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Flashcards in Renal Physiology Deck (35):
1

What vessels supply the kidneys with which type of blood?

- Renal artery = oxygenated blood
- Renal vein = deoxygenated blood

2

Outer region of kidneys

Cortex

3

Inner region of kidneys

Medulla

4

What are the functions of the kidneys

1. Homeostasis = regulate blood volume, BP, osmolarity (ion levels) and pH
2. Excretion
3. Endocrine/Hormonal = Produce erythropoietin and Vitamin D3

5

Why is erythropoietin important?

Produces RBC

6

Why is Vitamin D3 important?

- Important for Ca2+ homeostasis
- low Ca2+ = lead to rickets

7

How to you obtain Vitamin D3?

Exposure to sunlight

8

Where does the nephron lie?

Top region lies in cortex and bottom in medulla

9

How does blood flow into the glomerulus?

Via the afferent arteriole

10

What is glomerular filtration?

Movement of molecules from plasma in the glomerulus into Bowman's space

11

How is blood filtered from the glomerulus?

Efferent arteriole (going out) is narrower than the afferent arteriole (going into G) so blood is under pressure in the glomerulus and this aids glomerular filtration

12

What happens to molecules that are filtered out of the glomerulus?

Compounds are filtered out of plasma, into bowman's space and move down Loop of Hendle, back up, and eventually into bladder

13

What happens to molecules that are not filtered out of the glomerulus?

They continue from efferent vessel into vasa recta, and back into systemic circulation

14

What happens in the Loop of Hendle?

Some molecules such as water, are reabsorbed here

15

What is the Bowman's capsule composed of?

1. Capillary endothelium
2. Basement membrane
3. Capsule cells/podocytes

16

What happens to a large molecule in the glomerulus?

Too large to pass through the endothelial gaps, therefore remains in the glomerulus and is secreted via the efferent arteriole into vasa recta and into systemic circulation

17

What happens to a small molecule in the glomerulus?

Small enough to pass though the endothelial gaps and move into Loop of Gendle

18

Glomerular filtration rate (GFR)

- Volume of fluid filtered into Bowman's capsule per unit time OR rate at which fluid is filtered by the kidneys.
- Used to measure kidney function
- As CKD worsens = GFR decreases = albuminuria increases

19

How do kidney stones affect kidney function?

Cause obstructions and inflammation. This may affect filtration

20

Role of insulin in measuring kidney function

- Before measuring eGFR, administer insulin i.v.

21

Advantages of insuline when measuring kidney function

- Freely filtered
- Not reabsorbed or secreted by the nephron
- Not metabolised by the kidney
- Excreted in the urine

22

Disadvantages of insuline when measuring kidney function

i.v. so invasine

23

Advantages of creatinine when measuring kidney function

- Produced naturally by our muscles so no need for i.v.
- Freely filtered

24

Disadvantages of creatinine when measuring kidney function

Secreted to a small extent by the nephron (approx. 10%) so need to make adjustments for this

25

What is renal clearance

Volume of plasma from which a substance is completely removed / unit time

26

Why is renal clearance important?

Important when developing new drugs as we need to understand how the patient will metabolise the drug and how it will be cleared from the body

27

Renal clearance equation

Cx = [Ux] x V / [Px]

28

What measurements are needed to calculate renal clearance?

- V = volume of urine produced in given time (vol/time)
- [Ux] = urine conc. of X
- [Px] = plasma conc of X

29

OAT

Organic anion transporter = uptake transporter

30

OATP

Organic anion transporting polypeptide

31

OCT

Organic cation transporter

32

MRP

Multidrug resistance-associated protein

33

BCRP

Breast cancer resistance protein = efflux transporter

34

P-gp

P-glycoprotein = efflux transporter

35

Efflux transporters

Pump drugs out of kidney, prevent entering in the brain e.g. BCRP and PGP