Human Biology Ch.2 Section 2

The body needs energy and materials.Most of what you need comes from nutrients within food.
Nutrients are important substances that enable the body to move, grow and maintain homeostasis.
•Water – It is necessary for all living things.
•Protein – It is material that the body uses for growth and repair. (Cells are built of proteins)
•Carbohydrates – It make up cellulose, which helps move materials through the digestive system.
•Fat – It stores energy.

*Before your body can use these nutrients, digestive system transforms the energy and materials in food into forms your body can use.

The digestive system moves & breaks down food
Digestive system is process of breaking down food into usable materials.

Through muscular action called peristalsis, material is moved through the wavelike contractions of smooth muscles.
Mucous glands throughout system keep the material moist and muscles contract to push the material along.


Organs outside of the digestive tract, such as the pancreas, liver, and gall bladder, also aid in digestion by producing or concentrating important chemicals.Liver•The largest internal organ.
•Filters blood, cleansing it of harmful substances and stores unneeded nutrients for later use in the body.
•It produces bile to break down fats.
Gallbladder-A tiny pear shaped sac connected to the liver. Bile produced in the liver is stored and concentrated in the gallbladder. The bile is then secreted into the small intestine.
Pancreas- It produces chemicals that are needed as materials move between the two. The pancreas lowers the acidity in the small intestine and breaks down proteins, fats and starch.