Cheat Sheet 21: Endocrine System

Peptide Hormones

Bind to surface receptors, activate secondary messengers.

Steroid Hormones

Diffuse through membranes, bind cytoplasmic receptors.

Tyrosine Derivatives

Hormones derived from the amino acid tyrosine.

Catecholamines

Water-soluble hormones acting via cAMP secondary messenger.

Thyroid Hormones

Lipid-soluble, bind nuclear receptors, require protein carriers.

Exocrine Glands

Secrete enzymes into ducts, not bloodstream.

Endocrine Glands

Release hormones directly into the bloodstream.

Paracrine Signaling

Targets nearby cells for signaling.

Autocrine Signaling

Targets the secreting cell itself.

Hypothalamus

Secretes hormones regulating anterior pituitary gland.

Anterior Pituitary Gland

Secretes tropic and nontropic hormones.

Posterior Pituitary Gland

Stores and releases ADH and oxytocin.

ACTH

Stimulates adrenal cortex to release glucocorticoids.

TSH

Stimulates thyroid gland to release thyroid hormones.

GH

Stimulates growth in bones and muscles.

LH

Stimulates ovulation and testosterone production.

FSH

Stimulates ovarian follicles and sperm production.

Prolactin

Stimulates milk production in mammary glands.

Oxytocin

Increases uterine contractions and milk ejection.

ADH

Increases water reabsorption in kidneys.

Glucagon

Increases blood glucose levels when low.

Insulin

Decreases blood glucose levels when high.

Cortisol

Raises blood glucose levels, stress hormone.

Mineralocorticoids

Regulate sodium and potassium levels in kidneys.

Calcitonin

Lowers blood calcium levels by stimulating bone formation.

PTH

Raises blood calcium levels, antagonistic to calcitonin.

Thyroxine (T4)

Regulates metabolism and requires iodine.

Triiodothyronine (T3)

Active form of thyroid hormone, regulates metabolism.

Melatonin

Regulates circadian rhythms, secreted by pineal gland.

Thymosins

Stimulate T-cell development in the thymus.

Epinephrine

Hormone for 'fight or flight' response.

Norepinephrine

Hormone involved in 'fight or flight' response.

Somatostatin

Inhibits insulin and glucagon release.

Androgens

Hormones promoting male secondary sexual characteristics.

Estrogen

Regulates menstrual cycle and female characteristics.

Progesterone

Regulates menstrual cycle and supports pregnancy.

hGH

Stimulates growth and metabolism.

Glycogen

Stored glucose in liver and muscles.