17) Put these events in the correct order of occurrence: an action potential 1.
ID: 3507226 • Letter: 1
Question
17) Put these events in the correct order of occurrence: an action potential 1. ACh binds to nicotinic receptors and opens Na-/K channels, initiatin 2. Ca, is released from the sarcoplasmic reticulum 3. binding sites on actin exposed, allowing myosin and actin crossbridge formation 4. T-tubules spread the action potential to the lateral sacs of the SR 5. Ca binds to troponin, moving tropomyosin 6. ACh is released from synaptic end bulbs of a somatic motor neuron d) 6, 1, 4, 2, 5,3 e)3,4,5, 6,1,2 ) 6, 4, 3, 2, 1,5 b)6' 1, 3, 4, 2.5 c)1,6,5. 3, 2,4 18) What is asynchronous recruitment a) one motor neuron activating different muscle fibers at the same time to reduce muscle fatigue b) different motor neurons activating their respective muscle fibers at different times to prevent muscle fatigue c) one motor neuron activating a different fiber at different times to reduce muscle fatigue d) different motor neurons activating their respective muscle fiber at the same time to prevent muscle fatigue e) motor neurons activating opposite muscle fibers at different times to prevent muscle fatigue 19) In the arm, the biceps brachii is a flexor whereas triceps brachii is an extensor. Which of the following statements is TRUE? a) The biceps brachii is the primary muscle responsible for movement of the hand and forearm towards the shoulder. The triceps brachii is the primary muscle responsible for movement of the hand and forearm towards the shoulder. Theses muscles are an example of antagonistic muscles. A and C B and C b) c) d) e) 20) The brief period of time between the end of the action potential in the muscle and the beginning of contraction is referred to as a) the refractory period. b) the latent period. c) the relaxation phase. d) the depolarization period. e) the repolarization period.Explanation / Answer
17.A)
Acetylcholine released, sarcolemma and membranes depolarized
Action potential transmitted via T-tubules to SR
Ca++ released from SR terminal cisternae into sarcoplasm
Acetylcholine create action potential
Tropomyosin shift from actin binding site
18.a)
When the nervous system modulates the firing rates of the motor so that different motor units take turns maintaining muscle tension. The alteration of active motor units allows some of the motor units to rest between contractions and prevents fatigue
19.d) both A and C
biceps brachiihelps control the motion of two different joints, the shoulder and the elbow. The function of the biceps at theelbow is essential to the function of the forearm in lifting.
20.b) latent period
The latent period is the time from when the stimulus is delivered to the first indications of contraction in the muscle
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