osmolality Flashcards
When blood pressure drops what are the two main systems that come into play?
-RAAS
-prostaglandins
what 3 main things cause the release of renin
- increases sympathetic innervation: granular cells produce renin
- wall tension in arterioles fall: lower wall tension stimulates granular cells
- reduces Na to macula densa cells: they will release prostaglandins and granular cells release renin
what does RAAS do to help with low blood pressure?
- direct vasoconstriction in glomerulus: increase perfusion pressure
- release aldosterone: increase EnaC and more sodium reabsorption so more water reasorbed
- release ADH
- thirst
what role do prostaglandins have in reduced blood pressure
- reduced blood pressure means reduced perfusion to organs
- they cause vasodialation (prevent excessive vasoconstriction from the renin)
- so more perfusion to the organs
flow chart of the bodies response to reduced BP
what occurs when there is an increased blood pressure?
- ANP released (atrial natureric peptide)
- tries to increase extracellular fluid
- inhibit NA/K ATPase and close Na channels to prevent reabsorption of Na
- so reduced water reabsorption
- vasodialate afferent arterioles: increase GFR and reduce Na reasborption
- inhibit aldosterone
- inhibit ADH
- reduce renin
starlings forces in the PCT reducing blood pressure
- high hydrostatic pressure in peritubular capillaries
- reduced oncotic pressure
- water reabsorption reduces
what is pressure natriuresis?
increased sodium excretion
what is pressure diuresis
increased water excretion
how congestive cardiac failure effect the kidneys
- reduced CO
- reduced perfusion to kidney
- see this as hypovolemia (even tho its not, still normal volume heart is just weak)
- kidney will reabsorb more Na and H20
- odema and increased circulating fluid volume
congestive heart failure effect on the lungs
- kidneys mistake low CO as hypovolemia
- they increase NA and H20 reabsorption
- odema
- backs up into lungs
- pulmonary odema
managment of congestive heart failure
as it can cause pulmonary odema and odema in general must reduve fluid:
- diuretics (furezmide)
- ACE inhibitor (reduce RAAS)
- nitrates
- vasodialator (so blood vessels can compenstate foe extra fluid)
where commonly causes hypervolemia ?
- kidney retention of sodium and water
- excessive sodium intake
- cirrhosis
- hyperaldosteronism ( more aquaporins, more reabsorption of na and water)
what is hypovolemic shock
- vital organs are inadequately perfused
- anaerobic respiration
- tiredness and dizziness and thirst
- vasodialation to maintain blood supply
- tissue necrosis
in severe circumstances when there is a low BP what are the body response
- tachycardia
- peripheral vasoconstriction
- increase in myocardial contractility