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 atom

99% of living tissue is made up of only 7 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                 total mass

 

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