Biology

Nutrition: The process by which living organisms obtain food necessary for metabolism.

The stages of nutrition are ingestion of nutrients, digestion, absorption and the elimination of wastes.

• Nutrient: materials needed to maintain life functions
• Nutriment (food) = nutrients + indigestible wastes

 Nutrients

1. proteins
2. carbohydrates
3. fats (lipids)
4. fibres
5. vitamins –small organic molecules, which the body cannot synthesize, only from pro-vitamins -> must be supplied by the diet

           a) fat soluble: can accumulate -> disorder

1. • vitamin D
     • -> UV light in the skin
     • -> absorption of Ca -> bones => rickets
     • Egg yolk, liver, fish-liver oil
   • vitamin E
     • healthy cell membranes => red blood cells rupture (haemolysis)
     • vegetable oils, vegetables
     • normal blood clotting
     • liver functioning
     • vegetables, vegetable oils, liver, bacteria
   • vitamin A
     • -> skin => skin problems
     • -> light-sensitive pigment => night blindness
     • Milk, egg yolk, vegetables, fish-liver oil

            b) water soluble: excess leaves in urine; enzyme parts

1. • vitamin B1
     • nervous system => beriberi (tiredness, pain, circulatory problems)
     • yeast, meat, nuts, potato, legumes
   • vitamin B12
     • red blood cell production => anaemia
     • produced only by certain bacteria
     • meat, liver, egg, milk, sour cabbage
   • vitamin C (ascorbic acid)
     • for collagen synthesis =>scurvy
     • wound healing
     • resist infections
     • helps iron absorption
     • citrus fruits, tomato, green pepper, cabbage, potato
   • folic acid
     • production of red and white blood cells
   1. minerals
   2. water

   qualitative starvation: certain nutrients are lacking, in excess, or in the wrong proportions
   quantitative starvation: the organism gets less energy than needed