Renal Histology

Question 1

What is the function of the urinary system?

Answer 1

maintenance of water, electrolyte and acid-base homeostasis

Question 2

Describe the basic structure of the kidneys.

Answer 2

macroscopic examination reveals a

cortex - comprises the renal corpuscles and the convoluted tubules

the medulla - comprises the loops of henle and collecting ducts

Question 3

Describe the structure of the nephron.

Answer 3

nephron is the functional unit of the kidney, may be cortical or juxtamedullary

nephron has 5 main  structures: 
1- renal corpuscle (bowmans capsule + glomerulus)
2- proximal convoluted tubule 
3- nephron loop i.e. loop of henle 
4- distal convoluted tubule 
5- collecting duct

Question 4

What is the function of the nephron?

Answer 4

responsible for osmoregulation and excretion by the following processes:

• filtration of small molecules from the blood plasma to form an ultrafiltrate of plasma
• selective reabsorption in the tubule of most water and some molecules from the ultafiltrate leaving just behind the waste products to be secreted
• maintenance of acid-base balance by selective secretion by the tubule of H ions into the urine

Question 5

Explain the function of the renal corpuscle.

Answer 5

comprising the bowmans capsule and glomerulus

served by the afferent arteriole

collect the products of glomerular filtration , produces a filtrate of blood plasma that will eventually form urine

Question 6

What are the major cell types present in the renal corpuscle?

Answer 6

1 - endothelial cells (fenestrated)

2 - parietal epithelial cells lining the glomerulus capsule

3 - podocytes

4 - mesangial cells form a supporting tissue and can contract or relax to regulate capillary flow

Question 7

What is the function of the proximal convoluted tubules?

Answer 7

returns much of the filtrate back into the peripheral circulation via the peritubular capillaries

Question 8

How is the structure of the PCT adapted for its function?

Answer 8

PCT lined with simple cuboidal epithelium with a brush border of microvilli, this ensures a large surface area is available for the absorption of filtrate

Question 9

What is the function of the Loop of Henle?

Answer 9

involved in the reabsorption of water and solutes

Question 10

What is the loop of Henle comprised of?

Answer 10

Descending thick portion - simple cuboidal epithelium

Descending thin portion - simple squamous

Ascending thin portion - simple squamous

Ascending thick portion - simple cuboidal epithelium

Question 11

Function of the Distal Convoluted Tubules?

Answer 11

-returns useful components from the renal filtrate to the circulation

lined with simple cuboidal epithelium but lacks the brush border found lining the PCT

Question 12

Function of the Collecting Ducts?

Answer 12

Collect urine from the DCT

lined with simple cuboidal epithelium

Question 13

What does the classic H&E stain permit in terms of renal histology?

Answer 13

permits assessment of renal composition (no. of glomeruli) and the presence of cellular infiltrates

morphological analysis of;

• glomerular cells and capillaries
• glomerular basement membrane and space
• mesangial matrix

Question 14

What does the PAS stain show in terms of renal histology?

Answer 14

accentuates the components of the glomerulus

Question 15

What does the AZAN stain show in terms of renal histology?

Answer 15

accentuates the basement membrane thus demarcating the tubular and glomerular basement membranes

Question 16

What does trichrome show in terms of renal histology?

Answer 16

demonstrates excess collagen deposition in fibrosis. the glomerulus appears almost solid due to collagen deposition.

Question 17

What does PAS silver impregnation staining show in terms of renal histology?

Answer 17

demonstrates double contour to many basement membranes characteristic of membranoproliferative glomerulonephritis.