Glomerulus Flashcards
What 3 things make up the Glomerular Filtration barrier?
1) Fenestrated Capillary Endothelium
2) Double Layer Basement Membrane
3) Foot processes of podocytes
What 5 factors can determine a molecule crossing the GFB?
1) Pressure
2) Size of Molecule
3) Charge of molecule
4) Rate of blood flow
5) Binding to plasma protein
What force favours glomerular filtration?
Hydrostatic pressure of Glomerular Capsule
What 2 forces oppose the glomerular filtration?
1) Hydrostatic pressure of bowman’s space
2) Oncotic pressure of the glomerular capsule
Define the glomerular filtration rate
Volume of fluid filtered from glomeruli into the Bowman’s space per unit time
What equation can calculate net glomerular filtration pressure?
HPgc - HPbs - πgc
What effect do vasoconstriction and vasodilation of Afferent arteriole have on GFR?
VC: GFR V as HPgc decrease
VD: GFR ^ as HPgc increases
What effect on the efferent arteriole?
GFR decreases as HPgc decreases in VD
VC: Increases GFR as HPgc increases
What 2 methods regulate GFR?
1) Autoregulation
2) Tubuloglomerular Feedback
What happens in tubuloglomerular feedback?
DCT Macula Densa cells detect NaCl levels and use this as indicator of GFR
- NaCl levels increase as GFR increase
What happens if NaCl levels reaching macula densa were high?
Macula Densa cells signal to afferent arterioles to vasoconstrict causing GFR to decrease as HP decreases
What is Renal Clearance?
Volume of plasma from which substance is completely removed by kidney per unit time
What is the usual value of filtration fraction?
20%
What substance can clinically be used to estimate GFR?
Creatinine
