Renal 1 Flashcards
Formula for excreted amount
Filtered - reabsorbed + secreted.
Peritubular capillary
Capillary following the efferent arteriole
Glomerular filtration rate
Amount that enters bowman’s space, 125mL.
Renal plasma flow
Amount of blood passing through the glomerular capillary, 625mL/min
Filtration fraction
GFR/RPF, 0.2.
Podocyte
Modified epithelial cells that are involved in the filtration barrier.
Filtration barrier layers (3)
Fenestrations
Basement membrane
Podocyte slit pores
What properties determine glomerular filter ability
Size and Charge
18Å > 45Å
positive > negative
Proteins do/do not filter into bowman’s space
DO NOT! BAD THING IF SO.
GFR is the consequence of
ultrafiltration coefficient and net filtration pressure.
Hydrostatic pressure (P)
Limited containers cause pressure
Colloid pressure
Osmotic pressure due to many proteins in one fluid.
Forces favouring filtration
Pgc
πbs
Forces opposing filtration
Pbs
πgc
GFR =
Kf x (Pgc - Pbs - πgc)
Positive pressure goes from the ____ into the _____.
Glomerular capillary to the bowman’s space
Most important pressure
Pgc
Lower Pnet at the efferent end? why?
Protein concentration has increased, counter pressure goes up for πgc.
Constriction of the afferent
Blood flow through decreases.
Easily leaves glomerular, blood build up decreasing, pressure goes down.
GFR decreases.
Constriction of the efferent
Blood builds up in the glomerulus, causing the pressure to increase. GFR increases.
Dilation of the afferent
More blood flows in, leaves at the same rate causing it to build up. Pressure increases, and so does GFR.
Dilation of the efferent
Easier for blood to leave causing a decrease in blood in the glomerulus. This decreases pressure, decreasing GFR.
Natriuretic peptides as a vasodilator and constrictor in increasing urine production
Dilates afferent (increase GFR), constricts efferent (increase GFR).
Autoregulation of GFR and RBF (2) ways
- myogenic mechanism
- tubulogenic feedback