Chapter+21


 * Chapter 21 Nutrition and Digestion**

Food Processing Mechanical- physical break down of food                 Chemical- use of digestive enzymes to break down food
 * Ingestion**: The act of taking in food.
 * Digestion**: Breaking down of food molecules into small enough pieces for the body to absorb.
 * Absorption**: Cells lining the digestive tract absorb small nutrient molecules.
 * Elimination**: Undigested material passes out of the digestive tract.


 * Suspension Feeders**: Extract food particles suspended in surrounding water. i.e. humpback whale.
 * Substrate Feeders:** Live in or on their food source and eat their way through the food. i.e. caterpillar on leaf.
 * Fluid Feeders**: Take in food by sucking nutrient-rich fluids from a host. i.e. mosquitoes.
 * Bulk Feeders**: Ingest large pieces of food. Have claws, tentacles, pinchers, poisonous fangs, or jaws and teeth. i.e. humans.


 * Pharynx**: Passage way between the mouth and esophagus.
 * Esophagus**: Channel below the pharynx for food. It has muscle tissue to push food through by peristalsis.
 * Crop**: Pouch-like organ where food is softened and stored temporarily.
 * Stomach**: Stores food temporarily. Contains more muscle and churns and grinds food.
 * Gizzard**: Contains teeth or grit to assist in grinding.
 * Intestine**: Between stomach or gizzard and anus. Chemical digestion/nutrient absorption occurs.
 * Anus**: Opening where undigested materials are expelled.

Peristalsis- process by which food moves through digestive tract The muscles contract above the food and release below it to push it through

Pyloric Sphincter- muscular ring which controls movement of food from stomach to small intestine Cardiac Sphincter- controls food movement from esophagus to stomach. (like a valve).

(Third Edition Biology Concepts and Connections)