is this
repolarization
restoration of membrane potential to resting potential
Phase 3
restoring of the potential by Na+ (moving out), K+ (moving in) and Ca+ (moving out). Pumps ATP driven.
Multiple wave summation
results in complete and incomplete tetanus.
stabalizes, retracts, and rotates the scapula
rhomboids (major and minor)
What triggers action potentials in cardiac muscle?
rhythmic depolarizations due to pacemaker channels in the plasma membrane
Pulmonary Circuit
right side of the heart, carries blood to lungs for gas exchange, carries oxygen POOR blood.
myofibril
rodlike contractile elements within a muscle fiber containing microfilaments
For animals of an equal body weight, which one of the following types of movements has the highest energy cost? (p. 15)
running
Where is Titin found?
runs through core of each thick filament
The discoloration and swelling of a muscle strain is due to
ruptured blood vessels
the cell membrane of skeletal muscle is called the
sarcolemma
the membrane covering a striated muscle fiber
sarcolemma
T tubules are invaginations of the sarcoplasmic reticulum. sarcomere. myofibril. sarcoplasm. sarcolemma.
sarcolemma.
The distance from one Z disk to the next Z disk is called a(n)
sarcomere
The distance from one Z disk to the next Z disk is called a(n)...
sarcomere
The functional unit of contraction in a skeletal muscle fiber is the ____________. sarcoplasmic reticulum sarcolemma sarcomere myofibril myofilament
sarcomere
The region of the myofibril between two Z lines that is the contractile unit of a muscle cell is called a I band H zone A band sarcomere Z line
sarcomere
the contractile unit of a myofibril; repeating units, delimited by the z bands
sarcomere
the functional unit of a skeletal muscle fiber is the
sarcomere
The striated appearance of skeletal muscle fibers results from the
sarcomere organization.
calsequestrin
sarcoplasmic protein, binds calcium in absence of excitation and contraction, located in dilated terminal cisternae of sarcoplasmic reticulum, this assures proximity of calcium to transverse tubules which carry excitation wave deep in muscle cell
Calcium for muscle contraction is stored in the
sarcoplasmic reticulum
a system of membrane-bound tubules that surrounds muscle fibrils, releasing calcium ions during contraction
sarcoplasmic reticulum
the series of membraneous channels that surround each myofibril is what?
sarcoplasmic reticulum
An action potential causes calcium ions to diffuse from the ________ into the ________.
sarcoplasmic reticulum ------ sarcoplasm
An action potential causes calcium ions to diffuse from the ________ into the ________.
sarcoplasmic reticulum ; sarcoplasm
An action potential causes calcium ions to diffuse from the ________ into the ________.
sarcoplasmic reticulum; sarcoplasm
An action potential causes calcium ions to diffuse from the ________ into the ________. sarcoplasmic reticulum; sarcolemma sarcoplasmic reticulum; sarcoplasm sarcoplasm; sarcoplasmic reticulum sarcoplasm; sarcolemma sarcolemma; sarcoplasm
sarcoplasmic reticulum; sarcoplasm
An electrical impulse traveling along the sarcolemma and into transverse tubules causes calcium ions to diffuse from the ________ into the ________.
sarcoplasmic reticulum; sarcoplasm
The obturator nerve supplies all of the following muscles, EXCEPT the ____________. adductor brevis sartorius adductor magnus gracilis
sartorius
flexes, abducts, and laterally rotates thigh
sartorius
muscles on the side of the neck located deep to platysma and sternocleidomastoid
scalenus
Diastasis
second one-third; slower filling
The second heart sound is a result of the closure of the
semi lunar valves
composite muscle located along the back from thoracic region to head
semispinalis capitis, cervicis, and thoracis
muscle spindle (neuromuscular spindle)
sensory organ in skeletal muscle that functions as stretch receptor, participate in nervous control of body posture and coordinate action of opposing muscles, receives large afferent sensory nerve fiber with several types of nerve endings: annulospiral endings (wind around intrafusal fibers), flower spray endings (terminates in clusters), y-efferents, or fusimotor endings (form motor endplates near the poles of the spindle) appears as elongated fusiform encapsulated structure that contains several modified striated muscle fibers (intrafusal fibers) and associated nerve endings two types of intrafusal fibers: nuclear bag fibers with cluster of nuclei in nonstriated region that produce slight expansion in area thin nuclear chain fibers most common, nuclei arranged in a row
the term aponeurosis refers to what?
sheetlike indirect attachment to a skeletal element
proprioceptors
signal cardiac center (beginning of exercise, signals from joints and muscles reach the cardiac center of brain) sympathetic output from cardiac center increases cardiac output
Which of the following describes the mucus used by the RoboSnail?
silicon and clay
smooth muscle cells
single, fusiform, uninucleate; no striations
skeletal muscle fibers
single, very long, cylindrical, multinucleate cells with striations
In the heart, an action potential originates in the __________.
sinoatrial node The normal heartbeat is triggered by autorhythmic cells in the right atrium called the sinoatrial node.
The sequence of travel by an action potential through the heart is...
sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers.
In the heart, an action potential originates in the...
sinoatrial node.
Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the
size of muscle fibers
muscle cell regeneration
skeletal muscle has population of undifferentiated cells (satellite cells)-->have the ability to replace some cells lost by trauma and injury cardiac muscle cannot regenerate, when injured cells die and are replaced by scar tissue pericytes are stem cells of smooth muscle and are capable of regenerating small blood vessels that consist of smooth muscle, bladder and intestines are also capable of undergoing regeneration of smooth muscle
What happens to thin filaments during sarcomere contraction?
slide over thick filaments, and slide closer together
actin
slides toward the M line during contraction
Parasympathetic nerves
slow heart rate - Pathway begins with nuclei of the vagus nerves in the medulla oblongata - Extend to cardiac plexus and continue to the heart by way of the cardiac nerves
type of muscle fiber that have fatigue resistance and high oxidative/aerobic capacity
slow twitch fiber
Pacemaker cells - SA node - depolarizing current is carried by what currents?
slow, inward Ca++ currents. Unlike most other cells, there are no fast Na+ currents operating in SA nodal cells
First degree Heart Block
slowing conduction in AV node, PR interval is longer
Which type of muscle does not have a transverse tubule system or a well-developed sarcoplasmic reticulum?
smooth muscle
purkinje fibers
specialized conducting cells of atrioventricular bundle, very large modified muscle cells filled with glycogen and contain many mitochondria, contain few myofibrils which are located peripherally, make contact with cardiac muscle cells through gap junctions, desmosomes and fasciae adherentes (not through typical intercalated disks)
motor nerve ending
specialized region on the skeletal muscle fiber (cell) where a motor nerve terminates, as axon approaches muscle cell it loses its myelin sheath, Schwann cell continues to cover the nonsynaptic surface of the nerve terminal, nerve terminal lies in indentation (primary synaptic cleft) of the skeletal muscle fiber, additional invaginations of the sarcoplemma lining the primary synaptic cleft form junctional folds (secondary synaptic clefts)
AV node delays
spreading the electrical impulses for 0.1 secs to ensure the atria are completely empty
example second-class lever
standing on tip-toe
flexes and laterally rotates the head
sternocleidomastoid
Arteriosclerosis
stiffening of arteries due to deterioration of elastic tissues of artery walls
Regina began an exercise program six months ago, and the muscles of her upper limbs and lower limbs are more prominent. Exercise can lead to formation of new muscle by
stimulating skeletal muscle cells to release IL-6, which stimulates satellite cells to divide, producing more muscle cells.
The sarcoplasmic reticulum
stores calcium ions.
The sarcoplasmic reticulum stores calcium ions. shortens during muscle contraction. transmits nerve impulses to the myofibrils. connects adjacent sarcomeres. covers the muscle fiber.
stores calcium ions.
cardiac muscle
striated, involuntary, found in the heart
skeletal muscle
striated, voluntary, and attached to the skeleton
Smooth muscles lack ______ and contain less _________
striations; myosin
a fusion of twitch contractions; the second and subsequent contractions occur before the preceding one can relax
summation
Order of blood flow through heart
superior/inferior vena cavas - to right atrium - through tricuspid (atrioventricular) valve - to right ventricle - through pulmonary valve - to pulmonary arteries - to the lungs. Then it returns through pulmonary vein - to the L atrium - through the mitral (bicuspid) valve - to the L ventricle - through the aortic valve - into the aorta and rest of the body
Creatine phosphate
supplies energy for the synthesis of ATP.
perimysium
surrounds each muscle bundle (fascicle)
endomysium
surrounds each muscle fiber
Endomysium is a delicate network of loose connective tissue that surrounds each muscle fiber. forms a sheath around a fasciculus. is composed of elastic fibers. separates individual muscles. penetrates muscle fibers.
surrounds each muscle fiber.
epimysium
surrounds entire muscle
cramp
sustained spasm, or tetanic contraction
Which of the following is not considered a weight bearing activity?
swimming
The site where the neuron communicates with the muscle fiber is called a ________.
synapse
a muscle that assists the muscle that is primarily responsible for a given action is a(n)
synergist
the highest pressure exerted on the arterial walls during the heart cycle is referred to as
systolic blood pressure
normal blood pressure
systolic less than 120 and diastolic less than 80
pulse pressure
systolic pressure minus diastolic pressure, indicates actual working pressure
In Anna's cardiac workup anna was
tachycardic her heart rate was 90-105
Pressure point in front of the ear
temporal
elevates and retracts mandible
temporalis
muscle name that describes location
temporalis
this is the time required for the excitation and ________ of the elastic components of the muscle
tensing
once elastic components are taut, the muscle produces external ________
tension
in an isotonic contraction
tension rises and the skeletal muscle length changes
Smooth muscle generates less __________ but can contract over a ____________ range of lengths
tension; greater
Which of the following best describes the composition of the structure known as a triad in a skeletal muscle fiber? sarcolemma, sarcoplasm, and sarcoplasmic reticulum terminal cisterna, transverse tubule, and terminal cistern actin, troponin, and tropomyosin ATP, CP, and glycogen A band, I band, and H band
terminal cisterna, transverse tubule, and terminal cistern
the prolonged contraction of a muscle caused by rapidly repeated stimuli
tetanus
What happens during muscle contraction?
the A band remains the same and the I band narrows
During muscle contraction
the A band remains the same and the I band narrows.
electrical impulses travel through cardiac cells and cardiac muslce tissue to
the AV node
What do H zones and I bands contain?
the H zone contain only myosin and the I band only contain actin
Which of the following statements about H zones and I bands is TRUE?
the H zones contain only myosin, while the I bands contain only actin
An action potential enters the depths of a muscle fiber by way of __________. diffusion the T tubules the calcium ion channels the sarcoplasmic reticulum the actin myofilament
the T tubules
An action potential enters the depths of a muscle fiber by way of..
the T-tubules.
cisternae
the ____ are enlarged portions of the SR.
H
the ____ zone contains only myosin and is in the center of the sarcomere
Which of the following characteristics is unique to smooth muscle? hyperplasia the ability of ATP to energize the sliding process response to stretch the absence of striations
the absence of striations
Cross bridges form between _________________.
the actin filaments and the myosin heads
Cross bridges form between...
the actin filaments and the myosin heads.
preload
the amount of tension in ventricular myocardium immediately before it begins to contract - Increased preload causes increased force of contraction - Exercise increases venous return and stretches myocardium - Cardiocytes generate more tension during contraction - Increased cardiac output matches increased venous return • Frank-Starling law of the heart: SV ∝ EDV - Stroke vol. is proportional to the end diastolic volume - Ventricles eject almost as much blood as they receive - The more they are stretched, the harder they contract - Relates to length-tension relationship of striated muscle
When the pressure in the ventricles becomes lower than the pressure in the atria, __________.
the atrioventricular valves open When the ventricles relax, the pressure inside the ventricles decreases and becomes less than that of the atria. The decrease in pressure helps to open the atrioventricular valves.
When the pressure in the ventricles becomes lower than the pressure in the atria...
the atrioventricular valves open.
myofibrils
the contractile proteins in a muscle fiber organized into elongated bundles.
sarcomere
the contractile unit of a m. fiber. Restated: the sm., functional unit of contraction is____
cisternae
the expanded regions of the SR that are found on both sides othe TT are referred to as
perimysium
the fibrous connective tissue that surrounds fascicles within the muscle
aponeurosis
the fibrous sheet is found on the head and abdomen only and connects m.
Perfusion
the flow per given volume or mass of tissue in a given time (mL/min./g)
what makes an EKG have a larger upward or downward peak
the greater intensity of the impulse and the greater the difference in the charges
Mean arterial pressure (MAP)
the mean pressure one would obtain by taking measurements at several intervals throughout the cardiac cycle
transverse tubules
the membranous channel that extends inward from a m. fiber membrane and passes through the fiber
sarcoplasmic reticulum
the membranous network of channels and tubules within a muscle fiber, corresponding to the ER of other cells
In this experiment, immediately after the latency period has passed:
the muscle contracted isotonically and lifted the weight.
For an isometric muscle fiber contraction...
the muscle fiber length remains constant as the muscle tension changes.
In this experiment, when the muscle is stretched what happens to the length of the muscle fibers?
the muscle fibers get longer.
For an isotonic muscle fiber contraction...
the muscle tension remains constant as the muscle fiber length changes.
Which of the following muscles is voluntary? the muscle in the wall of the heart the muscle that extends the arm at the elbow the muscle in the wall of the urinary bladder the muscle of the stomach
the muscle that extends the arm at the elbow
During the latency period:
the muscle was contracting isometrically.
What happens when the ATP attaches the myosin head?
the myosin head breaks off from the actin binding site and then the ATPase, in the myosin head, hydrolyses the ATP into ADP + Pi "recocking" the head into the high energy position
the rate of ventricular conduction is best determined by the _______ on the ECG
the number of QRS complexes present within a specific unit of time
Whole muscles can respond in a graded fashion to stimuli by varying
the number of motor units recruited.
Whole muscles can respond in a graded fashion to stimuli by varying the force of contraction of individual muscle fibers. the number of motor units recruited. the amplitude of the action potential. the frequency of stimulus. thresholds.
the number of motor units recruited.
sarcolemma
the plasma membrane of a single muscle fiber
tropomyosin
the protein of actin that is a rod shaped protein spiraling around actin
What is the relationship with velocity of shortening vs. load for isotonic contraction?
the rate of muscle shortening is inversely related to the load of the muscle. A muscle with no laod wil shorten at its max velocity. As the load increases the velocity of shortening decreases. At max load there is no shortening.
load
the resistance
The functional unit of muscle contraction is
the sarcomere
The functional unit of muscle contraction is
the sarcomere.
Which of the following muscles aids inspiration by lifting the first two ribs? diaphragm internal intercostals rectus abdominis the scalenes
the scalenes
When the acetylcholine binds to the receptor sites...
the sodium channels open.
When the acetylcholine receptor sites are not occupied:
the sodium channels remain closed.
Which of the following muscles divides the neck into two triangles? the spinalis the platysma the sternocleidomastoid the digastrics
the sternocleidomastoid
During unfused tetanus...
the stimuli arrive at the muscle fiber at such a rate that the muscle fiber is unable to completely relax between stimuli, and sequential contractions exhibit an equal contractive force that is greater than when the muscle fiber is allowed to rest completely.
In the sarcomere of skeletal muscle, actin is found in:
the thin filaments.
latent period
the time between the stimulus or the electrical event and the mechanical event of contraction
relaxation period
the time in which the muscle is returning to its original length
refractory period
the time when fiber cannot be stimulated until repolarization is complete
During contraction of a muscle, calcium ions bind to...
the troponin molecule
During contraction of a muscle, calcium ions bind to...
the troponin molecule.
What is a sarcomere?
the unit of organization of skeletal muscle
Which of the following is not true for ventricular systole?
the ventricles relax
Which of the following statements is not true regarding ventricular systole?
the ventricles relax. Ventricular systole refers to the point in time when the ventricles are contracting.
refractory period
the very brief time period after one stimulus during which the muscle is unresponsive to a second stimulus
H
the zone that disappears in a fully contracted muscle.
Which of the following is a true statement about cardia muscle cells?
they are connected by intercalated discs, through which action potentials spread to all cells in the heart
Which of the following statements about the "heads" of the myosin molecules is true?
they can attach to different actin sites
What about the "heads" of the myosin molecules is TRUE?
they can attach to different sites on the actin filament
Which of the following statements about the "heads" of the myosin molecules is TRUE?
they can attach to different sites on the actin filament
T tubules
they function to conduct electro-chemical impulse ( or action potentials) inside the fiber from the surface of the cell
Describe the role of calcium ions in the contraction of a sarcomere. (4)
they interact with the tropomyosin molecule; to reveal binding sites on actin; allowing myosin heads to bind to exposed sites on actin filament; energy released from ATP moves myosin head back to its original position
A band is what kind of filament?
thick filament, dark
Staggered arrays of myosin molecules are ______
thick filaments
The M line holds?
thick filaments in place
I band contains what kind of filament?
thin filament, light color
The __________ is described as two strands of actin molecules wrapped together.
thin filaments
What are the two kinds of myofilaments?
thin filaments thick filaments
The most common lever systems in the body are those that have the applied force between the fulcrum and the resistance. These are called ______ levers. first-class second-class third-class fourth-class fifth-class
third-class
I
this band becomes narrowed in a fully contracted musle
A
this band remains unchanged in a fully contracted muscle.
contraction ends
this happens when the actin filaments on opp. sides of the sarcomere come into contact and myosin comes into contact with the Z lines
TT
this is formed by an invagination of the m. cell's sarcolemma
A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level.
threshold
A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level. threshold relaxation rigor mortis recruitment resting
threshold
How do calcium ions enter the cytoplasm during an action potential in smooth muscle?
through the plasma membrane
The ________________ is the prime mover of dorsiflexion of the foot. tibialis anterior gastrocnemius soleus popliteus
tibialis anterior
Trusses and arches which help form an internal scaffolding network, are found in
trabecular bone.
Transverse tubules
transmit muscle impulses into the cell interior.
Transverse tubules (what do they do)
transmit muscle impulses into the cell interior.
The binding of the chemicals to the muscle cell causes an electrical impulse to travel along the sarcolemma and down the _______ tubules.
transverse
The component of a muscle fiber that quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber is called the
transverse tubule (T-bulule)
Smooth muscle lacks
transverse tubules and striations.
stabalizes, elevates, rotates, and retracts the scapula; helps extend the head with the scapula fixed
trapezius
prime mover of forearm extension
triceps brachil
normal heartbeat
triggered by the SA node typically 70-80 bpm
Which one of the following molecules or structures would least likely be found at a neuromuscular junction? (p. 10)
tropomyosin
a protein of muscle that forms a complex with troponin regulating the interaction of actin and myosin in muscular contraction
tropomyosin
Using your knowledge of muscle contraction, explain the difference in the results between A and B. (2)
tropomyosin covers binding site on actin; no cross bridges formed so ATPase activity on myosin head reduced
what is the role of tropomyosin in skeletal muscles?
tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules
All of the following are filamentous proteins EXCEPT
troponin
Each myosin protein has a globular head that extends outward from the myosin filament.
true
Each myosin protein has a globular head that extends outward from the myosin filament. True or False
true
For isotonic contractions, the shortening velocity of a muscle fiber is inversely proportional to the mass of the load.
true
If the post-synaptic membrane potential reaches threshold level, an action potential will be produced.
true
Muscles surrounding external body openings have a fascicular pattern that is circular.
true
Muscles that act as sphincters to close openings are called circular muscles.
true
Relaxation requires uptake of calcium ion by the sarcoplasmic reticulum. True or False
true
The lining of the chambers and the covering of the heart are a simple squamous epithelium overlying a thin layer of loose connective tissue. A) True B) False
true
The rhomboid major and minor are muscles that stabilize and retract the scapula.
true
The sodium-potassium pump is involved in establishing the resting membrane potential.
true
Tropomyosin moves to expose myosin binding sites on actin. True or False
true
Troponin binds calcium ion and signals tropomyosin to move. True or False
true
True or False Action potentials are carried by the Purkinje fibers from the bundle branches to the ventricular walls
true
True or False In the ventricles, the action potential travels along the interventricular septum to the apex of the heart, where it then spreads superiorly along the ventricle walls.
true
True or False during the heart conduction system action potentials pass slowly through the atrioventricular node
true
True or False: In the absence of calcium ions, tropomyosin partially conceals the myosin binding site on an actin filament, preventing contraction. (p. 9)
true
True or False: Muscles can atrophy even if their nerve supply has not been disturbed. (p. 12)
true
True or False: Some disorders that affect the muscular system actually are caused by defects in the parts of the nervous system that control muscle contraction rather than in the muscle fibers themselves. (p. 17)
true
Unflexing of the myosin head requires ATP True or False
true
When cross bridges form and the muscle fibers contract, the actin myofilament slides past the myosin myofilament.
true
When you abduct your upper arm, the prime mover is the deltoid.
true
at maximal stimulus, the muscle is contracting at full strength and all motor units are recruited
true
cross bridges occur when myosin heads combine with the binding sites on actin
true
during the recovery period after exercise, the body's need for oxygen is increased
true
energy is needed to make muscles relax
true
in a contracting muscle the Z lines come closer together.
true
in isotonic contractions, the muscle changes in length and the tension remains constant through most of the contractile period
true
it takes about twice as long for a muscle to contract as it does to relax
true
lactic acid is an end product of anaerobic fermentation that contributes to muscle fatigue
true
relaxation occurs when Ca2+ is transported back into the sarcoplasmic reticulum
true
the area of the sarcomere that contains only thin and elastic filaments is the I band
true
the neurotransmitter that stimulates skeletal muscle is acetlycholine
true
the sequence of events that forms the link between electrical activity in the sarcolemma and the initiation of a contraction is called excitation-contraction coupling
true
the skeletal muscle complex known as the triad consists of the transfers tubule and terminal costernae
true
the sliding filament model explains how myofilaments slide past each other
true
In the ventricles, the action potential travels along the interventricular septum to the apex of the heart, where it then spreads superiorly along the ventricle walls.
true Firing of the SA node excites atrial cardiocytes and stimulates the two atria to contract almost simultaneously. The signal travels through the atrial myocardium and reaches the AV node. The signal at the AV node is delayed, giving the ventricles time to fill with blood before they begin to contract. Signals then travel through the AV bundle and Purkinje fibers. Consequently, the entire ventricular myocardium depolarizes within 200 ms after the SA node fires, causing the ventricles to contract in near unison. Signals reach the papillary muscles before the rest of the myocardium. Thus, these muscles contract and begin taking up slack in the tendinous cords an instant before ventricular contraction causes blood to surge against the AV valves. Ventricular systole begins at the apex of the heart, which is first to be stimulated, and progresses upward—pushing the blood upward toward the semilunar valves. Because of the spiral arrangement of ventricular cardiocytes, the ventricles twist slightly as they contract, like someone wringing out a towel.
The ventricles begin to fill during ventricular diastole.
true Most ventricular filling happens passively while the atrioventricular valves remain open in between ventricular contractions, a time known as ventricular diastole.
The P wave of the ECG coincides with ventricular filling.
true The P wave of the ECG coincides with ventricular filling.
T tubules
tube-like extensions of the sarcolemma that run over and around the SR are referred to as
What is recruitment?
turing on more and more motor units, to increase tension in whole muscles
a single contraction of a stimulated muscle
twitch
caused by a stimulus, a quick cycle of contraction and relaxation is called?
twitch
Each myofibril has __________
two kinds of myofilaments
Each actin filament is composed of _________________________.
two strands of actin molecules wrapped together
Each actin filament is composed of
two strands of actin molecules wrapped together.
Each actin filament is composed of:
two strands of actin molecules wrapped together.
twitch
type of contraction represented by a single stimulus/ contraction/ relaxation sequence
slow-oxidative fibers
type of muscle fibers that are most resistant to fatigue
fast-oxidative fibers
type of muscle fibers that contract quickly and rely on aerobic respiration for ATP
fast-glycolitic fibers
types of fibers that have few mitochondria
cardiodilatin
vascular smooth muscle relaxant that facilitates vasodilation
Which of the following muscles is a common site for injections in infants who have poorly formed buttocks? sartorius pectineus rectus femoris vastus lateralis
vastus lateralis
The heart chambers that have just been filled when you hear the first sound are the
ventricles
QRS complex represents the
ventricular contraction
QRS wave
ventricular contraction - ventricular depolarization
The atrioventricular valves open during..
ventricular diastole
The semilunar valves close during...
ventricular diastole
The atrioventricular valves open during __________.
ventricular diastole The atrioventricular valves refer to the tricuspid and mitral valves. While the ventricles are relaxed, also known as ventricular diastole, the papillary muscles on the inside of the ventricles tug on the chordae tendineae, pulling the cusps of these valves to an open position.
The semilunar valves close during __________.
ventricular diastole The semilunar valves refer to the aortic and pulmonary valves. While the ventricles are relaxed, also known as ventricular diastole, the pressures in the ascending aorta and pulmonary trunk are greater than the pressures in the ventricles. Since these one-way valves open into the vessels, the pressure difference causes them to close
During which phase of the cardiac cycle does aortic pressure reach its maximum?
ventricular ejection The volume of blood being forced into the aorta by the left ventricle during ventricular systole causes the highest pressure the aorta experiences.
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle?
ventricular ejection. As the ventricles contract, blood is forced through the semilunar valves and out into the arteries, resulting in a reduction in ventricular blood volume. At the end of this phase, ventricular volume is at a minimum−the "end-systolic volume" (ESV).
During which complete phase of the cardiac cycle do the atria both relax and contract?
ventricular filling Since the atrioventricular valves are open at rest, ventricular filling happens passively when the atria are relaxed and actively when the atria are contracted.
Isovolumetric relaxation
ventricular filling, complete one cardiac cycle
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle?
ventricular filling. During ventricular filling the AV valves remain open, which allows blood to flow from the atria into the ventricles. The passive flow of blood during this phase (before atrial contraction) accounts for roughly 80 percent of the increase in ventricular volume.
What causes them to close?
ventricular pressure > atrial pressure
What event causes the semi lunar valves to open
ventricular pressure > pressure in the arteries
What event causes the semilunar valves to open?
ventricular pressure > pressure int he great arteries (aorta and pulmonary trunk) leaving their chambers
What event within the heart causes the AV valves to open?
ventricular pressure is less than (<) atrial pressure
the T wave results from
ventricular relaxation which is a recovery of the ventricular muslce tissue to a resting state
T wave
ventricular repolarization - Ventricular repolarization and relaxation
At what point in the cardiac cycle is the pressure in the heart the highest
ventricular systole
An action potential arriving at the pre synaptic terminal causes:
voltage-gated calcium ion channels to open, and calcium ions to diffuse into the cell.
Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called ligand-gated or chemical-gated ion channels. non-gated ion channels. voltage-gated ion channels. obligated ion channels.
voltage-gated ion channels.
skeletal muscle
voluntary via axonal endings of the somatic nervous system
Where is smooth muscle mainly found?
walls of blood vessels and digestive tract organs
contraction
what happens when actin and myosin filaments slide past one another.
cardiac cycle phases time
• In a resting person - Atrial systole lasts about 0.1 second - Ventricular systole lasts about 0.3 second - Quiescent period, when all four chambers are in diastole, lasts about 0.4 second • Total duration of the cardiac cycle is 0.8 second in a heart beating 75 bpm
cardiac cycle phases
• Ventricular filling (during diastole) • Isovolumetric contraction (during systole) • Ventricular ejection (during systole) • Isovolumetric relaxation (during diastole) • The entire cardiac cycle (all four of these phases) are completed in less than 1 second
Both thick and thin filaments
A band
Uncovering binding sites for myosin on actin myofilaments is involves troponin binding to
Calcium ions.
____________ enter the axon terminal leading to the release of acetylcholine via __________.
Calcium ions; Exocytosis
In a muscle fiber a triad consists of a __________ and two adjacent terminal cisternae.
T-tubule
Voltage sensitive proteins respond to the action potential that spreads down the ______________.
T-tubule
An action potential enters a muscle cell at the
T-tubule.
During contraction, the myosin myofilaments shorten. T OR F
TRUE
Which one of the following does not shorten during skeletal muscle contraction? (p. 6)
A band
The area of the muscle fiber where the actin and myosin myofilaments overlap is the
A band.
True or False: Central fatigue is due to an accumulation of extracellular fluid K+
False
True or False: Eccentric contraction is when the muscle shortens while contracting
False
What are the areas near the edge of the sarcomere containing only thin filaments?
I bands
Ventricular myocytes
30-40bpm
endomysium
CT that surrounds a muscle fiber
Thick Filaments
Myosin, Myosin heads, Light chains, H band and M line.
What are the regions where thick and thin filaments overlap and correspond to the length of the thick filaments?
A bands
1. Muscle tension causes shortening ___ 2. Muscle tension does not cause shortening of the muscle ___ 3. Lengthening contraction ___
1. Concentric contraction 2. Isometric contraction 3. Eccentric contraction
What two other proteins are associated with each myosin molecule?
1. Essential light chain-stabilizes the bolular head of the myosin 2. Regulatory light chain-regulates the ATPase activity of the myosin
What are the four phases of Isotonic contractions?
1. Generating the tension, can't move the object 2. Shortening muscle-keeping the same amount of force generated. 3. Isotonic relaxation 4. Isometric relaxation.
List 4 things that increase contractility
1. Increased sympathetic stimuli 2. Certain hormones 3. Ca++ 4. Some drugs
When do we use isometric twitch? Compare and Contrast Isotonic vs Isometric?
1. Mechanical work is performed only during an isotonic contraction. Work =Force x distance 2. No shortening of the contractile elements in isometric contractions-no sliding between thick and thin filaments. Cross bridges are formed and broken but no net change in the relationship between actin and mysoin occurs. No external work is done. Energy consumed results in production of heat. 3. Isotonic muscle contraction must overcome the inertia of the object it is attempting to move by acceleration until a certain velocity is reached. Generally persist longer that isometric. 4. When muscle contracts isotonically and begins to shorten, the relationship between thick and thin filaments is continually changing. The net effect is change the number of potential cross bridges. This explains why a muscle at one position may nor be able to sustain further contractions or maintain isometric tension but may be able to do so at a different position.
2
2
Arrange the following in the proper order in which they occur at the postsynaptic side of a neuromuscular junction. 1. Action potential is propagated over the muscle cell membrane 2. Depolarization of the postsynaptic membrane 3. Sodium ions move into muscle cell
3, 2, 1
How many phrases does a muscle twitch have?
4
Twitch
A single action potential Not visible to the human eye
Motor Neuron
A single nerve cell that extends from the Brain or Spinal Cord to a muscle or gland.
striations
A skeletal muscle exhibits alternating light and dark transverse bands, or wHAT, that result from an overlapping arrangement of their internal contractile proteins.
muscle fibers
Because of their extraordinary length, skeletal muscle cells are usually called WHAT or myofibers.
Which of the following is the correct sequence for skeletal muscle contraction? A) An increase in cytosolic calcium binds to the troponin complex, which binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin heads, which binds to the actin filaments, resulting in contraction. B) An increase in cytosolic calcium binds to calmodulin in the cytosol, which binds with myosin, forming cross-bridges, resulting in contraction. An increase in cytosolic calcium binds to calmodulin in the cytosol, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin, forming cross-bridges, resulting in contraction. C) An increase in cytosolic calcium binds to troponin, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin, forming cross-bridges, resulting in contraction. D) An increase in cytosolic calcium binds to calmodulin in cytosol, which binds with myosin light-chain kinase, using ATP to phosphorylate the myosin heads, which bind to the actin filaments, resulting in contraction.
C) An increase in cytosolic calcium binds to troponin, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin, forming cross-bridges, resulting in contraction.
describes a route that blood can take in a normal human?
C) left atrium > bicuspid valve > left ventricle > aortic semilunar valve
Ventricular systole causes... A) blood to flow into the ventricles. B) blood to flow out of the atria. C) the atrioventricular valves to close, and then the semilunar valves to open. D) the semilunar valves to close, and then the atrioventricular valves to open. E) pressure to become greater in the aorta and pulmonary trunk than in the ventricles.
C) the AV valves to close, and then the semilunar valves to open.
All of the following are filamentous proteins EXCEPT A. tropomyosin. B. myosin. C. troponin. D. actin. E. troponin and tropomyosin.
C. troponin.
Movement of sodium ions into the muscle cell at the neuromuscular junction causes
Depolarization of the muscle cell membrane.
Which of the following is the correct sequence of smooth muscle contraction? A) An increase in cytosolic calcium binds to the troponin complex, which binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to actin filaments, resulting in contraction. B) An increase in cytosolic calcium binds to calmodulin in cytosol, which binds with myosin cross-bridges, resulting in contraction. An increase in cytosolic calcium binds to calmodulin in the cytosol, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin cross-bridges, resulting in contraction. C) An increase in cytosolic calcium binds to troponin, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin cross-bridges, resulting in contraction. D) An increase in cytosolic calcium binds to calmodulin in the cytosol. This complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to the actin filaments' active sites, resulting in contraction.
D) An increase in cytosolic calcium binds to calmodulin in the cytosol. This complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to the actin filaments' active sites, resulting in contraction.
The ____________ collects blood from all other veins draining the myocardium and returns this blood to the right atrium. A) great cardiac vein B) left circumflex artery C) posterior cardiac vein D) coronary sinus E) middle cardiac vein
D) coronary sinus
All of the following are cardiac stimulants except: A) epinephrine B) caffeine, nicotine, and chocolate C) thyroid hormone D) potassium and calcium ions
D) potassium and calcium ions
Which of the following is not true for ventricular systole? A) the ventricles contract. B) the atrioventricular valves close. C) the semilunar valves open. D) the ventricles relax. E) blood flows through the aorta and the pulmonary trunk.
D) the ventricles relax.
What is Depolarization?
DECREASE in the negative Resting Membrane Potential ( the VOLTAGE that exists across the plasma membrane ).
What happens to a muscle when it is significantly stretched both in vitro and invovo beyond the normal length?
Damage occurs to the structure of the muscle and the muscle may never again be capable of the maximum number of cross bridges. This is a typical hyperextension injuries to athletes.
During contraction, the actin myofilaments slide toward the
H Zone
During contraction, the actin myofilaments slide toward the...
H Zone
The steps of the cardiac cycle sequence is?
Isovolumic contraction,ejection, isovolumic relaxation,passive ventricular filling, active ventricular filling
Atria depolarize from what side to what side?
Left side to Right side
Cross bridges form between binding sites on actin myofilaments and
Myosin heads.
Energy produced when ATP is converted to ADP and phosphate is stored in
Myosin heads.
A conformational change to troponin-tropomyosin reveals binding sites for _________ located on the ____________.
Myosin, Actin filaments
which type of ion channels carry the muscle potential along the surface of the sarcolemma and down the T-tubules?
Na+
As actin and myosin filaments slide past each other during muscle contraction (what shortens; actin + myosin filaments)
Neither actin or myosin filaments shorten*** I think myosin filaments shorten, while actin filaments do not
The plasma membrane of the muscle cell is called the Sarcolemma Triad Terminal cisternae Sarcoplasmic reticulum T tubules
Sarcolemma
The specific name for a muscle fibers plasma membrane is the ________.
Sarcolemma
An action potential for a muscle cell is propagated along the
Sarcolemma.
The muscle cell membrane is called the
Sarcolemma.
The distance from one Z disk to the next Z disk is called a(n)...
Sarcomere
The area between two Z discs is termed a(an)
Sarcomere.
Calcium ions released from the sarcoplasmic reticulum enter the
Sarcoplasm.
Terminal Cisternae are a structural feature of the organelle called the ____________ _____________.
Sarcoplasmic Reticulum
Interconnecting tubules of endoplasmic reticulum that surround each myofibril are called Sarcolemma Triad Terminal cisternae Sarcoplasmic reticulum T tubules
Sarcoplasmic reticulum
S2
Similunar valves close
The sequence of travel by an action potential through the heart is?
Sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers
Which of the following is the correct sequential path of an action potential in the heart?
Sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers
In the heart the action potentials originates in the ?
Sinoatrial nodes
How do slow-twitch fibres differ from fast-twitch fibres in the way they function? (6)
Slow-twitch fibres: Contract more slowly; Provide less powerful contractions; Over a longer period; Fast-twitch fibres: Contract more rapidly; Produce powerful contractions; For a short period
In response to acetylcholine binding, ____________ move into the muscle fiber causing the membrane potential to rise.
Sodium ions
The neurotransmitter at the neuromuscular junction increases permeability of the muscle cell membrane to
Sodium ions.
What causes the systolic sound
Sound of turbulent blood flow as it first begins to move through the constricted artery
When the membrane potential reaches ____________ an action potential spreads across the sarcolemma due to the opening of ________________.
Threshold; Voltage-gated Na+ channels
Neither thick nor thin filaments
Titin
Tropomysoin
Tm elongated protein consisting of 2 alph helix chains which lie parallel to the actin chains within the groove formed by the 2 parallel actin strands There is one unit of Tm for each 7 G actins Tm functions to cover active sites on the corresponding actin chain to prevent bind of the thick filament to those sites of actin.
Which of the following would not be a possible application to a RoboSnail?
To assist in clam and oyster bed farms in the Atlantic North East.
excitability, contractility, extensibility, elasticity
To carry out the functions of movement, stability, communication, control of body openings and passages, and heat production, all muscles cells have the following characteristics: excitability, contractility, extensibility, elasticity
A group of one T tubule lying between two adjacent terminal cisternae is called a Sarcolemma Triad Terminal cisternae Sarcoplasmic reticulum T tubules
Triad
Right atrioventricular valve
Tricuspid
The atrioventricular valves open during?
Ventricular diastole
The semilunar valves close during ?
Ventricular diastole
In a cardiac muscle cell, the membrane potential increases rapidly ?
When sodium gates open and sodium diffuses into the cardiac muscle fiber.
In a cardiac muscle cell , the membrane potential decreases rapidly ?
When the potassium gates open and potassium diffuses out of the cardiac muscle fiber.
raises lateral corners of the mouth smiling muscle
zygomaticus major and minor
the PQRST waves are normally how long?
~.8 seconds
cardiac output
• Cardiac output (CO) - amount ejected by each ventricle in 1 minute • Cardiac output = heart rate x stroke volume - About 4 to 6 L/min at rest • Cardiac reserve - the difference between a person's maximum and resting CO - Increases with fitness, decreases with disease
Chronotropic Effects of Chemicals
• Electrolytes - K+ has greatest chronotropic effect • Hyperkalemia - excess K+ diffuses into cardiocytes • Hypokalemia - deficiency in K+ - Calcium • Hypercalcemia - excess of Ca2+ • Hypocalcemia - deficiency of Ca2+
overlap
In the fully contracted muscle, the ends of the actin myofilament ______
Electrical Behavior of the Myocardium
1. Na+ gates open 2. Rapid depolarization 3. Na+ gates close 4. Slow Ca2+ channels open 5. Ca2+ channels close, K+ channels open (repolarization)
H band
In the middle of the A band, there is a lighter region called the WHAT, into which the thin filaments do not reach. Thick but no thin filament.
Isovolumetric contraction
- Atria repolarize, relax and remain in diastole for rest of cardiac cycle - Ventricles depolarize, causing QRS complex, and begin to contract - AV valves close as ventricular blood surges back against the cusps - Heart sound S1 occurs at the beginning of this phase - Cardiocytes exert force, but with all four valves closed, the blood cannot go anywhere
Ventricular ejection
- Begins when ventricular pressure exceeds arterial pressure and semilunar valves open - Pressure peaks in left ventricle at about 120 mm Hg and 25 mm Hg in the right - Ejection lasts about 200 to 250 ms - corresponds to plateau phase of cardiac action potential - T wave of ECG occurs late in this phase - Stroke volume (SV) is about 70 mL • Ejection fraction is about 54% of EDV (130 mL) • 60 mL remaining blood is end-systolic volume (ESV) = EDV - SV
In the heart, which of the following apply?
1) Action potentials are conducted from cell to cell across the myocardium via gap junctions (2) the SA node sets the pace for the heart as a whole (3) spontaneous depolarization of cardiac cells can occur in the absence of nerve stimulation
During which processes is ATP required during muscle contraction?
1) Ca pumped back in by Ca2+ ATPase pump 2) Myosin heads release from binding sites 3) Cock myosin heads back into high energy formation
1. The maximum rate of oxygen consumption in the body ___ 2. The percentage of the oxygen uptake at which a significant rise in blood lactate levels occurs ___ 3. Reversible, exercise-induced reduced ability in the muscle to generate force ___
1. Aerobic capacity 2. Lactate threshold 3. Muscle fatigue
electrocardiogram in steps
1. Atrial depolarization begins 2. Atrial depolarization complete (atria contracted) 3. Ventricles begin to depolarize at apex; atria repolarize (atria relaxed) 4. Ventricular depolarization complete (ventricles contracted) 5. Ventricles begin to repolarize at apex 6. Ventricular repolarization complete (ventricles relaxed)
myosin heads
1. Binds to active sites on the actin molecules to form cross-bridges (actin binding site) 2. Attaches rod portion by a hinge region that can bend and straighten during contraction 3. Has ATPase activity: breaks down ATP, releasing energy. Part of the energy is used to bend the hinge region of the myosin molecule during contraction.
conduction system order
1. SA node fires 2. excitation spreads through atrial myocardium 3. AV node fiers 4. excitation spreads down AV bundle 5. Purkinje fibers distribute excitation through ventricular myocardium from outline: a. Sinoatrial (SA) node- located in the R atrium, acts as the pacemaker that initiates each heartbeat and determines heart rate. b. Signals from SA node spread throughout the atria c. Atrioventricular (AV) node- located near the R AV valve, acts as an electrical gateway to the ventricles, also acts as an insulator d. AV Bundle (bundle of His)- pathway which allows signals to leave the AV node, forks into R and L branches, descend towards apex of heart e. Purkinje fibers- spread throughout the ventricular myocardium, distribute the electrical signal to cardiocytes of ventricles, more elaborate in L than R ventricle f. Cardiocytes then pass ions from cell to cell through their gap junctions
heart blood flow
1. blood enters right atrium from superior and inferior venae cavae 2. blood in right atrium flows through right AV vale into right ventricle 3. contraction of right ventricle forces pulmonary valve open 4. blood flows through pulmonary valve into pulmonary trunk 5. blood is distributed by right and left pulmonary arteries to the lungs where it unloads CO2 and loads O2 6. blood returns from lungs via pulmonary veins into left atria 7. blood in left atrium flows through left AV valve into left ventricle 8. contraction of left ventricle (simultaneous with step 3) forces aortic valve open 9. blood flows through aortic valve into ascending aorta 10. blood in aorta is distributed to every organ in the body where it unloads O2 and loads CO2 11. blood returns to right atrium via venae cavae steps 4-6 is the pulmonary circuit steps 9-11 is the systemic circuit
conduction system order (long explanation)
1. the sinoatrial node (SA) is a patch of modified cardiocytes in the right atrium, just under epicardium near the superior vena cava. This is the pacemaker that initiates each heartbeat and determines the heart rate. 2. Signals from the SA node spread throughout the atria, as shown by the red arrows in fig. 19.12 (p. 721) 3. the atrioventricular (AV) node is located at lower end of the interatrial septum near right AV valve. This node acts as an electrical gateway to the ventricles; the fibrous skeleton acts as an insulator to prevent currents from getting to the ventricles by any other route. 4. the atrioventricular AV bundle or bundle of His, pathway by which signals leave the AV node. Bundle forks into right and left bundle branches, which enter the interventricular septum and descent toward the apex. 5. Purkinje fibers are nervelike processes that arise from the lower end of the bundle branches and turn upward to spread through the ventricular myocardium. Purkinje fibers distribute the electrical excitation to the cardiocytes of ventricles. they form a more elaborate network in the left ventricle than in the right.
10 Steps to a Contraction of a Motor neuron (Muscle Cell / Fiber)
1.) ACTION POTENTIAL arrives at the axon terminal. 2.) Calcium ions ENTER the axon terminal. 3.) Synaptic vesicles fuse to membrane of axon terminal. 4.) ACh is released, by EXOCYTOSIS, into the synaptic cleft; then calcium is pumped OUT of axon terminal. 5.) ACh binds to receptor sites on the motor end plate. 6.) Motor end plate becomes depolarized. 7.) Action Potential is initiated on the sarcolemma. 8.) Action Potential propagates along the sarcolemma and down the T-tubules. 9.) Calcium ions are released from the terminal cisternae. 10.) The muscle cell contracts.
Neuromuscular Junction & ACh
1.) An ACTION potential arrives at the axon terminal. 2.) Acetylcholine (ACh) is released from the axon terminal into the synaptic cleft. 3.) The motor end plate is DEPOLARIZED. 4.) The Depolarization triggers an ACTION potential which propagates along the sarcolemma and the T-Tubules. 5.) The Sarcomeres CONTRACT !!!
What two events happen after the Synaptic Vesicles Fuse with the membrane of the axon terminal?
1.) The neurotransmitter ACh contained with the Vesicles is liberated by EXOCYTOSIS into the Synaptic Cleft. 2.) Calcium ions are PUMPED OUT of the AXON TERMINAL.
The maximum amount of work done by the contracting muscle was observed when the muscle was lifting:
120 grams
there are ___ pairs of cranial nerves and ___ pairs of spinal nerves
12:31
Isometeric twitch
1st we start off giving an action potential to the muscle, sticking electrodes in it. AP happen really quickly. Only one AP so it goes back to normal. In response to the action potential, a large amount of Calcium is released into the cell. Ca binds to Troponin C, tropomyosin moves, power strokes move, a few cross bridge periods becasue there is some slack. After the latent period, we see tension is created. Over time Calcium get pumped back into SR. now we start to get relaxation. The Twitch force depends of Calcium concentration. Classic twitch in isometeric contraction
Each actin filament is composed of
2 strands of actin molecules wrapped together
The triads of a muscle fiber consist of
2 terminal cisternae 1 T tubule.
Troponin
3 protein subunits Tn Troponin T-TnT- binds to the other two troponin proteins and to Tm Tropoinin-C-has binding sites for Ca2+ each molecule binds up to 4 calicum, causing a conformational change in the Tn complex which changes the relationship of Tm to actin. Troponin I-functions as an inhibitory protein. When no Ca 2+ is present to bind the Tn-C, the troponin complex allows tropomyosin to cover the active binding site on the actin chain. The binding of Ca causes a conformation change which causes Tn-I to change its position. Tm is then rotated away from the actin binding sites it covers. Tn and Tm are considered regulatory proteins. The advantage of Tn-Tm arrangements is tha the change in conformation f the single Tn complex includes the rotation of the Tm out of the formed by the actin helix and permits the single Tm chain to expose the multiple binding sites on the actin chain that were covered by the single Tm chain.
How many steps are involved during a muscle contraction?
4
On how many separate occasions is flight believed to have evolved in the animal kingdom? (p. 16)
4
Arrange the following steps for contraction in the correct sequence. 1. The muscle impulse reaches the sarcoplasmic reticulum and calcium is released. 2. Thin filaments are pulled over the thick filaments. 3. Calcium floods the sarcoplasm and binds to troponin molecules leaving active sites. 4. The impulse arrives at the synapse and travels through the transverse tubules. 5. The muscle fiber shortens and contracts. 6. Tropomyosin molecules bind to exposed active sites, linking actin and myosin
4, 1, 3, 6, 2, 5
Purkinje fiber myocytes
40-50bpm
Incomplete Tetanus
5-10 stimulations per second 15 stimulations per second Wavering or visible relaxation between stimulations
At which of the following ages would calcium loss from bone be more than calcium deposits into bone, even when a high calcium diet is eaten?
50 years old
AV nodal myocytes
50-60bpm
Atrial myocytes
50-60bpm
Complete Tetanus
60 stimulations per second Smooth, sustained contraction Greatest force producing capability
The rate of change of percent maximum tension for muscle fibers is greatest from...
60% - 80% of relaxed length.
Sinus nodal myocytes (bpm)
60-80bpm
What is the average heart rate?
72 BPM
An artery is defined as:
A) a vessel that carries blood away from the heart
Match what happens during maximum muscle contraction to the following areas of a sarcomere. 1. A band Width 2. I band 3. H zone A remains constant B Narrows C Disappears
A,B,C
Which of the following best describes the role of Ca2+ in muscle contraction? Which of the following best describes the role of Ca2+ in muscle contraction? A. It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin. B. It binds to tropomyosin, moving troponin, so that actin heads can bind to myosin. C. It binds to actin, moving myosin, so that troponin can bind to tropomyosin. D. It binds to tropomyosin, moving troponin, so that myosin heads can bind to actin. E. It binds to troponin, moving tropomyosin, so that actin heads can bind to myosin.
A. Ca2+ binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
Click on the "Latency Period" button in the Journal to display a graph of your data. What is the effect of increasing the weight on the latency period?
The latency period increased as the weight was increased.
Function/s of muscle tissue includes Produce Skeletal Movement. Skeletal muscle contractions pull on tendons and move the bones of the skeleton. Guard Entrances and Exits. The openings of the digestive and urinary tracts are encircled by skeletal muscles. These muscles provide conscious control over swallowing, defecation, and urination. Maintain Posture and Body Position. Tension or tone in our skeletal muscles maintains body posture. Maintain Body Temperature. The heat released by working muscles keeps our body temperature in the range required for normal functioning. Support Soft Tissues. The abdominal wall and the floor of the pelvic cavity consist of layers of skeletal muscle. These muscles support the weight of internal organs and shield internal tissues from injury. All are true.
All are true.
Cardiac muscle -contracts as a syncytium. -excites itself. -responds in an all-or-none manner. -is only in the heart. -all of the above.
All of the above
What are the various types of Tension?
Almost all this resting tension, is due to titan. Range of motion after ligaments and bone problems are eliminated, has to do with titan. 1. Developed or active tension (formed by cross-bridge formation). 2. Passive or resting tension - This is affected by the elasticity of the muscle tissue and connective tissue that are in parallel and series with the contractile elements (thick and thin filaments). When the maximum resting tension is exceeded, then the muscle will rupture or pull loose from the tendon or bone. 3. Total tension = Active + passive tension
what is the neurotransmitter necessary for muscle contraction
acetylcholine
Facioscapulohumeral Dystrophy
An autosomal dominant (* locus 4q35: Am. J. Hum. Genet. Aug. 1992) with varying expressivity, and not lethal. Patients' shoulders and upper arms waste away, beginning in their teens or twenties. Staining muscle with NADH reveals "moth-eaten" or "mottled" myofibers. Other changes are not usually striking.
Becker's Muscular Dystrophy
Another sex-linked muscular dystrophy, caused by milder abnormal alleles at the Duchenne's locus. "Becker's" is defined to be "Duchenne's" in which patients can still walk by their 16th birthday. It's less common than Duchenne's: Lancet 337: 1022, 1991; Am. Heart J. 132: 642, 1996. The problem in most cases is that dystrophin, though present, is mutated into a less-effective form. Dystrophin has several domains which do different things, and Becker's is very heterogeneous. For a recent review, see Brain 125: 4, 2002
...How does the maximum load relate to the number of cross bridges?
As you increase the weight, velocity decrease of that contraction. More cross bridges need to be formed to create the initial tension, and what is left in cross bridges allows for the speed. Like a centipede carrying a weight. If you have the same weight that you can lift all three points of the length tension relationship, let's say 5 lbs. It is gives you the same max velocity because, you will eventually get enough cross bridges.
Na+ channel dependent
Atria, Ventricles and Purkinje fibers with a fast conduction and slow automaticity
PQ segment
Atrial systole begins about 100 ms after P wave begins. This segment is about 160 ms long and represents the time required for impulses to travel from the SA node to AV node
A child ingested an organophosphate poison used to kill insects. Soon the child's muscles began spastic contractions. Predict what occurred at the synaptic cleft. A decreased release of acetylcholine from presynaptic neurons B increased accumulation of acetylcholine in the synapse C the poison binds to acetylcholine receptors and stimulates them D increased breakdown of acetylcholine in the synaptic cleft E Both increased accumulation of acetylcholine in the synapse and increased breakdown of acetylcholine in the synaptic cleft.
B
In the carbon nanotube joint replacement alternative, what would provide the bone strength?
Calcium ions that are attracted to the carbon fiber
What are the two types of muscle that are used involuntary? (2)
Cardiac muscle; Smooth muscle
sarcomere
Each segment of a myofilament from one Z disc to the next is called a WHAT, the functional contractile unit of the muscle fiber. About 10,000 sacromeres per myofibril each about 2 um long (The distance from one Z disc to the next; the contractile unit of a muscle fiber)
troponin
Each tropomyosin molecule has a smaller calcium-binding protein called WHAT bound to it. It is composed of 3 subunits: Tn-A: binds to actin, Tn-T: binds to tropomyosin, Tn-C: binds to calcium ions
titin filaments
Elastic chains of amino acids; keep thick and thin filaments in proper alignment. This helps to stabilize the thick filament, center it between the thin filaments, and prevent overstretching.
A muscle recoils to its original resting length after having been stretched.
Elasticity
Which connective tissue wrapping separates individual muscle fibers?
Endomysium.
(Refer to exam q) The table shows some properties of slow and fast muscle fibres. Endurance athletes, such as marathon runners, nearly always have a high proportion of slow muscle fibres in their muscles. Explain the benefit of this. (6)
Endurance athletes exercise for long periods of time; Respire aerobically; Slow fibres adapted to aerobic respiration; As they have many mitochondria; Which is the site of Kreb's cycle; Producing large amount of ATP
The outermost layer of connective tissue surrounding a skeletal muscle is the
Epimysium
The first event in muscle fiber contraction is that
acetylcholine is released from the end of the motor neuron
Myasthenia gravis
In this disease, which is fairly common especially among young women, polyclonal antibodies attack the acetylcholine receptor (a-bungarotoxin binding site) of the post-synaptic membrane of the neuromuscular junction. This is unwholesome, since binding of acetylcholine is blocked, and receptors are degraded too rapidly. Interestingly, about 30% of these patients have a thymoma, and most of the rest have thymic hyperplasia (i.e., germinal follicles in the thymus gland).
Using what you know about motor units. Lets say you have two different ones A and B. A is size 3 and B is size 9. If you wanted to lift a heavy object what would you use? If you wanted to lift a light object what you do?
If you wanted to lift a heavy object you would use B. If you wanted to lift and EVEN heavier object you could use both A and B. Light objects you would use A. For a smooth muscle contraction you would want a higher frequency. But based on how you want the muscle to move, depends on how much and what size motor unit you use. This is a learned response.
Hemodynamics
Important for delivery of nutrients and oxygen, and removal of metabolic wastes - Physical principles of blood flow based on pressure and resistance • F ∝ ∆P/R (F = flow, ∆P = difference in pressure, R = resistance) • The greater the pressure difference between two points, the greater the flow; the greater the resistance, the less the flow
What causes skeletal muscle cells to contract? Impulses from motor neurons. Impuses from the heart. Impulses from smooth muscle fibers. Scientists do not know.
Impulses from motor neurons.
Which of the following statements concerning types of muscle contractions is false? In isometric contractions, the amount of tension produced by the muscle is constant. In isotonic contractions, the muscle fibers shorten. The contractile processes in isometric and isotonic contractions are the same. Most skeletal muscle contractions are a combination of isometric and isotonic contractions. In isotonic contractions the amount of tension produced by the muscle fibers is constant during the contraction.
In isometric contractions, the amount of tension produced by the muscle is constant.
extensibility
In order to contract, a muscle cell must also be extensible- able to stretch again between contractions. Most cells rupture if they are stretched even a little, but skeletal muscle fibers can stretch to as much as 3x their contracted length
Which of the following statements is true concerning calcium ions? In smooth muscle, it binds with calmodulin. In skeletal muscle, it binds with calmodulin. In smooth muscle it binds with troponin. In skeletal muscle, it binds with tropomyosin. In smooth muscle, it binds with myosin light-chain kinase.
In smooth muscle, it binds with calmodulin.
What is the thin filament?
Made of multiple proteins Actin, tropomyosin, troponin,
What event results in the pressure deflection called the dicrotic notch?
Momentary increase in aortic pressure that occurs when its semilunar valve snaps shut
Epimysium covers
Muscle
glycogen
Muscle fiber also contains an abundance of WHAT, a starchlike carbohydrate that provides energy for the cell during heightened levels of exercise.
Endomysium covers
Muscle fibers
myoblasts
Muscle fibers have multiple flattened nuclei pressed against the inside of the sarcolemma. Their unusual multinuclear condition results from their embryonic development- several stem cells called WHAT fuse to produce each muscle fiber, with each myoblast contributing a nucleus to the mature fiber.
While the muscle rests...
calcium ions are no longer present at their attachment site.
Excitation causes?
Opening of voltage sensitive membrane calcium channels on the t-tubules
Which of the following is true? The greater the overlap of actin and myosin, the stronger the contraction. Overstretching a muscle will increase its tension. Optimal actin and myosin overlap will produce maximal contraction. The greatest amount of tension is achieved when actin and myosin do not overlap. Tension is great when actin and myosin overlap as much as they can.
Optimal actin and myosin overlap will produce maximal contraction.
quadratus lumborum
Origin: iliac crest Insertion: transverse processes of lumbar vertebrae L1-L4; lower margin of 12th rib
popliteus
Origin: lateral condyle of femur and lateral meniscus Insertion: proximal tibia
sternocleidmastoid
Origin: manubrium of sternum and medial clavicle Insertion: mastoid process; superior nuchal line of occipital bone
buccinator
Origin: molar region of maxilla and mandible Insertion: orbicularis oris
temporalis
Origin: temporal fossa Insertion: coronoid process of mandible
scalenes
Origin: transverse processes of cervical vertebrae Insertion: anterolateral portion of first two ribs
masseter
Origin: zygomatic arch and zygomatic bone Insertion: angle and ramus of mandible
levator labil sperioris
Origin: zygomatic bone and infraorbital margin of maxilla Insertion: skin and muscles of upper lip
In a fully contracted sarcomere, the actin myofilaments
Overlap.
Which of the following events occurs during the latent phase of a muscle twitch? Muscle fibers shorten. Cross-bridges form, move, release, and reform many times. The action potential is propagated from presynaptic to postsynaptic terminal. Calcium is pumped back into the sarcoplasmic reticulum. All of these occur in the latent phase.
The action potential is propagated from presynaptic to postsynaptic terminal.
Click on the "Short (mm)" button in the Journal to display a graph of your data. Look at your graph and determine the relationship between the amount of muscle shortening and weight
The amount of muscle shortening generally decreased as the weight was increased.
Which of the following is caused by ventricular contraction?
The atrioventricular valves close, and then the semilunar valves open. When the ventricles contract, the walls of the ventricles come together, releasing tension on the chordae tendineae. In addition, the pressure inside the ventricles greatly increases. The decrease in tension and the increase in pressure causes the atrioventricular valves to close. The increase in pressure also causes the semilunar valves to open into the ascending aorta and pulmonary trunk.
When the pressure in the ventricles becomes lower than the pressure of the atria?
The atrioventricular valves open
Ventricular systole causes
The atrioventricular valves to close , and then the semilunar valves to open
Explain the relationship between muscle length and tension via the Sliding Filament Theory
The degree of passive stretch (length) of the muscle determines the relationship between the thick and thin filaments. The amount of OVERLAP determines the number of potential cross bridges that may be formed. At short L, there is overlap of the thin filament into the region of the thick filament center with no mysoin heads or cross bridges. As the length increases to Lo, more and more possible cross bridges may be formed. When Lo is is exceeded, then there will be myosin heads in the center of the sacromere that can't bind to actin sites and the number of the potential cross bridges are reduced.
What is responsible for a graded response?
The combination of motor units and the frequency of APs generated.
Which one of the following statements about skeletal muscle contraction is incorrect? (p. 9)
The cytosolic concentration of Ca2+ in resting muscle is typically high.
What is a sarcomere? (1)
The distance between adjacent Z-lines
Which of the following is equivalent to the ventricular volume during isovolumetric contraction?
The end diastolic volume (EDV). Isovolumetric contraction occurs at the beginning of ventricular systole when the ventricular volume is at its maximum value−the end diastolic volume (EDV). Because no volume changes occur during isovolumetric contraction, ventricular volume remains at this value throughout the phase.
Describe the Isometric Length Tension Relationship at each key point.
a. A muscle at its passive length (i.e., not stretched at all) develops very little tension. b. As a muscle is stretched (i.e., its length progressively increased) up to some point (Point B on the graph), there is a corresponding increase in the developed tension. When there is perfect overlap between thin and thick filaments, we now can generate the maximum amount of tension. c. There is a optimal length (Lo) where the peak developed tension occurs (Po). That length occurs when the sarcomere length is between 2-2.2 . d. When the muscle length exceeds the Lo, then the developed tension begins to progressively decline (e.g., at Points C and D) steric hinderence can between protein in the thin filament can cause them not to overlap well. seen A If we stretch the sacromere too much, Ca no long stimulate the contraction, bc the thin and thick filaments don't even overlap, no contraction.
Which of the following statements describe histological characteristics of smooth muscle? presence of visible striations & single, centrally-located nuclei presence of visible striations & multiple peripheral nuclei absence of visible striations & single, centrally-located nuclei number of nuclei
absence of visible striations & single, centrally-located nuclei number of nuclei
What is the first step of muscle contraction?
acetyl choline released from lower motor neuron, binds to ligand-gated sodium channels (nicotenic receptors located on the postsynaptic membrane, specifically the motor end plate), causes sodium influx/depolarization and massive EPSP
The primary neurotransmitter at the neuromuscular junction is
acetylcholine
When the atria begin depolarizing, which of the following is occuring? A) ventricular filling B) ventricular ejection C) atrial filling D) atrial ejection
c.) atrial filling
calmodulin
calcium binding protein that is involved in contraction of smooth muscle and nonmuscle cells, calcium-calmodulin complex activate myosin light-chain kinase--enzyme responsible for phosphorylation of myosin
Which of the following is necessary for cross-bridge binding?
calcium binds to the troponin molecule.
