Question

We eat food composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water. After digestion, these are absorbed in the form of glucose, amino acids, fatty acids, glycerol etc. What mechanisms are involved in the absorption of digested food and water?

Answer 1

Absorption:

1. The process in which water and digested food are absorbed by the blood is known as absorption.
2. The absorbed food and water are then supplied to all parts of the body.
3. The mechanisms involved in the absorption of food are simple diffusion, active transport, facilitated transport, and passive transport.
4. The mechanism involved in the absorption of water is osmosis.

Mechanisms involved in the absorption of digested food:

Simple diffusion:

1. During simple diffusion, digested food molecules in the small intestine go into the blood.
2. Here, the digested food molecules move from the region of lower concentration to the region of higher concentration.
3. Simple diffusion occurs till all the digested food molecules are uniformly distributed throughout.

Active transport:

1. During active transport, digested food moves from lower concentration to higher concentration.
2. External energy is required for active transport.
3. Example: Sodium ions are absorbed through active transport.

Facilitated transport:

1. During facilitated transport, solutes are transported through a membrane with the help of carrier proteins.
2. Example: Absorption of digested proteins in the form of amino acids.

Passive transport:

1. During passive transport, the movement of solute in simpler forms takes place through a cell membrane.
2. External energy is not required during passive transport.

The mechanism involved in the absorption of water:

Osmosis:

1. During osmosis, water moves from the region of high water concentration to the region of low water concentration.
2. Water moves from the small intestine to blood through a semi-permeable membrane.