function of the kidneys Flashcards
1
Q
what is ultrafiltration and where does it happen
A
- happens in the bowman’s capsule
- filtration of small molecules from the blood plasma to the lumen of the bowman’s capsule under high pressure
2
Q
why is there high pressure in the glomerulus
A
- there is high hydrostatic pressure
- the diameter of the lumen is small creating friction
3
Q
what is the glomerulus
A
- a bundle of capillaries
3
Q
what are the three layers of filtration
A
- the walls of capillaries have fenestrations
- basement membrane acts as a molecular filter
- walls of bowman’s capsule contain podocytes which have extensions called pedicles
4
Q
how does the bowman’s capsule act as a selective barrier
A
- molecules smaller than 30,000 can pass through
- molecular sieve
- large plasma proteins, blood cells and platelets cannot pass through
5
Q
what does glomerular filtrate contain
A
- water
- glucose
- amino acids
- urea
- vitamins
- salts
6
Q
what is the glomerular filtration rate
A
- rate at which fluid passes from the blood in the glomerular capillaries into the lumen of the bowman’s capsule
- approximately 125 cm3 per minute
7
Q
why does filtration happen
A
- because of the water potential
- there is high hydrostatic pressure in the capillary and low solute potential in the Bowman’s capsule
