58 Questions
Which property of muscle allows it to respond to a stimulus?
Excitability
Which type of muscle tissue is responsible for locomotion and facial expressions?
Skeletal
Which system controls the contraction of cardiac muscle?
Autonomic nervous system
Which protein aligns the thick and thin filaments properly in skeletal muscle tissue?
Dystrophin
What is the function of myosin in skeletal muscle tissue?
Generates force during contraction
What happens when calcium ions bind to troponin in relaxed muscle?
Tropomyosin moves away from myosin-binding sites
What is the role of titin in skeletal muscle tissue?
Stabilizes the position of myosin
Which ion has a higher concentration inside the cell compared to outside the cell?
K+
What is the resting membrane potential of a cell?
-70 mV
What type of ion channels open and close in response to small voltage changes across the plasma membrane?
Voltage-gated
What is the phase of an action potential where the inside of the plasma membrane becomes less negative?
Depolarization
According to the text, what is the response of a muscle fiber to a sub-threshold stimulus?
No action potential; no contraction
According to the text, what is the strength of contraction dependent on?
Size of the motor unit and number of units recruited
According to the text, what happens to the strength of contraction as the number of motor units responding to a stimulus increases?
Increases
According to the text, what is the term used to describe the phenomenon where each subsequent contraction is stronger than the previous one until they all become equal?
Treppe
According to the text, what happens to muscle tension as the frequency of action potentials increases?
Muscle tension increases
According to the text, what is the term used to describe the phenomenon where there is no relaxation between muscle contractions?
Complete tetanus
Which connective tissue surrounds a whole muscle and many fascicles?
Epimysium
Which connective tissue surrounds a group of muscle fibers?
Perimysium
What is the function of Transverse (T) tubules in a muscle cell?
Ensure that action potential excites all parts of the muscle fiber at the same time
What is the basic functional unit of a myofibril?
Sarcomere
Which of the following is true about the neuromuscular junction?
The neuromuscular junction is where communication occurs between a motor neuron and a muscle fiber
What is the role of acetylcholine in the neuromuscular junction?
Acetylcholine is a neurotransmitter released from the presynaptic membrane that stimulates the production of an action potential in the postsynaptic membrane
What happens when acetylcholine binds to ligand-gated Na+ channels on the postsynaptic membrane?
Ligand-gated Na+ channels open and Na+ enters the postsynaptic cell, causing the postsynaptic membrane to depolarize
What is the role of acetylcholinesterase in the neuromuscular junction?
Acetylcholinesterase is an enzyme that removes acetylcholine from the synaptic cleft, preventing its accumulation
Which of the following is true during the depolarization phase of the action potential?
The membrane potential becomes more positive
What is the role of sodium (Na+) channels during the depolarization phase of the action potential?
They open and allow sodium ions to diffuse into the cell
What causes the repolarization phase of the action potential?
The opening of potassium (K+) channels
Which of the following is NOT a function of the muscular system?
Constriction of organs and vessels
Which property of muscle allows it to respond to a stimulus?
Excitability
Which type of muscle tissue is controlled involuntarily by the endocrine and autonomic nervous systems?
All of the above
Which connective tissue surrounds a whole muscle and many fascicles?
Epimysium
Which ion has a higher concentration inside the cell compared to outside the cell?
K+
What is the resting membrane potential of a cell?
-85 mV
What is the role of the sodium-potassium pump?
To pump sodium ions out of the cell in exchange for potassium ions
What is the function of Transverse (T) tubules in a muscle cell?
To transmit action potentials deep into the muscle cell
Which protein stabilizes the position of myosin and accounts for much of the elasticity and extensibility of myofibrils?
Titin
What is the region in the A band where actin and myosin do not overlap called?
H zone
What is the role of tropomyosin in muscle contraction?
Moves tropomyosin away from myosin-binding sites
What is the function of the M line in skeletal muscle tissue?
Forms the M-line and binds Titan
Which connective tissue surrounds a group of muscle fibers?
Perimysium
What is the function of Transverse (T) tubules in a muscle cell?
To ensure that action potential excites all parts of the muscle fiber at the same time
What is the role of acetylcholine in the neuromuscular junction?
To stimulate muscle fibers to contract
What is the basic functional unit of a myofibril?
Sarcomere
Which structure releases the neurotransmitter acetylcholine into the synaptic cleft?
Synaptic vesicles
What is the role of acetylcholinesterase in the neuromuscular junction?
To remove acetylcholine from the synaptic cleft
What is the function of the sarcoplasmic reticulum in muscle contraction?
To reabsorb calcium ions from the cytoplasm
What is the role of troponin in muscle contraction?
To bind to calcium ions and initiate muscle contraction
What is the term used to describe the phenomenon where the strength of contraction increases as the number of motor units responding to a stimulus increases?
Multiple-wave summation
What is the term used to describe the phenomenon where each subsequent contraction is stronger than the previous one until they all become equal?
Treppe
What is the term used to describe the phenomenon where there is no relaxation between muscle contractions?
Complete tetanus
What is the term used to describe the phenomenon where the strength of contraction depends upon recruitment of motor units?
Multiple motor unit summation
What is the term used to describe the phenomenon where muscle fibers partially relax between contractions during high frequency stimulation?
Incomplete tetanus
What is the term used to describe the phenomenon where muscle fibers do not relax between contractions during high frequency stimulation?
Complete tetanus
During the depolarization phase of the action potential, the membrane potential changes from approximately -85 mV to approximately +20 mV. During the repolarization phase, the inside of the plasma membrane changes from approximately +20 mV back to -85 mV.
a) -85 mV to +20 mV
What is the change in membrane potential during the repolarization phase of the action potential?
a) +20 mV to -85 mV
What is the difference in membrane potential between the depolarization and repolarization phases of the action potential?
b) 105 mV
What is the total change in membrane potential during the action potential?
c) -20 mV to +85 mV
Test your knowledge on the contraction and relaxation of skeletal muscles and the neuromuscular junction. This quiz covers topics such as motor neurons, action potentials, synapses, and synaptic clefts. Get ready to flex your muscle knowledge!
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