all living organisms ned matter to build up the body and energy to operate the metabolic reaction that sustain life.
the material which provde these 2 primary requirement of life are called nutrients or food. The sum of the process by which the living organism obtain matter and energy is treamed nutriention .
animal such as rabiits that subsist entire on plant material are called hervbivores . So there are nutrition of 2 types-
A autotropic nurtion
- all green plants and certain protists have evolved a meachnism to directly use the energy of sunlight for preparing organic materials. This process of making food is called photosynthesis and the organism capable of its termed is called "phototrophs" .
B Heterotropic nutrition
- animals fungi some prostists and many bacteria cann’t utilize sun energy . they use chemical bound – enery .they use chemical bound energy of organism molecules synthezied by other molecules such a mode of feeding is called "heterotropic Nutrition" .
C heterotriphic Nutrition
- Saprotrophic nutrition – many organism absorb fluid food through their body surface . this is called saprotrophic nutrition the enzyme hydrolyzed the organism matter into simple soluble product that are then absorbed .This method of up take is called "saprotropic nutrition" .
- holotropic nutrition – majority of invertebrates and all vertebrates take plant , animal or their product through the mouth and break up the large organism molecules into smaller ones.In their own body with the help of enzymes .this mode of taking food intake is called holotropic nutrition.
here nutrition are further divided into 2 types:-
- macro nutrition
- micro nutrition
macro nutrition -
with few notable exceptions heterotrrophs requires organic molecules , such as carbohydrates, lipids na dproteins when these molecules are broken down by enzymes into components .They can ebe form a energy and are know as the building block elements for the body .
- micro nutritionas -
they are usually small ions Vitamins , inorganic mineral and molecules that are used over and over proteins.
Deficiency of nutrition
it may lead to
malnutrition, kwashiorkor, marasmus and for pregnant women leads to featal death .
Digestion is simple the intake of food which would be further broken down in smaller particles helping for proper absorption of nurtitions.The process starts from the- :-
Oral Cavity , teeth, tongue:-
- as we take food there is an enzyme named alfa- salivary lipas which helps in digestion of food. Partcials into some extent.And in oral cavity there is presence of sliva as well which mixed food and makes it properly to swallow.
Salivary glands – secretion of lubricating fluid containg eneymes also help in break down of carbohydrates.
Pharynx- in pharynx muscle popel material into esophagus .
Esophagus- it Helps in transport of material to the stomach .
Stomach – chemical breakdown of materials via acid and enzymes , mechanical process through muscular contration .
Liver – Secretion of bile for lipid digestion , storage of nutrients , takes place .
Gallbladder- storage and concentration of bile helping in digestion of food .
Pancreas – Exocrine cell secrete buffer and digestive enzymes , endocrine cells secrete hormones.
Small intestine – Enzymatic digestion and absorption of water organic substance , vit and ions.
large intestine – Dehydration and compaction of indigestible material in preparation for elimination .
Agrawal, sarita. principle of biology. 2nd edition . kathmandu: Asmita book Publication, 2068 ,2069
Mehta, Krishna Ram. Principle of biology. 2nd edition. kathmandu: Asmita, 2068,2069.
Jorden, S.L. principle of biology. 2nd edition . Kathmandu: Asmita book Publication, 2068.2069.