Urinary system histology

Question 1

Name the types of epithelium and their types. Where are they found?

Answer 1

Simple

• Squamous (loop of Henle)
• Cuboidal (PCT, DCT, collecting tubule)
• Columnar (collecting duct)

Stratified (multiple layers)
- Transitional (ureter, bladder)

Question 2

What is the nephron made up of and what each part contains?

Answer 2

- in the lobes of the kidney
Cortex
- Renal corpuscle
- PCT and DCT
- Proximal and distal tubule
- Macula densa (regulates blood pressure)
- Glomerulus and Bowmans capsule 
- Connecting tubule 
Medulla (pyramids and papillae)
- Loop of henle (passive diffusion of Na and H20 occur in descending limb)
- collecting ducts that drain into the minor calyx
-Medullary collecting tubule

Question 3

Which type of epithelium would you find in the proximal convoluted tubule?

Answer 3

simple small cuboidal epithelium

Question 4

Which type of epithelium would you find in the distal convoluted tubule?

Answer 4

simple cuboidal epithelium

Question 5

What is the renal corpuscle made up of? What is it the site of?

Answer 5

• Glomerulus
• Bowmans capsule
• it is continuous with the PCT
• site of ultrafiltration of blood

Question 6

What does afferent arteriole and podocytes do?

Answer 6

Afferent arteriole - brings blood into capillary beds

Podocytes- indigitate to form slits and to filter large molecules like proteins

Question 7

The efferent arteriole at renal corpuscle will continue as which vessel?

Answer 7

the vasa recta

Question 8

What is PCT made up of? Function? And what is it continuous with?

Answer 8

PCT is made up of simple cuboidal epithelium with microvilli and its function is to absorb sodium ions
PCT epithelium is continuous with parietal layer of Bowmans capsule

Question 9

What are components of the loop of henle and the medulla ?

Answer 9

Thin limb (simple squamous epithelium) - thick limb is simple cuboidal epithelium
Vasa recta
Collecting ducts
Collecting tubules

Question 10

How does the thin limb assist in allowing Na to leave?

Answer 10

as water moves through the thin limb the medulla becomes more isolated so when the thin limb passes superiorly as the ascending limb, Na will leave via passive diffusion

Question 11

What cells are DCT made of? Function

Answer 11

simple cuboidal epithelium
It has no microvilli= clear lumen
Active reabsorption of Na+ and secretion of H+

Question 12

What does juxtaglomerular apparatus and what is it function?

Answer 12

• It regulates blood pressure
• It is made uo of the juxtaglomerular cells and the macula densa (DCT)
• the juxtaglomerular cells in walls of the afferent arteriole detect blood pressure and cause release of renin

Question 13

what is the purpose of the collecting tubules and collecting ducts?

Answer 13

They reabsorb water and urea into medulla

The water reabsorption is controlled by ADH

Question 14

How can you differentiate between the PCT and DCT in a histological section?

Answer 14

PCT has a cloud definition

• PCT has a dark-pink cytoplasm with prominent brush border
• DCT has smaller cells and less cytoplasm
• impression of ‘more nuclei’ in the cross-section

Question 15

What cells and muscle is ureter made up of? What do these muscles do?

Answer 15

Transitional epithelium ‘urothelium’
- highly folded with ability to stretch
- umbrella cells create impermeable barrier to toxic urine
Longitudinal smooth muscle
Circular smooth muscle ; aid in peristaltic movement of urine through the ureter

Both LSM and CSM are controlled by the automatic nervous system and is not under voluntary control

Question 16

What type of cell and muscle is the bladder made up of?

Answer 16

Transitional epithelium ‘urothelium’

• highly folded with ability to stretch
• umbrella cells create impermeable barrier to toxic urine

Smooth muscle layers in the wall

Question 17

What is the function of the urothelium in the ureter?

Answer 17

The urothelium is the first line of defence in the bladder
Controls permeability, immune responses and cell-cell communication
Contains umbrella cells
- line the bladder surface
- maintain an impermeable barrier to toxic urine and resist cyclical changes as bladder stretches when it fills

Question 18

Which type of epithelium would you find in the bladder?

Answer 18

Transitional epithelium

Question 19

What effect do loop diuretics, thiazides and potassium-sparing diuretics have on the nephron?

Answer 19

Loop diuretics (in the loop of Henle):
- in thick ascending limb, reduces Na+ and water reabsorption, diuresis
Thiazides:
- in the distal convoluted tubule. It reduces Na+ reabsorption
Potassium-sparing diuretics:
- acts as an aldosterone receptor antagonist at the DCT. It reduces water reabsorption