control of plasma Flashcards
three main classes of hormones
1) proteins and polypeptides
-example hormone
-example site of syntehsis
-chemical nature
-synthesis
-storage
-release
-transport in blood
1) insulin, GH, TSH, ADH
-anterioir and posterioir pituitary, pancreas, parathyroid
-hydrophilic
-synthesised in advance
-stored in vesicles untill triggered to release
-exocytosis
-dissolved in plasma
2) steroids
-cortisol, oestrogen, aldosterone
-adrenal cortex, ovaries, testes
-hydrophobic
-synthesised on demand
-released upon synthesis (not stored in advance)
-simple diffusion
-bound to plasma proteins
3) derivitives of amino acid
1) thyroid hormones
2) catecholamines
1) throxine
-thyroid
-hydrophobic
-synthesied from tyrosine
-made in advance
-transport proteins
bound to plasma proteins
2) adrenaline
-adrenal medulla
-hydrophobic
-synthesied from tyrosine
-stored in secretory vehicles
-exocytosis
-freely dissolved
example of negative feedback on hormone secretion
1) response driven
2) axis driven
blood glucose
blood calcium
blood osmolarity
1) based on direct effects of hormone action e.g. insulin
2) regulation of multiple hormones within endocrine acis
example of positive feedback in endocrine system (less common)
-oxytosin during childbirth
stretching of cervix leads to oxytosin release.
-leads to uterous contractions, more stretch therefore more oxytosin release
example of feed forward control in hormone secretion
-SCN
allows the human body to prepare and adapt for changes in the environment
-SCN sends signals to hypothalamus even before dawn
-hypothalamus release corticotropin releasing hormone (CRH)
-stimulates adrenal glands to release cortisol in anticipation of waking state and it;s increased energy demands
key organs for regulation of sodium and water balance
1) hypothalamus
2) pituitary gland
3) kidneys
4) adrenal gland
1) hypothalamus: senses changes in blood osmolarity. ADH release
2) pituitary gland (posterioir): releases ADH
3) kidneys: regulates excretion or reabsorbtion of water and sodium based on hormone signals
4) adrenal glands: secrete aldosterone in repsonse to signals from renin angiotensin aldosterone system. aldosterone promotes sodium and water reabsorbtion in the kidney
function of ADH
peptide hormone
released from posterioir pituitary in response to increased blood osmolarity e..g dehydration
-increases water reabsorbtion and permeanbility from collecting duct in renal tubule
-allows more water to be absorbed decreasing urine production
-concentrating urine and increases blood pressure
-decreasing osmolarity
function of aldosterone
steroid hormone
-released in response to low blood volume.
-increases sodium and water reabsorbtion in distal tubules of collecting ducts and pottassium secretion
-increasing blood pressure without affecting blood osmolarity
-activates renin angiotensin system
function of angitension 11
stimulates thirst, leading to incresed fluid intake
-causes vasoconsriction contributing to blood pressure regulation
type of ADH receptor
V2 receptor
G protein coupled receptor
-diurnal variation in ADH secretion
-gender considerations
-in adults there is an increase in ADH secretion during the night
-females thought to be more sensitive to the effects of ADH
function of atrial natiuretic peptide (ANP)
secreted by right cardiac atrium
-promotes the loss of water and sodium, counteracting the effects the ADH and aldosterone
