The opening and closing of the heart valves is caused by
A. contraction and relaxation of papillary muscles that pull on heart strings.
B. action potentials within the cusps of the valves.
C. pressure changes of alternating contraction and relaxation during the cardiac cycle.
D. contraction of the smooth muscle in the walls of the great vessels leaving the heart.
Answer: C
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Myopia generally occurs when the ________.
A. cornea is uneven B. eyeball is too long C. lens is uneven D. eyeball is too short
Which of the following is NOT a symapthetic effect on the body?
A. increased coagulation B. relaxation of ciliary muscle for far vision C. constriction of the pupil D. decreased insulin secretion
What is the specialization of embryonic tissue into adult forms called?
A. Dedication B. Metaplasia C. Atrophy D. Differentiation E. Dysplasia