Digestion+and+Nutrition


 * 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.

http://images.jupiterimages.com/common/detail/33/44/22564433.jpg http://www.colinlmiller.com/wildlife/lepidoptera/caterpillar_10.jpg http://michaelscomments.files.wordpress.com/2007/03/mosquito.jpg Bulk Feeders**: Ingest large pieces of food. Have claws, tentacles, pinchers, poisonous fangs, or jaws and teeth. i.e. humans. http://images.jupiterimages.com/common/detail/74/11/23421174.jpg
 * 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.
 * [[image:http://michaelscomments.files.wordpress.com/2007/03/mosquito.jpg width="204" height="154"]]
 * 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. The small intestine breaks down food and absorbs nutrients, and the large intestine re-absorbs water.
 * Duodenum**: The first 25 cm of the small intestine. Where the acid chyme (pulpy acidic fluid consisting of acid and partially digested food) mixes with bile (from gallbladder) and digestive enzymes from the pancreas and the wall of the intestine. In the doudenum, carbohydrates, proteins, nucleic acids, and fats are digested. Starches are broken down by pancreatic amylase (from the pancreas) into the disaccharide maltose. Then maltose is broken down by maltase into monosaccharide glucose. Maltase is in a family of enzymes that each hydrolyze a different disaccharide. Sucrase hydrolyzes sucrose and lactase hydrolyzes lactose.
 * Anus**: Opening where undigested materials are expelled.


 * Villi**: Small fingerlike projections extending out on the wall of the small intestine. On top of the villi are **Microvilli**. They are like villi, but smaller and on the villi themselves. The purpose of both is to increase the surface area of the small intestine, so that more nutrients can be absorbed faster.

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

Saliva Stomach Acids and Enzymes The Life of a Turkey Chapter 21 (The content of this page has been moved to the page you're currently on) Large intestine Saturated vs. Unsaturated fat
 * 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).
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