Histology

Question 1

Describe the appearance of the cortex and medulla

Answer 1

Cortex: dark, renal corpuscles and mitochondria

Medulla: Lighter, less biologically active - less mitochondria

Question 2

What are the properties of renal epithelia, what holds them together and what are the 2 types?

Answer 2

Protective, absorptive and secretory
*tight junctions on luminal side

Squamous: filtration and diffusion
Cuboidal: active transport

Question 3

Explore the structure and function of different epithelial cells along the nephron

Answer 3

PCT: large cuboidal cells (active transport), microvilli

LOH:

• Thick segments (upper): cuboidal (resorbing sodium, Na-K-Cl co transporter)
• Thin segments (lower): squamous (passive water outflux)

DCT and CT: cuboidal cells (few mitochondria, no microvilli)

Question 4

What is the purpose of the JGA and where is it? and how does it perform its role?

Answer 4

Thickened region of ductal epithelia where DCT passes close to glomerulus

Macula densa cells sense increase sodium -> vasoactive compounds -> constrict around afferent -> reduces GFR ->

-> less Na and Cl makes it to DCT -> Shuts off macula

Question 5

What are the 2 types of cells that contain renin?

Answer 5

JG cells: modified sm muscle cells (renin in their zygotes granules)

Lacis cells: support, (pale), outside the glomerulus

Question 6

What is meant by the vascular pole? Where does the PCT leave the corpuscle?

Answer 6

The afferent and efferent arterioles

PCT leaves corpuscle at the tubular pole

Question 7

Describe the parietal and visceral layer of the glomerulus

Answer 7

Parietal: simple squamous cells

Visceral: podocytes - processes extend to form pedicles that envelop BM of capillaries, between pedicles are filtration slits

Question 8

Discuss the levels of filtration as substances move through the glomerular capillaries

Answer 8

1. Capillary endothelia: fenestrations prevent RBCs and platelets
2. BM: negatively charged, repels proteins
3. Filtration slits between pedicels, -ve to restrict passage of small proteins and organic anions
   - > Bowman’s space -> PCT

Question 9

What should happen to any proteins that are accidentally absorbed in the glomerulus?

Answer 9

Degraded into amino acids and resorbed in PCT

Question 10

What keeps fluid in the PCT isotonic?

Answer 10

Glomerular filtrate has same osmolarity as plasma

Water and salt are absorbed into the PCT in equal amounts

Question 11

Discuss the differing epithelial cells as you progress through the LOH

What is the overall function of the LOH?

Answer 11

Descending thick: simple cuboidal actively resorbs Na+

Descending thin: simple squamous, water passively leaves (hypertonic medullary interstitium)

Ascending thin: simple squamous, IMPERMEABLE to water, active and passive reabsorption of ions

Ascending thick: cuboidal epithelium: lots of Na-K-Cl cotransporters to actively recover Na+ and Cl

-> dilute urine?

Question 12

What is the role of aldosterone? What stimulates it?

Answer 12

Angiotensin II -> aldosterone -> Na+ and water reabsorption in DCT (and K+ loss)

Question 13

What does PTH stimulate?

Answer 13

Ca2+ reabsorption in the DCT.

Question 14

What is a histological difference between the CT and the LOH?

Answer 14

The CT lumen is larger and more irregular

Question 15

What’s the other name for ADH?

Answer 15

Vasopressin

Question 16

What buffers the H+ in the filtrate?

Answer 16

H+ joins phosphate or ammonia and is excreted.

Question 17

What are the 3 layers of the ureters?

Answer 17

1. Mucosa: transitional epithelium
2. Circular,longitudinal layers of muscularis externa
3. Adventitia

Question 18

What are umbrella cells?

Answer 18

Outer layer, lipid rafts in membranes and plaques containing uroplakins (protective protein).
Rafts unfold -> SA increases

Question 19

What is the function of transitional cells and where are they found?

Answer 19

Distension, protects tissues from urine.

Renal calyces -> proximal urethra

Question 20

What type of tissue surrounds the bladder?

Answer 20

Serosa superiorly, adventitia the rest

Question 21

How many layers are there in the detrusor muscle? How much can the bladder hold?

Answer 21

3 layers.

The bladder can hold up to 600 mL for 5 hours, then a sharp rise in pressure will give the urge to urinate

Question 22

What type of epithelia lines the different regions of the male urethra?

Answer 22

Prostatic urethra: urothelium
Membranous urethra: stratified and pseudostratified columnar
Spongy: stratified squamous

Question 23

What type of epithelia is present in the female urethra?

Answer 23

Transitional -> stratified squamous