The

dropdown

secretes a hormone that increases the body's metabolic rate promotes alertness, quickens reflexes, and stimulates the fetal nervous system.

A. thymus: The thymus secretes thymosins that influence T-cell maturation (immune function), not hormones that raise blood calcium - so it does not respond to hypocalcemia.
B. thyroid gland: The thyroid’s parafollicular (C) cells secrete calcitonin, which lowers blood calcium in response to hypercalcemia, not hypocalcemia.
C. pituitary gland: The pituitary releases many trophic hormones, but it does not directly secrete the primary hormone (PTH) that corrects hypocalcemia.
D. parathyroid glands: The parathyroid glands secrete parathyroid hormone (PTH) in response to low blood Ca²⁺; PTH raises serum calcium by acting on bone, kidney, and vitamin D activation.
E. pineal gland: The pineal gland secretes melatonin to regulate circadian rhythms, not calcium homeostasis.

A. It acts on the hypothalamus to decrease appetite: Appetite regulation is linked to hormones like leptin and ghrelin, not ADH.
B. It causes the release of hormones from the adrenal cortex: ACTH from the anterior pituitary does this, not ADH.
C. It causes smooth muscle contraction in the female reproductive tract: Oxytocin is responsible for uterine contractions, not ADH.
D. It causes vasodilation: ADH (vasopressin) actually causes vasoconstriction, not vasodilation.
E. It increases water retention from renal tubules: ADH acts on the collecting ducts of the kidney to promote water reabsorption, reducing urine output and conserving body water.