Into the blood

The idea

Digested nutrients pass from the small intestine into blood in vessels in its walls (absorption); thousands of finger-like projections on its thin lining increase the surface area for efficient absorption, and blood carries nutrients around the body.

Where do nutrients go?

The food is now in simple forms inside the small intestine.

How do these nutrients reach all parts of the body?

• They pass into the blood, which carries them
• The air carries them away
• They stay in the intestine for ever

Absorb

Compare a flat lining with a lining that has finger-like projections. Press Absorb for each one.

More surface

In this drawing, the lining with finger-like projections has a longer surface, so more dots passed into the blood vessel.

Digested nutrients pass from the small intestine into the blood in vessels in its walls. This is absorption. Thousands of finger-like projections on its thin lining increase the surface area for efficient absorption, and the blood carries the nutrients around the body.

Notes

Digested nutrients pass from the small intestine into the blood in vessels in its walls (absorption). Thousands of finger-like projections on its thin lining increase the surface area for efficient absorption, and the blood carries the nutrients around the body.

Check yourself

What is absorption of nutrients?

What increases the surface area of the lining of the small intestine?

Why is a large surface area useful in the small intestine?

What carries the absorbed nutrients to different parts of the body?

• Food being chewed by the teeth. Chewing is mechanical digestion. Absorption is nutrients passing into the blood.
• Digested nutrients passing into the blood — correct. Yes!
• Waste leaving through the anus. That is egestion. Absorption is nutrients passing into the blood.
• Nothing, the lining is a flat sheet. The lining is not flat. Its finger-like projections increase the surface area.
• A layer of stones. There are no stones in the lining. The finger-like projections increase the surface area.
• Thousands of finger-like projections — correct. Yes!
• More nutrients can be absorbed efficiently — correct. Yes!
• It makes the intestine shorter. A large surface helps absorption. It does not shorten the intestine.
• It makes the food colder. Surface area has nothing to do with temperature. It helps in efficient absorption.
• Air. Air goes to the lungs. Blood carries nutrients around the body.
• Blood — correct. Yes!
• Saliva. Saliva is made in the mouth. Blood carries nutrients around the body.