Yr 2

Question 1

Kidney capillary network

Answer 1

1. highly specialises, v different
2. runs parallel to LOH and blood flow in OPPO direction
3. this is called VASA RECTA
4. allows supply of O2 adn nutrients deep into medulla
5. creates an osmotic gradient

Question 2

What is fluid like in DCT

Answer 2

HYPO osmotic - v dilute

Question 3

Hypothalamus and pituitary

Answer 3

1. brain base
2. under = bright red cherry pituitary
3. important endocrine, releases lots of hormones
4. posterior pit
5. anterior pit

Question 4

Posterior pituitary

Answer 4

• Bit of brain tissue embedded in P gland
• Nerves continuous with P hold chemical substances, neuroendocrine.
• ADH MADE in brain, travels to P pituitary where released
• ADH =
i. Small peptide, released pp

Question 5

ADH

Answer 5

• ADH affects number of aquaporins in CD = affects permeability of CD to water
• ADH synthesized in brain, released from PP into BLOOD
• Receptors downstream activate 2nd messengers – APorins inserted in CD membrane so water moves down conc gradient
• Greater ability of water to leave filtrate and get absorbed
• Drink lots = no ADH
- No water drunk = inc ADH = inc permeability of CD to water

Question 6

Calcium in kidney

what is it important for?

Answer 6

1. important: second messenger, muscle contraction and many other
2. 50% protein bound so only free Ca goes through into PCT
3. in PCT 70% reabsorbed
4. There is selective reabsorption of calcium in DCT and CD under hormone control
5. Normally only 1-2% filtered Ca is excreted

Question 7

Phosphorus in kidney

Answer 7

1. Inorganic phosphate 100% filtered
2. Reabsorption in PCT by Na+ cotransport under hormone control
3. Not reabsorbed in DCT and CD
4. Eat a lot (cell membranes) so dietary XS is excreted in via kids

Question 8

How does body respond to decreased conc Ca2+ in blood?

Answer 8

• PARATHYROID hormone is released in response
o Decreases reabsorption of phosphate in proximal tubule
o Increases reabsorption Ca2+ in ascending loop of Henle, distal tubule and collecting duct

Question 9

…. by time filtrate has entered DCT what has happened to Na

Answer 9

1. 100% filtered approx. 90% reabsorbed -most in PCT some in LoH

Question 10

Principle cells allow what in terms of Na and K

Answer 10

reabsorption of Na and secretion of potassium

Question 11

by time filtrate has entered DCT what has happened to K

Answer 11

1. 100% filtered
2. 100% reabsorbed
3. more reabsorbed in PCT than LOH

Question 12

By the time the filtrate has entered DCT what ahs happened to bicarbonate? HCO3-

Answer 12

• Freely filtered
• 100% reabsorbed
• 80-90% reabsorbed in PCT
• 10-20% in LoH

Question 13

By the time the filtrate has entered DCT what ahs happened to H+

Answer 13

• Freely filtered
• Unregulated secretion into PCT via secretion of NH4
• Unregulated secretion into PCT via secretion of H+