Unit II A & P Exam (Muscles)
In the contraction phase of a single muscle twitch, maximum tension is reached approximately how long after stimulation? 5 msec 25 msec 50 msec 15 msec
15 msec
muscle fiber
A cylindrical, multinucleate cell composed of numerous myofibrils that contracts when stimulated.
_______ is the length of time muscle contractions can be supported by glycolysis and existing energy reserves of ATP and creatine phosphate (CP). [Level 2]
Anaerobic endurance
role of Ca++
Calcium is the "key" that "unlocks" the active sites and starts a contraction. Calcium will bond to troponin.
What is "carboloading," and why do endurance athletes engage in this activity? [Level 2]
Carboloading" is the act of loading up on carbohydrates, typically the day before an athletic event, because they are rich sources of glucose. Aerobic endurance is determined by the availability of substrates for aerobic metabolism from the breakdown of carbohydrates, lipids, or amino acids. For endurance athletes, glucose is a preferred energy source because it provides the substrate for sustained low levels of muscular activity that is supported by mitochondrial activities.
Muscle Functions:
1) Produce body movements 2) Stabilize body positions 3) Store and move substances 4) Produce heat 5) Guard entrances & exits
T-tubules
Transverse tubular extensions of the sarcolemma that extend deep into the sarcoplasm to contact terminal cisternae of the sarcoplasmic reticulum
When a sarcomere contracts, the entire muscle contracts? T or F
True
M-line
_____ is located in the center of the sarcomere.
Each muscle begins at an origin, ends at a(n)_________ , and contracts to produce a specific action.
insertion
Part E How is acetylcholine (ACh) removed from the synaptic cleft? a) a reuptake pump on the axon terminal b) Acetylcholinesterase breaks it down. c) diffusion into the skeletal muscle cell
b) Acetylcholinesterase breaks it down.
What causes the release of calcium from the sarcoplasmic reticulum within a muscle cell? a) ATP b) actin c) arrival of an action potential d) protein complex
c) arrival of an action potential
Which structure found in cardiac muscle is labeled "D"? (Photo of cardiac muscle cell) a) nucleus b) pacemaker cells c) intercalated disc d) myofibril
c) intercalated disc
To what does the myosin head bind in order to form a cross bridge? a) protein complex b) sarcoplasmic reticulum c) calcium d) actin
d) actin
Myofibrils are made primarily of a) tropomyosin. b) ATP and ADP. c) epimysium. d) actin and myosin. e) troponin.
d) actin and myosin.
Which of the following muscles is named for its shape? erector spinae tibialis anterior deltoid pectoralis major biceps brachii
deltoid
The term used to describe muscular growth in response to usage is a) atrophy. b) muscular dystrophy. c) myopathy. d) multiple sclerosis. e) hypertrophy.
e) hypertrophy.
What are sarcomeres made up of?
thick and thin filaments
Which of the muscle twitch phases is labeled "C"? latent period resting phase contraction phase relaxation phase
...
Which portion of the sarcomere is labeled "B"? Z line I band A band H band
...
labeling of twitch/tension cycle
...
lactic acid
...
tetanus
...
The thick filaments of sarcomeres are contained in which band? I band Z line A band S band
A band
myoglobin
A globular protein found in muscle tissue that has the ability to bind oxygen. Myoglobin helps to store oxygen in the muscle for use in aerobic respiration (it does not move, just stays there). Muscles that participate in endurance activities (including cardiac muscle) have abundant supplies of myoglobin.
troponin
A globular protein that ssociated with tropomyosin as part of the thin filament of the sarcomere. Troponin binds Ca2+, which causes the conformaiton change in tropomyosin required to expose the myosin-binding sites on actin and initiate muscle contraction.
acetycholine
A neurotransmitter associated with voluntary movement, sleep and wakefulness.
actin
A protein found in muscle that together with myosin functions in muscle contraction
tropomyosin
A regulatory protein that, on a resting muscle fiber, covers myosin binding sites along the thin filament, preventing actin and myosin from interacting
Rigor mortis occurs due to the lack of what molecule? Sodium Acetylcholine ATP Calcium
ATP
Which muscles are involved in the action of chewing?
During chewing, contraction and relaxation of the buccinator muscles move food back across the teeth from the space inside the cheeks. The chewing motions are primarily produced by contractions of the masseter, assisted by the temporalis and the pterygoid muscles used in various combinations.
myofilaments
The contractile proteins, actin and myosin, of muscle cells
atrophy
Wasting away of tissue from lack of use, ischemia, or nutritional abnormalities
What does the term pulled groin usually mean for an athlete? [Level 1]
When an athlete suffers a pulled groin, the problem is a strain (a muscle tear or break) in one of the adductor muscles of the thigh (adductor magnus, adductor brevis, adductor longus, pectineus, and gracilis muscles).
A muscle that may either provide additional pull near the insertion or stabilize the point of origin is called ___________. a prime mover a synergist an agonist an antagonist
a synergist
Which of the following is one of the steps that ends a contraction? a) Acetylcholine is broken down by acetylcholinesterase. b) An action potential spreads across the entire surface of the muscle fiber. c) Sarcoplasmic reticulum absorbs sodium ions. d) Calcium ions bind to troponin. e) Acetylcholine binds to receptors on the sarcolemma.
a) Acetylcholine is broken down by acetylcholinesterase.
Which of the following parts of a neuromuscular junction is a specialized portion of the sarcolemma that contains receptors for acetylcholine? a) motor end plate b) synaptic knob c) axon terminal d) motor neuron e) synaptic cleft
a) motor end plate
The area between Z lines is the myofilament. a) sarcomere. b) myofibril. c) sarcolemma. d) sarcoplasmic reticulum.
a) sarcomere.
Smooth muscle tissue lacks __________. a) sarcomeres b) actin c) myosin d) actin, myosin, and sarcomeres
a) sarcomeres
What is each fascicle made up of?
muscle fibers
isometric
static - no movement
myogram
records strength of muscle contraction
The oblique muscles and the muscles form the muscular walls of the thoracic and abdominopelvic cavities between the first thoracic vertebra and the pelvis. [Level 2]
rectus
What is the functional unit of the muscle?
sarcomere
motor neuron
a cell that is specialized to conduct nerve impulses
Define and describe the events in complete tetanus.
Complete tetanus occurs when the rate of stimulation is increased until the relaxation phase is completely eliminated, producing maximum tension. In complete tetanus, action potentials are arriving so fast that the sarcoplasmic reticulum does not have time to reclaim calcium ions. The high calcium ion concentration in the cytoplasm prolongs the state of contraction, making it continuous.
Compare the type of contraction and energy source used for skeletal muscle fibers, cardiac muscle cells, and smooth muscle cells. [Level 2]
Contraction in skeletal muscle fibers has a rapid onset and can attain fatigue rapidly, and tetanus can occur. By contrast, cardiac muscle cells and smooth muscle cells have slower onset of contraction and are resistant to fatigue; the only difference between the two is that tetanus cannot occur in cardiac muscle cell. Skeletal muscle fibers at rest or at moderate levels of activity use aerobic metabolism, whereas at peak activity they use glycolysis (anaerobic metabolism) as the source of energy. Cardiac muscle cells obtain energy source through aerobic metabolism, usually using lipid or carbohydrate substrates. For smooth muscle cells, aerobic metabolism is the primary source of energy.
What is creatine phosphokinase, and what is its clinical significance? [Level 2]
Creatine phosphokinase (CPK or CK) is an enzyme that regulates the reaction that converts ADP (with creatine phosphate, CP) to ATP. When muscle cells are damaged, CPK leaks into the bloodstream. Thus, a high blood level of CPK usually indicates serious muscle (cardiac or skeletal) damage.
Describe the actions of the lungs during exercise. [Level 1]
During exercise, air moves into and out of the lungs more quickly, keeping pace with the increased rate of blood flow through the lungs.
What is fibrosis? [Level 1]
Fibrosis is the age-related process in which organs develop increasing amounts of fibrous connective tissue. In the muscular system, the process makes muscles less flexible, and the greater abundance of collagen fibers can restrict movement and circulation.
How does the level of muscle activity affect the level of energy use and the source of energy? [Level 3]
In a muscle at rest or at moderate levels of activity, aerobic metabolism in mitochondria can provide more than enough or most, respectively, of the ATP required to support muscle contraction. As long as sufficient oxygen is available, the mitochondria can meet the demand for ATP. At periods of peak activity, though, oxygen cannot diffuse into the muscle fiber fast enough to enable the mitochondria to produce the required ATP. As a result, the muscle cells must rely heavily on the anaerobic process of glycolysis to generate ATP.
Why do the elderly tend to overheat during exercise? [Level 1]
Individuals over age 65 tend to overheat because they cannot eliminate muscle-generated heat as effectively as younger people.
What do cell have?
Organelles - nucleus, mitochondria, golgi apparatus, endoplasmic reticulum, cell membrane, ribosomes, etc..
myofibrils
SKELETAL MUSCLE FIBERS
Describe skeletal muscles as organs, and indicate their relationship to the skeletal system.
Skeletal muscles are organs composed primarily of skeletal muscle tissue, but they also contain connective tissues, nerves, and blood vessels. The skeletal muscles are directly or indirectly attached to the bones of the skeleton.
Openings scattered across the surface of the sarcolemma lead into a network of narrow structures called the _____________.
T tubules (or transverse tubules)
glycolysis
The anaerobic cytoplasmic breakdown of glucose into two three carbon molecules of pyruvate, with a net gain of two ATP molecules
sarcoplasmic reticulum
The form of endoplasmic reticulum found in striated muscle fibers. ENDO=A membrane network within the cytoplasm of cells involved in the synthesis, modification, and transport of cellular materials.
How do skeletal muscle contractions cause movement of the bones? a) They pull on fibroses. b) All of the above statements are true. c) They pull on tendons. d) They pull on ligaments.
They pull on tendons.
When the biceps brachii muscle flexes the elbow, it acts as a(n) __________. antagonist fixator agonist synergist
agonist
Smooth muscle forms __________. bundles sheets sheaths around other tissues all of the above
all of the above
Botulism is caused by a bacterial toxin that prevents the release of ACh at the axon terminals. What happens as a result? a) Muscles are not capable of relaxing. b) Muscles are not capable of contracting. c) Muscles contract at a slow rate. d)Muscles contract too fast.
b) Muscles are not capable of contracting.
The skeletal muscles store calcium ions in the terminal cisternae of the a) sarcosome. b) sarcolemma. c) sarcoplasmic reticulum. d) sarcoplasm. e) sarcomere.
c) sarcoplasmic reticulum.
Myosin molecules are found in which of the following structures? a) sarcoplasmic reticulum b) sarcolemma c) thick filaments d) thin filaments e) T tubules
c) thick filaments
During which phase is the stimulus frequency so high that the relaxation phase is eliminated? recruitment complete tetanus recovery incomplete tetanus a twitch
complete tetanus
Which of the following terms defines a force that tends to push an object away from the source of the applied force? twitch tension compression resistance
compression
During exercise, the rate and ________ of respiration increase. [Level 1]
depth
A bundle of muscle fibers is called a(n)___________ .
fascicle
A muscle ________ contains a sarcolemma, sarcoplasm, myofilaments, and myofibrils. fiber motor end plate T-tubule myofibril intercalated disc
fiber
Which is of the following concepts is defined as the maximum amount of tension produced by a particular muscle or muscle group? [Level 1] force endurance tetanus fatigue
force
Calcium ions are released from the sarcoplasmic reticulum during the ________ phase of contraction. contraction recovery twitch relaxation latent
latent
What are muscle fibers made up of?
myofibrils
Muscles whose names contain the root cervi- would be found in the neck. chest. groin. head. abdomen.
neck
glycogen
one form in which body fuel is stored
What is the I Band of a sarcomere?
only thin filament
isotonic
produces a movement
The _________ of decline in muscular performance is the same in all people, regardless of their exercise patterns or lifestyle. [Level 1]
rate
creatine phosphate
reacts with ADP in contraction process
Which of the following appendicular muscles originates on the anterior superior spine of ilium? pectineus gracilis semimembranosus sartorius
sartorius
The layers of skeletal muscle in the abdominal wall and the pelvic floor function in __________. a) supporting the skeleton b) shielding internal tissues from injury c) supporting the upper limbs d) none of the above
shielding internal tissues from injury
As a skeletal muscle contraction is initiated, acetylcholine binding alters the motor end plate membrane's permeability to acetylcholinesterase. sodium ions. chloride ions. calcium ions. potassium ions.
sodium ions.
In the digestive and urinary systems, rings of smooth muscles called regulate movement along internal passageways. [Level 1]
sphincters
Sliding Filament Model
states that the thick and thin filaments slide past each other so that their degree of overlap increases.
Acetylcholinesterase is found within the ________. myofibril sarcolemma nucleus sarcomere synaptic cleft
synaptic cleft
No muscles that move the hand and fingers originate on the phalanges, and only extend across the distal joints of the fingers. [Level 2]
tendons
recruitment
the activation of more and more motor units
summation
the addition of one twitch to another
Which of the following muscles dorsiflexes the ankle? [Level 1] tibialis anterior fibularis gastrocnemius tibialis posterior soleus
tibialis anterior
Aerobic endurance is determined by the availability of substrates for aerobic metabolism from the breakdown of which of the following substances? [Level 1] lipids carbohydrates amino acids all of the above
all of the above
Skeletal muscles encircle openings to provide voluntary control over __________. a) urination b) swallowing c) defecation d) all of the above
all of the above
A broad sheet formed by the collagen fibers of the connective tissues of skeletal muscle is called ___________. a) a fascicle b) an aponeurosis c) endomysium d) epimysium e) perimysium
an aponeurosis
Which of the following structures controls individual muscle fibers? a) a fascicle b) an aponeurosis c) epimysium d) an axon (or nerve fiber)
an axon (or nerve fiber)
At rest, a skeletal muscle fiber produces more ATP than it needs; the excess ATP then transfers energy to creatine, which results in the creation of another high-energy compound called . [Level 2]
creatine phosphate
A triad is ___________. a) a pair of T tubules and a terminal cisterna of the SR b) an actin molecule and two surrounding myosin molecules c) a pair of thick filaments with a T tubule between them d) a pair of terminal cisternae of the SR with a T tubule between them
d) a pair of terminal cisternae of the SR with a T tubule between them
The muscles of the neck ___________. a) control the position of the larynx b) tense the floor of the mouth c) provide a stable foundation for the tongue and pharyngeal muscles d) perform all of the above functions
d) perform all of the above functions
Which of the following structures is a specialized form of smooth endoplasmic reticulum that forms a tubular network around each myofibril? a) transverse tubules b) sarcomere c) sarcoplasm d) sarcoplasmic reticulum
d) sarcoplasmic reticulum
The structure that ties adjacent muscle fibers together is the __________. epimysium fascicle endomysium perimysium
endomysium
Each cell in skeletal muscle tissue is a single ___________.
fiber
In which of the following phases of a twitch is no tension produced by the muscle fiber? stimulus contraction phase relaxation phase latent period
latent period
Which of the following stabilizes the positions of bones and joints by tensing and firming the muscle? muscle tone muscle recruitment motor units isometric contractions
muscle tone
The amount of tension produced by an individual muscle fiber depends solely upon which of the following factors? the number of pivoting cross-bridges the length of the contraction phase the presence of summation all of the above
the number of pivoting cross-bridges
Labeling parts of the muscle
...
sarcomere
Contractile unit of muscle
What is the H Zone of a sarcomere?
area that has only thick filament
Slow muscle fibers contain the red pigment __________, a globular protein that is structurally related to hemoglobin, the oxygen-carrying pigment found in blood. [Level 1]
myoglobin
myosin
the commonest protein in muscle
sarcoplasm
the cytoplasm of a striated muscle fiber
neuromuscular junction
the junction between a nerve fiber and the muscle it supplies
anaerobic
without oxygen
Continuous muscle contractions maintain body position and ________.
posture
What are the organizational levels of skeletal muscle?
1) Muscle - surrounded by EPIMYSIUM (layer of connective tissue) 2) Fascicle - many fascicles make up a whole skeletal muscle. Surrounded by connective tissue called PERIMYSIUM 3) Muscle Cell (Muscle Fiber) - many muscle cells are packed into a fascicle. Surrounded by ENDOMYSIUM 4) Myofibril - numerous myofibrils are contained in a muscle cell or muscle fiber. 5) Myofilaments: thick and thin myofilaments. Many myofilaments bundled together make up a single myofibril.
What are the 3 layers of connective tissue in muscles:
1) epimysium - surrounds the entire muscle 2) perimysium - surrounds the fascicle. Perimysium also contains blood vessels and nerves that supply the fascicles 3) endomysium - surrounds each muscle fiber (cell)
The 3 types of muscle tissue, skeletal, cardiac, and smooth can be distinguished by:
1) shape 2) number of nuclei 3) position of nuclei 4) presence of striations 5) under voluntary or involuntary control
3 types of muscle:
1) skeletal - striated and voluntary 2) Cardiac - striated and involuntary 3) Smooth - non-striated and involuntary
Describe the six interlocking steps of the contraction process.
1)The contraction cycle starts when calcium ions arrive in the zone of overlap. 2)The active site is exposed following the binding of calcium ions to troponin. 3)The myosin cross-bridge forms and attaches to the exposed active site on the thin filaments. 4)The attached myosin head pivots toward the center of the sarcomere, causing the release of ADP, and a phosphate group. 5)The cross-bridges detach when the myosin head binds another ATP molecule. 6)The detached myosin head is reactivated as it splits the ATP and captures the released energy.
For each pyruvic acid molecule broken down in the TCA cycle (or Krebs cycle, or citric acid cycle), the cell gains how many ATP molecules? 2 8 17 34
17
Which of the following statements describes the cause for the cessation of an action potential? Acetylcholinesterase breaks down acetylcholine. Calcium ions bind to troponin. Acetylcholine is released by the synaptic terminal. The sarcoplasmic reticulum releases stored calcium ions.
Acetylcholinesterase breaks down acetylcholine.
Describe the effects of exercise on the cardiovascular system. [Level 1]
During exercise, increases in heart rate, and dilation of blood vessels in active muscles and in the skin, speed the delivery of oxygen and the removal of carbon dioxide at the muscle, and bring heat to the skin for radiation into the environment.
What is a muscle fiber?
It is a muscle cell.
What is sarcoplasm?
It is the cytoplasm of our muscle cells. Contains ATP.
muscle fatigue
Muscle fatigue is caused by the exhaustion of energy reserves or the decline in PH due to the production and dissociation of lactic acid
What important roles do blood vessels play in skeletal muscle contraction?
Skeletal muscle contraction requires tremendous amounts of energy, and the blood vessels coursing along the connective tissues of the epimysium and perimysium deliver the necessary oxygen and nutrients, and carry away the metabolic wastes generated by active skeletal muscles.
Which of the following statements describes how muscles help maintain homeostasis? Skeletal muscles are responsible for guarding the openings of the digestive and urinary tracts. Skeletal muscle contractions help maintain body temperature. Skeletal muscles are responsible for the pumping action of the heart. The contractions of skeletal muscles pull on tendons and move elements of the skeleton. Skeletal muscles support the weight of some internal organs.
Skeletal muscle contractions help maintain body temperature.
What is a Z disc of a sarcomere?
The beginning and end of a sarcomere. Attached to interconnecting proteins. Its the protein that separates sarcomeres.
Identify and describe the actions of the muscles that move the forearm and wrist but do not originate on the humerus. [Level 1]
The biceps brachii and the long head of the triceps brachii originate on the scapula and insert on the bones of the forearm. Although their contractions can have a secondary effect on the shoulder, their primary actions are at the elbow. The triceps brachii extends the elbow when, for example, one does pushups. The biceps brachii both flexes the elbow and supinates the forearm. With the forearm pronated, the biceps brachii cannot function effectively. As a result, flexion of the elbow is strongest with a supinated forearm.
ATP cycle
The complete breakdown of organ substrates into carbon dioxide and water; a process that yields large amounts of ATP but requires mitochondria and oxygen
aerobic metabolism
The complete breakdown of organic substrates into carbon dioxide and water; a process that yields large amounts of ATP but requires mitochondria and oxygen
zone of overlap
The zone of overlap is the point where actin myofilaments overlay the myosin myofilaments as it (actin) gets pulled towards the m-line (mid-point of sarcomere). The zone of overlap increases during muscle contraction, resulting in the shortening of the muscle.
Which of the following is NOT a function of skeletal muscles? a) Balance body temperature b) Maintain body posture c) Contraction of the heart d) Produce bone movement
c) Contraction of the heart
ATP
a nucleotide derived from adenosine that occurs in muscle tissue The major source of energy for cellular reactions
motor unit
a single motor neuron and all the muscle fibers it innervates.
Which of the following pairs are mismatched? a) T tubules; centrioles b) sarcolemma; plasma membrane c) sarcoplasmic reticulum; smooth endoplasmic reticulum d) sarcoplasm; cytoplasm
a) T tubules; centrioles
Which of the following statements is FALSE? a) The more muscle fibers a motor unit contains, the finer the movement. b) Muscle tone exists when muscles contract with no movement. c) A motor unit is a single motor neuron and all the muscle fibers it innervates. d) Atrophy may result when muscles are not regularly stimulated.
a) The more muscle fibers a motor unit contains, the finer the movement.
Unlike skeletal muscle tissue, smooth muscle tissue ________. a) is involuntary, lacks sarcomeres, and is not striated b) is involuntary, contains thick and thin filaments, and is not striated c) is involuntary, contains sarcomeres, and is not striated d) is involuntary, contains sarcomeres, and is striated
a) is involuntary, lacks sarcomeres, and is not striated
Exhaustion of energy reserves or decline in pH due to production and dissociation of lactic acid causes a) muscle fatigue. b) the striated appearance of skeletal muscle. c) muscle contraction. muscle relaxation. the conduction of neural information to the muscle fiber.
a) muscle fatigue.
A sheath of connective tissue surrounding a bundle of striated muscle a) perimysium b) endomysium c) epimysium d) sarcolemma e) sarcoplasmic reticulum
a) perimysium
The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell? a) sarcoplasmic reticulum b) synaptic cleft c) within the sarcolemma d) cytosol
a) sarcoplasmic reticulum
Most of the ATP needed by muscle cells is provided through ________. creatine phosphate reserves anaerobic metabolism aerobic metabolism glycolysis
aerobic metabolism
sarcolemma
an extensible membrane enclosing the contractile substance of a muscle fiber
Muscles whose actions oppose one another are referred to as ________. prime movers synergists antagonists agonists
antagonists
Intercalated discs __________. [Level 1] contain tight junctions that allow the rapid passage of action potentials from cell to cell are specialized sites of contact between cardiac muscle cells are attached to microfilaments, allowing the cells to "pull together" quite efficiently all of the above
are specialized sites of contact between cardiac muscle cells
What is the Zone of overlap of a sarcomere?
area that contains all of it
The ________ contains vesicles filled with acetylcholine. synaptic cleft transverse tubule motor end plate axon terminal neuromuscular junction
axon terminal
The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur? a) Binding causes potassium voltage-gated channels to open in the motor endplate. b) Binding of the neurotransmitter causes chemically-gated, sodium channels to open in the motor end plate. c) Binding causes chemically-gated, potassium channels to open in the motor end plate. d) Binding causes voltage-gated, sodium channels to open in the motor endplate.
b) Binding of the neurotransmitter causes chemically-gated, sodium channels to open in the motor end plate.
Which of the following muscles is named according to the body region in which it is found and its shape? a) Temporalis b) Orbicularis oculi c) Gluteus maximus d) Tibialis anterior
b) Orbicularis oculi
Which of the following does NOT occur in the sarcomere during muscle contraction? a) The H band decreases. b) The Z-lines move further apart. c) The I band gets smaller. d) The width of the A band remains the same.
b) The Z-lines move further apart.
Part A In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter? a) dopamine b) acetylcholine (ACh) c) norepinephrine d) serotonin
b) acetylcholine (ACh)
When a calcium ion binds to troponin: a) active sites on actin are exposed. b) actin heads will bind to myosin. c) muscle relaxation occurs. d) acetylcholine is released. e) active sites on myosin are exposed.
b) actin heads will bind to myosin.
Skeletal muscle fibers differ from "typical cells" in that these muscle fibers a) lack mitochondria. b) have many nuclei. c) contain endoplasmic reticulum. are very small. d) lack a plasma membrane
b) have many nuclei.
What stops the further binding of actin to myosin once an action potential stops? a) release of ADP and Pi from the myosin head b) return of calcium to the sarcoplasmic reticulum c) lack of available ATP
b) return of calcium to the sarcoplasmic reticulum
The enzyme acetylcholinesterase causes acetylcholine to break down. be secreted. bond to actin. form cross-bridges. synthesize.
break down
Which of the following is ranked from smallest to largest? a) Sarcomere, H-band, muscle fiber, myofibril, fascicle, muscle b) Muscle, fascicle, muscle fiber, myofibril, sarcomere, H-band c) H-band, sarcomere, myofibril, muscle fiber, fascicle, muscle d) Muscle, fascicle, myofibril, muscle fiber, H-band, sarcomere
c) H-band, sarcomere, myofibril, muscle fiber, fascicle, muscle
In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases acetylcholinesterase. calcium ions. sodium ions. potassium ions. acetylcholine.
calcium ions.
Which statement regarding skeletal muscle is true? a) Skeletal muscles do not contain nervous tissue. b) Skeletal muscles do not contain connective tissue. c) Skeletal muscles do not maintain body temperature. d) Skeletal muscles contain blood vessels. e) Skeletal muscles are directly, but not indirectly, attached to bones.
d) Skeletal muscles contain blood vessels.
What causes the myosin head to disconnect from actin? a) binding of calcium b) hydrolysis of ATP c) binding of the protein complex d) binding of ATP
d) binding of ATP
What causes the myosin binding sites to be exposed? a) hydrolysis of ATP bound to the myosin head b) release ADP and Pi from the myosin head c) binding of ATP to the myosin head d) binding of calcium to the protein complex
d) binding of calcium to the protein complex
When an action potential arrives at the axon terminal of a motor neuron, which ion channels open? a) chloride channels b) potassium channels c) sodium channels d) calcium channels
d) calcium channels
What means of membrane transport is used to release the neurotransmitter into the synaptic cleft? a) a protein carrier b) a channel c) simple diffusion across the plasma membrane d) exocytosis
d) exocytosis
What energizes the power stroke? a) action potential b) calcium c) binding of ATP d) hydrolysis of ATP
d) hydrolysis of ATP
Unlike skeletal tissue, cardiac muscle tissue ________. a) is striated, and contains intercalated discs and myoglobin b) is voluntary, and contains intercalated discs and myglobin c) is involuntary, striated, and does not contain myoglobin d) is involuntary, and contains branched cells and intercalated discs
d) is involuntary, and contains branched cells and intercalated discs
Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur? a) complete tetanus b) tension plateau c) latency d) resting period e) incomplete tetanus
e) incomplete tetanus
What is the A Band of a sarcomere?
entire length of thick filament
A layer of collagen fibers that surrounds an entire muscle is called perimysium. endomysium. sarcomere. sarcolemma. epimysium.
epimysium.
Which of the following processes occurs at the skin surface and removes the excess heat generated by muscular activity? [Level 1] evaporation dilation condensation fibrosis secretion
evaporation
What is each muscle made up of?
fascicles
Muscle contractions require energy, some of which is converted to ____________ when used in the body.
heat
hypertrophy
increase in muscle diameter
hypertrophy
increase in the size of tissue without cell division
During exercise, blood vessels in the skin dilate, and sweat gland secretion _________. [Level 1]
increases
As you unsuccessfully attempt to lift the 300-pound weights off the ground, you are demonstrating ________. isometric contraction hypertonic contraction hypotonic contraction isotonic contraction pg 206
isometric contraction
When one is standing for long periods, a slight _________ rotation of the tibia can lock the knee in the extended position. [Level 2]
lateral
muscle tone
no definition
The less-movable end of a skeletal muscle is the proximal end. belly. distal end. origin. insertion.
origin
Which shoulder muscle inserts on the coracoid process of the scapula and elevates the ribs if the scapula is stationary? [Level 1] levator scapulae rhomboid muscles trapezius pectoralis minor serratus anterior subclavius
pectoralis minor
Which of the following functions is NOT characteristic of skeletal muscle? supporting soft tissues producing blood cells maintaining body temperature guarding entrances and exits
producing blood cells
What are the five primary functions of skeletal muscles?
producing movement of the skeleton; maintaining posture and body position; supporting soft tissues; guarding entrances and exits; maintaining body temperature
myoglobin
protein found in muscle cells
Lactic acid is recycled by converting it to which of the following compounds? ATP glucose glycogen pyruvic acid
pyruvic acid
In the lower lumbar and sacral regions, the border between the longissimus and iliocostalis muscles is indistinct, and these muscles are sometimes known as the _______ muscles.
sacrospinalis
The _________ is the smallest functional unit of the muscle fiber.
sarcomere
What are myofibrils made up of?
sarcomeres - the functional unit of the muscle
During the triggering of a muscular contraction, calcium ions are released by the __________when the muscle fiber is stimulated by the associated motor neuron.
sarcoplasmic reticulum
When an injury occurs in the elderly, repair capabilities are limited, and __________formation is the usual result. [Level 1]
scar tissue
sarcoplasmic reticulum
the endoplasmic reticulum of cardiac muscle and skeletal striated muscle that functions especially as a storage and release area for calcium
What is the source of most of the calcium ions that enter smooth muscle cells to trigger contractions? [Level 1] the rough endoplasmic reticulum CaCl the extracellular fluid the sarcoplasmic reticulum
the extracellular fluid
threshold stimulus
the membrane potential at which at which an action potential begins
The reduction in size of skeletal muscle reflects a decrease in ___________. [Level 1] the number of myofibrils the diameter of myofibrils the diameter, number, and length of myofibrils the length of myofibrils
the number of myofibrils
What is the function of the transverse tubule? to store sodium ions to produce myofibrils to allow cross-bridge attachment to transmit electrical impulses to the cell's interior the storage of calcium ions
to transmit electrical impulses to the cell's interior
Tropomyosin strands are held in position by which of the following? actin molecules troponin molecules myosin molecules calcium ions ATP molecules
troponin molecules
A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a(n) ________. twitch complete tetanus latent period incomplete tetanus summation
twitch
What is a motor unit? Explain how its size relates to its level of control of movement. [Level 2]
A motor unit consists of all the muscle fibers controlled by a single motor neuron. The relationship between a motor unit's size (whether it consists of a single muscle fiber, or thousands of muscle fibers) and the fineness of control of movement is an inverse one: The more muscle fibers that are controlled by a single motor neuron, the less precise is the control.
Briefly describe the events that occur during the production of an action potential in a skeletal muscle fiber.
An action potential, or electrical impulse, arrives at the synaptic terminal. Vesicles then release the neurotransmitter acetylcholine (ACh) into the synaptic cleft. The ACh molecules bind to ACh receptors on the sarcolemma at the motor end plate. As a result, the action potential spreads over the entire surface of the sarcolemma and travels down all of the T tubules toward the terminal cisternae, triggering a sudden, massive release of calcium ions.
Which of the following statements describe a response of an organ system to exercise? Blood vessels in the skin dilate to allow heat loss. The nervous and endocrine systems exert no control over heart rate, respiratory rate, and sweat gland activity. Carbon dioxide is received by the cardiovascular system. All of the above statements are correct.
Blood vessels in the skin dilate to allow heat loss.
Explain the role of calcium in muscle contraction.
Calcium is the "key" that "unlocks" the active sites and starts a contraction. When calcium ions bind to the protein troponin, it changes shape, swinging the tropomyosin away from the active sites. Myosin-actin binding can then occur, and a contraction begins. (The terminal cisternae of the sarcoplasmic reticulum are the source of the calcium that triggers muscle contraction.)
Compare and contrast fast and slow fibers structurally and functionally. [Level 2]
Fast fibers respond to stimulation in 0.01 second or less. They are large in diameter and contain densely packed myofibrils, large reserves of glycogen, and relatively few mitochondria. They produce rapid and powerful contractions of relatively short duration, and are supported by glycolysis. Slow fibers, by contrast, are smaller in diameter and take three times as long to contract after stimulation. Specializations such as an extensive capillary supply, abundant mitochondria, and high concentrations of myoglobin enable them to contract for long periods of time.
Discuss the neural control of smooth muscle cells. [Level 2]
Many smooth muscle cells are not innervated by motor neurons, and the muscle cells contract either automatically (in response to pacesetter cells) or in response to environmental or hormonal stimulation. When smooth muscle fibers are innervated by motor neurons, the neurons involved are not under voluntary control.
Discuss how the actions of muscles may be described in two ways. [Level 1]
Muscle actions may be described in terms of the bone, or structure, affected. For example, the biceps brachii muscle is said to perform "flexion of the forearm." Alternatively, muscle actions may be described in terms of the joint involved. Thus, the biceps brachii muscle is said to perform "flexion at (or of) the elbow." Most anatomy texts and specialists in human motion (kinesiologists) use the second approach.
Which of the following statements is true regarding the effects of aging on the muscular system? Regular exercise improves the quality of life at all ages. Exercise prolongs life expectancy. Performance declines at a faster rate in people who do not exercise regularly. All of the above statements are true.
Regular exercise improves the quality of life at all ages
Describe how a tendon's structure aids in its function in muscular contractions.
Tendons are bands of collagen fibers that attach skeletal muscles to bones. Tendon fibers are firmly interwoven into the periosteum of the bone, such that any contraction of a muscle exerts a pull on its tendon, and in turn on the attached bone.
Describe the axial musculature's general organization and function(s). [Level 2]
The axial musculature, which arises on the axial skeleton, positions the head and spinal column and also moves the rib cage, assisting in the movements that make breathing possible. It does not play a role in movement or support of the pectoral or pelvic girdles or appendages. This division of the muscular system contains roughly 60 percent of the skeletal muscles in the body.
Describe the mechanism of the sliding filament theory.
The mechanism responsible for sliding filaments involves the binding of the myosin heads of thick filaments to active sites on thin filaments. When they connect thick filaments and thin filaments, the myosin heads are called cross-bridges, which bind to the active sites. This binding causes the cross-bridge to pivot toward the center of the sarcomere, pulling the thin filament in the same direction. The cross-bridge then detaches and returns to its original position, ready to repeat a cycle of "attach, pivot, detach, and return," like a person pulling in a rope one-handed.
What is the perineum, and what is its function? [Level 1]
The perineum, the floor of the pelvic cavity, is formed by a broad sheet of muscles that connects the sacrum and coccyx to the ischium and pubis. These muscles support the organs of the pelvic cavity, flex the coccyx, and control the movement of materials through the urethra and anus.
Which of the following features is NOT a basis for muscle terminology? a muscle's fascicular count a muscle's primary function orientation of the muscle fibers a muscle's origin and insertion regional location of the muscle none of the above
a muscle's fascicular count
Which of the following phrases best describes the cyclical actions of a myosin cross-bridge during a muscle contraction? a) "attach, pivot, detach, and return" b) "attach, detach, pivot, and return" c) "activate, attach, pivot, and detach" d) "activate, pivot, detach, and attach"
a) "attach, pivot, detach, and return"
Regarding flexion at the elbow joint, the primary action of the triceps brachii muscle is considered to be __________. a) antagonistic b) agonistic c) synergistic
a) antagonistic
Which organ system directs the responses of other organ systems during exercise? a) endocrine system b) integumentary system c) cardiovascular system d) respiratory system
a) endocrine system
Which of the following structures is composed of a layer of collagen fibers that separates a muscle from surrounding tissues and organs? a) endomysium b) an aponeurosis c) a fascicle d) perimysium e) epimysium
a) endomysium
Which muscle functions in abduction of the wrist? a) flexor carpi radialis b) extensor carpi ulnaris c) flexor carpi ulnaris d) brachioradialis
a) flexor carpi radialis
In aerobic metabolism, the maximum rate of ATP generation within mitochondria is limited by the availability of ___________. a) oxygen b) carbon dioxide c) small organic substrate molecules d) ADP e) phosphate ions
a) oxygen
Cardiac muscle tissue contracts without neural stimulation, a property called_________ .
automaticity
Which of the following statements regarding smooth muscle is true? a) Actin and myosin filaments are rigidly organized. b) Contraction occurs over a greater range of lengths than occurs in cardiac muscle or skeletal muscle. c) Most of the calcium ions used in smooth muscle contraction are derived from the sarcoplasmic reticulum. d) All smooth muscle cells are innervated by motor neurons.
b) Contraction occurs over a greater range of lengths than occurs in cardiac muscle or skeletal muscle.
Which of the following statements concerning the recovery period of muscle activity is true? a) Heat is gained. b) Lactic acid removal occurs. c) The metabolic activity focuses on the production of lactic acid. d) Glycolysis occurs at a high rate.
b) Lactic acid removal occurs.
Which of the following structures is composed of proteins that connect the central portions of each thick filament to its neighbors? a) I band b) M line c) H band d) A band e) Z line
b) M line
Which of the following trunk muscles depresses the ribs? a) transversus abdominis b) external obliques, internal obliques, and rectus abdominis c) rectus abdominis d) external oblique e) internal oblique f) external intercostals
b) external obliques, internal obliques, and rectus abdominis
The sudden rush of which ion into the sarcoplasm produces an action potential in the sarcolemma? a) calcium b) sodium c) phosphate d) magnesium
b) sodium
During the start of a skeletal muscle contraction, calcium binds to which molecule? a) G-actin b) troponin c) F-actin d) tropomyosin
b) troponin
Which of the following statements correctly defines tension? a) It is a force that tends to push an object away from the source of the force. b) It is a passive force that opposes movement. c) It is a force applied to an object that tends to pull the object toward the source of the force. d) It is a single stimulus-contraction-relaxation sequence in a muscle fiber.
c) It is a force applied to an object that tends to pull the object toward the source of the force.
Which of the following muscles is named according to the body region in which it is found and its muscle fiber orientation? a) Deltoid b) Radialis anterior c) Rectus abdominis d) Gluteus maximus
c) Rectus abdominis
Which of the following statements regarding fast fibers is true? a)They use the breakdown of carbohydrates, lipids, and amino acids for energy. b) Their power comes from aerobic metabolism. c) Their power comes from the anaerobic process of glycolysis. d) None of the above statements are true.
c) Their power comes from the anaerobic process of glycolysis.
Which of the following statements concerning slow fibers is NOT true? a) They contain a large number of mitochondria. b) They contain a more extensive network of capillaries. c) They contain large glycogen reserves. d) They contain myoglobin. e) All of the above statements are characteristics of slow fibers.
c) They contain large glycogen reserves.
Which of the following structures surrounds each skeletal muscle fiber and ties adjacent muscle fibers together? a) epimysium b) aponeurosis c) endomysium d) perimysium
c) endomysium
With the exception of the platysma and the________ , the complete name of every muscle includes the word muscle. [Level 1]
diaphragm
Of the following list, which item(s) is/are primary function(s) of skeletal muscle? A) produce movement of the skeleton B) guard entrances and exits C) maintain body temperature D) support soft tissues E) all of the above
e) all of the above
Which of the following changes in the muscular system result(s) from aging? a) lower tolerance for exercise b) limited repair capabilities c) increased amounts of fibrous connective tissue in skeletal muscles d) tendency to fatigue rapidly e) all of the above
e) all of the above
During active-site exposure, calcium ions bind to which of the following? a) actin b) myosin c) the sarcolemma d) the sarcoplasmic reticulum e) troponin
e) troponin
There are no slow fibers in muscles of the ___________. [Level 1] foot and hand foot and eye hand and eye hand eye foot
hand and eye
Which muscle or muscle group of the spine inserts onto the processes of cervical vertebrae? a) splenius capitis b) iliocostalis, longissimus, and spinalis groups c) spinalis group d) longissimus group e) semispinalis capitis f) iliocostalis group
iliocostalis, longissimus, and spinalis groups
A muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in __________. incomplete tetanus twitch summation latency complete tetanus
incomplete tetanus
Which of the following muscles acts to depress the ribs? internal and external intercostals external intercostals internal intercostals transversus abdominis
internal intercostals
Muscle fatigue __________. [Level 1] is not caused by the exhaustion of energy reserves is caused by the buildup of lactic acid will occur until glycogen and other reserves such as lipids and amino acids are depleted all of the above
is caused by the buildup of lactic acid
In a(n) contraction, the muscle as a whole does not change length, and the tension produced never exceeds the resistance.
isometric
The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the __________ .
oxygen debt
Which property of the sarcolemma is affected by the neurotransmitter acetylcholine? contractility regeneration elasticity permeability cellularity
permeability
The ________ is a narrow space that separates the synaptic terminal from the sarcolemma of the motor end plate.
synaptic cleft
A myogram is a graph of __________ development in a muscle during a twitch. [Level 2]
tension
