Kidney Anatomy

Question 1

Name each relevant aspect of the nephron in order of blood flow

Include a labelled diagram

Answer 1

1. Renal Artery
2. Afferent Arteriole
3. Glomerulus
4. Renal (Bowman’s) Capsule
5. Efferent Arteriole
6. Proximal Convoluted Tubule
7. Loop of Henle
8. Distal Convoluted Tubule
9. Collecting Duct

Question 2

Explain the steps in which a concentration gradient is maintained in the intermedullar space

Answer 2

1. Ions are actively pumped out of the Ascending limb of the LOH (to maintain a gradient of -200 mOsm/L)
2. In the descending limb, water osmoses into the IMS until the point of equilibrium
3. As the filtrate flows, it causes an increasing osmolarity gradient in the filtrate from High to Low in the descending limb
4. As the fluid with greater osmolarity is pushed into the ascending limb, a similar gradient is formed (as the existing liquid already lost ions actively in step 1)
5. As step 1 and 2 are repeated simultaneously alongside a continuous fluid rate in the descending limb, active pumping and osmosis will transfer this gradient to the IMS

Question 3

Why is an intermedullary concentration gradient necessary for nephron function?

Answer 3

To ensure maximum passive transportation of water through the aquaporins in the collecting duct.

Without this gradient, the decreasing water potential of the fluid in the collecting duct would lower the rate of osmosis result in water loss through the ureter.

Question 4

Define Ultrafiltration

Answer 4

The process by which filtrate - containing glucose, urea and mineral ions - is squeezed from the glomerulus owing to the hydrostatic pressure resulting from difference in diameter between the afferent and efferent artery

Afferent > Efferent

Question 5

In which part of the nephron is 85% of nutrients - including amino acids, Cl-, and Glucose - reabsorbed into the blood?

Answer 5

The proximal convoluted tubule

Question 6

Describe the three methods of transport in which nutrients are reabsorbed in the PCT

Answer 6

1. Co-transport
2. Pinocytosis
3. Active Transport

Question 7

Define Pinocytosis

Answer 7

A specialised form of Endocytosis in which small molecules suspended in ECF are enclosed in a small vesicle through invagination of the plasma cell membrane to be ingested by a cell

Question 8

How is osmoregulation acheived through ADH?

Answer 8

Question 9

Draw a diagram of Osmoregulation through ADH

Answer 9