Pituitary and Thyroid Hormones 1 Topics for today: • Anterior pituitary hormones • Posterior pituitary hormones • Portal system & releasing factors • Structure of thyroid gland • Action of thyroid hormones 2 Major endocrine glands of the body pineal gland pituitary gland parathyroid glands thyroid gland adrenal glands thymus gland pancreas ovaries (female) testes (male) 3 1 Hydrophilic hormone action mechanism cytoplasm Extracellular fluid second messenger hormone Multiple effects in the cell membrane receptor 4 Example: Action of Epinephrine 5 Pituitary/hypothalamus axis ...interaction of nervous system & endocrine system 6 2 Pituitary secretions neurosecretory cells anterior pituitary in hypothalamus - TSH - ACTH - growth hormone posterior pituitary - FSH - oxytocin - luteining hormone - antidiuretic hormone - prolactin 7 Pituitary secretions neurosecretory cells anterior pituitary in hypothalamus - TSH - ACTH - growth hormone posterior pituitary - FSH - oxytocin - luteining hormone - antidiuretic hormone - prolactin 8 Physiologic effects of hormones from the anterior pituitary • TSH - stimulates release of hormones from thyroid • ACTH - stimulates release of hormones from adrenal cortex • growth hormone - stimulate growth of somatic tissues • FSH - stimulates gamete formation and follicle development • luteining hormone - affects corpus luteum & Leydig cells • prolactin - stimulates development of mammary ductules 9 3 Physiologic effects of hormones from the posterior pituitary •ADH - increases reabsorption of water from kidney tubules • oxytocin - stimulate uterine contraction& milk let-down 10 Origins of anterior/posterior pituitary...effects on control* hypothalamus anterior pituitary Rathke’s pouch posterior pituitary buccal cavity *Posterior pituitary derives from neural tissue but anterior pituitary is of endodermal origin - control 11 of hormone release from the two lobes is different. Hypothalamus control of posterior pituitary Neurosecretory cells in the hypothalamus send impulses that control hormone secretion from the posterior pituitary Hormones released from the posterior pituitary are synthesized in hypothalamus and stored in the posterior pituitary. 12 4 Hypothalamus control of anterior pituitary Hypothalamus secretes releasing factors which control anterior pituitary Releasing factors from hypothalamus: CRF TSHRF STRF FSHRF LHRF PIF 13 Thyroid gland anterior view 14 Posterior view of thyroid gland 15 5 Thyroid microanatomy site of formation and storage of thyroxin (thyroid hormone) releases calcitonin16 Thyroid gland hormones & effects • lipid mobilization & oxidation I I • increased glucose uptake HO O CH2CHCOOH • increased glycogen synthesis • increased protein synthesis I I NH2 Thyroxine • increased cardiac output (amino acid deriv) • elevated body temperature • increased bone growth • promotes neural development calcitonin (a peptide) • decreased plasma calcium level • increased calcium deposition in bone matrix • reduced Ca absorption in GI tract 17 • increased Ca excretion in urine Topic for Monday: Pancreatic and Adrenal Hormones 18 6.