Glomerular filtration Flashcards
What are the 3 basic renal processes
filtration
reabsorption
secretion
Give some examples of substances reabsorbed
sodium chloride, water, glucose, amino acids
Give some examples of substances secreted
organic ions, drugs,
How much of the cardiac output do the kidneys receive and what is the significance of this?
20-25%
vulnerability to damage by vascular disease
What tissue in the body has the highest BF/g?
kidneys!
Why does the kidneys receive such a large blood flow?
filtration! - not for oxygen
How long does it take for the volume for the total BV to pass through the renal circulation?
5 mins
Are red cells filtered into bowmans capsule?
no
What is the renal plasma flow?
660mls/min
What is the % filtration fraction?
19% - usually say 20
What is glomerular filtration dependent on the balance between?
starling’s forces
hydrostatic and oncotic pressures
Which of hydrostatic and oncotic pressure favours reabsorption and which favours filtration?
Hydrostatic - filtration
oncotic - reabsorption
3 things the permeselectivity of glomerular barrier is dependent on
molecular size, charge and shape
How does the glomerulus make sure proteins don’t get filtered
fenestration pore - prevents filtration of blood cells only
basal lamina - prevents filtration of larger proteins
slit membrane between pedicles - prevents filtration of medium proteins
Is the glomerular capillary pressure higher or lower than most capillaries? why?
higher
afferent arteriole - short and wide and little resistance