The Force for Glomerular Filtration: Renal Physiology Quiz and Flashcards

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Questions and Answers

What is the primary function of the peritubular capillary beds and vasa recta?

To filter blood and form urine

To contract and regulate blood pressure

To supply oxygen to the renal tubules

To absorb substances from the renal tubules (correct)

What is the relationship between the afferent and efferent arterioles and the glomerulus?

Afferent arterioles and efferent arterioles are both connected to the glomerulus

Afferent arterioles bring blood to the glomerulus, efferent arterioles take blood away (correct)

Afferent arterioles and efferent arterioles are not connected to the glomerulus

Afferent arterioles take blood away from the glomerulus, efferent arterioles bring blood to the glomerulus

What is the role of the podocytes in the visceral layer of Bowman's capsule?

They have extensions (pedicels) that form the filtration slits (correct)

They produce the filtrate that is collected in Bowman's space

They secrete hormones to regulate blood pressure

They contract to regulate blood flow through the glomerulus

Which of the following is a unique feature of the kidney's vascular system?

The existence of a portal system where capillaries are fed and drained by arterioles Signup and view all the answers

What is the purpose of the negative charge on the surface of the podocyte pedicels?

To provide a selectively permeable barrier for the filtration of blood Signup and view all the answers

What is the purpose of Bowman's space in the nephron?

To provide a site for the initial filtration of blood Signup and view all the answers

What is the composition of the filter membrane in the kidney?

Endothelium, basement membrane, podocytes Signup and view all the answers

What is the function of the negatively charged pedicel membranes in the filtration process?

Blockage of small proteins Signup and view all the answers

What is the pore diameter of glomerular capillaries?

~70nm Signup and view all the answers

When fluid is forced through capillary fenestrations in the kidney, where does it pass into?

Bowman’s space Signup and view all the answers

What components are prevented from crossing endothelium in the kidney filtrate?

Blood cells, platelets, most proteins Signup and view all the answers

What determines the degree of filtration in Bowman’s capsule?

Net filtration pressure Signup and view all the answers

What is the net filtration pressure given the provided data: glomerular blood hydrostatic pressure = 60mm, blood colloid osmotic pressure = 32mm, and capsular hydrostatic pressure = 18mm?

$10\ \mathrm{mm}$ Signup and view all the answers

If the glomerular blood hydrostatic pressure increases, what would happen to the net filtration pressure?

It would increase Signup and view all the answers

What structure encircles the afferent and efferent arterioles, allowing regulation of pressure within the glomerulus?

Smooth muscle cells Signup and view all the answers

If a kidney stone blocks a renal calyx, how would this affect the filtration pressure in the nephrons emptying into it?

Filtration pressure would decrease Signup and view all the answers

What would be the effect of constricting the afferent arteriole on the glomerular blood hydrostatic pressure?

It would decrease Signup and view all the answers

If both the afferent and efferent arterioles are constricted, what would be the effect on the glomerular blood hydrostatic pressure?

The effect cannot be determined Signup and view all the answers

Study Notes

Filtration Membrane

Composed of: fenestrated endothelium of glomerular capillaries, basement membrane, and podocytes
Podocytes form the visceral membrane of the glomerular capsule
Pedicels of adjoining podocytes interdigitate, forming filtration slits
Surface of pedicels is negatively charged

Glomerular Capillaries

Fenestrated capillaries with pore diameter of ~70nm
100X more permeable than continuous body capillaries
Provide a large surface area for filtration
Prevent blood cells, platelets, and most proteins from crossing endothelium
Allow water and most solutes to cross

Pressure Filtration

Means of forcing fluids and dissolved substances through a membrane
In the kidney, fluid is forced through capillary fenestrations into Bowman's space
Degree of filtration depends on the net filtration pressure

Peritubular Capillary Beds and Vasa Recta

Low-pressure capillaries adapted for absorption
Arise from efferent arterioles and surround renal tubules
Empty into the renal venous system
Vasa recta capillaries of juxtamedullary nephrons have similar properties

Glomerulus

Group of renal capillaries connecting afferent and efferent arterioles
Afferent arterioles bring blood to the glomerulus, efferent arterioles take blood away
Unlike veins, arterioles contain smooth muscle, which can contract and affect blood pressure

Bowman's Capsule

Encircles a glomerulus
Has two layers of epithelium separated by Bowman's space
Inner layer of epithelium is in intimate contact with glomerular capillaries
Visceral layer (filtration membrane) has specialized cells (podocytes) with many extensions (pedicels)

Net Filtration Pressure

Determined by: glomerular blood hydrostatic pressure, capsular hydrostatic pressure, and blood colloid osmotic pressure
Calculated as: gbhp - (bcop + chp) = 10mm
Net filtration pressure would increase if gbhp was higher and decrease if gbhp was lower
If a kidney stone blocked a renal calyx, filtration pressure in the nephrons emptying into it would decrease

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Description

Learn about the forces involved in glomerular filtration, including glomerular blood hydrostatic pressure, capsular hydrostatic pressure, and blood colloid osmotic pressure. Understand how arterioles regulate pressure within the glomerulus.

Renal Physiology: Glomerular Filtration Forces

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