Control of plasma volume

Question 1

What molecule/ion in plasma is mostly responsible for its osmolality?

Answer 1

Sodium ions

Question 2

How does changing the concentration of sodium ions in the plasma affect its osmolality?

Answer 2

Increasing or decreasing sodium ion concentration in the plasma
results in change in plasma osmolality in same direction

Question 3

What is the effect of changing the osmolality of plasma on plasma?

Answer 3

Increasing or decreasing plasma osmolality
makes water move into the plasma or leave it by osmosis
increases or decreases the volume of plasma

Question 4

What is the effect of changing the volume of plasma on blood?

Answer 4

Increasing or decrease plasma volume

increases or decreases blood pressure

Question 5

What is the source of most of the sodium ions in the plasma?

Answer 5

Diet

Question 6

What is responsible for most of the removal of sodium ions from the blood?

Answer 6

Kidneys excreting it into urine

Question 7

What contains small amounts of sodium ions removed from the blood?

Answer 7

Faeces

Sweat

Question 8

What is the relative range of sodium ions that the kidneys can excrete into urine?

Answer 8

Wide range of sodium ions

Question 9

What is the advantage of the kidneys being able to excrete sodium ions in wide ranges?

Answer 9

So can match sodium ion excretion into urine with sodium ion ingestion in diet

Question 10

Why does sodium ion excretion into urine need to match sodium ion ingestion in diet?

Answer 10

To prevent changes in plasma sodium ion concentration
plasma osmalility
plasma volume
blood pressure

Question 11

How can plasma volume be changed without changing plasma osmalility?

Answer 11

Add or remove volume of a solution to plasma

that is iso-osmotic to plasma

Question 12

How can a solution that is iso-osmotic to plasma be added or removed?

Answer 12

By adding or removing sodium ions to plasma

water will follow sodium ions