Chemical messengers that reach their target cells traveling in blood are called __________.
A.)neurotransmitters
B.)second messengers
C.)hormones
D.)autocrine chemicals
C.)hormones
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How is polyspermy prevented?
A) sperm migration B) acrosomal reaction C) capacitation D) cortical reaction
What would happen if all of the hemoglobin contained within the RBCs became free in the plasma?
A. It would drastically increase osmotic colloid pressure. B. It would considerably increase blood oxygen carrying capacity. C. It would facilitate delivery of oxygen into tissues supplied by small capillaries. D. It would significantly increase blood osmolarity. E. It would facilitate oxygen diffusion into cells distant from blood capillaries.
The relative refractory period of an axon coincides with the period of
A. increased K+ permeability of the cell. B. increased K+ flux into the cell. C. Na+ permeability that is greater than that during the depolarization phase. D. Increased Na+ flux through K+ channels. E. activation and inactivation of voltage-dependent Na+ channels.
Metabolism tends to add:
a. more bases than acids to the blood b. more acids than bases to the blood c. about an equal amount of acids and bases d. only neutral substances to the blood