Final answer:
Osmoreceptors are receptor cells in the hypothalamus that detect increases in solute concentration due to water loss, triggering the release of antidiuretic hormone to adjust water balance. The process involves increased water reabsorption in the kidneys, mediated by the insertion of aquaporins.
Step-by-step explanation:
The statement that osmoreceptors are cells able to detect an increase in solute concentration in extracellular fluid caused by water loss is true. Osmoreceptors are specialized receptor cells located in the hypothalamus of the brain that sense changes in the osmotic pressure of bodily fluids. These receptors play a critical role in maintaining the water balance within the body by regulating the concentration of solutes in the bloodstream.
When the solute concentration in the blood increases, indicative of a decrease in water volume (as might be experienced during dehydration), these osmoreceptors activate. They trigger the release of antidiuretic hormone (ADH), also known as vasopressin, from the posterior pituitary gland. ADH then acts on the kidneys, signaling them to reabsorb more water from the filtrate, which leads to less water being excreted in the urine.
This process effectively increases the water content in the blood, diluting the solutes and bringing the osmotic pressure back within normal ranges. In the kidneys, ADH increases the insertion of aquaporins, which are water channels that increase water reabsorption. As a result, if there's an increase in blood osmolarity, there will be an increase in water retention to maintain homeostasis.