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Flashcards in Physiology 4 (easy) Deck (27)
1

How much urea is reabsorbed?

50%

2

How much amino acid reabsorbed?

100%

3

How much creatine reabsorbed?

0%

4

Roughly how many mls filtered fluid is reabsorbed in the proximal tubule?

80ml/min

5

What is reabsorbed in the PT?

Sugars
Amino acids
Phosphate
Sulphate
Lactate

6

What is secreted in the PT?

H+
Hippurates
Neurotransmitters
Bile pigments
Uric acid
Drugs
Toxins

7

What is primary active transport?

Energy is directly required to operate the carrier and move the substrate against its concentration gradient

8

What is secondary active transport?

The carrier molecule is transported coupled to the concentration gradient of an ion (usually Na+)

9

What is facilitated diffusion?

Passive carrier-mediated transport of a substance down its concentration gradient

10

Which transporter at basolateral membrane essential for Na+ reabsorption?

Na+/K+ ATPase

11

How is glucose reabsorbed?

Luminal: co-transport
Basoalteral: facilitated diffusion, and also in exchange for K+ (might be primary active transport)

12

Renal threshold for glucose reabsorption

(i.e. Tm (transport maximum))

10-12 mmol/l

(clearane of reabsorbed substance is not constant once Tm reached)

13

Percentage of all salt and water reabsorbed in the proximal tubule

67%

14

Na+ reabsorption also drves reabsorption of what through the paracellular pathway?

Cl- !!!

15

Is the tubular fluid iso-osmotic when it leaves the proximal tubule?

Yes (i.e. 300mosmol/l)

16

Which part of the nephron is responsible for creating a cortico-medullary solute concentration gradient?

Loop of Henle

17

Is urine hypotonic or hypertonic?

Hypotonic

18

Which part of the loop of henle reabsorbs Na+ and Cl-?

Ascending limb

(thick - active transport
thin - passive)

19

This part of loop of henle does not reabsorb NaCl and is highly permeable to water

Descending limb

20

Is fluid entering the distal tubule iso-osmotic or hypo-osmotic?

Hypo-osmotic

21

Where is urea absorbed etc?

50% of urea diffuses passively into the loop of Henle
-distal tubule not permeable to urea
-Collecting ducts absorbs 50% urea

22

Effect of ADH on urea absorption?

ADH promotes urea absorption

23

What is the purpose of the countercurrent multiplier?

-Concentrates the medullary interstitial fluid and enable the kidney to produce urine of different volume and concentration according to the amounts of circulating antidiuretic hormone (ADH = vasopressin)

24

Vasa recta and the loop of henle

Blood osmolality rises as it dips down into the medulla (i.e. water loss, solute gained)

Blood osmolality falls as it rises back up into the cortex (i.e. water gained, solute lost)

25

Purpose of the vasa recta

Passive exchange across the endothelium preserves medullary gradient - blood equilibrates at each layer.
Ensures that the solute is not washed away

26

The high medullary osmolarity allows the production of hypertonic urine in the presence of

ADH

27

What creates the medullary osmotic gradient?

The countercurrent multiplier and the urea cycle

(the countercurrent exchanger (vasa recta) preserves that gradient)