1. The digestive System

2. Why do you eat?
The human body needs energy in order to function on a daily basis and food provides your body with the energy and nutrients it needs to survive
The amount of energy a person needs depends on several factors:
Weight
Age
Activity level
Gender
Food is made of nutrients, which are substances that provide energy and materials for cell development, growth, and repair; there are 6 groups of nutrients needed in the diet and each one has a different function in the body

3. Nutrients
Proteins help relay signals between cells, protect against disease, provide cell support, and speed up chemical reactions
Help the body maintain homeostasis, which is the regulation of the organism’s internal condition regardless of environmental changes
The more active a person is, the more protein the body will need
Made up of a combination of 20 different amino acids or building blocks
Carbohydrates are usually in the form of starches, sugars, or fibers
It is best to eat whole grain foods because they are easier to digest
Usually the body’s major source of energy
Carbohydrates come from bread, pasta, potatoes

4. Nutrients Cont’d
The human body needs a certain amount of fat to stay healthy; fats provide energy and help the body absorb vitamins, as well as a major part of the cell membrane
Body fat helps to insulate the body against cold temperatures
Rarely is there a deficiency in fat in the diet, but to much fat can cause health problems
There are 2 types of fats: saturated and unsaturated
Vitamins are nutrients needed in small amounts for growth, regulation of body functions, and prevention of some diseases
Most vitamins can be obtained by eating a well-balanced diet
Vitamins are good for vision, skin, bones
Get vitamins from foods such as meats, vegetables, and milk

5. Nutrients Cont’d
The human body is mostly water, which is needed for chemical reactions
Water is lost while sweating, breathing, and urinating; so it must be replaced or dehydration will occur
Symptoms of dehydration include thirst, headaches, weakness, dizziness, and little/no urination
You can drink too much water which can be toxic and even fatal; the kidneys cannot filter the excess water and the cells basically “flood” and drown
Minerals help regulate the body’s chemical reactions; these are inorganic nutrients
People can develop a mineral deficiency and must find a supplement to fulfill the need
Minerals can be found in foods such as meats, milk, vegetables, and fish

6. Digestive System
The actual process of digestion is the mechanical and chemical breakdown of food that your body can absorb and use; The digestive system will process the food and release energy that is used for cellular processes and all activities

7. Route of Digestion
Food is taken in through the mouth where both mechanical and chemical digestion begin and then pushed to the back by the tongue and swallowed
The food then travels down the esophagus to the stomach where muscles continue to further mix and mash food. Chemicals in the stomach begin to break down the food to prepare it for absorption by the body
The wavelike muscle contractions of smooth muscles that move food through the digestive system is known as peristalsis

8. Digestion Continues
The partially broken down food moves into the small intestine where chemicals are released by the pancreas, liver, and gallbladder to break down the nutrients; most of the nutrients are absorbed in the small intestine and then transported throughout the body by the circulatory system
In the large intestine, water and other nutrients are absorbed from the digested material; any solid material remaining is waste and is compacted and stored until it is eliminated

9. Other organs
The liver filters blood and stores unneeded nutrients for later use by the body; produces bile the helps break down fats; breaks down medicines and produces proteins, such as those that help blood clot
The gallbladder stores the bile produced by the liver and secretes it into the small intestine
The pancreas produces chemicals that are needed as materials move between the stomach and small intestine; lowers the acidity in the small intestine and breaks down proteins, fats, and starches