ECF Regulation 2

Question 1

What promotes Na excretion?

Answer 1

ANP

Question 2

What is the function of ANP?

Answer 2

Regulate Na excretion

Question 3

Aldosterone promotes what?

Answer 3

Na+ reabsorption

K+ secretion

Question 4

How does aldosterone increase weight?

Answer 4

Retention of water following ↑Na+

Question 5

How does increased volume cause Na+ excretion?

Answer 5

↑Na+ = ↑water
↑water = ↑volume
↑volume triggers ANP from atrial cells
↑ANP = Natriuresis

Question 6

Aldosterone acts where?

Answer 6

Distal tubule

Question 7

What is Conn’s syndrome?

Answer 7

Primary hyperaldosteronism due to tumour of adrenal cortex

Too much ANP

Question 8

How does Conn’s syndrome present?

Answer 8

Hypokalemia

NO hypernatraemia

Question 9

ANP is secreted in response to what?

Answer 9

Expansion of ECF volume

Question 10

What is the action of ANP?

Answer 10

Inhibit renin

Oppose actions of angiotensin II

Question 11

What is the effect of ANP on the hypothalamus?

Answer 11

Reduced ADH release

Question 12

What is the effect of ANP on the kidney?

Answer 12

Decreased renin
Increased GFR
(more salt and water excretion)

Question 13

What is the effect of ANP on the adrenal cortex?

Answer 13

Less aldosterone

Question 14

What is the effect of ANP on the medulla oblongata?

Answer 14

Decreased blood pressure

Question 15

Why does excess glucose in the collecting duct cause diuresis?

Answer 15

Glucose in the tubule has an osmotic effect and H2O is retained

Question 16

The osmotic effect in the proximal tubule has what effect on sodium?

Answer 16

Dilution - reducing the driving force of Na into the cell (the gradient)

Question 17

Why does excess glucose in the proximal tubule cause reduced Na reabsorption?

Answer 17

Main driver of reabsorption is the gradient, excess glucose means excess water which means ↓ [Na]

Question 18

How does reduced Na reabsorption effect glucose?

Answer 18

Na+ and Glucose share a symport

If Na+ isnt taken up, glucose isnt either

Question 19

How does uncontrolled diabetes effect the descending limb?

Answer 19

Excess glucose and Na+ in the descending loop exerts an osmotic effect - retaining H2D

Fluid in descending limb is not as concentrated

Question 20

How does uncontrolled diabetes effect the ascending limb?

Answer 20

Fluid arriving is less concentrated

NaCl pumps are gradient limited, so it stays in the tubule

Question 21

What is the effect of uncontrolled diabetes on the interstitium?

Answer 21

Similar to loop diuretic - loss of interstitial gradient

Question 22

In uncontrolled diabetes, what happens at the distal tubule?

Answer 22

Large volumes of NaCl and H2O are delivered

Question 23

Large volumes of NaCl and H2O in the distal tubule have what pathological effect?

Answer 23

Macula Densa detects high levels of NaCl, so it will inhibit secretion of renin

Question 24

What is the net effect of uncontrolled diabetes on the loop of henle?

Answer 24

Loss of interstitial gradient

Very little NaCl or H2O is reabsorbed

Question 25

What should the osmolarity of the distal tubule be?

Answer 25

100mOsM

Question 26

What does the Macula densa do when detecting a high rate of NaCl delivery?

Answer 26

Supress renin secretion Leading to reduced Na+ reabsorption at distal tubules

Question 27

How much NaCl and H2O is reabsorbed at the proximal tubule?

Answer 27

65-75%

Question 28

How much NaCl and H2O is reabsorbed at the distal tubule/collecting duct?

Answer 28

15-20%

Question 29

How much NaCl and H2O is reabsorbed at the loop of Henle?

Answer 29

5-20%

Question 30

What is the most important factor controlling reabsorption of NaCl and H2O in the proximal tubule?

Answer 30

Oncotic pressure

Question 31

How does diabetes affect the collecting duct?

Answer 31

Abolishing the interstitial gradient means water no longer flows down that gradient into the vasa recta from the lumen of the collecting duct

Question 32

What sort of urine will be excreted in uncontrolled diabetes?

Answer 32

Large volume of nearly isotonic urine

Question 33

What will the net effect of large volumes of nearly isotonic urine being excreted be?

Answer 33

Decreased plasma volume | Severe salt and water depletion

Question 34

Uncontrolled DM can produce urine up to what volumes?

Answer 34

6-8L/day

Question 35

What is the cause of hyperglycaemic coma?

Answer 35

Inadequate brain perfusion due to hypotension

Question 36

What is the cause of hypoglycaemic coma?

Answer 36

Inadequate glucose for the brain

Question 37

Why does baroreceptor activation in uncontrolled diabetes not cause a reduction in diuresis?

Answer 37

↓baroreceptor = ↑ADH, but there is no interstitium gradient for water to follow

Question 38

Why is over-excretion of glucose not self-limiting in uncontrolled diabetes?

Answer 38

Liver - glycogenolysis/gluconeogenesis

Question 39

How do Loop diuretics cause K+ wasting?

Answer 39

Active transport mechanism on luminal surface is Na-K-2Cl-cotransporter Blocking Na absorption also blocks K+ ion absorption