Posterior pituitary gland?

• A. It stores and secretes two hormones made by the hypothalamus; it is controlled by action potentials from the hypothalamus
• B. It produces insulin
• C. It secretes thyroid-stimulating hormone
• D. It regulates circadian rhythms

Answer: (A)

The posterior pituitary acts as a storage and release site for two hormones that are made in the hypothalamus. Neurons in the hypothalamus synthesize oxytocin and vasopressin (antidiuretic hormone) and send them down their axons into the posterior pituitary, where they are stored. When an action potential reaches these nerve endings, the hormones are released into the bloodstream. So the statement that the posterior pituitary stores and secretes hypothalamic hormones, controlled by action potentials from the hypothalamus, is the correct description.

Insulin is produced by the pancreas, not the pituitary. Thyroid-stimulating hormone is produced by the anterior pituitary, not the posterior. Regulating circadian rhythms involves the pineal gland and brain clock, not the posterior pituitary.