Renal Histology and Cell Bio

Question 0

Main function of the loop of Henle?

Answer 0

Urine concentration.

Question 1

If you see glomeruli, what layer of the kidney are you in?

Answer 1

The cortex.

Question 2

Main functions of the distal convoluted tubule? (2 things… probably an oversimplification)

Answer 2

Acid-base balance.

Urine concentration.

Question 3

Where within the lobule is each medullary ray?

Answer 3

The medullary ray is at the center of each lobule.

Question 4

Where are the interlobular arteries relative to the lobules?

Answer 4

They flank the lobules (half way between medullary rays).

Question 5

What’s the significance of a lobule?

Answer 5

All the nephrons in a lobule drain into the same collecting duct(s) (within a medullary ray).

Question 6

What part of the proximal convoluted tubule is within the medullary ray?

Answer 6

The proximal straight tubule (he called it the thick part…).

Question 7

What part of the distal convoluted tubule is within the medullary ray?

Answer 7

The straight part of the distal tubule (he called it the thick part).

Question 9

Which tubule, proximal or distal, will you see more of?

Answer 9

The proximal convoluted tubule, because it’s longer.

Question 10

How can proximal tubules be distinguished from distal tubules in in histology?

Answer 10

Proximal tubules have a prominent brush border and indistinct cell borders.
Distal tubules have less brush border and more distinct cell borders.

Question 11

Why does it make sense for proximal convoluted tubule (PCT) cells to have lots of brush border?

Answer 11

PCTs do most of the water resorption, and need a lot of surface area to do so.

Question 12

Proximal convoluted tubule (PCT) cells are packed with mitochondria. Why?

Answer 12

To provide ATP to all the pumps used in resorption.

Question 13

What’s in the outer zone of the medulla that’s not the inner zone of the medulla?

Answer 13

The outer zone of the medulla has thick ascending limbs present.

Question 14

What are the 2 different types of nephron? Where is each? What’s the difference between them?

Answer 14

Cortical nephrons - higher up in cortex - short loops of Henle.
Juxtamedullary nephrons - lower - longer loops of Henle.

Question 15

How deep do the loops of Henle from cortical nephrons go?

Answer 15

They only go into the outer medulla, and turn around at the interface with inner medulla.

Question 16

How deep do the loops of Henle from juxtamedullary nephrons go?

Answer 16

They go way into the inner medulla. (presumably for greater urine concentration)

Question 17

What are the two layers of epithelium in Bowman’s capsule?

Answer 17

Parietal epithelium (outer).
Visceral epithelium (inner), composed of podocytes.

Question 18

Podocytes are pretty rad with their interdigitating foot processes.

Answer 18

Yes they are.

Question 19

What’s special about the endothelium of the capillaries of the glomerulus?

Answer 19

It’s fenestrated.

Question 20

What’s the deal with the basement membrane of the glomerulus endothelium?

Answer 20

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.

Question 21

What’s are the structures between podocyte food processes?

What’s the name of a key protein there?

Answer 21

Slit membranes.

Nephrin is a key component of slit membranes. (but not the only one

Question 22

Prominent form of collagen found in the glomerular basement membane?

Answer 22

Type IV - probably not that important.

just kidding, that’s really important… for Goodpasture’s, Alport’s, etc.

Question 23

What cells are prominent in the glomerulus other than endothelial cells and podocytes?

Answer 23

Mesangial cells

Question 24

3 functions of mesangial cells?

Answer 24

Phagocytosis.
Secretion of ECM.
Contractile function.

Question 25

Which type of nephron has efferent arterioles that give rise to vasa recta?

Answer 25

Juxtomedullary efferent arterioles give rise to vasa recta.

Question 26

Countercurrent between loops of Henle and vasa recta is important.

Answer 26

Yep. More on this later, I’m sure.

Question 27

2 rare, but important, endocrine cells in the kidney?

Answer 27

Epo-producing cells

Renin-producing cells (juxtoglomerular cells)

Question 28

What stimulates renin to be release? What cells are involved?

Answer 28

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)

Question 29

What molecules do macula densa cells release to stimulate renin release from juxtaglomerular cells?

Answer 29

PGE2

NO

Question 30

What’s the transcription factor for EPO?

Answer 30

Hypoxia inducible factor - HIF

Question 31

Where are the EPO-producing cells located within the kidney?

Answer 31

In the interstitium (between tubules)

Question 32

How is HIF activated, or rather, kept inactivated normally?

Answer 32

Proline hydroxylation of HIF targets it for destruction under normoxic condition.
This phosphorylation/destruction is done by PHD and VHL if O2 is present.

Question 33

What happens if you have a defect in PHD or VHL?

Answer 33

One can’t degrade HIF -> too much EPO -> polycythemia vera.