Skeletal Muscles Physiology Flashcards
What is the name of the functional unit of skeletal muscle?
a) Sarcomere
b) Myofibril
c) Muscle fiber
d) Myosin
Sarcomere
Which protein is responsible for the sliding of actin and myosin filaments during muscle contraction?
a) Troponin
b) Tropomyosin
c) Myosin
d) Actin
Actin
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
Both actin and myosin filaments
Which protein blocks the myosin-binding sites on actin filaments in a resting muscle?
a) Troponin
b) Tropomyosin
c) Myosin
d) Actin
Tropomyosin
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.
Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the myosin-binding sites on actin filaments.
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
Sarcoplasmic reticulum
True or false: Skeletal muscle fibers are multinucleated.
True
Skeletal muscle contraction is a result of the _______ of sarcomeres.
Shortening or contraction.
The entire muscle is surrounded by an
external connective tissue, called?
EPIMYSIUM
Each fascicle is surrounded by a connective tissue, called?
PERIMYSIUM
What is the name of the neurotransmitter released at the neuromuscular junction?
a) Acetylcholine
b) Dopamine
c) Serotonin
d) Epinephrine
Acetylcholine
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 muscle fiber and a nerve fiber
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
Axon terminal
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
Nicotinic acetylcholine receptor
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.
Calcium ions bind to the synaptic vesicles, causing them to fuse with the nerve terminal membrane and release acetylcholine into the synaptic cleft.
True or false: Acetylcholine receptors on the sarcolemma are ligand-gated ion channels.
True
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
Part of the sarcolemma that contains acetylcholine receptors
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
Acetylcholinesterase
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)
Myasthenia gravis
The binding of acetylcholine to its receptor on the sarcolemma triggers the opening of ________ channels.
Sodium
The sliding filament theory describes the process of muscle contraction at the __________ level.
a) Cellular
b) Tissue
c) Organ
d) System
Cellular
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
Myosin and actin
During muscle contraction, the __________ filaments slide towards the center of the sarcomere, shortening its length.
a) Myosin
b) Actin
c) Troponin
d) Tropomyosin
actin
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
Troponin
True or false: The sliding filament theory explains how muscle fibers generate force, but not how they produce energy.
True
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
Movement of myosin along actin
The movement of myosin along actin is known as the ________ cycle.
Crossbridge
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 band
True or false: During muscle contraction, the length of the sarcomere decreases, but the length of the myofibril remains the same.
True
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
Titin
Rigor mortis occurs due to the depletion of ATP in muscle fibers after death. True or False?
True
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
Stiff, contracted
Muscular dystrophy is a genetic disorder that primarily affects the __________ muscles.
a) Cardiac
b) Skeletal
c) Smooth
d) Both cardiac and skeletal
Skeletal
The most common type of muscular dystrophy is __________ muscular dystrophy.
a) Duchenne
b) Becker
c) Limb-girdle
d) Myotonic
Duchenne
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
Dystrophin
The absence of dystrophin leads to the progressive degeneration and weakening of __________ fibers.
muscle
Myasthenia gravis is an autoimmune disorder that affects the __________ junctions.
a) Neuromuscular
b) Musculoskeletal
c) Cardiovascular
d) Respiratory
Neuromuscular
Myasthenia gravis is caused by antibodies that attack the __________ receptors on the muscle fibers.
a) Acetylcholine
b) Norepinephrine
c) Dopamine
d) Serotonin
Acetylcholine
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
Double vision
The treatment for myasthenia gravis involves medications that __________ the activity of acetylcholine at the neuromuscular junction.
a) Increase
b) Decrease
c) Inhibit
d) Stimulate
increase
Which of the following is a treatment for muscular dystrophy?
a) Gene therapy
b) Physical therapy
c) Corticosteroids
d) All of the above
All of the above
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
Joint pain
True or False: Myasthenia gravis is a hereditary disorder.
False.
