3. NUTRITION
It is the science that interprets the relationship of food to
the functioning living organisms.
It involves the following processes. They are
1. Ingestion:-Chewing and swallowing to the initial digestive
organs
2. Digestion:-Reduction of food to the utilizable form/Physical
and chemical processing of ingested food.
3. Absorption:-Active transport and passive diffusion
4. Metabolism:-Body converts what you eat and drink into
energy.
4. Needs for nutrients
1. Maintenance
2. Energy for vital function :Heart, respiratory and
membrane transport
3. Maintain body Temperature
4. Protein for repair of tissue
5. Growth:-Increase muscle, bone and connective tissue.
5. Nutrient types
Organisms can be classified into various nutrient types
I.With respect to source of Energy:-Under this category there are
three types
1. Chemotrophic:These organisms obtain their energy from
inorganic reaction such as oxidation of sulfur and
iron.Eg.Bacteria
2. Phototrophic:Obtain their energy from photosynthesis.Eg.Green
plants
3. Heterotrophic organisms:Get their energy by oxidizing pre-
existing organic compounds like carbohydrate and
lipids.Eg.Animals
6. II.With respect to source of Nitrogen:
Three types under this category. They are
Autotrophs:-They use inorganic Nitrogen such as nitrates
and ammonia. Eg:-Photosynthetic algae and higher plants
Mesotrophs:-They use single aminoacid or ammonia and
fatty acids.
Metatrophs:-They require many aminoacids
7. III.With respect to carbon source
Organisms can be categorized into two types
Autotrophs:-They obtain carbon from inorganic sources such as
Carbondioxide.
Heterotrophs:-They depends on organic sources for carbon:They
depends on autotrophs for their carbon.They feed on complex
ready made organic food.
They use it as a source of
1.Energy for their vital activities
2.Building materials
3.Vitamins
9. • Most of our food materials are
complicated chemical compouns.
• They may absorbed and utilized by the
body.
• It may be broken down into relatively
simple molecules.
• Carbohydrates must be hydrolysed
into monosaccharides.
• Fats into glycerol and fatty acids and
proteis into amino acids.
