Download Regulation: Endocrine System II

Unit IV: Regulation
Endocrine 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
Adrenal Gland (Suprarenal)
• Arises from two different fetal glands
Capsule
Cortex
Medulla
Capsule
Zona
Glomerulosa
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
Notes
• Hyperglycemic hormones raise blood glucose
– Glucagon, GH, epinephrine, NE, cortisol and corticosterone
• Hypoglycemic hormones lower blood glucose
– insulin
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 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