Stevens and lowe: urinary tract

Question 1

What % of the total cardiac output do the kidneys receive?

Answer 1

20%

Question 2

What is the arterial supply to the kidneys?

Answer 2

• The renal artery

- Direct branch of the abdominal aorta

Question 3

What happens when the renal artery reaches the hilum of the kidney?

Answer 3

Divides into an anterior and posterior branch

Question 4

Describe the epithelial cells of the Bowman’s capsule

Answer 4

• Flat and simple

- Exception: near opening of tubular system (more cuboidal)

Question 5

Describe the epithelial cells coating the glomerular capillary tuft

Answer 5

• Highly specialised
• Called podocytes
• Have foot processes

Question 6

Name the three distinct zones of the glomerular basement membrane

Answer 6

1. ) A central electron-dense lamina densa
2. ) Electron lucent lamina rara interna on the capillary lumen side
3. ) Electron lucent lamina rara externa on the epithelial podocyte side

*(electron lucent = transparent to electrons)

Question 7

Describe each of the zones of the glomerular basement membrane

Answer 7

1. ) Lamina densa: has type IV collagen. Fibril networks acts as a PHYSICAL BARRIER to large molecules from blood-> urinary space
2. ) Lamina rara layers: contain polyanionic sites (fixed negatively charge): acts as a CHARGE BARRIER. Prevents passage of cationic molecules

Question 8

Describe the podocyte foot processes

Answer 8

• Foot processes are adjacent. Lie on the glomerular basement membrane
• Between the foot processes is a consistent gap of 30-60nm

Question 9

Describe the gap between the foot processes

Answer 9

• Gap is called the filtration slit membrane

- Contains nephrin: which connects with actin filaments within the adjacent foot processes

Question 10

Describe the mesangial support

Answer 10

• It supports the glomerular capillary network

- Has two compartments: mesangial cells and extracellular mesangial matrix

Question 11

Roles of the mesangium

Answer 11

1. ) Support of the glomerular capillary loop system
2. ) Possible control of blood flow through the glomerular loop by the myosin-angiotensin mechanism
3. ) Possible phagocytic function
4. ) Possible maintenance of the glomerular basement membrane

Question 12

Describe the histology of the proximal tubule cells

Answer 12

• Are cuboidal or columnar
• Have a centrally placed nucleus
• Have a well-developed luminal brush border (with microvilli)

Question 13

What is embedded in the luminal brush border of the PCT?

Answer 13

• membrane ion pumps (ATPases) that bring Na+ ions into the cell from the glomerular filtrate passing through the tubular lumen
• Other ions e.g. K+ are exchanged and pass into the lumen from the cell

Question 14

Describe the histology of the loop of Henle

Answer 14

Flat epithelium

Question 15

Describe the histology of the distal tubule

Answer 15

• Lined by cuboidal epithelial cells
• Microvilli on luminal surface are less well formed (unlike PCT)
• Contains specialised cells for detecting NaCl levels: macula densa cells

Question 16

Describe the histology of the collecting duct

Answer 16

• Contain principal cells: H20 regulation. Cuboidal.

- Intercalated alpha and beta cells: Acid-base regulation. Rich in mitochondria/well developed microvilli

Question 17

What cells are in the afferent arteriole

Answer 17

• Renin producing cells

- Have type 1 (irregular) and type 2 granules (larger + more spherical)

Question 18

Where does the nerve supply to the kidney arise from?

Answer 18

Mainly arises from the celiac plexus

Question 19

What does the urinary tract include in it?

Answer 19

1. ) The calyceal collecting system (contain collecting ducts of Bellini)
2. ) The renal pelvis
3. ) The kidney
4. ) The ureter
5. ) The bladder
6. ) The urethra

Question 20

With exception to the urethra, what epithelium lines the lower urinary tract?

Answer 20

Urothelium (specialised transitional epithelium). It is waterproof

Question 21

What are three layers of smooth muscle?

Answer 21

1. ) An inner layer continuous with the inner longitudinal layer of the ureter
2. ) A middle layer continuous with the outer circular layer of the ureter
3. ) An additional outer layer in which the fibres run in approximately the same direction as the innermost layer