Which of the following statements concerning the cardiac cycle is true?
A. Blood enters the right and left atria only during diastole.
B. During ventricular systole, the AV valves open.
C. The semilunar valves remain closed throughout ventricular systole.
D. Most of end-diastolic volume comes from active filling.
E. Most ventricular filling occurs before the atria contract.
Answer: E
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Fill in the blank(s) with the appropriate word(s)
Which neurotransmitter ensures skeletal muscles receive the supply of nutrients needed to make ATP by stimulating the release of more fatty acids and glucose into the blood stream?
A) epinephrine B) norepinephrine C) acetylcholine D) aldosterone
Which of the following is not a role of the pericardium?
a. It facilitates heart contraction. b. It prevents overfilling of the heart with blood. c. It anchors the heart to surrounding structures. d. It protects the heart.
Myocardial cells exhibit a plateau phase instead of quickly repolarizing. This is due to ________.
A. inward diffusion of sodium through fast Na+ channels B. inward diffusion of potassium through voltage-gated K+ channels C. inward diffusion of calcium through slow Ca2+ channels D. outward pumping of sodium by the Na+/K+ pump