Renal Histology

Question 1

What are the functions of the kidney and renal tract?

Answer 1

Maintain water and electrolyte homeostasis, body fluid osmolarity and acid-base balance
Excrete toxic metabolic waste products
Act as an endocrine gland to produce renin and erythropoietin

Question 2

What covers the kidney?

Answer 2

Fibrous capsule which is continuous with the connective tissue that lines the renal sinus

Question 3

What is the nephron made up of?

Answer 3

Renal corpuscle (glomerulus and bowman’s capsule) and renal tubules (proximal convoluted tubule, loop of henle and distal convoluted tubule)

Question 4

What is the function of the renal corpuscle?

Answer 4

Production and collection of glomerular filtrate

Question 5

What type of epithelium is bowman’s capsule?

Answer 5

Simple squamous epithelium

Question 6

What cell layers separate the blood from the glomerular filtrate?

Answer 6

Capillary endothelium and a specialised epithelium which lies on top of the glomerular capillaries - podocytes

Question 7

What type of capillary is present at the glomerulus?

Answer 7

Fenestrated endothelium

Question 8

What do mesangial cells produce?

Answer 8

Connective tissue core called the mesangium

Question 9

What is at the apical and basal poles of a renal corpuscle?

Answer 9

Vascular pole

Urinary pole - into the proximal convoluted tubule

Question 10

What must filtrate from the blood pass through to reach the medullary apex?

Answer 10

Endothelium fenestration 
Basal lamina (made up of GAGs)
Filtration slits of podocytes

Question 11

What is the function of the proximal convoluted tubule?

Answer 11

Reabsorption of water (70% of sodium and water reabsorbed) proteins, amino acids, carbohydrates and glucose

Question 12

What is special about the apical and basal membrane of the cells in the proximal convoluted tubule?

Answer 12

Cuboidal cells with a brush border to allow for a large SA - maximal amount of absorption

Question 13

What is the function of the loop of henle?

Answer 13

Creation of hyperosmotic environment in medulla

Question 14

What makes up the loop of henle?

Answer 14

Thick descending limb (simple cuboidal epithelium)
Thin descending limb (simple squamous epithelium)
Thin ascending limb
Thick ascending limb

Question 15

How is the medulla supplied with blood?

Answer 15

Thin walled blood vessels that dip down into the medulla from above and then climb back up to the cortex
Loops of blood vessels are called the vasa recta

Question 16

What is the function of the distal convoluted tubule?

Answer 16

Acid-base and water balance (absorption of water, sodium and bicarb, excretion of potassium and hydrogein ions)

Question 17

Describe the cells in the distal convoluted tubule?

Answer 17

Small villi at the apical membrane

Large villi at the basal membrane

Question 18

What controls the reabsorption of sodium in the distal convoluted tubule?

Answer 18

Aldosterone, secreted by the adrenal cortex and results in greater sodium and water retention and therefore it increased BP

Question 19

What is the function of the collecting ducts?

Answer 19

Reabsorption of water under the control of ADH

Question 20

Where does the collecting duct end?

Answer 20

Medullary papilla at the apex of the medullary pyramid - duct of bellini

Question 21

How does ADH control the collecting ducts?

Answer 21

ADH increases the permeability of the collecting duct to water
In the presence of high ADH (hot day with low water intake), permeability of the duct is high during passage through the medulla and because of the high salt content in the surrounding tissue, water passes out of the lumen and a concentrated urine results

Question 22

How does the urine go from the renal pyramids to exiting the body?

Answer 22

Renal papilla
Minor calyx
Major calyx
Bladder via ureteric orifices
Urethra via internal urethral orifice

Question 23

What type of epithelium lines the conducting areas of the urinary tract?

Answer 23

Transitional epithelium - stratified made up of 3-6 layers

Question 24

What are the cells at the luminal surface of the urinary tract called?

Answer 24

Umbrella cells because they are domed

Question 25

What smooth muscle lines the bladder?

Answer 25

Detrusor muscle which is responsible for micturition, and the internal urethral sphincter

Question 26

What nerves control the micturition reflex?

Answer 26

Parasympathetic ganglia by neurones in the sacral spinal cord in the muscle and adventitia

Question 27

What lines the urethra in females?

Answer 27

Initially transitional then stratified squamous near its termination

Question 28

What lines the urethra in males?

Answer 28

Prostatic: transitional
Membranous: stratified columnar
Penile: stratified columnar becomes stratified squamous