1. The Digestive System

2. Overview
The organs and glands in the body that are responsible for digestion (the breakdown of large food molecules into simpler compounds)
Begins with the mouth and extends through the esophagus, stomach, small intestine, and large intestine, ending with the rectum and anus

3. The Mouth Place where food enters the body
Two types of digestion occurs: mechanical and chemical
Mechanical digestions, or mastication, is the physical chewing and breaking up of food
Chemical digestion uses enzymes in saliva (salivary amylase) to breakdown starch into maltose
Once chewed the food moves through the pharynx into the esophagus in a wavelike motion known as peristalsis

4. The Stomach
Several functions: temporarily stores ingested food, partially digests proteins, and kills bacteria
Secretes gastric juices which contain enzymes and hydrochloric acid(HCL)
Pepsin is one enzyme made that breaks down proteins into smaller peptides
HCL lowers pH of the stomach making it an acidic environment
Secretion of mucus protects the stomach lining
Food is mechanically broken down by churning in the stomach
This partially digested food, or chyme, is now ready for the small intestines

5. The Small Intestine Three regions: duodenum, jejunum, and ileum
Chyme moves into the small intestine through the pyloric sphincter
The walls secrete enzymes that break down all three food groups
Digestive juices from the pancreas, liver, and gallbladder along with the enzymes
Bile is a substance made from the liver that breaks down fats and other lipids
Most of the absorption of nutrients happens through large folds in the walls called villi

6. The Large Intestine Large intestine includes colon, cecum, and rectum
Colon is the junction of small and large intestines; major function is to absorb water from digestion
Cecum is important in fermenting ingested material (mainly plant material)
Feces moves through large intestine by peristalsis
Too little water absorbed by the colon results in diarrhea and too much results in constipation
Mostly harmless bacteria live in the colon and give off gasses that have offensive odors; these are expelled through the anus
Feces is stored in the rectum

7. The Anus Two sphincters lie between the rectum and the anus
The inner one is involuntary and the outer one is voluntary
Periodically strong contractions of the colon create an urge to defecate feces through the anus

8. Presentation by: Brantley West and Katie Norflus