Renal Histology and Cell Bio Flashcards
Main function of the loop of Henle?
Urine concentration.
If you see glomeruli, what layer of the kidney are you in?
The cortex.
Main functions of the distal convoluted tubule? (2 things… probably an oversimplification)
Acid-base balance.
Urine concentration.
Where within the lobule is each medullary ray?
The medullary ray is at the center of each lobule.
Where are the interlobular arteries relative to the lobules?
They flank the lobules (half way between medullary rays).
What’s the significance of a lobule?
All the nephrons in a lobule drain into the same collecting duct(s) (within a medullary ray).
What part of the proximal convoluted tubule is within the medullary ray?
The proximal straight tubule (he called it the thick part…).
What part of the distal convoluted tubule is within the medullary ray?
The straight part of the distal tubule (he called it the thick part).
Which tubule, proximal or distal, will you see more of?
The proximal convoluted tubule, because it’s longer.
How can proximal tubules be distinguished from distal tubules in in histology?
Proximal tubules have a prominent brush border and indistinct cell borders.
Distal tubules have less brush border and more distinct cell borders.
Why does it make sense for proximal convoluted tubule (PCT) cells to have lots of brush border?
PCTs do most of the water resorption, and need a lot of surface area to do so.
Proximal convoluted tubule (PCT) cells are packed with mitochondria. Why?
To provide ATP to all the pumps used in resorption.
What’s in the outer zone of the medulla that’s not the inner zone of the medulla?
The outer zone of the medulla has thick ascending limbs present.
What are the 2 different types of nephron? Where is each? What’s the difference between them?
Cortical nephrons - higher up in cortex - short loops of Henle.
Juxtamedullary nephrons - lower - longer loops of Henle.
How deep do the loops of Henle from cortical nephrons go?
They only go into the outer medulla, and turn around at the interface with inner medulla.
How deep do the loops of Henle from juxtamedullary nephrons go?
They go way into the inner medulla. (presumably for greater urine concentration)
What are the two layers of epithelium in Bowman’s capsule?
Parietal epithelium (outer). Visceral epithelium (inner), composed of podocytes.
Podocytes are pretty rad with their interdigitating foot processes.
Yes they are.
What’s special about the endothelium of the capillaries of the glomerulus?
It’s fenestrated.
What’s the deal with the basement membrane of the glomerulus endothelium?
It’s shared with that of the visceral epithelium (podocytes) - the glycocalyx is at points the only separation between blood and Bowman’s space.
Notably, it’s negatively charged.
What’s are the structures between podocyte food processes?
What’s the name of a key protein there?
Slit membranes.
Nephrin is a key component of slit membranes. (but not the only one
Prominent form of collagen found in the glomerular basement membane?
Type IV - probably not that important.
just kidding, that’s really important… for Goodpasture’s, Alport’s, etc.
What cells are prominent in the glomerulus other than endothelial cells and podocytes?
Mesangial cells
3 functions of mesangial cells?
Phagocytosis.
Secretion of ECM.
Contractile function.
Which type of nephron has efferent arterioles that give rise to vasa recta?
Juxtomedullary efferent arterioles give rise to vasa recta.
Countercurrent between loops of Henle and vasa recta is important.
Yep. More on this later, I’m sure.
2 rare, but important, endocrine cells in the kidney?
Epo-producing cells
Renin-producing cells (juxtoglomerular cells)
What stimulates renin to be release? What cells are involved?
Macula densa cells sense NaCl flux through the distal tubule. If it’s too low, they signal renin-producing (JG) cells to release renin.
(JG cells can also direct sense afferent arteriolar pressure)
What molecules do macula densa cells release to stimulate renin release from juxtaglomerular cells?
PGE2
NO
What’s the transcription factor for EPO?
Hypoxia inducible factor - HIF
Where are the EPO-producing cells located within the kidney?
In the interstitium (between tubules)
How is HIF activated, or rather, kept inactivated normally?
Proline hydroxylation of HIF targets it for destruction under normoxic condition.
This phosphorylation/destruction is done by PHD and VHL if O2 is present.
What happens if you have a defect in PHD or VHL?
One can’t degrade HIF -> too much EPO -> polycythemia vera.
