Which of the following statements correctly describes a communication or homeostatic control mechanism in multicellular organisms?
When blood water potential decreases, osmoreceptors in the pituitary gland shrink, stimulating the direct secretion of antidiuretic hormone (ADH) to decrease the permeability of the collecting duct to water.
In blood glucose regulation, the peptide hormone insulin binds to specific cell-surface receptors, triggering an intracellular signaling cascade that causes vesicles containing GLUT4 transporter proteins to fuse with the cell-surface membrane.
In thermoregulation, the hypothalamus acts as both the primary receptor and the sole effector, directly decreasing the metabolic rate of hepatocytes to generate heat when core temperature falls below the set point.
The initial depolarization stage of an action potential in a sensory neurone is controlled by negative feedback, as the influx of Na+\text{Na}^+Na+ ions causes the membrane potential to become less negative, which directly closes voltage-gated sodium channels.
