AP BIOLOGY

Detailed explanation-1: -An osmoreceptor is a sensory receptor primarily found in the hypothalamus of most homeothermic organisms that detects changes in osmotic pressure. Osmoreceptors can be found in several structures, including two of the circumventricular organs – the vascular organ of the lamina terminalis, and the subfornical organ.

Detailed explanation-2: -Osmoreceptors (Fig. 4-11) located in the hypothalamus (and also in the carotid artery) are capable of sensing the concentrations of solutes, particularly sodium ion. This leads to a secretion of vasopressin.

Detailed explanation-3: -Osmoregulation is an example of a negative feedback, homeostatic control system. This system detects changes in the salinity of the water Chinook salmon live in, working to keep the body water concentration constant.

Detailed explanation-4: -Osmoreceptors regulate sodium and water balance in a manner that maintains the osmotic pressure of the extracellular fluid (ECF) near an ideal set point.