12. How are the action potentials converted to Ca ++ signals in all types of mus
ID: 206768 • Letter: 1
Question
12. How are the action potentials converted to Ca++ signals in all types of muscle (very brief answer)?
Briefly compare release of Ca++ from the SR in all three muscle types; use the term CICR where appropriate:
13. Skeletal:
14. Smooth:
15. Cardiac:
16. Which of the three muscle types exhibit graded contractions?
Calcium levels link electrical signaling to mechanical “twitches”; what calcium binding proteins mediate this process in:
17. Skeletal muscle:
18. Smooth muscle:
19: Cardiac muscle:
What transport proteins are involved in relaxation in:
20. Skeletal muscle:
21. Smooth muscle:
22: Cardiac muscle:
The action potentials that lead to contraction are characteristic of the muscle fiber type. In the figure below, indicate what ion’s movement is responsible for the labeled portion of each action potential.
23. Skeletal muscle: _____ Cardiac Muscle: ______ Autorhythmic Cell ______
24. Skeletal muscle: _____ Cardiac Muscle: ______ Autorhythmic Cell ______
25. Cardiac Muscle: ______
20 25 24 23 20 23 24 hreshold-- 40 23 24 -60 Action potential potential Cardiac Action Potential Pacemaker Action Potential Skeletal Muscle Action PotentialExplanation / Answer
(12)
When an action potential reaches the end of an axon at the neuromuscular junction voltage regulated Ca++ channels open and allow Ca++ to enter the axon terminal which causes synaptic vesicles containing acetylcholine to fuse with the axonal terminal releasing acetylcholine into the synaptic cleft via exocytosis.
Acetylcholine diffuses across the synaptic cleft and binds to acetylcholine receptors on the sarcolemma of the muscle cell and initiates an action potential
The receptors open, allowing sodium ions to flow into the muscle's cytosol causing depolarization of the cell. This results in sarcoplasmic reticulum to open and release Ca2+ ions from their storage place in the cisternae. Ca2+ ions diffuse through the cytoplasm where they bind to troponin, ultimately allowing myosin to interact with actin in the sarcomere; this sequence of events is called excitation-contraction coupling.
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