Digestive System Objectives What are the nutrients that the body uses What is the purpose of digestion Organs of the Digestive System

Nutrients of the Body Carbohydrates – Provide energy for the body Fiber – helps food move through your digestive tract Starch – Complex carbohydrate Sugar – Simple carbohydrate. It is the building block of all carbohydrates

Fats Provides energy for the body when carbohydrates are not available Fatty acids and glycerol – building blocks of fats Saturated – from animals mainly Unsaturated – from plants mainly

Proteins Provides energy for the body when fats and carbohydrates are not available. Used to build and repair the body Amino acids – building blocks of proteins

Minerals, Vitamins, Water Minerals -- Helps your body function properly (ex. Keeps muscle, bones, nerves healthy) Vitamins – needed for chemical reaction to occur in the body (ex. Aids in blood clotting) Water – chemical reactions of the body take place in water.

Digestive System Purpose of the digestive system is to fuel the body with energy from nutrients. Types of Digestion Mechanical – physical action of breaking food down into smaller pieces (done in mouth and stomach) Chemical – food is broken down into the essential nutrients the body can use with the help of chemicals such as enzymes

“Lock and Key” System = + enzyme carbohydrate Sugars

“Lock and Key” System Enzymes Examples: Chemicals that help bread down substances (foods) Often end in “ase” Examples: Amylase  carbohydrates Protease  proteins Lipase  fats (lipids)

Mouth Tongue Esophagus Liver Stomach Gall bladder Pancreas Large Intestine Small Intestine Rectum Anus

Organs of the Digestive System Mouth Food is mechanically disgested with the help of the teeth and tongue Food is chemically digested with the help of saliva and the enzyme amlyase Saliva breaks down carbohydrates into sugars Salivary glands – secretes saliva into the mouth Food doesn’t enter the salivary glands Chyme is the name of the chewed food in your mouth

Esophagus and Stomach Esophagus – transports food to the stomach. Smooth muscles push food through the digestive tract, this is known as peristalsis Stomach – produces gastric juice. A layer of mucus protects the stomach lining from gastic juice. Churns food with strong muscles Gastric juice breaks down proteins into amino acids

Liver and Gall Bladder Liver – produces bile Gall Bladder – small sac Bile chemically digests food in the small intestine. Food doesn’t enter the liver Bile breaks down fats into fatty acids Gall Bladder – small sac underneath the liver which stores bile.

Pancreas Known as the “super gland” Produces pancreatic juice. It chemically digests food in the small intestine Food doesn’t enter the pancreas Pancreatic juice breaks down carbohydrates, fats, and proteins

Small Intestine The most important digesting organ (22-24ft long) Bile and pancreatic juice digest food in the small intestine The small intestine produces intestinal juice Intestinal juice breaks down carbohydrates and protein Most nutrients digested are absorbed in the lining of the small intestine (villi)

Villi Fingerlike projections inside the small intestine Increase the surface area for the absorption of nutrients Absorption = mechanical digestion

Large Intestine Water is absorbed in the large intestine (3-4 ft long) Waste products are collected in the large intestine (feces) and are stored in the rectum Wastes are expelled from the body through the anus No digestion occurs here