EXAM III

Question 1

What are the 3 mechanisms that help maintain and keep GFR constant?

Answer 1

Sympathetic system

Hormones

Autoregulation

Question 2

Define autoregulation

Answer 2

The consistency of GFR and renal blood flow

Question 3

What are the layers of the filtration barrier?

Answer 3

Endothelium - w/ fenestrae & (-) charges

Basement membrane - w/ collagen & proteoglycan fibers and strong (-) charges

Podocytes - with (-) charges

Question 4

What is GFR determined by?

Answer 4

The balance of hydrostatic and colloid osmotic forces acting across capillary membrane (i.e. Starling forces)

The capillary filtration coefficient (which depends on the leakiness of the capillaries and the number and size of pores) K1 - product of permeability and filtering SA of capillaries

Albumin is slightly smaller than filtration pores but have (-) charges

Question 5

What are factors that increase glomerular colloid osmotic pressure?

Answer 5

Increasing the filtration fraction

Question 6

What are the variables that determine glomerular hydrostatic pressure? (3)

Answer 6

Arterial Pressure (pressure going to the glomerulus)

Increases = greater Pg –> increase GFR

Afferent arteriolar resistance

Increase –> less PG –> less GFR

Efferent arteriolar resistance

Increase –> greater PG –> slightly greater GFR

Question 7

Define autoregulation and state its primary function

Answer 7

The relative constancy of GFR and renal blood flow

Primary function = Maintain a relatively constant GFR

Allow precise control of renal excretion of H2o & solutes

Prevent relatively large changes in GFR & renal excretion that would otherwise occur w/ changes in BP

Question 8

If no autoregulation were to occur in the kidneys, how high can GFR and urine flow increase?

Answer 8

GFR up to 225 L/day (normal 180 L/day)

Urine flow = 46.5 L/day (normal 1.5 L/day)

Question 9

What is the juxtaglomerular complex and where is it?