Fingers that soak up food
Villi absorb digested food.
A bigger surface
Digested food has to pass through the lining of the small intestine to reach the blood.
What would many tiny finger-like folds do for this lining?
What this lesson covers
The idea
Finger-like villi on the inner lining of the small intestine increase the surface area for absorbing digested food, and their rich blood supply carries it to every cell for energy, new tissues and repair.
A bigger surface
Digested food has to pass through the lining of the small intestine to reach the blood.
What would many tiny finger-like folds do for this lining?
- Give a bigger surface to absorb food
- Make it slower to digest
- Make the food go backwards
Add villi
Use the + button to add villi to the lining. The numbers are only for this picture.
A huge surface, a rich supply
The inner lining of the small intestine has numerous finger-like projections called villi. In the picture, each new villus lengthened the lining that touches the food, so more digested food can be absorbed. Each villus is richly supplied with blood vessels, which carry the absorbed food to every cell of the body.
Finger-like villi on the inner lining of the small intestine increase the surface area for absorbing digested food, and their rich blood supply carries it to every cell for energy, new tissues and repair.
Notes
Villi on the inner lining of the small intestine increase the surface for absorption, and their blood supply carries the food to every cell for energy, new tissues and repair.
Check yourself
What is the job of the villi?
Why are the villi richly supplied with blood vessels?
In this picture the flat lining is 240 units long and each villus adds 40 units of lining. How long is the lining with 5 villi?
Answer: 440 units
240 + 5 × 40 = 240 + 200 = 440 units.
Where are villi found?
- To increase the surface area for absorbing digested food — correct. Yes!
- To make bile. Bile is made by the liver, not by the villi.
- To push food forward along the gut. Peristaltic movements of the muscles in the lining push food forward.
- To make the food alkaline. Bile from the liver makes the acidic food alkaline.
- The blood carries absorbed food to every cell of the body — correct. Yes!
- To break proteins into amino acids. Enzymes of the intestinal juice finally convert proteins to amino acids; the blood vessels carry the absorbed food away.
- In the mouth. In the mouth, teeth crush the food and saliva wets it.
- In the stomach wall. The stomach wall has gastric glands that release hydrochloric acid, pepsin and mucus.
- On the inner lining of the small intestine — correct. Yes!