The Process of Absorption

Absorption is a crucial part of human nutrition, facilitating the movement of digested food substances into the bloodstream.

Absorption predominantly occurs in the small intestine where the majority of digested food substances are absorbed.

Structure and Functioning of the Small Intestine in Absorption

The inner lining of the small intestine is covered with villi and microvilli. These finger-like projections increase the surface area for absorption.
Each villus houses a network of capillaries and a lacteal, aiding in the absorption of different nutrients.
The capillaries absorb amino acids, vitamins, and monosaccharides derived from the digestion of proteins and carbohydrates.
The lacteal, part of the lymphatic system, absorbs fats and fat-soluble vitamins into the bloodstream.
Simple diffusion, facilitated diffusion, and active transport are the main mechanisms by which nutrients are absorbed.

Molecules passively move from an area of higher concentration to an area of lower concentration.
Small fatty acids and fat-soluble vitamins are absorbed in this way.

Involves the use of a carrier protein to move molecules across the cell membrane.
This process doesn’t require energy and also moves molecules from high to low concentration.
Several monosaccharides, such as fructose, are absorbed through facilitated diffusion.

Active transport occurs against the concentration gradient, requiring energy in the form of ATP.
Minerals and other nutrients such as glucose and amino acids are absorbed through active transport.

Absorption enables nutrients to be transported to cells where they are used for various bodily functions.
It allows for the regulation of nutrient intake according to the body’s needs.

Remember, understanding these concepts well is essential for a good grasp of human nutrition and the digestive process.