unit 5.5

renin

enzyme released by juxtaglomerular apparatus when blood pressure decreases

what does renin do?

converts angiotensinogen → angiotensin I → angiotensin II
results = angiotensin ii increase = vasoconstrictor that stimulate release of aldosterone

atrial natriuetic hormone (anh)

hormone secreted by the atria of the heart when its vessels are stretched due to increasing blood volume

it also inherits the secretion of renin

aldosterone

hormone relased by adrenal cortex in response to decreasing blood pressure

what are the functions of aldosterone

causes Na reabsorption and K excretion at distal convoluted tubule

H2O will always follow Na → Na reabsorption = H2O reabsorption

what is hypotension

low blood pressure that stimulates aldosterone release

in hypotension, what does the low blood Na concentration mean?

not enough H2O beng reabsorbed

what is hypertension

high blood pressure where too much aldosterone is being released

in hypertension, what does the high blood Na concentration mean?

too much H2O being reabsorbed

scenarios in blood pressure regulation 1

increasing blood [Na+ ] = high BP = increasing H2O retention in the kidneys/body = blood volume is increasing

heart releases ANH

results in kidneys excrete Na+ , water follows, BP returns to normal

scenarios in blood pressure regulation 2

increasing blood [Na+ ] = low BP = increasing H2O retention in the kidneys/body = blood volume is increasing

kidneys release renin, which causes the release of aldosterone

results in kidneys absorbing Na+ , water follows, BP returns to normal

antidiuretic hormone (adh)

hormone released by posterior pitituary gland when increasing [solute] in blood is detected

functions of adh

Casuses H2O to be reabsorbed in the DCT & collecting duct

Osmoreceptors in hypothalamus detects the [solute] in blood

Results in lower urine volume (more concentrated urine) & increase blood volume

adh negative feedback loop

once the action of the chemical occurs the chemical’s release will be STOPPED (negated)

applications of adh

Diuretic drugs for high blood pressure

Alcohol/caffeine, where increased urination leads to dehydration

Diabetes insipidus, which is the inability to produce ADH = watery urine

Blood electrolyte balance, which is maintained by reabsorption of ions

blood pH maintenance

When blood is ACIDIC at DCT:

More H+/NH3 is excreted into the DCT, as NH3 is a weak base that will absorb the excess H+ to form NH4 + which is then excreted in the urine

More Na+ is reabsorbed into the blood, as where Na+ goes, H2O will follow leading to ↓ [H+ ] in blood

When blood is BASIC at DCT

Less H+/NH3 is excreted and less Na+ is reabsorbed