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Committee Exam 4 > Skeletal Muscles Physiology > Flashcards

Skeletal Muscles Physiology Flashcards

1
Q

What is the name of the functional unit of skeletal muscle?
a) Sarcomere
b) Myofibril
c) Muscle fiber
d) Myosin

A

Sarcomere

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2
Q

Which protein is responsible for the sliding of actin and myosin filaments during muscle contraction?
a) Troponin
b) Tropomyosin
c) Myosin
d) Actin

A

Actin

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3
Q

The A band of the sarcomere contains:
a) Only actin filaments
b) Only myosin filaments
c) Both actin and myosin filaments
d) None of the above

A

Both actin and myosin filaments

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4
Q

Which protein blocks the myosin-binding sites on actin filaments in a resting muscle?
a) Troponin
b) Tropomyosin
c) Myosin
d) Actin

A

Tropomyosin

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5
Q

What is the role of calcium ions in muscle contraction?
a) Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the myosin-binding sites on actin filaments.
b) Calcium ions bind to myosin, causing a conformational change that allows it to bind to actin filaments.
c) Calcium ions act as a fuel source for muscle contraction.
d) None of the above.

A

Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the myosin-binding sites on actin filaments.

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6
Q

What is the name of the specialized endoplasmic reticulum in muscle cells that stores calcium ions?
a) Sarcoplasmic reticulum
b) Golgi apparatus
c) Mitochondria
d) Nucleus

A

Sarcoplasmic reticulum

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7
Q

True or false: Skeletal muscle fibers are multinucleated.

A

True

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8
Q

Skeletal muscle contraction is a result of the _______ of sarcomeres.

A

Shortening or contraction.

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9
Q

The entire muscle is surrounded by an
external connective tissue, called?

A

EPIMYSIUM

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10
Q

Each fascicle is surrounded by a connective tissue, called?

A

PERIMYSIUM

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11
Q

What is the name of the neurotransmitter released at the neuromuscular junction?
a) Acetylcholine
b) Dopamine
c) Serotonin
d) Epinephrine

A

Acetylcholine

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12
Q

The neuromuscular junction is a synapse between:
a) Two muscle fibers
b) A muscle fiber and a nerve fiber
c) Two nerve fibers
d) None of the above

A

A muscle fiber and a nerve fiber

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13
Q

The neurotransmitter is released from the ________ of the nerve fiber at the neuromuscular junction.
a) Axon terminal
b) Myelin sheath
c) Dendrite
d) Synaptic cleft

A

Axon terminal

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14
Q

What is the name of the protein that receptors for acetylcholine are located on the sarcolemma of the muscle fiber?
a) Actin
b) Myosin
c) Troponin
d) Nicotinic acetylcholine receptor

A

Nicotinic acetylcholine receptor

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15
Q

What is the role of calcium ions in the release of acetylcholine from the nerve terminal?
a) Calcium ions bind to acetylcholine, causing it to be released from the nerve terminal.
b) Calcium ions bind to the synaptic vesicles, causing them to fuse with the nerve terminal membrane and release acetylcholine into the synaptic cleft.
c) Calcium ions cause the nerve terminal to depolarize, which triggers the release of acetylcholine.
d) None of the above.

A

Calcium ions bind to the synaptic vesicles, causing them to fuse with the nerve terminal membrane and release acetylcholine into the synaptic cleft.

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16
Q

True or false: Acetylcholine receptors on the sarcolemma are ligand-gated ion channels.

A

True

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17
Q

The motor end plate is the:
a) Axon terminal of the motor neuron
b) Part of the sarcolemma that contains acetylcholine receptors
c) Space between the nerve terminal and the muscle fiber
d) None of the above

A

Part of the sarcolemma that contains acetylcholine receptors

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18
Q

What is the name of the enzyme that breaks down acetylcholine in the synaptic cleft?
a) Acetylcholinesterase
b) Choline acetyltransferase
c) Nicotinic acetylcholine receptor
d) Dopamine transporter

A

Acetylcholinesterase

19
Q

What is the name of the disease in which antibodies attack acetylcholine receptors at the neuromuscular junction, leading to muscle weakness and fatigue?
a) Parkinson’s disease
b) Multiple sclerosis
c) Myasthenia gravis
d) ALS (Amyotrophic lateral sclerosis)

A

Myasthenia gravis

20
Q

The binding of acetylcholine to its receptor on the sarcolemma triggers the opening of ________ channels.

A

Sodium

21
Q

The sliding filament theory describes the process of muscle contraction at the __________ level.
a) Cellular
b) Tissue
c) Organ
d) System

A

Cellular

22
Q

What are the two filaments that slide past each other during muscle contraction?
a) Myosin and actin
b) Troponin and tropomyosin
c) Calcium and ATP
d) Sarcomere and myofibril

A

Myosin and actin

23
Q

During muscle contraction, the __________ filaments slide towards the center of the sarcomere, shortening its length.
a) Myosin
b) Actin
c) Troponin
d) Tropomyosin

A

actin

24
Q

What is the name of the protein that binds to calcium ions and moves tropomyosin away from the binding site on actin?
a) Myosin
b) Troponin
c) Tropomyosin
d) Actin

A

Troponin

25
Q

True or false: The sliding filament theory explains how muscle fibers generate force, but not how they produce energy.

A

True

26
Q

During muscle contraction, ATP is hydrolyzed by myosin, which provides the energy for the:
a) Binding of myosin to actin
b) Release of myosin from actin
c) Movement of myosin along actin
d) All of the above

A

Movement of myosin along actin

27
Q

The movement of myosin along actin is known as the ________ cycle.

A

Crossbridge

28
Q

What is the name of the region where actin and myosin overlap in the sarcomere?
a) A band
b) I band
c) H zone
d) M line

A

A band

29
Q

True or false: During muscle contraction, the length of the sarcomere decreases, but the length of the myofibril remains the same.

A

True

30
Q

What is the name of the protein that anchors the myosin filaments in place in the sarcomere?
a) Actin
b) Troponin
c) Tropomyosin
d) Titin

A

Titin

31
Q

Rigor mortis occurs due to the depletion of ATP in muscle fibers after death. True or False?

A

True

32
Q

During rigor mortis, muscles become _________ and _________ due to the inability of myosin and actin to detach from each other.
a) Stiff, relaxed
b) Stiff, contracted
c) Relaxed, elongated
d) Elongated, contracted

A

Stiff, contracted

33
Q

Muscular dystrophy is a genetic disorder that primarily affects the __________ muscles.
a) Cardiac
b) Skeletal
c) Smooth
d) Both cardiac and skeletal

A

Skeletal

34
Q

The most common type of muscular dystrophy is __________ muscular dystrophy.
a) Duchenne
b) Becker
c) Limb-girdle
d) Myotonic

A

Duchenne

35
Q

Muscular dystrophy is caused by the deficiency or absence of a protein called __________, which is essential for muscle function.
a) Collagen
b) Elastin
c) Dystrophin
d) Myosin

A

Dystrophin

36
Q

The absence of dystrophin leads to the progressive degeneration and weakening of __________ fibers.

A

muscle

37
Q

Myasthenia gravis is an autoimmune disorder that affects the __________ junctions.
a) Neuromuscular
b) Musculoskeletal
c) Cardiovascular
d) Respiratory

A

Neuromuscular

38
Q

Myasthenia gravis is caused by antibodies that attack the __________ receptors on the muscle fibers.
a) Acetylcholine
b) Norepinephrine
c) Dopamine
d) Serotonin

A

Acetylcholine

39
Q

Which of the following is a common symptom of myasthenia gravis?
a) Difficulty breathing
b) Double vision
c) Muscle cramps
d) All of the above

A

Double vision

40
Q

The treatment for myasthenia gravis involves medications that __________ the activity of acetylcholine at the neuromuscular junction.
a) Increase
b) Decrease
c) Inhibit
d) Stimulate

A

increase

41
Q

Which of the following is a treatment for muscular dystrophy?
a) Gene therapy
b) Physical therapy
c) Corticosteroids
d) All of the above

A

All of the above

42
Q

Which of the following is not a common symptom of muscular dystrophy?
a) Muscle weakness
b) Muscle atrophy
c) Joint pain
d) Difficulty standing or walking

A

Joint pain

43
Q

True or False: Myasthenia gravis is a hereditary disorder.

A

False.

Committee Exam 4 (35 decks)

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