Digestion Lifetime Nutrition and Wellness - PowerPoint Presentation

Slide1

Digestion

Lifetime Nutrition and WellnessTEKS: 2ABC

http://kidshealth.org/kid/htbw/_bfs_DSmoviesource.html

Digestion

Before your body can use the nutrients in the food you eat, it must go through digestion.Then nutrients must go through absorption.Digestion

-the bodily process of breaking food down into simpler compounds the body can useAbsorption-the process of taking in nutrients and making them part of the body

The Digestive Tract

The digestive or gastrointestinal tract is a tube about 30 feet long.It extends from the mouth to the anus.

Contains the esophagus, stomach, small intestine, and large intestineThey work together to both mechanically and chemically help the body use food.

The Digestion Process

The body breaks down complex molecules from the food into simple, soluble materials.They pass through the digestive tract into the blood and lymph systems.Vitamins and minerals undergo very little chemical change during digestion.

Fats, proteins, and carbs undergo many changes.

The Mechanical Phase

Begins in the mouth, the teeth chew the food and break it down into small piecesContractions of the muscular walls of the digestive tract carry on the mechanical action.

The contractions mix food particles and break them into smaller piecesWaves of contractions knows as peristalsis, the muscles push food through the digestive tract

Emotions can slow down or speed up the process

The Chemical Phase

Begins in the mouthAs you chew, food is mixed with

saliva. (mucus and enzyme containing liquid)It moistens food particles, helping them move down the esophagus into the stomach.Saliva also begins

to break down starches.

The Chemical Phase

In the stomach, gastric juices containing hydrochloric acid and several enzymes are secreted.

These juices break down the food more.Ordinary meal usually leaves the stomach in about 2 to 3 hoursCarbs leave the stomach first, proteins second, fats last

You will feel hungry sooner after a meal high in

carbs

Chemical continued…

Then the semi-liquid food leaves the stomach and enters the small intestineIntestinal juices, pancreatic juices, and bile act on the food

Digestive enzymes help break down the carbs, proteins, and fats into simple substances the body can absorb and use.

Once digestion is complete absorption can take place.

Large Intestines

Indigestible residues, bile pigments, other wastes, and water travel from the small intestine to the large intestine.The large intestine acts as a reservoir, or storage area.

Eventually the body will excrete these materials.

Absorption Process

The body can absorb water, ethyl alcohol and simple sugars directly from the stomach.They pass through the stomach walls into the bloodstream.

However, most absorption takes place in the small intestines.

Absorption Process

Millions of hair like fingers called villi line the small intestines.The villi

increase the absorptive surface of the small intestine by more than 600%.Each villus contains a lymph vessel surrounded by a network of capillaries.Nutrients absorbed by the capillaries pass into the portal vein and travel directly to the

liver

.

Metabolism

The chemical processes that take place in the cells after the body absorbs nutrientsEnzymes cause nearly all metabolic reactions.The body uses nutrients to replace substances used for growth and to carry out body processes.

Metabolism

The body breaks down some nutrients into simpler substances to release energy.The body uses part of this energy to carry out metabolic reactions.It converts the rest into heat.

The body converts all carbs into glucose for use as an energy source.If they are not needed for immediate energy, they can be converted to glycogen or in the body as fat tissue.

Metabolism

During fat metabolism, fatty acid chains are shortened. The body uses most fat for fuel.The body can use amino acids from protein metabolism for cell maintenance or cell growth.It can also use amino acids to make enzymes, antibodies, nonessential amino acids, and as an energy source.

http://kidshealth.org/parent/general/body_basics/digestive.html

http://www.neok12.com/php/watch.php?v=zX43417c4d68676e7352667b&t=Digestive-System