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Food and Digestion

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Greg Evans

on 20 September 2014

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Transcript of Food and Digestion

Chapter 2: Food and Digestion
2.1 - Food and Energy
Why You Need Food
substances in food that provide the raw materials and energy the body needs to carry out all its essential processes
The energy used by your body is measured in unit called calories.
1 Calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius.
Nutrients made up of carbon, hydrogen, and oxygen. These are a major source of energy.
Simple Carbohydrates
aka Sugars
glucose is the main source of energy for your body's cells
Complex Carbohydrates
made of many sugar molecules linked together in a chain
Starch is found in plants such as wheat, potatoes, and corn.
made of carbon, hydrogen, and oxygen but they give you twice as much energy as carbohydrates.
Important for cell membranes, supporting organs, and insulating your body.
Kinds of Fats
waxy, fatlike substance found in animal products
Your liver can make all the cholesterol you need.
nutrients that contain carbon, hydrogen, and oxygen, plus nitrogen.
Needed for tissue growth and repair
Amino Acids
small units that link together to make proteins
1/2 the amino acids you need come from the food you eat.
has essential amino acids
lacks some essential amino acids
Vitamins and Minerals
help the body to carry out different kinds of processes
Fat Soluble & Water Soluble Vitamins
stored in fatty tissues in your body
dissolve in water and not stored in your body
Importance of Vitamins
Importance of Minerals
most important nutrient because it is vital to your body's processes
65% of your body weight
What does eating healthy mean to YOU?
2.2 - Healthy Eating
Guidelines for a Healthy Diet
The USDA guidelines provide a personalized way to help people make healthy food choices based on their age, sex, and amount of physical activity.
Limiting Sugars and Fats
Did you notice that sugars and fats were not included in the pyramid?
Why would they be left out?
ice cream vs. low-fat milk
Food Labels
Food labels allow you to evaluate a single food as well as to compare the nutritional value of two different foods.
Dietary Reference Intakes (DRIs)
Your digestive system is about 9 meters long!
2.3 - The Digestive Process Begins
Functions of the Digestive System
break down food molecules
absorb the molecules into the blood
eliminate waste
-the process by which your body breaks down food into small nutrient molecules
Two types of Digestion:
- the process by which nutrient molecules pass through the wall of your digestive system and into your blood
- materials that can not be absorbed are eliminated from the body as waste
The Mouth
Both mechanical and chemical digestion begin in the mouth.
The fluid released when your mouth waters is saliva.
Your teeth carry out the first stage of mechanical digestion in the mouth.
Your saliva has enzymes. Enzymes are proteins that speed up chemical reactions.
The Esophagus
epiglottis - closes off your windpipe
esophagus - muscular tube that connects the mouth to the stomach
mucus - thick, slippery substance that lines the esophagus
Peristalsis - involuntary waves of muscular contractions that push food in one direction
The Stomach
J-shaped muscular pouch in the abdomen
3 strong layers of muscle contract to do most of the mechanical digestion.
Digestive juices produced by the cells in the lining of your stomach continue chemical digestion.
2.4 - Final Digestion and Adsorption
How is this picture like your digestive system?
The Small Intestine
The part of the digestive system where most chemical digestion takes place.
Your small intestine is about 6 meters long!
The Liver
largest organ inside the body
main job is to produce bile
Bile breaks up fat particles.
The bile produced by the liver flows into the gallbladder.
The Pancreas
Produces enzymes that flow into the small intestine and help break down starches, fats, and proteins.
Triangular organ between the stomach and first part of the small intestine.
Absorption in the Small Intestine
There are millions of tiny finger-like structures called villi on the surface of the small intestine.
The Large Intestine
1.5 meters long
contains bacteria that make vitamins like vitamin K
absorbs water into the bloodstream
Rectum - short tube at the end of the large intestine
Anus - the muscular opening at the end of the rectum
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