Muscle Quiz
Section I – Multiple choice: (65 points; 2.5 points each). Bubble your answers on your scantron.
1. A motor unit refers to a. a single muscle fiber plus all of the motor neurons that innervate it b. all of the motor neurons supplying a single muscle c. *a single motor neuron plus all the muscle fibers it innervates d. a pair of antagonistic muscles e. all of the muscles that affect the movement of any given joint
2. Which of the following is NOT associated with the thin filaments in skeletal muscle: a. tropomyosin b. *titin c. actin d. troponin e. nebulin
3. What produces the symptoms of rigor mortis following death? a. the storage vesicles for ATP begin to break down at death, leading to …show more content…
Tropomyosin changes its location relative to actin molecule. c. *Calcium is transported to the sarcoplasmic reticulum. d. Calcium in sarcoplasm diffuses along myofibril. e. All of the above occurs during the latent period.
2. If action potentials are an all or none response, how do we produce variable force of contraction in our skeletal muscles? List and describe the two (2) principal ways the central nervous system controls/varies the force of contraction of skeletal muscle. (4pts)
a. Summation/tetanus – Increased frequency of action potentials within the somatic motor neuron leads to increased frequency of stimulation of muscle fiber causing increased force of contraction because another AP (stimulus) arrives in muscle cell before muscle fully relaxes resulting in increased intracellular calcium. b.- Increased recruitment of addition motor neurons (and therefore motor units) causes increased force of contraction.
4. Match the following terms with the appropriate definitions from the list on the right. For each term there may be more than one correct definition. Each definition may be used more than once. Not all definitions will be used. (1.5 pts each; 18 pts)
A. _b_d__ …show more content…
__r___ DHP receptor
K. __f_t__ tropomysosin
L. __s_t__ troponin
5. Muscle contraction is energetically expensive and ATP is required for many of the activities involved in muscle contraction. List and describe three (3) ways that demonstrate ATP requirements during muscle contraction (6 points)
1) In cross-bridge cycle: • binding of ATP causes myosin head to release actin • hydrolysis of ATP by myosin used to energize (“cock”) the myosin head
2) Ca2+ reuptake into SR terminates muscle contraction • 1° active transport via Ca2+ ATPase pumps • Pump hydrolyzes ATP to pump Ca2+ into SR
3) After opening of nicotinic receptors, Na+/K+ ATPases help restore ion disequilibrium across membrane • 1° active transport via Na+/K+ ATPases • Pump hydrolyzes ATP to pump 3 Na+ ions out of cell and 2 K+ ions into cell.
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Definitions:
a. ATP binding protein
b. Protein directly involved in forming crossbridge
c. Voltage sensing protein in axon terminal
d. Main protein that composes the thin filament
e. Helps stabilize thick filaments
f. Protein that blocks myosin binding sites for actin
g. Mechanosensitive ion channel
h. Bundle of muscle
1. A motor unit refers to a. a single muscle fiber plus all of the motor neurons that innervate it b. all of the motor neurons supplying a single muscle c. *a single motor neuron plus all the muscle fibers it innervates d. a pair of antagonistic muscles e. all of the muscles that affect the movement of any given joint
2. Which of the following is NOT associated with the thin filaments in skeletal muscle: a. tropomyosin b. *titin c. actin d. troponin e. nebulin
3. What produces the symptoms of rigor mortis following death? a. the storage vesicles for ATP begin to break down at death, leading to …show more content…
Tropomyosin changes its location relative to actin molecule. c. *Calcium is transported to the sarcoplasmic reticulum. d. Calcium in sarcoplasm diffuses along myofibril. e. All of the above occurs during the latent period.
2. If action potentials are an all or none response, how do we produce variable force of contraction in our skeletal muscles? List and describe the two (2) principal ways the central nervous system controls/varies the force of contraction of skeletal muscle. (4pts)
a. Summation/tetanus – Increased frequency of action potentials within the somatic motor neuron leads to increased frequency of stimulation of muscle fiber causing increased force of contraction because another AP (stimulus) arrives in muscle cell before muscle fully relaxes resulting in increased intracellular calcium. b.- Increased recruitment of addition motor neurons (and therefore motor units) causes increased force of contraction.
4. Match the following terms with the appropriate definitions from the list on the right. For each term there may be more than one correct definition. Each definition may be used more than once. Not all definitions will be used. (1.5 pts each; 18 pts)
A. _b_d__ …show more content…
__r___ DHP receptor
K. __f_t__ tropomysosin
L. __s_t__ troponin
5. Muscle contraction is energetically expensive and ATP is required for many of the activities involved in muscle contraction. List and describe three (3) ways that demonstrate ATP requirements during muscle contraction (6 points)
1) In cross-bridge cycle: • binding of ATP causes myosin head to release actin • hydrolysis of ATP by myosin used to energize (“cock”) the myosin head
2) Ca2+ reuptake into SR terminates muscle contraction • 1° active transport via Ca2+ ATPase pumps • Pump hydrolyzes ATP to pump Ca2+ into SR
3) After opening of nicotinic receptors, Na+/K+ ATPases help restore ion disequilibrium across membrane • 1° active transport via Na+/K+ ATPases • Pump hydrolyzes ATP to pump 3 Na+ ions out of cell and 2 K+ ions into cell.
-----------------------
Definitions:
a. ATP binding protein
b. Protein directly involved in forming crossbridge
c. Voltage sensing protein in axon terminal
d. Main protein that composes the thin filament
e. Helps stabilize thick filaments
f. Protein that blocks myosin binding sites for actin
g. Mechanosensitive ion channel
h. Bundle of muscle