Other Endocrine Glands

Pineal gland

Location of pineal gland

hangs off roof of third ventricle beneath corpus callosum

what is involution

shrinkage with age that happnes with pineal gland

what are cells of pineal glands called and what do they secrete, whihc has what function (3)

pinealocytes → melatonin → circadian rhythm (day night cycle), promote sleep, influence puberty timing

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thymus

Thymus

• location

• how many lobes

• does it undergo involution

• what 3 body systems is it part of

• mediastinum

• bilobed

• yes

• endocrine, lymphoid, immune

what does the thymus do and what 3 hormones

secrete hormones that stimulate development of other lymphoid organs and T lymphocyte activity

• thymopoietin, thymosin, thymulin

Thyroid - largest endocrine gland

Thyroid

• location

• how many lobes and what are they

• anterior of trachea under thyroid cartilage and larynx

• biloped connected by isthmus (pyrimidal + lateral lobes)

What is the thyroid made up of

made up of thryoid follicles which contain protein rich colloid surrounded by follicular cells

Colloid

Thyroglobulin + iodine → in lumen of thyroid follicle → make thyroid hormones

What does the thyroid gland secrete (2)

Thyroid Hormone (TH) → includes T3 (triiodiothyronine) and T4 (tetraiodothyronine/ thryoxine)

calcitonin

TH + functions

Thyroid hormones → T3 (10%) + T4 (mostly)

• effects all cells of body

• increases metabolic rate & heat production

Calcitonin - what is it produced by

parafollicular cells / C cells

What does calcitonin do

antagonist to parathyroid hormones

• inhibits osteoclast activites (which breakdown/ resorb bone matrix to release Ca2+ into blood)

• stimulates osteoblast activities & bone formation

LOWERS blood Ca2+

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parathyroid

Parathyroid - where is it and what does it contain

4 small glands on thyroid gland posteriorly

contains chief cells that secrete parathyroid hormones (PTH)

PTH → 4 functions

Parathyroid hormones → increases Ca2+ levels

• promote synthesis of calcitriol

  • increase Ca2+ absorption

  • decrease urinary excretion

  • increase bone resorption / breakdown by stimulating osteoclasts

adrenal gland / suprarenal gland

adrenal gland/ suprarenal gland

• how many lobes, what shape

• location

• 2 parts

2 lobes, pyramid shaped

above kidney (suprarenal)

cortex (outside) medulla(inside)

Adrenal cortex

Adrenal cortex and what does it produce

thicker outer layer of adrenal gland

produces corticosteroids/ corticoids (3 groups)

What are the three layers of the adrenal cortex from superficial to deep

zona glomerulosa

zona fasciculata

zona reticularis

zona glomerulosa what layer and waht does it secrete

superficial layer → mineral corticoids (aldosterone)

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zona fasciculata - what layer and waht does it secrete

middle layer → glucocorticoids (cortisol)

zona reticularis - what layer and waht does it secrete

innermost deep layer → gonadocorticoids ( sexhormones; androgens)

Mineral corticoids (aldosterone) → where , what does it regulate

zona glomerulosa of adrenal cortex

regulates electrolytes (Na+ and K+) in extracellular fluid

RAAS - renin angiotensin aldosterone system

low bp → angiotensin II → aldosterone → Na+ resorption and water retention by kideny (keep Na+ and water which follows Na+) → retaining fluid keeps bp up

Glucocorticoid (cortisol) - where, when is it released (3)

zona fasciculata and some in zona reticularis,released in response to adrenal corticotropin hormones by anterior pituitary gland + eating and activity + stress (fight or flight)

cortisol/ glucocorticoid main metabolic effect
+ 2 aditional effect

gluconeogenesis (formation of glucose from fat and protein) -
> incRease blood glucose level, fatty acids, and amino acids

keep bp constant - vasoconstrict

antinflamatory

gonadocorticoids (sex hormones) - where and when is it released

zona fasciculata and zona reticularis (mainly)

released in response to adrenocorticotropic hormones from anterior pituitary

2 main gonadocorticoids

androgen → testerosterone in male and estrogen in female

estradiol → source of estrogen during women menopause

Adrenal medulla

Adrenal medulla - what 2 systems

endocrine + autonomic nervous system (innervated by sympathetic preganglionic fibers)

What cells do adrenal medulla have which secrete what

chromaffin cells → catecholamines (mostly epinephrine, 20% norepinephrine, some dopamine)

Catecholamine functions

increase everything fight or flight

decrease digestion and urine

increase blood glucose level → glycogenolysis , glyconeogenesis, glucose sparing effect (epi)

norepinephrine → vasoconstriction → increase BP

Pancreas

what cells does the pancreas have

exocrine and endocrine cells

Pancreatic exocrine cell

acinar cells → produce pancreatic juice

Pancreatic endocrine cells

pancreatic islets (or islets of langerhorn) → alpha and beta

pancreatic islets alpha vs beta

alpha produces glucagon (hyperglycemic increasing blood glucose)

beta produces insulin (hypoglycemic decreasing blood glucose)

Glucagon targets ____ where it promotes

liver → glycogenolysis (glycogen → glucose) and gluconeogenesis

→ release glucose into blood

Insulin does what

inhibits glycogenolysis and gluconeogenesis → lower blood glucose level

increasing glucose transport into fat and muscle cells

Ovary

Testes

Gonads (ovary and testes) → exocrine product

ovaries → eggs

testes → sperm

gonads endocrine product

gonadal hormones (mostly steroids)

ovary → estradiol and progesterone

teste → testosterone, estrogen, weak androgens

ovaries produce what which does what

progesterone and estrogen → female development

Placenta secretes what

estrogen, progesterone, human chorionic gonadotropin

Testes produce what

testosterone→ male characteristics