chapter 8: motor nervous system

Question 1

what happens in muscle cells during muscle contraction?

Answer 1

1. action potential generated in motor neuron from CNS integrating system
2. action potential causes motor neuron to release Ach at neuromuscular junction
3. Ach from neuron binds to nicotinic receptors on sarcolemma (muscle plasma membrane)=> sodium ion channels open=> action potential on muscle cell
4. action potential travels into T-tubules that alter DHP receptors that are linked to sarcoplasmic reticulum
5. calcium from sarcoplasmic reticulum is released to increase calcium concentration in cell
6. calcium binds to tropin
7. tropomysin is pulled away from myosin binding site on actin (exposes myosin binding site)
8. myosin binds to actin; ATP transformed into ADP and P= power stroke/muscle contraction

Question 2

what happens in muscle cells during muscle relaxation?

Answer 2

1. (after contraction) calcium is pumped back into sarcoplasmic reticulum (calcium ions unbind with troponin)
2. sarcomere elongates
3. creatine phosphate converts ADP back into ATP

Question 3

what are reflexes?

Answer 3

involuntary muscle contraction caused by integration at spine only (not the brain)

Question 4

what are contralateral reflexes?

Answer 4

activated on one side of the body, causes a reflex on the other

Question 5

what are ipsilateral reflexes?

Answer 5

stimulus and response occur on the same side of the body