Glomerular Filtration and Tubular Function

What are the membranes in the bowman’s capsule

Capillary Endothelium- many fenestrations make it leaky

Basement membrane- collagen and negatively charged glycoproteins repel plasma proteins

Gaps between podocytes are called filtration slits

List and explain the different types of Glomerular filtration forces

Glomerular Capillary Blood Pressure- The large diameter of the afferent arteriole v small diameter of the efferent arteriole forces plasma out of the capillaries.

Plasma-Colloid Osmotic Pressure- Osmotic gradient out of Bowman’s capsule. large plasma proteins in capillaries

Bowman’s Capsule Hydrostatic Pressure- filtered fluid in Bowman’s capsule its against filtration

Net filtration

What passes through the filtration barrier?

All components of the plasma except the cells and proteins

What is Glomerular Filtration Rate? and what is the GFR for males and females

GFR is the milliliters of plasma filtered per minute (through both kidneys)

Male: 125ml/minute

Female:115ml/minute

What is transepithelial transport?

1. Luminal membrane of tubule epithelial cell

2. Pass through cytosol of tubular cell

3. Cross basolateral membrane of tubule epithelial cell

4. Diffuse through interstitial fluid

5. Penetrate capillary wall to enter blood plasma

Why are Na+ levels regulated?

Too much Na+= increases blood pressure

Too little Na+= decreases blood pressure

What controls sodium reabsorption and water reabsorption

Sodium reabsorption is controlled by Aldosterone

Water reabsorption is controlled by anti-diuretic hormones

How is glucose reabsorbed

Glucose is reabsorbed by Na+- dependent secondary active transport in the proximal tubule

Active due to Na+k+ ATPase pump on basolateral membrane which creates Na+ concentration gradient

Na+ transported down concentration gradient

Glucose gets a “free ride”

Inside tubular cell glucose diffuses down concentration gradients

glucose transporters (GLUT) carry glucose across the basolateral membrane and capillary membrane into the plasma

In tubular secretion, what gets secreted?

H+, K+, organic ions

• Drugs, food additives, pollutants