Absorption

This lesson covers: 

1. How large food molecules are broken down and absorbed
2. The structure and function of villi in the small intestine
3. The importance of gut bacteria

Food molecules are absorbed in the small intestine

Large food molecules are too large pass through the lining of the small intestine into the bloodstream.

The following steps need to happen for food molecules to be carried to body cells:

1. Digestive enzymes break large food molecules down into smaller, soluble molecules that can be absorbed.
2. The small molecules pass through the lining of the small intestine into the blood, which transports them around the body.
3. These nutrient molecules then move from the blood into body cells, where they are used.

Villi increase surface area for absorption

The small intestine is lined with microscopic, finger-like projections called villi that increase the surface area for absorption.

Villi have three key features that make them effective at absorbing nutrients:

1. A thin outer layer of cells.
2. A good blood supply.
3. A large surface area.

Bacteria play an important role in your digestive system

Some bacteria can cause illness if they enter tissues, but your digestive system bacteria provide essential functions.

The bacteria in your digestive system are responsible for:

1. Producing some digestive enzymes to break down certain foods.
2. Producing useful vitamins like vitamin K.
3. Producing useful hormones.
4. Preventing the growth of harmful bacteria.