Week Two - Histology

Question 1

What is the macula densa?

Answer 1

Area of closely packed cells on lining of the cortical thick ascending limb as it transitions to the distal convoluted tubule. They are sensitive to sodium choline.
Low = decreases resistance to blood flow in aff arterioles via vasodilation. Increases renin release from JGcells
High= vasoconstriction of aff art.

Question 2

What are the Extraglomerular mesangial cells?

Answer 2

Pericytes- resemble smooth muscle cells - renal autoregulation and systemic regulation of BP through renin-angiotensin system

Question 3

What are the juxtaglomerular cells?

Answer 3

Synthesise, store and secrete the enzyme renin. Specialised smooth muscle cells in wall as of afferent arterioles.
Stimulated by macula densa cells and by stretch receptors in vascular walls.
Also harbour b1 adrenergic receptors - stimulated by adrenaline =renin

Question 4

What cells line the proximal convoluted tubule?

Answer 4

Simple cuboidal with brush border - because of reabsorption.

Question 5

What are the four parts of loop of henle?

Answer 5

Pars recta (straight bit)
Thin descending limb
Thin ascending limb
Thick ascending limb

Question 6

What cells line the thin limb of LoH

Answer 6

Simple squamous, no brush border, no active transport

Will look like a small capillary

Question 7

What cells line the thick ascending limb?

Answer 7

Simple cuboidal, no brush, active transport

Best seen in medulla, will be interspersed with thin limbs, vasa recta and collecting ducts.

Question 8

What cells line the distal convoluted tubule?

Answer 8

Simple cuboidal, no brush border, lots of mitochondria for active transport.

Question 9

What is the juxtaglomerular apparatus?

Answer 9

Regulates function of each nephron. Consists of three types of cells : juxtaglomerular cells, macula dense and extraglomerular mesangial cells.