Describe what is occurring during the 4 phases of the cardiac cycle.

2. How is an action potential in a contractile cardiac cell different from action potential in a pacemaker cell? (Write the phases and the channels involved for each phase).

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4. The ECG records the electrical stimulation of cardiac muscle by the conduction system and not the contraction of the muscle itself.? True or False ?

1. Explain in words and provide a drawing that demonstrates the variable that describes the difference between end systolic volume (ESV) and end diastolic volume (EDV).

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4. Explain how each of the following will affect the cardiac rate and/or the stroke volume. a. Increase venous return: b. Increase sympathetic activity: c. Increase parasympathetic activity: d. Vasoconstriction in arterioles: in veins: e. Vasoconstriction

22. Ventricular Contractility increases in response to circulating Epinephrine. What factor is responsible for this increase in the force of the contraction?   A.the Na+ current (depol.) B.the Ca++ current which causes the plateau (trigger Ca++) C.the K+ current D.a decreased Central Venous Pressure   23. Normally, Systole takes up about 80% of the Cardiac Cycle.   A. true B. false       24.Which of the following is not an affect of circulating Angiostensin II (AII)?   A.thirst B.selective vasodilation C.increased peripheral vascular tone & resistance D.the release of Aldosterone from the adrenal cortex     25. Blood Volume affects blood pressure because it directly increases:   A.Total Peripheral Resistance B.Stroke Volume C.End Systolic Volume D.Central Venous Pressure     26. Atrial Naturetic Factor is released to adjust blood pressure. Which organ releases this hormone?   A.the heart B.the kidneys C.the adrenal cortex

3 describe why arteries that are no longer stretchy can cause the heart muscle to wear out and fail *