Water and Electrolytes

Distribution of body fluids

Blood 3.5 litres

Interstitial 10.5 litres

Intracellular 28 litres

Applications

The body has a fluid reserve

Sweating ----- sweat is produced from the plasma ------ fluid is lost from blood -------- blood becomes more osmotic ------ more fluid is sucked in from tissue fluid ------ osmotic pressure of tissue fluid is increased --------- fluid is osmotically sucked out of cells

Haemorrhage ------- drop in capillary blood pressure (hydrostatic pressure) -------- osmotic pressure of the blood remains the same (as does haematocrit) ------ fluid is not formed at arterial end of capillary -------- osmotic suction of blood sucks in water from tissue fluid ------ blood volume restored

Fluid loss from tissue fluid ---- increased osmotic pressure of tissue fluid ------- fluid osmotically sucked from body cells

Atom

Basic building block of matter

Element

A substance made up of only one form of element

99% of living tissue is made up of only 6 elements,

Carbon - C

Nitrogen - N

Hydrogen - H

Oxygen - O

Phosphorous - P

Sulphur - S

Potassium - K

Atoms are composed of protons, neutrons and electrons

Proton +

Electrons -

Neutrons 0

Hydrogen

Carbon

Oxygen

Nitrogen

Ions

An ion is a charged particle

Electrolytes

Substances that dissociate when dissolved in water releasing ions

NaCl ------- Na⁺ and Cl^-

KCl ------- K⁺ and Cl^-

CaCl₂ ------- Ca⁺² and 2Cl^-

Other ions

Mg⁺² Magnesium

CO^-3 Carbonate

PO₄^-3 Phosphate

SO ₄^-2 Sulphate

Why electrolytes are essential to life