THE DIGESTIVE SYSTEM Recall the major organs of the human body and their functions within their particular body system.

Functions of the Digestive System:  Breakdown food into nutrients that the body can use  Absorb nutrients necessary for energy, growth and maintenance  Rid the body of solid wastes

Why am I Hungry?  You need food to provide energy for your body.  Food contains Nutrients that are important substances that enable you to move, grow, and maintain homeostasis.  Examples of Nutrients: Proteins, Carbohydrates, fats, and water.

What Jobs do Nutrients Have in My Body?  Proteins: Growth & Repair  Makes your muscles, bones, and skin  Carbohydrates: Energy for Cells and contain cellulose which helps in digestion.  Fat: Energy Storage  Water: Necessary for all living things. More than ½ your body is made up of water.

Digestion: What happens to My Lunch?  Before you can use nutrients, food most be broken down into smaller substances.  Digestion is the process of breaking down food into usable materials.

Types of Digestion:  Mechanical:  Physical changes  Break food into smaller pieces  Occurs in Mouth when Chewing  Chemical:  Actually change food into different substances  Ex. Saliva in mouth changes starch to sugars  The change in taste is a chemical reaction

The Digestive System:  Performs the complex jobs of moving and breaking down food. Includes:  Mouth- Mechanical Digestion  Salivary Glands  Stomach  Small Intestine  Large Intestine  Liver  Gallbladder  Pancreas

Movement of Food Through Digestive System  Food is moved in wavelike contractions called Peristalsis  Mucous Glands can be found throughout the entire system to keep food moist.

Mouth and Esophagus  Mouth  Teeth break food down via mechanical digestion  Saliva softens food and begins chemical digestion  Esophagus  Muscle contractions of peristalsis move solid food from the throat to the stomach in about eight seconds. Liquids take about two seconds!

Digestive System  Liver  Largest Internal Organ  Filters blood  Produces Bile which breaks down fat  Gallbladder  Stores bile to be sent to the small intestine.  Pancreas  Produces digestive juices that help break down food in small intestine.

Digestive System Continued  Strong muscles in the stomach mix and mash food.  Stomach acid breaks down food.  Small Intestine  Partially digested food moves from stomach  Uses digestive juices from pancreas, liver, and gallbladder to breakdown nutrients.  Tiny folds called villi that absorb nutrients.  Large Intestine  Water and other nutrients are absorbed.  Tightly packs waste and sends it to the rectum for disposal.