Renal Physiology Part 4 Flashcards
(26 cards)
What does the renal corpuscle form?
A filtrate from blood that is free of cells, large polypeptides, and proteins.
What structure is responsible for filtration in the renal corpuscle?
The filtration membrane (or glomerular filtration barrier).
What are the three layers of the glomerular filtration barrier?
- Capillary endothelium
- Basement membrane
- Podocyte layer (epithelial cells)
Why does the filtration membrane filter fluid at a high rate?
Because it has many holes (fenestrations) in its structure.
What determines whether a molecule can pass through the glomerular filtration barrier?
Molecular size and electrical charge.
What does a filterability value of 1.0 indicate?
The substance is filtered as freely as water through glomerular capillaries.
What does a filterability value of 0.75 indicate?
The substance is filtered at 75% the rate of water.
Which substances have a filterability of 1.0?
Water, sodium, glucose, and inulin.
What is the filterability of albumin and its molecular weight?
Filterability: 0.005, Molecular weight: 69,000.
How does molecular weight affect filterability?
Filterability of solutes is inversely related to their size—larger molecules are filtered less.
Why does albumin have such a low filterability?
Because of its large molecular size, which prevents it from passing freely through the filtration membrane.
How is filterability of solutes related to their size?
Filterability is inversely related to solute size—larger molecules are filtered less easily.
Besides size, what other factor influences filtration rate through the glomerular membrane?
Electrical charge of the molecule.
Which type of charged molecule is filtered most easily through the glomerular membrane?
Positively charged molecules.
How does the filterability of neutral molecules compare to negatively charged molecules of equal size?
Neutral molecules are filtered more readily than negatively charged molecules.
