Glomerular Filtration & Renal Blood Flow Flashcards
Filterability through the glomerulus drops off at ___________.
60 kDa
The cells on the opposite side of the glomerulus from the blood are called the __________.
podocytes
Glomerular filtration rate is determined by ___________.
Starling forces
GFR = ________
NFP x k
NFP = ____________
P(gc) - P(t) - pi(gc)
What does k equal (in the GFR equation)?
p(A) x surface area
What do the afferent arterioles of the glomerulus do in response to increases in mean arterial pressure, and why?
They vasoconstrict (via the myogenic response) to limit flow to the glomerulus. They do this because the kidneys normally operate near their maximum potential (in terms of reabsorption), so increasing GFR would lead to “peeing yourself to death.”
How does the afferent arteriole respond to hypovolemia?
It constricts (due to the sympathetic response). The afferent arteriole does this to limit excessive water loss.
How does diabetes affect the glomerulus?
It thickens the glomerular basement membrane and effaces the podocyte slits.
In response to chronic hypovolemia, how does angiotensin II affect the kidneys?
It constricts the efferent arteriole, thus increasing filtration fraction and decreasing GFR.
What is the formula for filtration fraction (FF)?
FF = GFR/RPF FF = filtration fraction GFR = glomerular filtration rate RPF = renal blood flow
Are the juxtaglomerular cells in the afferent or efferent arteriole?
Afferent
What is normal GFR?
90 - 125 ml/min
In severe hypovolemia, higher oncotic pressure in the ultrafiltrate leads to ____________.
decreased GFR
Albumin is roughly ____________.
67 kDa and thus does not pass into the ultrafiltrate
What do mesangial cells do?
Contract, to decrease GFR if needed
Mesangial cells cover ____________.
glomerular capillaries
What do renal prostaglandins do?
In response to chronic hypovolemia, they dilate the afferent arteriole. This helps to preserve the GFR. Also, it is thought that prostaglandins help increase oxygen delivery to the tissues, thus preventing the likelihood of sudden renal failure.
