endocrine system

what are the key glands in the endocrine system and what hormones do they release

• hypothalamus

  • GHRH, GHIH, TRH, CRH

• parathyroid

  • PTH

• pituitary gland

  • anterior

    • GH, TSH, ACTH

  • posterior

    • ADH, oxytocin

• thyroid

  • TH

• adrenal

  • adrenaline

  • cortisol

• pancreas

  • glucagon

  • insulin

what are the different solubilities of hormones

lipid soluble

• bound to carrier protein

• intracellular receptors — enters cell

• gene transcription

• slow

water soluble

• unbound

• plasma membrane receptors

• second messengers

• fast

what are the main differences between posterior and anterior pituitary gland

posterior

• neural connection to hypothalamus

• made in cell bodies, stored in axon terminals

• oxytocin (love) and ADH (reabsorbs water)

anterior

• vascular connection to hypothalamus

• releasing or inhibiting hormones (TSH for thyroid hormone, ACTH for cortisol, GH)

what is the pathway of the growth hormone axis

hypothalamus releases GHRH, causing anterior pituitary to release GH, causing liver to release IGF-1. all of which work to increase blood glucose levels.

what are the growth hormone disorders

• dwarfism — low GH

• giantism — lengthened growth

• acromegaly — thickened growth

what are thyroid hormones made from and what are the types

T3 is active — 3 iodine, 1 tyrosine

T4 is inactive — 4 iodine, 1 tyrosine

lipid soluble, increases alertness, regulars basal metabolic rate

outline the thyroid hormone axis

hypothalamus releases thyroid releasing hormone

anterior pituitary gland releases thyroid stimulating hormone

thyroid gland releases T3/T4

what are the thyroid hormone disorders

• infantile hypothyroidism (lack of iodine reduces T3/T4 levels, causing low metabolic rate, delayed growth)

• adult hypothyroidism (autoimmune disease or iodine deficiency reduces T3/T4 levels, causing weight gain, brain fog and enlarged thyroid gland)

• graves’ disease (autoimmune diseases causes high T3/T4 levels and weight loss, anxiety, sweating, bulging eyes and enlarged thyroid)

what are the parathyroid glands and what do they do

4 glands on the thyroid, secreting PTH during low blood calcium levels (hypocalcaemia)

• resorption (osteoclasts break down bone)

• reabsorption (kidneys)

what are the parathyroid hormone disorders

• hypoparathyroidism causes hypocalcaemia causing spasms bc the AP threshold is lowered

• hyperparathyroidism causes hypercalcaemia causing soft bones from high bone resorption

what do the adrenal glands do

HPA axis

• hypothalamus releases CRH, causing anterior pituitary to release ACTH, stimulating adrenal cortex to release cortisol (lipid-soluble, slow)

SAM pathway

• hypothalamus activates sympathetic nervous system, stimulating the adrenal medulla to release adrenaline (water-soluble, fast)

cortisol disorders

• addison’s disease

  • adrenal insufficiency, lowering cortisol, lowering blood glucose and blood pressure

• cushing’s disease

  • hyperactive pituitary gland releases excess cortisol, high blood glucose and blood pressure

what does ADH do

ADH: add water, drive pressure, help cortisol

what are clusters of endocrine cells in the pancreas called and what do the cells do

islets of langerhans

• alpha secrete water-soluble glucagon, increasing blood glucose

  • glycogenolysis converts glycogen to glucose

• beta secrete water-soluble insulin, lowering blood glucose levels

  • glycogenesis converts glucose to glycogen

what are the pancreatic diseases

• type 1 diabetes mellitus

  • autoimmune destruction of beta cells, producing no insulin

  • polyuria, polydipsia, polyphagia, weight loss

• type 2 diabetes mellitus

  • insulin resistance

  • polyuria, polydipsia, weight gain, infections