2.Put these events in the correctchronological sequence:
1. Upper motor neuron fires an actionpotential
2. T-tubules convey action potentialsinto the interior of the cell.
3. Acetylcholine is released from thelower motor neuron.
4. Ca2+ is released from thesarcoplasmic reticulum.
A) 1, 2, 3, 4
B) 3, 1, 2, 4
C) 2, 1, 4, 3
D) 1, 3, 2, 4
E) 4, 3, 2, 1
4.Which of the following sequencesrepresent muscle contraction?
A)Action Potential leads to Ca++release- troponin pulls troposmyosin -Ca++ binds to troponin- awaythe myosin binding site- myosin heads pull actin toward the M line- myosin head binds to myosin binding site on actin
B)Action Potential leads to Ca++release- - myosin head binds to myosin binding site on actin- Ca++binds to troponin--troponin pulls troposmyosin away from the myosinbinding site - myosin heads pull actin toward the M line
C)Action Potential leads to Ca++release- Ca++ binds to tropomyosin-tropomyosin pulls troponin awayfrom the myosin binding site- myosin head binds to myosin bindingsite on actin- myosin heads pull actin toward the M line
D)Action Potential leads to Ca++release- Ca++ binds to troponin-troponin pulls troposmyosin awaythe myosin binding site- myosin head binds to myosin binding siteon actin- myosin heads pull actin toward the M line
E)Ca++ binds to troponin -ActionPotential leads to Ca++ release- -troponin pulls
