Unit IV: Regulation Endocrine System II Chapter 16 pp

Thyroid Gland High blood flow per gram of tissue

Thyroid Gland Thyroid follicles (follicular cells) –Two hormones: Triiodothyronine (T 3 ) and Thyroxine (T 4 ) –thyroid hormones  body’s metabolic rate and O 2 consumption calorigenic effect -  heat production  heart rate and contraction strength;  respiratory rate stimulates appetite and breakdown CHO, lipids and proteins C (calcitonin) cells –calcitonin that  blood Ca 2+, promotes Ca 2+ deposition and bone formation

Parathyroid Glands PTH release in response to hypocalcemia –  blood Ca 2+ levels –Mechanisms: 1.promotes synthesis of calcitriol in kidneys 2.  re-absorption of Ca 2+ and  urinary excretion 3.  bone resorption   osteoclasts 4.  collagen synthesis by osteoblasts   bone deposition

Capsule Cortex Medulla Adrenal Gland (Suprarenal) Arises from two different fetal glands Zona Glomerulosa Capsule Zona Fasciculata Zona Reticularis Adrenal Medulla

Sympathetic ganglion innervated by sympathetic preganglionic fibers –catecholamines (epinephrine, NE) Hormonal effect to stress is longer lasting –Increases alertness, anxiety, or fear –increases BP, heart rate and air flow –Increased sweat gland activity –raises metabolic rate inhibits insulin secretion stimulates gluconeogenesis and glycogenolysis Stress causes medullary cells to stimulate cortex

Adrenal Cortex Corticosteroids –Aldosterone / mineralcorticoids control electrolyte balance  promotes Na + retention and K + excretion –Cortisol / glucocorticoids (hydrocortisone) stimulates fat and protein catabolism, gluconeogenesis and release of fatty acids and glucose into blood anti-inflammatory effect –sex steroids androgen (DHEA  testosterone) estrogen (important after menopause)

Pancreas

Insulin (70%, beta cells) –secreted during/immediately after a meal when blood glucose and amino acid levels rise –stimulates glucose and amino acid uptake –nutrient storage effect   blood glucose level Glucagon (20%, alpha cells) –secreted between meals when blood glucose levels fall –stimulates glycogenolysis, release of FFA’s, and promotes absorption of amino acids for gluconeogenesis   glucose level Gastrin  stimulates stomach acid secretion, motility, and emptying  also secreted by stomach and small intestine

Hyperglycemic hormones raise blood glucose –Glucagon, GH, epinephrine, NE, cortisol and corticosterone Hypoglycemic hormones lower blood glucose –insulin Notes

Gonads Ovaries and Testes Estradiol and Progesterone −Development of female physique −Development of female reproductive system Testosterone −Development of male physique −Development of male reproductive system Inhibin −Suppress FSH secretion

Endocrine Functions of Other Organs Heart – –atrial natriuretic peptide (ANP) –  blood volume and  BP by  Na + and H 2 O loss by kidneys Liver –Erythropoietin (EPO) 15% –angiotensinogen precursor of angiotensin II –IGF-I –Hepcidin – promotes intestinal absorption of iron –role in making calcitriol

Endocrine Functions of Other Organs Kidneys –Erythropoietin (85%) –Role in making Angiotensin II –Calcitriol (active form of vitamin D) more blood Ca 2+ available for bone deposition Stomach and small intestines –enteric hormones coordinate digestive motility and secretion –CCK, Gastrin, Ghrelin, Peptide YY Placenta –secretes estrogen, progesterone and others regulate pregnancy, stimulate development of fetus and mammary glands