Renal physiology 2 Flashcards
how much( in %) of renal plasma flow gets filtrated?
~25%
~125 ml/min
~180 L/day
what is the main driver of glomerular filtration?
Glomerular blood hydrostatic pressure(GBHP)
net filtration pressure
determines how much water and small dissolved solutes leaves the blood
what are the forces driving plasma filtration?
glomerular blood hydrostatic pressure(GBHP)
what are the forces opposing the filtration of plasma?
capsular hydrostatic pressure(CHP)
Blood colloid osmotic pressure(BCOP)
capsular hydrostatic pressure(CHP)
the pressure exerted on the plasma filtrate by the elastic recoil of the glomerular capsule
what is the normal capsular hydrostatic pressure(CHP) value?
~ 15 mmHg
Blood colloid osmotic pressure (BCOP)
the osmotic force of the proteins left in the plasma: the proteins exert an increasing osmotic “pull” on the water in the plasma filtrate
(Water wants to move in from the capsule to dilute the plasma)
what is the normal BCOP?
~30 mmHg
what is the normal net filtration pressure (NFP)?
~10 mmHg
what is the normal glomerular blood hydrostatic pressure(GBHP)?
~ 55mmHg
what is the relationship between renal pressure and urine output?
directly proportional
Higher pressure-> more urine output
what is the relationship between renal pressure and glomerular filtration rate?
Glomerular filtration rate is relatively constant as blood flow to kidney is tightly regulated even if the pressure is increased
autoregulation in the kidney(2 mechanisms)
glomerular filtration rate and blood flow is tightly regulated
Autoregulation happens in 2 ways:
-Myogenic autoregulation: Elevations in transmural pressure induce contraction of preglomerular arterioles, predominantly at the level of afferent arterioles.
-Tubuloglomerular feedback: It senses changes in the amount of sodium chloride in the tubular fluid reaching the macula densa cells in the distal tubule and adjusts the diameter of the afferent arteriole accordingly. Tubuloglomerular feedback serves as an effective autoregulatory mechanism because the sodium chloride concentration of the fluid reaching the macula densa is dependent on flow rate, which in turn, is related to the GFR and glomerular capillary pressure.
how can increases and decreases in arterial blood pressure be buffered with the help of myogenic autoregulation?
increase in arterial pressure can be buffered by vasoconstriction of the afferent arteriole:
constriction of afferent arteriole-> decrease in renal blood flow-> decrease in glomerular pressure
decreases in pressure can be buffered by vasoconstriction of efferent arteriole:
constriction of efferent arteriole-> decrease in renal blood flow-> increase in glomerular pressure
what are the different mechanisms for regulation of glomerular filtration rate?
– Autoregulation: myogenic autoregulation or tubuloglomerular
feedback
– Neural: Increased sympathetic nerve activity leads to vasoconstriction of the afferent arterioles.
– Hormonal:
* Production of Angiotension II ->vasoconstriction of afferent and efferent arterioles
* Stretching of Atria of the heart stimulates Atrial Natriuretic Peptide production-> relaxation of mesangial cells, increasing the surface area available for filtration
tubuloglomerular feedback
Tubuloglomerular feedback: It senses changes in the AMOUNT( NOT CONCENTRATION) of sodium chloride in the tubular fluid reaching the macula densa cells in the distal tubule and adjusts the diameter of the afferent arteriole accordingly
what types of epithelium are there in different parts of the nephron?