Chapter 9 muscle fibers and tissue
The sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated is known as the ___________. membrane hyperpolarization motor end plate potential resting potential membrane repolarization action potential
action potential An action potential is the result of a predictable sequence of electrical changes that occurs along the length of the sarcolemma. ...
dense irregular connective tissue surrounding the whole muscle.
epimysium
group or bundle of muscle fibers
fascicle
The thick filament is composed of what molecule?
myosin
fibrous connnective tissue around the fascicles
perimysium
in direct attachments where is the epimysium fused?
periosteum of the bone
muscle tension decreases to zero, muscle returns to its normal length (K+ leaves the muscle cell)
relaxation period
what attaches muscles to bones?
tendons
final trigger for contraction
Calcium ion
used in accelerating production of ATP, providing the phosphate needed for converting ADP to ATP. Pathway for producing ATP from ADP
Creatine phosphate
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 calmodulin Ca2+ myosin troponin
... Ca2+ Ca2+ combines with troponin, changes shape, and removes the blocking action of tropomyosin, allowing cross bridges to form.
The binding of what to the myosin head puts the cross bridge in its high-energy conformation?
ATP
What must bind to the cross bridge for it to disconnect from the actin molecule?
ATP
Which molecule is responsible for moving the calcium back into the terminal cisternae (sarcoplasmic reticulum)?
ATP
power source for contraction
ATP
The head of the myosin molecule binds to what molecule to form the cross bridge?
Actin
protein which has a kidney-like shape. thin filament
Actin
sheet-like connective tissue connecting muscle to bone/or muscle
Aponeurosis
Three words to describe cardiac muscle
cardiac, striated and involuntary
cross bridges are active-period of contraction (Na+ entering the cell)
contractile period
An entire skeletal muscle is surrounded by ___________. epimysium endomysium. tendon sheath perimysium sarcolemma
epimysium
What are the connective tissue sheaths from external to internal?
epimysium, perimysium, endomysium
a neuron and all the muscle fibers it supplies. Muscle fibers in a single motor unit are not clustered together but are spread throughout the muscle.
motor unit
A motor neuron and all the muscle fibers it supplies is called a(n) ____________. motor unit synaptic cleft neuromuscular junction motor end plate axon terminal
motor unit...
a fascicle of muscle fibers
muscle bundle
response of a motor unit to a single action potential (nerve input).
muscle twitch
another name for plasma membrane
sarcolemma
region of a myofibril between two successive Z discs. Smallest contratile unit of a muscle fiber. It is the contractural unit of muscle
sarcomere
another name for the cytoplasm of a muscle cell
sarcoplasm
Three words to describe skeletal muscle tissue
skeletal, striated and voluntary
Which of the following statements about smooth muscle is true? Fibers are small and spindle-shaped. It has branching fibers. Smooth muscle is striated and involuntary. Contractions are rapid and forceful. Nuclei are peripherally located in the fibers.
...Fibers are small and spindle-shaped. Smooth muscle fibers are small and spindle-shaped. Cardiac muscle has branching fibers and is striated and involuntary. Skeletal muscle has peripherally located nuclei and has rapid and forceful contractions.
Which of the following is NOT a characteristic of skeletal muscle contraction? It can contract for long periods of time without tiring. It contracts rapidly. It is voluntary. It can exert tremendous power.
...It can contract for long periods of time without tiring.
Which of the following statements is INCORRECT? The contractions of skeletal muscles pull on tendons and move elements of the skeleton. Skeletal muscle contractions help maintain body temperature. Skeletal muscles support the weight of some internal organs. Skeletal muscles form valves regulating the passage of substances through internal openings of the digestive and urinary tracts. Skeletal muscles are responsible for the pumping action of the heart.
...Skeletal muscles are responsible for the pumping action of the heart. The muscles that are responsible for the pumping action of the heart are the cardiac muscles.
Where does 95% of the energy needed for contraction come from during moderate exercise? aerobic respiration creatine phosphate lactic acid anaerobic glycolysis
...aerobic respiration Aerobic respiration provides 95% of energy during moderate exercise.
Which of the following does NOT occur during skeletal muscle contraction? Calcium binds to myosin heads. The I bands shorten and H zones disappear. Myosin heads bind to actin. Calcium concentration in the sarcoplasm increases. ATP is hydrolyzed.
...calcium binds to myocin heads
What is the cause of rigor mortis? calcium influx into the sarcoplasm after death diffusion of potassium out of the cell after death high levels of sodium in the cell after death breakdown of protein in the cell after death
...calcium influx into the sarcoplasm after death
Which one of the following binds calcium ions in a smooth muscle, causing contraction? myosin calmodulin actin tropomyosin troponin
...calmodulin Calmodulin causes smooth muscle contractions.
All of the following terms refer to the ability to receive and respond to a stimulus, EXCEPT ___________. contractility excitability responsiveness irritability
...contractility Contractility is the ability of a muscle to shorten forcibly when adequately stimulated.
Which of the following allows recoil of the muscle fiber when contraction ends? tropomyosin elastic filaments myosin troponin actin
...elastic filaments Elastic filaments maintain the organization of the A band and provide for elastic recoil when muscle contraction ends.
The dense layer of collagen fibers that surround an entire skeletal muscle is the ___________. perimysium fascicle endomysium epimysium tendon
...epimysium.
"Cross bridges" that link between the thick and thin filaments are formed by the ___________. F actin globular actin globular head of thick filaments tails of myosin filaments
...globular head of thick filaments
Which of the following is thought to be an autoimmune disease of acetylcholine receptors? myotonic dystrophy fibromyalgia myasthenia gravis muscular dysthrophy
...myasthenia gravis
A sarcomere is part of a(n) ___________. perimysium myofilament myofibril endomysium
...myofibril The sarcomere is the contractile unit of the myofibril.
In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and _________. thin filaments tropomyosin troponin actin myosin
...myosin
Each skeletal muscle fiber is controlled by a neuron at a single ___________. synaptic knob synaptic cleft neuromuscular junction transverse tubule sarcomere
...neuromuscular junction
The alternating contraction and relaxation of opposing layers of smooth muscle is referred to as ___________. isometric contraction peristalsis isotonic contraction automatic contraction
...peristalsis Peristalsis is the term used to describe the squeezing action produced when opposing layers of smooth muscle alternate contraction and relaxation.
Elasticity refers to the ability of a muscle fiber to ___________. shorten forcibly when adequately stimulated be stretched recoil and resume its resting length after being stretched receive and respond to a stimulus
...recoil and resume its resting length after being stretched Elasticity is the ability of a muscle fiber to recoil and resume its resting length after being stretched.
The refractory period in which the muscle will NOT contract if stimulated occurs during __________ of the muscle cell. hyperpolarization polarization repolarization depolarization
...repolarization The refractory period occurs during repolarization.
The space between the neuron and the muscle is the ___________. motor end plate M line motor unit synaptic knob synaptic cleft
...synaptic cleft The axonal ending and the muscle fiber do not actually touch and remain separated by a space called the synaptic cleft, which is filled with a gel-like substance rich in glycoprotein.
Which of the following characteristics is unique to smooth muscle? the ability of ATP to energize the sliding process the absence of striations response to stretch hyperplasia
...the absence of striations Only smooth muscle is non-striated.
Which of the following muscles is voluntary? the muscle in the wall of the urinary bladder the muscle that extends the arm at the elbow the muscle of the stomach the muscle in the wall of the heart
...the muscle that extends the arm at the elbow The muscle that extends the arm at the elbow is skeletal muscle and it is a voluntary muscle.
The term that means a continued mild or partial contraction of a muscle that keeps it healthy and ready to respond is muscle ___________. twitch tetanus stimulation summation tone
...tone Muscle tone is a state of partial, sustained contraction in a muscle that results from tetanic contraction of about 10% of the muscle fibers on a rotating basis. Tetanic contraction is sustained and forceful contraction that results from high-frequency stimulation from the nervous system. A muscle twitch is a brief, maximum contraction of a muscle in response to a stimulus.
The functional unit of contraction in a skeletal muscle fiber is the ____________. sarcolemma myofilament sarcomere myofibril sarcoplasmic reticulum
..sarcomere
What 4 characteristics enable muscle tissue to perform its duties?
Excitability, contractility, extensibility, elasticity
the lighter region in midsection of a muscle fiber
H zone
dark line formed by molecules of the protein moymesin. bisects the H zone in a muscle fiber.
M line
What does contractility mean?
ability to shorten forcibly when adequately stimulated
found only in skeletal muscle and stores oxygen. it's red, similar to hemoglobin
Myoglobin
protein shaped with long smooth tail and knob like heads, thick filaments
Myosin
What are the 3 types of muscle tissue?
Smooth, Cardiac, skeletal
darker area in middle of I band
Z disc or z line
what does elasticity mean?
ability of a muscle cell to recoil and resume its resting length after stretching.
What does responsiveness or excitability mean?
ability to receive and respond to a stimulus, that is, any change in the environment either inside or outside the body.
what does extensibility mean?
ability to return to normal shape and size
where is skeletal muscle found?
covering the bony skeleton
connective tissue that lies between neighboring muscles
deep fascia
What is the cause of rigor mortis?
depletion of ATP
What causes the sliding of the thin filament toward the middle of the sarcomere?
flexing of the cross bridge (power stroke)
granules of stored glycogen that provide glucose during muscle cell activity
glycosomes
The type of muscle contraction in which the muscle fibers produce increased tension, but the muscle neither shortens nor lengthens, is called _____________. tetany concentric isometric isotonic treppe
isometric Muscles that maintain upright posture are contracting isometrically. ...
Which of the following substances increases in quantity during repetitive muscle contraction during oxygen deficit? creatine phosphate adenosine triphosphate (ATP) lactic acid oxygen glucose
lactic acid ATP, CP, glucose, and oxygen all decrease during muscle contraction....
regarding muscle twitches; what is the time delay between stimulation and response (impulse is reaching its threshold)
latent period
rod like muscle fibers within a single muscle fiber that account for 80% of cellular vollume
myofibrils
red pigment that stores oxygen
myoglobin
regarding nerve and blood supply, what is found in each muscle?
one nerve, an artery, and one or more veins
4 muscle functions
producing movement, maintaining posture, stabilizing joints, generating heat
narrow ridge of connective tissue midway in shape between a tendon and an aponeurosis
raphe
Which of the following best describes the composition of the structure known as a triad in a skeletal muscle fiber? terminal cisterna, transverse tubule, and terminal cistern actin, troponin, and tropomyosin ATP, CP, and glycogen sarcolemma, sarcoplasm, and sarcoplasmic reticulum A band, I band, and H band
terminal cisterna, transverse tubule, and terminal cistern The triad refers to a set of three membranous channels and is formed by a single transverse tubule and two terminal cisternae, or elements of the sarcoplasmic reticulum. ...
regarding gross anatomy of skeletal muscle what has reticular connective tissue and wraps around each individual muscle fiber?
the Endomysium
Which of the following does NOT shorten during muscle contraction?
the thin fillament
What regulatory molecule on the thin filament covers the myosin head binding site on actin?
tropomyosin
Which molecule on the thin filament has a binding site for calcium?
troponin
Three words to describe smooth muscle
visceral, nonstriated, and involuntary
where is smooth muscle tissue found?
walls of hollow visceral organs. ie: stomach, bladder, respiratory passages