Fluid and Electrolyte Balance

Question 1

What is the total length of glomeruli in the kidney?

Answer 1

1.5m

Question 2

What happens to body fluid when the kidneys stop working?

Answer 2

Fluid begins to accumulate

• pulmonary oedema
• interstitial oedema

Question 3

What electrolyte is increase when kidneys stop working?

Answer 3

Potassium
= hyperkalaemia

ECG

• arrhythmia
• asystole (flat line)

Question 4

What’s the main ion inside cells?

Answer 4

K+

Question 5

What’s the main ion ECF

Answer 5

Na+

Question 6

Which compartment contains most fluid?

Answer 6

IC 60%

Question 7

How much CO do the kidneys receive?

Answer 7

20%

Question 8

What is the response of SNS on the kidney?

Answer 8

decrease plasma volume

SNS vasoconstricts the afferent arterioles to restrict blood flow

Question 9

What is the response of Ang II on the kidney?

Answer 9

decrease BP

Ang II vasoconstricts efferent arterole to maintain eGFR

Question 10

What is the response of prostaglandins on the kidney?

Answer 10

Dilate afferent arteriole

Question 11

What charge is the glomerular BM?

Answer 11

Negatively

Question 12

How much of the filtrate is reabsorbed?

Answer 12

99%

180L/day

Question 13

What’s the average amount of urine produced per day?

Answer 13

approx. 1.8L

Question 14

What’s the unit of measure of concentration of a solute?

Answer 14

Osmole

Question 15

is osmolality temperature-dependent?

Answer 15

No its temperature-independent

Question 16

What’s the concentration of solutes in plasma?

Answer 16

285-295mOsm/kg

approx. 300mOsm/kg

Question 17

Where does majority of reabsorption take place?

Answer 17

70% PCT

Question 18

On the luminal side what is the main exchangers for reabsorption

Answer 18

Mainly

1. Na-X co-transporters
2. Na+/H+ exchanger

Question 19

What is the driver of absorption?

Answer 19

Basolateral 3Na+/2K+-ATPase

- creates concentration gradient for Na+

Question 20

How long is the PCT?

Answer 20

14mm

Question 21

Which part of the nephron concentrates urine?

Answer 21

LOH and CD

Question 22

What system does the LOH use?

Answer 22

Countercurrent multiplier system

Question 23

Which part of the nephron is impermeable to H2O?

Answer 23

TALH

Question 24

What main channel is found on TALH? And what drug can be used to inhibit this?

Answer 24

NKCC

Loop diuretic

Question 25

What's the main function of TALH?

Answer 25

Increases interstitium concentration | Providing a concentration gradient to promote H2O rebasorption from thin DLH

Question 26

How does the vasa recta work to maintain gradient?

Answer 26

It doesn't wash away the gradient by using countercurrent exchange

Question 27

What is the main channel on DCT?

Answer 27

NCC | Na/Cl co-transporter

Question 28

What drug acts on DCT and on what channel?

Answer 28

Thiazide | NCC

Question 29

How long is the DCT?

Answer 29

1mm

Question 30

By the time the filtrate reaches the CD how much of the filtrate is left? And why?

Answer 30

5% PCT -70% LOH -20% DCT -5% = 5% left

Question 31

What acts on the CD to decrease volume loss?

Answer 31

1. ADH (posterior pituitary gland) - binds to V2R - inserts AQs 2. Aldosterone - causes translocation of ENaC into cortical CD - promotes Na+ reabsorption and K+ loss

Question 32

What diuretics can be used on the CD

Answer 32

K+-sparing - MR-antagonist: spironolactone - ENaC blockers: amiloride

Question 33

Where is aquaporin I and II inserted?

Answer 33

I - TDLH | II - CD

Question 34

What are the main channels on PCT?

Answer 34

Basolateral: 3Na+/2K+-ATPase Luminal: Na+/H+ antiporter

Question 35

What are the main channels on TDLH?

Answer 35

AQ I

Question 36

What are the main channels on TALH?

Answer 36

NKCC -inhibited by loop diuretics e.g. flurosemide and bumetinde

Question 37

What are the main channels on CCD?

Answer 37

AQ II (ADH) ENaC (aldosterone)

Question 38

What is the hereditary disorder that effects the PCT?

Answer 38

Fanconi's syndrome

Question 39

What is the hereditary disorder that effects the NKCC2?

Answer 39

Bartter's syndrome

Question 40

What is the hereditary disorder that effects the NCC?

Answer 40

Gitelman's syndrome

Question 41

What is the hereditary disorder that effects the eNaC

Answer 41

Liddle's

Question 42

What are the main waste products measured?

Answer 42

Creatinine and urea

Question 43

What is Hemolytic-uremic syndrome?

Answer 43

Hemolytic-uremic syndrome is a disease characterized by a triad of 1. hemolytic anemia (anemia caused by destruction of red blood cells) 2. acute kidney failure (uremia) 3. low platelet count (thrombocytopenia).

Question 44

How is urea formed?

Answer 44

byproduct of AA metabolism in the liver

Question 45

What's the importance of urea in kidney function?

Answer 45

Urea trapping - reabsorbed in the inner medullary CD - involved in countercurrent exchange and maintaining concentration gradient for H2O reabsorption

Question 46

What is creatinine made from?

Answer 46

Breakdown product of creatinine phosphate | - muscle metabolism

Question 47

What's the importance of creatinine in kidney function?

Answer 47

Freely filtered NOT re-absorbed - can be used as a reliable marker of kidney function

Question 48

What is the range of urine concentration?

Answer 48

200-1400mOsm/kg

Question 49

What is the minimum urine osmolality?

Answer 49

50mOsm/kg

Question 50

What is the minimum urine output?

Answer 50

0.4L/day

Question 51

What is the maximum urine output?

Answer 51

12L/day

Question 52

What is the concentration of waste products excreted/day

Answer 52

600mOsmol

Question 53

What's the volume of glomerular filtrate generated from plasma per min and how much if reabsorbed?

Answer 53

100mL/min | 99% reabsorbed - 70% PCT