Endocrine System: Hormones, Targets, and Actions

Pineal - Melatonin

Target: Melanocytes | Action: Antioxidant, causes drowsiness, regulates sleep-wake cycle

Anterior Pituitary - Growth Hormone (GH)

Target: Bones, muscles, organs | Action: Stimulates growth/cell reproduction, releases IGF-1, promotes protein anabolism

Anterior Pituitary - Thyroid-stimulating hormone (TSH)

Target: Thyroid | Action: Promotes secretory activity (T₃ and T₄)

Anterior Pituitary - Follicle-stimulating hormone (FSH)

Target: Ovaries, seminiferous tubules | Action: Follicle development & estrogen secretion (females); sperm maturation (males)

Anterior Pituitary - Luteinizing hormone (LH)

Target: Follicle, intestinal cell | Action: Promotes ovulation, corpus luteum formation, progesterone/testosterone secretion

Anterior Pituitary - Prolactin (PRL)

Target: Corpus luteum, breast | Action: Maintains corpus luteum/progesterone, stimulates milk production, sexual gratification

Anterior Pituitary - Adrenocorticotropic hormone (ACTH)

Target: Adrenal cortex | Action: Stimulates corticosteroid synthesis/secretion

Anterior Pituitary - Lipotropin (LPH)

Target: Corticotropes (anterior pituitary) | Action: Breaks down fat (lipolysis), stimulates melanin production

Anterior Pituitary - Melanocyte-stimulating hormone (MSH)

Target: Melanotropes (anterior pituitary) | Action: Produces melanin in skin and hair

Posterior Pituitary - Antidiuretic hormone (ADH)

Target: Distal tubules of kidney | Action: Water reabsorption, vasoconstriction, stimulates ACTH release

Posterior Pituitary - Oxytocin (OXT)

Target: Uterus | Action: Stimulates contractions, milk release, regulates circadian rhythm

Thyroid - Thyroxine (T₄) & Triiodothyronine (T₃)

Target: Widespread (heart, muscle, liver) | Action: Regulates metabolism, gluconeogenesis, fat mobilization, protein synthesis, ↑ BMR, ↑ catecholamine sensitivity

Thyroid - Calcitonin

Target: Skeleton | Action: Calcium/phosphorus metabolism, constructs bone, lowers serum calcium

Parathyroid - Parathyroid hormone (PTH)

Target: Bone, kidney, intestinal tract | Action: Regulates calcium & phosphorus metabolism, bone calcification

Adrenal Cortex - Aldosterone (Mineralocorticoid)

Target: Widespread, primarily kidney | Action: Maintains fluid/electrolyte balance, Na⁺ reabsorption, K⁺ secretion

Adrenal Cortex - Cortisol (Glucocorticoid)

Target: Widespread | Action: Stress response, preserves carbs, mobilizes amino acids, gluconeogenesis, suppresses inflammation/immune system

Adrenal Cortex - Sex Hormones (Androgens, Estrogen, Progesterone)

Target: Gonads | Action: Influence secondary sex characteristics

Adrenal Medulla - Epinephrine

Target: Widespread | Action: Fight-or-flight: ↑ HR, BP, glucose, vasoconstriction, stimulates ACTH

Adrenal Medulla - Norepinephrine

Target: Widespread | Action: Vasoconstriction, effects similar to epinephrine

Pancreas - Insulin

Target: Widespread | Action: Increases carbohydrate utilization, decreases blood glucose

Pancreas - Glucagon

Target: Widespread | Action: Raises blood glucose via glycogenolysis

Pancreas - Amylin

Target: Pancreatic beta cells | Action: Slows gastric emptying, inhibits digestion, reduces food intake

Ovaries - Estrogen

Target: Widespread | Action: Secondary sex traits, maturation, sexual function, multiple systemic effects

Ovaries - Progesterone

Target: Uterus, breast | Action: Prepares/maintains pregnancy

Testes - Testosterone (Androgen)

Target: Widespread | Action: Secondary sex traits, maturation, normal sex function

Ovaries/Testes - Inhibin

Target: Anterior pituitary | Action: Inhibits FSH production

Adipose Tissue - Leptin, Adiponectin, Angiotensin

Target: Widespread | Action: Controls metabolism, hunger, vasoconstriction