B2 - Absorption In The Small Intestine

What is the main function of the small intestine?

To absorb the products of digestion into the bloodstream

Why must large food molecules be broken down during digestion?

Because they are too large to be absorbed into the bloodstream

Which enzyme digests starch into simple sugars?

Amylase

What is one key structural adaptation of the small intestine for absorption?

It is very long (around 5 meters), providing a large surface area

What structures cover the inner surface of the small intestine?

Millions of villi

How do villi help with absorption?

They increase the surface area for diffusion of digested molecules

What are microvilli?

Tiny projections on the surface of villi that increase surface area even more

How does a good blood supply help absorption in the small intestine?

It maintains a steep concentration gradient by rapidly carrying away absorbed molecules

Why is a thin membrane important in the small intestine?

It provides a short diffusion path for efficient absorption

What process is used to absorb molecules that cannot diffuse naturally?

Active transport

Why is active transport important in the small intestine?

It allows absorption of molecules against the concentration gradient

What are the two main methods by which the products of digestion are absorbed?

Diffusion and active transport

What is the advantage of having both villi and microvilli?

They massively increase the total surface area for absorption

How does the structure of the villi help maintain a concentration gradient?

The blood flow constantly removes absorbed molecules

What type of membrane do villi have?

A thin, permeable membrane to speed up diffusion