The period of time during the cardiac cycle when cells cannot respond to a stimulus, no matter how strong, is the relative refractory period.
Indicate whether the statement is true or false
Question 2Which of the following are semilunar valves?
a. Aortic and pulmonic
b. Aortic and tricuspid
c. Pulmonic and mitral
d. Tricuspid and mitral
Question 3The base of the heart is found at approximately the level of the _____ rib(s).
a. first
b. second
c. fourth
d. fifth and sixth
Question 4Rapid ejection of blood from the ventricular chambers of the heart occurs because the _____ and _____ valves open.
a. pulmonic; aortic
b. tricuspid; mitral
c. pulmonic; mitral
d. tricuspid; aortic
Question 5Blood flows from the right atrium through the _____ valve into the right ventricle.
a. mitral
b. aortic
c. pulmonic
d. tricuspid
Question 6The thick, muscular middle layer of the heart wall that contains the atrial and ventricular muscle fibers necessary for contraction is the _____.
a. epicardium
b. pericardium
c. myocardium
d. endocardium
Question 7Which side of the heart is a low-pressure system that pumps venous blood to the lungs?
a. Left
b. Right
Question 8Stimulation of alpha-adrenergic receptors results in _____.
a. increased heart rate
b. peripheral vasoconstriction
c. constriction of bronchial smooth muscle
d. increased force of myocardial contraction
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