RAAS system Flashcards
What is responsible for long term regulation of Na+ excretion?
What is responsible for short term regulation of Na+ excretion?
Long term- RAAS
Short term- GFR
What is major hormone responsible for Na+ reabsorption?
Aldosterone
What 3 factors initiate RAAS system?
1) Macula densa cells in the distal CT detect less NaCl
2) Sympathetic stimulation
3) Little or no arteriolar stretch (from low blood volume due to low Na+ and thus H2O)
Outline RAAS system?
1) Macula densa cells detect low levels Na+
2) Juxtaglomerular cells in afferent arterioles stimulated release renin from granular cells
3) Renin cleaves angiotensiongen (made liver) to angiotensin 1
4) Angiotensin 1 cleaved by angiotensin converting enzyme (ACE- made lungs to form angiotensin II
Stimulate adrenal glands secrete aldosterone
Aldosterone increases Na+ reabsorption- increases volume
Stimulate thirst- vasopressin release
Ang II vasoconstricts arterioles
Draw RAAS system?
What are 2 enzymes involved in RAAS?
Function?
Located?
Renin- cleave angiotensinogen to angiotensin I
- released by liver
Angiotensin converting enzyme (ACE)- convert angiotensin 1 to
angiotensin II
- released lungs
What detects low Na+ lvls?
Macula densa cells
Where is renin released from?
Granular cells of juxtaglomerular apparatus
What stimulates release renin? (2)
What detected by?
1) Low Na+ lvls detects by macula densa cells
2) Low perfusion pressure detects by baroreceptors in afferent arteriole
What inhibits renin?
When is it released?
Inhibited by Atrial Natriuretic Peptide (ANP)
Released by stretched atria response to increase blood pressre
How is RAAS system inhibited?
1) Increase in BP
2) Stretch atria releases atrial natriuretic peptide (ANP)
Label
Where is angiotensinogen produced?
Liver
What occurs to angiotensinogen?
Cleaved by renin to form angiotensin I
What enzyme cleaves angiotensin I to angiotensin II?
Where is it found?
Angiotensin converting enzyme (ACE)
Lungs
State 5 actions of angiotensinII?
1) Vasoconstriction of arterioles
2) Stimulates Na+ resabsorption in kidney
3) Stimulate release aldosterone from adrenal cortex
4) Increase thirst
Stimulate ADH release from hypothalamus
5) Release noradrenaline (symp ns)
Where is aldosterone released from when stimulated by angiotensin II?
Adrenal cortex
Where is ADH released from?
Posterior pituitary gland
What does release noradrenaline do?
Vasoconstrict arterioles
Release renin
Function of ADH?
Increase promotion aquaporin 2 channels
Where is aldosterone released from?
Zona glomerulus of adrenal cortex
What cells do aldosterone act on?
Principal cells of collecting ducts
Increases expression Na+ channels
How are aldosterone and potassium linked?
Aldosterone act principal cells increase Na+
Na+/K+/ATPase pump used
Potassium moved into cell
Potassium into renal tubule- excreted into urine
What does angiotensin II do to aldosterone lvls?
Stimulate adrenal cortex increase secretion aldosterone
Does angiotensin II cause vasoconstriction or dilation?
Vasoconstriction
Draw RAAS system
Draw RAAS system and effects angiotensin II?
What is aim of RAAS system increasing? (2)
Increase circulating blood volume
Increase BP
State effects of angiotensin II? (6)
1) Stimulate zona glomerulosa in adrenal cortex to secrete aldosterone (increase sodium uptake), increases water
2) Vasoconstriction efferent arterioles- increase pressure causing GFR to fall- harder blood leave glomerulus- more reabsorption
3) Increase Na+ reabsorption in proximal convoluted tubule
4) Stimulates thirst
5) Stimulate aldosterone- act pprinciple increase aqua porin
6) Stimulate vasopressin (ADH)- aquaporin expression
