Unit IV: RegulationEndocrine System II

Chapter 16

pp. 552 - 573

Thyroid Gland

• High blood flow per gram of tissue

Thyroid Gland

• Thyroid follicles (follicular cells)– Two hormones:

• Triiodothyronine (T3) and Thyroxine (T4)– thyroid hormones

body’s metabolic rate and O2 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 Ca2+ , promotes Ca2+ deposition and

bone formation

Parathyroid Glands

• PTH release in response to hypocalcemia blood Ca2+ levels

– Mechanisms:

1. promotes synthesis of calcitriol in kidneys

2. re-absorption of Ca2+ and urinary excretion

3. bone resorption osteoclasts

4. collagen synthesis by osteoblasts bone deposition

CapsuleCortex

Medulla

Adrenal Gland (Suprarenal)

• Arises from two different fetal glands Zona Glomerulosa

Capsule

Zona Fasciculata

Zona Reticularis

Adrenal Medulla

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

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

GonadsOvaries 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 H2O 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 Ca2+ 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