osmolality Flashcards
(34 cards)
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
during execssive vasoconstriction what are secereted in the kidneys
- prostaglandins to maintain some dialation
- to maintain blood flow
- suffiecient GFR
what are some common causes for hypovolemia
- burns
- haemmorage
- vomiting and diarrhoea
hypertensive renal disease
- high BP is transferred to the kidney
- arteriosclerosis of renal arteries
- hylanization (scarring and thickening) of small vessels
- can lead to chronic renal damage
what are some renal causes of secondary hypertension?
- impaired Na and water excretion
- stimulation of renin
- renal artery stenosis ( kidneys constantly think there is reduced perfusion to the kidney and stimulate RAAS which increases the blood pressure)
what is osmolality and osmolarity a rough measure of
amount of solute in the solvent (how dilute or concentrated)
which two systems are involved in regulating osmolarity
what are osmorecpetors and where are they made
- found in the hypothalamus
- made from the supraoptic nucleus
- sense change in plasma osmolarity
- can either change: conc of urine or thirst
how does ADH work
- anti-diuretic hormone released when there is high plasma osmolarity
- synthesized in the supraoptic nucleus of the hypothalamus
- causes more H20 to be reabsorbed
- bind to V2 receptors -> causes fusion of 2 aquaporin channels for water to pass
how does release of ADH
- High BP:
ADH has a higher set point so less water is reabsorbed - Low BP:
ADH has a lower setpoint so that more water can be reabsorbed
