Parathyroid Glands Located on thyroid glands usually 4

Parathyroid Glands • Located on thyroid glands (usually 4) • Release parathyroid hormone (PTH) • Increase blood calcium and decrease blood phosphate • Affects kidneys, bones, and absorption in intestine • Controlled by blood calcium levels

Adrenal Gland • • • Located on top of kidneys embedded in fat Two parts Central medulla Outer cortex Run together structurally but secrete very different hormones • Medulla affected by autonomic nerves • Cortex well supplied with blood vessels and respond to chemical concentrations

Adrenal Medulla • Epinephrine (adrenaline): • Norepinephrine (nonadrenaline): – Increase heart rate – Increase force of heart contractions – Increase breathing rate – Elevate blood pressure – Decrease digestive activity • Sympathetic nerves responding to “fight or flight” stimulate adrenal medulla

Adrenal Cortex • Aldosterone • Controls concentrations of sodium ions (Na+) (keep ‘em) & potassium ions (K+) (get rid of ‘em) • Cortisol • Affects glucose metabolism – Inhibit protein synthesis – Promote fatty acid release to use as energy – Build glucose from non-carbohydrate sources • Both controlled by ACTH • Adrenal sex hormones—supplement those produced in reproductive organs

Pancreas • Endocrine portions called islets of Langerhans • Glucagon • Stimulates the liver to break down glycogen to increase blood sugar • Insulin • Stimulates liver to form glycogen from glucose and lowers blood sugar • Controlled by blood sugar levels • Some cells lack insulin receptors so are more sensitive to BLOOD sugar levels

Other glands • Pineal gland found deep in the brain • Secretes melatonin in response to light conditions and controls circadian rhythms (repeated activity in a day-night cycle) • Thymus gland behind sternum between lungs • Secretes thymosins • Affect maturation and differentiation of white blood cells

Other glands • Reproductive glands • Ovaries, placenta, and testes secrete gonadotropins and the sex hormones (estrogen and progesterone in females, testosterone in males) • Digestive glands • Cholecystokinin slows down digestion • Heart and kidneys also secrete hormones

Stress and Health • A factor that can stimulate an autonomic sympathetic response is a stressor • Condition it produces is called stress • Stress can be physical (hot-cold, low O 2, injuries) or psychological (real or imagined dangers, anger, guilt, joy, happiness) • Stress can be good or bad

19 Clinical Terms related to the Endocrine System • Know them