6.1 Glomerular Filtration and its Determinants Flashcards
Define ultrafilter
A semipermeable membrane used as a filter to separate colloids and large molecules from water and small molecules which pass through
What forces define ultrafiltration?
Hydrostatic pressure in glomerular capillary
Hydrostatic pressure in Bowmans Space
Oncotic pressure in glomerular capillary
Oncotic pressure of filtrate in bowmans space
Which pressures favour and oppose ultrafiltration?
Hydrostatic pressure in gomerular capillary and oncotic pressure in bowmans spce favour filtration
Hydrostatic in bowmans space and oncotic of filtrate in bowmans space oppose
What are the three filter elements?
Endothelial fenestrations (between cells) Matrix of basement membrane Podocytes of endothelial cells
How are trapped moelcules in glomerulus eliminated?
Glomerular podocytes -> pinocytosis, endocytosis
Phagocytic mesangial macrophages
Functions of renal blood flow
- Delivers substrates for excretion
- delivers oxygen, nutirients and hormones to renal cells
- returns CO2 and reabsorbs fluids/solutes
- Determines GFR
- Modulates rate of solute and water reabsorption in proximal tubule
- participates in urine concentration/dilution
What factors control autoregulation of RBF?
- Changes in MAPr (myogenic)
2. Changes in [NaCl] via juxtaglomerular apparatus
what happens to GFR and RBF in Afferent vessel constirction
RBF decrease
GFR decrease
what happens to GFR and RBF in Efferent vessel constriction
RBF decrease
GFR increase
what happens to GFR and RBF in efferent vessel dilation
RBF increase
GFR decrease
what happens to GFR and RBF in afferent vessel dilation
RBF increases
GFR increases
what factors cause Renal smooth muscle constrction
Endothelin and AT1
what factors cause Renal smooth muscle dilation
NO
PGI2 and PGE2
