Define Nutrition?

How does Nutrition take place in animals/humans?

Nutrition is the process in which food is taken in and then converted into the living matter that is used up by the human body. Animals or Humans take in the complex organic matter(Holozoic Nutrition) that needs to be converted into a simpler one to become part of the body.

Nutrition in humans and animals takes place in the form of the following processes:

  • Ingestion: in this process, food is taken in the body through the mouth.
  • Digestion: in this process, large/complex food particles are broken down into smaller or simpler one that can be absorbed by the body. The digestion can be physical/mechanical or chemical.
  • Absorption: in this process, food is reached till the cells where it is absorbed by different cells.
  • Assimilation: in this process, the absorbed food becomes part of the cells.
  • Egestion/Defecation: it is the removal of undigested or unwanted part of the food in the form of faeces through the anus.

Human Digestive System (organs related to Alimentary Canal)

Organs related to Digestive system and their brief introduction is as follows:

What is a peristalsis movement?

Peristalsis movement is a series of involuntary wave-like contraction and relaxation of longitudinal(outside of the gut) and circular muscles(inside of the gut). This movement helps the food to mix with digestive juices and to move the food along the alimentary canal. These movements occur in oesophagus, stomach and intestines.

The circular muscles constrict the lumen where the longitudinal muscles shorten the lumen. These muscles are antagonistic muscles. It means when circular muscles contracts, then longitudinal muscles relax and vice versa.

How does the food moves in the oesophagus with the help of peristaltic movements?

  • When the circular muscles contract, the longitudinal muscles relax. As a result, the wall of the gut constricts, that is, the gut becomes narrower and longer. The food is squeezed or pushed forward.
  • When the longitudinal muscles contract, the circular muscles relax. The gut dilates, that is, it becomes wider and shorter. It becomes wider and shorter. And this widens the lumen for food to enter.

Try yourself:

  • Define Nutrition.
  • Define Holozoic Nutrition.
  • Name the four process of Holozoic Nutrition.
  • Define chemical/physical or Mechanical Digestion.
  • Tell one difference between egestion and excretion.
  • Why is peristaltic movement essential in the movement of food?
  • What are antagonistic muscles?
  • How do antagonistic muscles work?
  • Which type of digestion takes place by our teeth?
  • In which organ of the alimentary canal, the process of digestion starts?
  • In which organ of the alimentary canal, most of the chemical digestion takes place?
  • What is chyme?
  • What are the functions of HCL that produced in the stomach?
  • Why does HCL not dangerous for our stomach?
  • Name the enzymes produced by the pancreas.
  • In which part of the alimentary canal, chemical digestion of carbohydrates starts?
  • Which biomolecule starts to digest in the stomach?
  • What is bile?
  • Name the organ that produces bile?
  • Where does bile store?