This provitamin can be synthesized from dietary cholesterol. Then when the
provitamin stored in the skin is exposed to ultraviolet light, it is changed to an
inactive form of vitamin ______ .
Fill in the blank(s) with correct word
D
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Because lymphatic vessels have three tunics (intima, media, and externa) and valves, they structurally resemble
A. venules. B. veins. C. arterioles. D. arteries E. All of the choices are correct.
The DCT secretes hydrogen ions in exchange for sodium ions by the process of
A) diffusion. B) facilitated diffusion. C) osmosis. D) cotransport. E) energy-dependent exchange pump.
Drug Z is an agonist for a neurotransmitter receptor. It has a much higher affinity for the receptor and binds four times longer than the endogenous neurotransmitter. If you compare drug Z with the endogenous neurotransmitter, it's likely that drug Z will cause more frequent action potentials than the endogenous ligand.
Answer the following statement true (T) or false (F)
As the total cross-sectional area of the vessels increases, the velocity of blood flow
A. increases. B. decreases. C. does not change.