The Integrated CV System Flashcards
long-term mechanisms for BP regulation
related to maintaining homeostasis of body fluid volume
based on maintaining a balance between intake and output of body fluid
-overall regulation of kidney excretion of H2O and Na+
variables account for variation in blood volume
relationship between extracellular fluid, blood volume, and kidney excretion
increase in extracellular fluid results in increased blood volume and arterial pressure
normal body response: kidneys excrete excess extracellular fluid and returns the pressure to normal
mechanism reverses if reduced blood volume
what is pressure diuresis
renal output of water
what is pressure natriuresis
renal output of salt
what results with excess salt intake
increased H2O retention
increased MAP
renal output curve and net water/salt intake
-what affects the renal output curve
over long term, water and salt intake must equal output
two determinants of long-term arterial pressure
-location of renal output curve
-level of intake line
TPR, arterial pressure and kidney function
-if you increase TPR…
arterial pressure = CO x TPR
increase TPR
-get acute rise in arterial pressure
-however, normal kidney function will respond by returning arterial pressure to the pressure level of the equilibrium point
effect of fluid volume on arterial pressure flow chart
increased extracellular fluid volume --> increases blood volume --> increased mean circulatory filling pressure --> increased venous return --> increased CO --> increased arterial pressure
CO: 2 mechanisms to increase arterial pressure
direct effect -increased CO increases pressure indirect effect -autoregulation -local tissue control
salt intake
effect of increased Na+ greater than effect of increased H2O
amount of salt accumulation in body is main determinant of extracellular fluid volume
chronic hypertension
-criteria
MAP > 110
results of pathology
with dialysis, what happens if a patient’s body fluid level is not kept at a normal level
volume loaded hypertension
- too much volume being replaced
- increased CO
renal mechanisms for control of BP
review: 1st mechanism of kidney control of arterial pressure
2nd system: Renin-Angiotensin
Renin-Angiotensin System
- what is renin
- function
- released from…
renin -hormone that acts as an enzyme -released when arterial pressure drops - i.e. when renal perfusion is inadequate helps raise arterial pressure release from juxtaglomerular cell
renin-angiotensin pathway
decreased arterial pressure –>
renin release –>
acts on renin substrate (angiotensinogen) –> results in Angiotensin I –> transforms into angiotensin II (powerful vasoconstrictor) –> leads to retention of salt/H2O, vasoconstriction, and inactivation
all these lead to increased arterial pressure
