Digestive System

Where does our food go?

Body Fuel

Just like cars need gas to run, we need fuel for our bodies to function

Rather than pouring gas into our bodies, we fuel up on food

Your digestive system is what turns food into fuel for your body to function

Classified as mammals

We are consumers – we eat plants or other animals for food

We are not able to make food within our own bodies like producers

Food for energy

We need energy for everything we do in the day

Food provides us with the energy that keeps us going

Food for building

Needed to build our bodies as we grow Needed to make new bone cells and

new muscle cells Provides us with the material that

helps our hair and nails grow, too The faster your grow and change, the

more food you will need

Food for repairing

Rebuild parts of our bodies Think about when you have scraped

your knee. The food you eat can be used to make new skin cells, fix the broken blood vessels and replace the blood cells you lost.

Digestion process

Break down of food into smaller parts that your body can use

Two ways your food can change: Mechanical digestion

Physical changing of food Chemical digestion

Broken down into carbohydrates, proteins and fats

The Beginning: Your Mouth

Mouth, or oral cavity, contains: Teeth, tongue, and salivary glands

Teeth tear and grind up food Mechanical digestion

Tongue allows you to enjoy the flavors Help swallow

Organs that Help Digestion

Salivary Glands Make saliva, or watery liquid, that you

may call spit Help moisten food making it softer and

easier to swallow Beginning of chemical digestion Contain enzymes that speed up chemical

reactions. These enzymes are called salivary amylase

The Food Tube: The Esophagus

Muscular tube About 10 in. (25 cm) long Stretches to allow food to pass through it Involuntary muscles contract and relax

pushing your food toward your stomach The movement created by the contracting

and relaxing muscles is called peristalsis

An Expandable Bag: The Stomach

Attached to the end of the esophagus Looks like a bag shaped like a “j” When food enters your stomach it mixes with

gastric juices. Enzymes, acids and mucus

Pepsin – enzymes that break down protein and fat Hydrochloric acid – breaks down protein Mucus – protects the stomach walls so they are not

attacked by the strong acids and enzymes that are breaking down your food.

An Expandable Bag: The Stomach

Food stays in your stomach 2 to 6 hours Mechanical digestion takes place as food and

gastric juices are mixed Chemical digestion also takes place as the

enzymes and acid break down the food you have eaten

When the food and juices are fully mixed, the resulting mixture is called chyme

A Seven-Meter Tube: The Small Intestines

When your food has been completely mixed and churned in your stomach, it moves to the small intestines

2.5 cm wide and over 21 feet long Long tube that is divided into three parts:

Duodenum Jejunum Ilium

A Seven-Meter Tube: The Small Intestines

Duodenum Digestive juices are added to chyme The juices are made in the pancreas

Break down carbohydrates, protein and fat Bile, made by the liver and stored in the

gall bladder, is responsible for breaking fats into smaller molecules

A Seven-Meter Tube: The Small Intestines

Digestion is completed in the small intestines

Food moves along through the long organ by the process of peristalsis

A Seven-Meter Tube: The Small Intestines

Inside the small intestines are millions of villi Tiny fingerlike projections surrounded by

capillaries The nutrients is absorbed by the villi and

into the capillaries and put into the circulatory system.

A Two-Meter Tube:The Large Intestines

Waste materials and fiber remain in your digestive system after nutrients have been removed

6 cm wide and 1.5-2 m long Water is absorbed by the blood from the large

intestines leaving a semisolid waste product. The waste product moves through the large

intestines and is stored in the rectum The waste product is called feces. When the rectum becomes full, the fecal wastes are

removed from the body through the anus.

Digestive System = mouth (teeth, tongue, saliva,

enzymes) esophagus stomach (acids, enzymes,

mucus, “chyme”) small intestines (nutrients absorbed,

pancreas, liver, gallbladder) large intestines (water absorbed

by blood) rectum anus