Kidney

Question 1

Describe the structure of the pelvis in terms of the kidney.

Answer 1

Outer region of the kidney. Contains Bowmans capsule, convoluted tubules and blood vessels.

Question 2

Describe the structure of the capsule in terms of the kidney.

Answer 2

Funnel shaped to collect urine to ureter. Outer membrane to protect kidney.

Question 3

Describe the structure of the the renal artery in terms of the kidney.

Answer 3

Supplies kidney with oxygenated blood.

Question 4

Describe the structure of the renal vein in terms of the kidney.

Answer 4

Leaves kidney containing deoxygenated blood.

Question 5

Describe the structure of the cortex medulla in terms of the kidney.

Answer 5

Darker inner region of the kidney. Contains the loops of Henle, collecting duct and blood vessels.

Question 6

Draw and label the structure of the nephron.

Answer 6

*Refer to Kidney notes.

Question 7

Describe ultrafiltration (6 points).

Answer 7

1. Hydrostatic pressure: High hydrostatic pressure in glomerulus than in Bowman’s capsule.
2. Small molecules: Forces small molecules, e.g: glucose, and fluid out of the glomerulus.
3. Capillary walls: Through gaps in the capillary walls (endothelium) into the Bowmans capsule.
4. Basement membrane: Basement membrane acts as a filter.
5. Proteins too large: Prevents large plasma proteins and red blood cells from leaving the glomerulus.
6. Podocytes: Podocytes are finger-like projections that increase surface area. They support the glomerulus.

Question 8

Describe and explain 4 cell adaptations in kidney cells.

Answer 8

1. Many mitochondria for active transport providing ATP.
2. Many carrier / co-transport proteins for active transport.
3. Many channel proteins for facilitated diffusion.
4. Many microvilli to increase surface area for absorption.

Question 9

Describe selective re-absorption (6 points).

Answer 9

1. Sodium ions are actively transported from inside the PCT cells into the blood.
2. Lowering the sodium ion concentration inside the PCT cell.
3. Sodium ions diffuse down a concentration gradient from the lumen of the PCT to inside the PCT cells through a co-transporter protein.
4. The co-transporter protein also carries all the glucose or all the amino acids.
5. The glucose and the amino acids will then diffuse from the PCT cells into the blood by facilitated diffusion.
6. This is selective re-absorption.

Question 10

Describe the loop of Henle (8 points).

Answer 10

1. In the ascending limb, sodium ions are actively removed into the medulla lowering water potential.
2. Ascending limb is impermeable to water.
3. In the descending limb, sodium ions diffuse out.
4. Descending limb water moves out by osmosis down a water potential gradient into tissue fluid, then blood.
5. Low water potential in the medulla maintained.
6. The longer the loop / the deeper into the medulla, the lower the water potential in medulla.
7. Water also leaves collecting duct / DCT by osmosis.
8. Example of counter current multiplier.

Question 11

Describe negative feedback for osmoregulation if blood plasma water potential is low (5 points).

Answer 11

1. Osmoreceptor in the hypothalamus detects a decrease in water potential.
2. The water potential in the osmoreceptor is higher than the water potential in the blood.
3. Water leaves the osomoreceptor by osmosis down a water potential gradient.
4. Osmoreceptor shrinks deforming the membrane of the sensory neuron.
5. Increasing frequency of action potentials to the pituitary gland causing the release of ADH into the blood capillaries.

Question 12

Describe negative feedback of osmoregulation if blood plasma water potential is high (5 points).

Answer 12

1. Osmoreceptor in the hypothalamus detects an increase in water potential.
2. The water potential in the osomoreceptor is lower than the water potential of the blood.
3. Water enters the osmoreceptor by osmosis down a water potential gradient.
4. Osmosreceptor swells. Membrane is not deformed.
5. Decreasing frequency of action potentials of the pituitary gland stopping the release of ADH into the blood.

Question 13

Describe the responses brought about by the release of ADH (6 points).

Answer 13

1. ADH in the blood.
2. Binds to complementary receptors on the surface of collecting duct cells.
3. Causes vesicles with aquamarine to move and fuse to collecting duct cells surface membrane.
4. Increases permeability of collecting duct cells to water.
5. More water moves by osmosis down a water potential from collecting duct, into cells, then into the blood.
6. More concentrated urine / smaller volume of urine.