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Flashcards in Yr 2 Deck (13)
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1

Kidney capillary network

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

2

What is fluid like in DCT

HYPO osmotic - v dilute

3

Hypothalamus and pituitary

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

4

Posterior pituitary

• 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

5

ADH

• 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

6

Calcium in kidney
what is it important for?

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

7

Phosphorus in kidney

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

8

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

• 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

9

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

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

10

Principle cells allow what in terms of Na and K

reabsorption of Na and secretion of potassium

11

by time filtrate has entered DCT what has happened to K

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

12

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

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

13

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

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