Major Endocrine Glands

Hypothalamus

Releasing and inhibiting hormones
Peptide
Targets anterior pituitary
Regulate secretion of anterior pituitary hormones

Anterior pituitary

Thyroid-stimulating hormone (TSH)

Peptide
Targets thyroid gland
Stimulates secretion of thyroid hormones and growth of thyroid gland

Anterior pituitary

Adrenocorticotropic hormone (ACTH)

Peptide
Targets adrenal cortex
Stimulates secretion of glucocorticoids by adrenal cortex

Anterior pituitary

Follicle-stimulating hormone (FSH)

Peptide
Targets ovaries in females, testes in males
Stimulates egg growth and development and secretion of sex hormones in females; stimulates sperm production in males

Anterior pituitary

Luteinizing hormone (LH)

Peptide
Targets ovaries in females, testes in males
Regulates ovulation in females and secretion of sex hormones in males

Anterior pituitary

Prolactin (PRL)

Peptide
Targets mammary glands
Stimulates breast development and milk secretion

Anterior pituitary

Growth hormone (GH)

Peptide
Targets bone, soft tissue
Stimulates growth of bones and soft tissues; helps control metabolism of glucose and other fuel molecules

Anterior pituitary

Melanocyte-stimulating hormone (MSH)

Peptide
Targets melanocytes in skin of some vertebrates
Promotes darkening of the skin

Anterior pituitary

Endorphins

Peptide
Targets pain pathways of PNS
Inhibit perception of pain

Posterior pituitary

Antidiuretic hormone (ADH)

Peptide
Targets kidneys
Raises blood volume and pressure by increasing water reabsorption in kidneys

Posterior pituitary

Oxytocin

Peptide
Targets uterus, mammary glands
Promotes uterine contractions; stimulates milk ejection from breasts

Thyroid gland

Calcitonin

Peptide
Targets bone
Lowers calcium concentration in blood

Thyroid gland

Thyroxine and triiodothyronine

Amine
Targets most cells
Increase metabolic rate; essential for normal body growth

Parathyroid glands

Parathyroid hormone (PTH)

Peptide
Targets bone, kidneys, intestine
Raises calcium concentration in blood; stimulates vitamin D activation

Adrenal medulla

Epinephrine and norepinephrine

Amine
Targets sympathetic receptor sites throughout body
Reinforce sympathetic nervous system; contribute to responses to stress

Adrenal cortex

Aldosterone (mineralocorticoid)

Steroid
Targets kidney tubules
Helps control body’s salt-water balance by increasing Na⁺ reabsorption and K⁺ excretion in kidneys

Adrenal cortex

Cortisol (glucocorticoid)

Steroid
Targets most body cells, particularly muscle, liver, and adipose cells
Increases blood glucose by promoting breakdown of proteins and fats

Testes

Androgens, such as testosterone

Steroid
Targets various tissues
Control male reproductive system development and maintenance; most androgens are made by the testes

Testes

Oxytocin

Peptide
Targets uterus
Promotes uterine contractions when seminal fluid is ejaculated into vagina during sexual intercourse

Ovaries

Estrogens, such as estradiol

Steroid
Targets breast, uterus, other tissues
Stimulate maturation of sex organs at puberty, and development of secondary sexual characteristics

Ovaries

Progestins, such as progesterone

Steroid
Targets uterus
Prepare and maintain uterus for implantation of fertilized egg and the growth and development of embryo

Pancreas (islets of Langerhans)

Glucagon (alpha cells)

Peptide
Targets liver cells
Raises glucose concentration in blood; promotes release of glucose from glycogen stores and production from noncarbohydrates

Pancreas (islets of Langerhans)

Insulin (beta cells)

Peptide
Targets most cells
Lowers glucose concentration in blood; promotes storage of glucose, fatty acids, and amino acids

Pineal gland

Melatonin

Amine
Targets brain, anterior pituitary, reproductive organs, immune system, possibly others
Helps synchronize body’s biological clock with day length; may inhibit gonadotropins and initiation of puberty

Many cell types

Growth factors

Peptide
Targets most cells
Regulate cell division and differentiation

Many cell types

Prostaglandins

Fatty acid
Targets various tissues
Have many diverse roles