Thin filaments are composed of the protein actin?
a. true
b. false
Ans: a. true
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The layer of hard keratin that acts as the surface of the hair is termed the
A) medulla. B) cuticle. C) hair bulb. D) root. E) shaft.
What effect does a long period of skeletal muscle inactivity have on blood flow?
A. It causes blood pooling and a slowing of blood flow. B. It causes a compensatory increase in arterial pressure. C. It causes a sharp decrease in heart rate. D. It causes a sharp decrease in respiratory rate.
Which of the following is most likely to be a cause of hypotension?
A. an increase in blood volume B. sweating, vomiting, or emotional responses C. decreased firing of the arterial baroreceptors D. increased release of epinephrine by the adrenal medulla E. a sudden decrease in firing of the parasympathetic nervous system
Pulmonary arterioles ________ and system arterioles ________ when PO2 is low.
A. dilate; dilate B. constrict; constrict C. constrict; dilate D. dilate; constrict