Proximal Tubule and Loop of Henle Flashcards Preview

Human Epithelial Biology > Proximal Tubule and Loop of Henle > Flashcards

Flashcards in Proximal Tubule and Loop of Henle Deck (45)
1

What do the kidneys reabsorb?

99% fluid and salt
100% glucose and amino acids
50% urea
0% creatinine

2

What amount of filtered fluid is reabsorbed in the proximal tubule?

80 ml/min

3

What is iso-osmotic with filtrate?

fluid reabsorbed in the proximal tubule

4

What is secreted in the proximal tubule?

H
Hippurates
NTs
Bile pigments
Uric acid
Drugs
Toxins

5

What is reabsorbed in the pT?

sugars
amino acids
phosphate
sulphate
lactate

6

What are the steps involved with tubular reabsorption?

transcellular
paracellular

7

What are the types of carrier mediated transport?

primary active transport
secondary active transport
facilitated diffusion

8

What diffuses through lipid bilayer?

O2 and CO2

9

What diffuses through channels?

Na

10

What is facilitative diffusion molecule?

glucose

11

What is reabsorbed through primary active transport?

K and Na through Na-K ATPase - essential for Na reasborption

12

What is reabsorbed through secondary active transport?

Na and Glucose

13

What is the iso-osmotic fluid reabsorption across leaky PT due to?

standing osmotic gradient
oncotic pressure gradient

14

How is glucose absorbed into the tubular epithelial cell?

SGLT

15

How is water reabsorbed?

through the NaCl osmotic gradient

16

What is the transport maximum for glucose?

2mmol/min

17

What is the renal threshold for glucose?

10-12mmol/l

18

What happens when Tm is reached?

clearance of reabsorbed or secreted substances is not constant

19

What is Na reabsorption driven by?

Na-K ATPase

20

What is the osmolarity of the tubular fluid?

300mosmol/l

21

What is the function of the loop of henle?

generates a cortico-medullary solute concentration gradient

22

WHat does the solute concentration gradient allow?

the formation of hypertonic urine

23

How does the loop function?

as a countercurrent multiplier

24

What is the function of the ascending limb?

Na and Cl reabsorbed in thick ascending limb
impermeable to water

25

What is the function of the descending limb?

does not reabsorbed NaCl
highly permeable to water

26

What ensures that NaCl is absorbed into the interstitial fluid?

K recycling

27

What allows K recycling and Na, Cl reabsorption?

NKCC channel

28

What blocks the NKCC channel?

loop diuretics

29

What is the effect of solute being removed in the ascending limb?

tubular fluid is diluted and osmolality of interstitial fluid is raised

30

How is the osmolality maintained?

interstitial solute cannot enter the descending limb

31

What does the high osmolality allow?

water to leave descending limb by osmosis

32

What type of fluid moves into the distal tubule?

200mOsmol/l

33

What is the osmolarity at the renal pelvis?

1200mosmol/l

34

What contributes to approx half of the medullary osmolality?

the urea cycle

35

Where is urea impermeable?

the distal tubule

36

Where is 50% of urea absorbed?

the collecting duct

37

Where does urea diffuse passively?

into the loop of henle

38

What is the purpose of countercurrent multiplication?

to concentrate the medullary interstitial fluid

39

Why is counter current multiplication important?

to enable the kidney to produce urine of different volume and concentration according to the amounts of circulating ADH

40

What is the Vu on normal fluid intake?

around 1ml/min

41

what is the counter current exchanger?

the vasa recta run alongside the long loop of henle of the juxtamedullary nephrons

42

Where does blood osmolality rise?

as it dips into the medulla - water loss and solute gained

43

Where does blood osmolality fall?

as it rises back to the cortex - water gained and solute lost

44

How does the countercurrent system solve the problem of NaCl being washed away by essential blood flow?

vasa recta capillaries follow hairpin loops
vasa recta capillaries freely permeable to NaCl and water
Blood flow to vasa recta is low

45

What is the function of the countercurrent exchange?

ensures that solute is not washed away