Electrolyte Disturbances and Fluid Balance

Question 1

How much of the body’s water is in the blood?

Answer 1

Around 15%

(in an average adult male)

i.e. we only have access to 15% of the water in our bodies.

(to give fluid etc.)

Question 2

What are the sources of water gain and loss?

Answer 2

Gain:

• Food/drink and metabolism.

Loss:

• Urine, faeces, skin and lungs.
  
  • (skin and lungs are hard to measure accurately = insensible losses)

Question 3

What is controlling the level of sodium and potassium in electrolyte distribution?

Why is Ca_[i] blank?

Answer 3

The Na/K - ATPase

Ca_[i] is blank becasue Ca²⁺ inside cells is variable,

• (it’s used for intracellular messages)

Question 4

What is the normal Na range in plasma?

Answer 4

135-145 mmol/L.

Question 5

What is sodium excretion regulated by?

(three things)

Answer 5

Renin-Angiotensin-Aldosterone.

Natriuretic Peptides.

Intrinsic Renal mechanisms.