Sodium and Water Balance

Question 1

What is the key hormone that controls water balance?

Answer 1

ADH

Question 2

What is the key hormone that controls sodium balance?

Answer 2

Steroid hormones from the adrenals

Question 3

Where is ADH released from?

Answer 3

Posterior pituitary

Question 4

What is another name for ADH?

Answer 4

Arginine Vasopressin

Question 5

What does an increase in ADH secretion cause in the urine?

Answer 5

Small volume of concentrated urine

Question 6

What does a decrease in ADH cause?

Answer 6

Large volume of dilute urine

Question 7

What is the meaning of urine osmolality?

Answer 7

A measure of urine concentration, in which large values indicate concentrated urine and small values indicate diluted urine

Question 8

What does ADH cause in the kidney?

Answer 8

Causes the kidneys to reabsorb water

Question 9

How does ADH cause water resorption?

Answer 9

Countercurrent multiplication

Question 10

What is mineralocorticoid activity?

Answer 10

Na+ reabsorption in renal tubules in exchange for K+/H+

Question 11

What is the steroid with the main mineralocorticoid activity?

Answer 11

Aldosterone

Question 12

What does an increase in mineralocorticoid activity cause?

Answer 12

Sodium gain

Question 13

What dies a decrease in mineralocorticoid activity mean?

Answer 13

Sodium loss

Question 14

What scenarios would result in hyponatraemia?

Answer 14

Decreased sodium

Water retention

Question 15

What scenarios would result in hypernatraemia?

Answer 15

Increased sodium

Water excretion

Question 16

In which fluid compartment is most of the water in the body stored?

Answer 16

Intracellular fluid compartment

Question 17

In which fluid compartment is there a higher concentration of sodium?

Answer 17

Extracellular fluid compartment

Question 18

What factors are present to keep intracellular Na+ levels relatively constant?

Answer 18

Na+/K+ ATPase

Question 19

If sodium is lost from the body, which compartment is it lost from?

Answer 19

ECF since this is where sodium concentration is confined

Question 20

What is the significance of losing Na+ from the ECF?

Answer 20

Water follows Na+ by osmosis therefore if you lose Na+ from the ECF, water will follow it resulting in a loss of water from the DECF alone and not from the ICF

Question 21

What is the most common type of sodium-water imbalance?

Answer 21

Decreased water excretion from SIADH leading to Hyponatraemia