Major Endocrine Glands of the Body Pineal Gland Pituitary Gland

Home , Anterior pituitary, Posterior pituitary

Topics for today:

• Anterior pituitary hormones • Posterior pituitary hormones • Portal system & releasing factors • Structure of thyroid gland • Action of thyroid hormones

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

Pituitary/hypothalamus axis ...interaction of nervous system & endocrine system

2 Pituitary secretions

neurosecretory cells anterior pituitary in hypothalamus - TSH - ACTH - growth hormone posterior pituitary - FSH - oxytocin - luteining hormone - antidiuretic hormone - prolactin

Pituitary secretions

neurosecretory cells anterior pituitary in hypothalamus - TSH - ACTH - growth hormone posterior pituitary - FSH - oxytocin - luteining hormone - antidiuretic hormone - prolactin

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

3 Physiologic effects of hormones from the posterior pituitary

•ADH - increases reabsorption of water from kidney tubules • oxytocin - stimulate uterine contraction& milk let-down

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.

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

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