Session 3- GFR/Glomerulus Flashcards
Describe entire order of renal arteries and veins
Aorta - renal artery - segmental a - lobular a - arcuate a -interlobular a - afferent arteriole - glomerulus - efferent arteriole - peritubular capillaries - interlobular v - arcuate v- lobular v - segmental v - renal vein - IVC
If its a juxtamedullary nephron then how is the blood route different?
After the efferent arteriole it goes to vasa recta and then back to interlobular v. It skips out peritubular capillaries
What is the equivalent of peritubular capillaries in a juxtamedullary nephron
Vasa recta
Does a juxtamedullary nephron have peritubular capillaries?
Yes, but only at the top
What % of nephrons are cortical
70-80
Differences between cortical and JXM nephron AA:EA diameter?
Cortical AE > EE
JXM AE = EE
Differences between cortical and JXM nephron sympathetic innervation?
Cortical rich innervation, JXM poor
Renin concentration in cortical vs JXM nephrons
High in cortical, 0 in JXM
How much renal plasma flow/min?
605ml/min
How much of blood coming in AA gets filtered?
20%
Renal corpuscle is what?
glomerulus + Bowman’s capsule
What stops proteins getting into bowman’s?
Basement membrane has glycoproteins with negative charge, repels negatively charged proteins
Also fenestrations and filtration slits formed by pedicels
Why can more positively charged proteins get inside bowman’s than negative?
Because basement membrane has negative glycoproteins so repels them but not positive
What is a pedicel
A foot process of a podocyte
Describe the forces in and out between the glomerulus and Bowman’s
So small oncotic pressure out, small hydrostatic pressure out, and big hydrostatic pressure in
Describe main ways GFR is kept constant (4)
- Myogenic: if P up then AA constricts, if P down AA dilates
Occurs more in AA than AE (but opposite in AE) - Tubuloglomerular feedback: macula densa cells in JGA sense NaCl conc, if low then secrete prostaglandins to dilate AA. If high secrete adenosine for A1R on AA to vasoconstrict, A2R on AE to dilate.
- Neural- sympathetic innervation of AA and EA can vasoconstrict
- As second line, if more stuff comes in more is reabsorbed. The same fraction is reabsorbed.
If tubular hydrostatic pressure increased, GFR would
Decrease
If glomerular oncotic pressure decreased, GFR would
Increase
Bowman’s capsule oncotic pressure is…
Negligible (all the big proteins stay in glomerulus)
If AA relaxed, glomerular hydrostatic P would…
Increase
If both AA and EA relaxed, GFR would
Decrease
In haemorrhage what decreases GFR?
SNS
How does tubular glomerular feedback work?
Macula densa cells in the JGA detect NaCl levels to infer GFR levels
If high NaCl then release adenosine to dilate the EA and constrict the AE
If low NaCl then release PGs to dilate AE only
