DigestionDigestion

The final The final chapter!!!chapter!!!

The Small The Small IntestineIntestine

» Is about Is about 66 meters long! meters long!» Most Most chemical digestionchemical digestion and the and the absorptionabsorption of nutrients take place of nutrients take place here here (in the small intestine)(in the small intestine)..

» Food arriving here from the stomach Food arriving here from the stomach is mostly liquid . It then mixes is mostly liquid . It then mixes with secretions and enzymes with secretions and enzymes (delivered from the two organs on (delivered from the two organs on the next two slides). the next two slides). Finally, Finally, nutrient molecules are absorbed into nutrient molecules are absorbed into the bloodstream.the bloodstream.

Everyone’s Favorite: Everyone’s Favorite: Organ #1:Organ #1:LiverLiver!!!!!!

» It’s the largest organ found in the It’s the largest organ found in the body. body.

» As part of the digestive system, it As part of the digestive system, it produces produces bilebile (which gets stored in (which gets stored in the gall bladder and is delivered the gall bladder and is delivered through tubes to the small through tubes to the small intestine).intestine). BileBile is a chemical that is a chemical that breaks fats down into smaller fat breaks fats down into smaller fat molecules. These fats molecules are molecules. These fats molecules are later further broken down by enzymes later further broken down by enzymes produced in the pancreas. produced in the pancreas.

Organ #2:Organ #2:The The PancreasPancreas

o As part of the digestive As part of the digestive system, the system, the pancreaspancreas produces enzymes that flow produces enzymes that flow into the small intestineinto the small intestine and break down fats, and break down fats, starches, and proteins.starches, and proteins.

Food travels directly Food travels directly from the stomachfrom the stomach to the to the small intestinesmall intestine, it , it nevernever enters either the enters either the liver or pancreasliver or pancreas

RememberRemember!!!!!!

Absorption in the Absorption in the Small IntestineSmall Intestine

The inner surface (or wall) of the The inner surface (or wall) of the small intestine is lined with small intestine is lined with millions of finger-like millions of finger-like projections called projections called villivilli.. Each Each villivilli is filled with tiny blood is filled with tiny blood vessels. vessels.

Nutrients from digested food are Nutrients from digested food are absorbed into the absorbed into the villivilli, where , where the blood then carries those the blood then carries those nutrients to the rest of the body.nutrients to the rest of the body.

The The LargeLarge Intestine Intestine» By the time material moves out of By the time material moves out of the small intestine into the large, the small intestine into the large, almost all nutrients have been almost all nutrients have been absorbed.absorbed. The remainder is water The remainder is water and undigested food like fiber. and undigested food like fiber. BacteriaBacteria (good ones) feed on this (good ones) feed on this (yikes!) and (yikes!) and produce vitamin Kproduce vitamin K..

» In the large intestine, the In the large intestine, the waterwater is absorbedis absorbed and the rest compressed and the rest compressed in a short tube (rectum) and in a short tube (rectum) and eliminated as feces through the eliminated as feces through the anus.anus.