Which statement about the action potential is false: a. the overshoot is caused

Question

Which statement about the action potential is false: a. the overshoot is caused by the inward diffusion of sodium ions b. first, sodium ions diffuse inward, and then, potassium ions diffuse outward. c. the absolute refractory period is caused by the voltage-gated sodium inactivation gate closed being d. at threshold, the voltage-gated sodium activation gate begin to open e. the after potential is caused by some voltage-gated sodium channels remaining The moment when the inactivation gate of the voltage-gated sodium channel closes best describes: a. the end of the relative refractory period b. the moment when the action potential reaches + 30mv c. the end of the after potential d. the moment of threshold e. the end of the absolute refractory period What causes the sarcoplasmic reticulum of skeletal muscle cells to release calcium onto the sarcomere: a. the movement of tropomyosin off of the binding site of actin b. the binding of acetylcholine with its receptor c. the binding of calcium with troponin d. the movement of the action potential down the T-tubules e. the binding of ATP to the Ca-ATP ase on the sacroplasmic reticulum "Rigor Mortis" is caused by: a. the inability of the myosin head to detach from on actin b. a lack of calcium in the sarcomere c. the inability of the myosin head to bind with their binding sites on actin d. the inability of the myosin head to reset to its "ready" position e. listening to a Trump speech

Explanation / Answer

40) Cardiac muscles function as a functional syncytium. The contraction of cardiac muscles is initiated by electrical impulse originating in sinoatrial node (SA node) which is presnt in the right atrium near the opening of superior vena cava. Cells within the SA node are the primary pacemaker cells of the heart. Depolarisation occurs first by opening of sodium ions and then by slow calcium channels. Repolarisation and hyperpolarisation occurs through opening of potassium channels. Overshoot reaches +40 mV. So, the answer for this question is option (f) b and c.

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