Increased blood volume and increased blood pressure will increase GFR. Constriction in the afferent arterioles going into the glomerulus and dilation of the efferent arterioles coming out of the glomerulus will decrease GFR. Hydrostatic pressure in the Bowman’s capsule will work to decrease GFR.
Why does dilation of efferent arteriole decrease GFR?
The net result of efferent arteriolar constriction is an increased filtration fraction. The GFR most likely decreases because the RBF decreases, but the decrease in the GFR will not be proportionate because of the increase in glomerular capillary pressure. Dilation of the afferent arteriole has opposite effects.
What causes the afferent arteriole to dilate?
Afferent arteriole constriction leads to decreased GFR and decreased RPF, resulting in no change in FF. One important function of prostaglandins is to dilate the afferent arteriole.
Does angiotensin II dilate efferent arteriole?
Angiotensin II exerts a vasoconstrictive effect on both afferent and efferent arterioles, but because the efferent arteriole has a smaller basal diameter, the increase in efferent resistance exceeds the increase in afferent resistance.
What happens to the efferent arteriole after it leaves the glomerulus?
The efferent arterioles of the undifferentiated cortical glomeruli are the most complex. Promptly on leaving the glomerulus they break up into capillaries and become part of a rich plexus of vessels surrounding the cortical portions of the renal tubules.
What happens in the afferent arteriole?
The afferent arteriole is an arteriole that feeds blood into the glomerulus. The afferent arterioles modulate their vascular resistance in response to changes in intraluminal pressure or composition of tubular fluid at the macula densa. In this manner, they control the glomerular filtration.
How would dilating the afferent arteriole affect GFR?
An increase in the afferent arteriolar diameter (decrease in resistance) causes an increase in the glomerular capillary hydrostatic pressure and an increase in GFR. A decrease in the diameter of the afferent arteriole has the opposite effect.
Do ACE inhibitors constrict or dilate efferent Arteriole?
Unlike the direct-acting smooth muscle vasodilators or adrenergic inhibitors, ACE inhibitors dilate the efferent as well as the afferent glomerular arterioles and thereby reduce glomerular hydrostatic pressure and renal filtration fraction, even though renal blood flow and glomerular filtration rate are preserved.
Does angiotensin II constrict efferent or afferent?
Angiotensin II constricts both the afferent (preglomerular) and efferent (postglomerular) arterioles but preferentially increases efferent resistance [2].
What is the function of afferent arteriole in kidney?
The afferent arteriole is an arteriole that feeds blood into the glomerulus. The renal arterioles play a central role in determining glomerular hydraulic pressure, which facilitates glomerular filtration.
What happens when blood flow through afferent arterioles increases?
Arteriole Myogenic Mechanism This mechanism works in the afferent arteriole that supplies the glomerulus. When blood pressure increases, smooth muscle cells in the wall of the arteriole are stretched and respond by contracting to resist the pressure, resulting in little change in flow.
What is the difference between afferent and efferent arterioles?
The main difference between afferent and efferent arterioles is that afferent arterioles carry blood to the glomerulus whereas efferent arterioles take the blood away from the glomerulus. An afferent arteriole is a branch of the renal vein, which carries blood containing nitrogenous wastes.
How does constriction of the afferent arterioles affect renal blood flow?
Constriction of the afferent arterioles has two effects: it increases the vascular resistance which reduces renal blood flow (RBF), and it decreases the pressure downstream from the constriction, which reduces the GFR. Constriction of the efferent arterioles also increases the vascular resistance so it reduces RBF.
How does afferent arteriole constriction affect GFR and RPF?
Afferent arteriole constriction leads to decreased GFR and decreased RPF, resulting in no change in FF. One important function of prostaglandins is to dilate the afferent arteriole.
Do calcium antagonists cause vasodilation of the afferent arteriole?
Several lines of recent investigations documented that within the renal vasculature, calcium antagonists cause a preferential vasodilation of the afferent arteriole, with only modest action on the efferent arteriole (2-4).
