1. How nutrients become you Pg 43
Chapter 3
How nutrients become you
Pg 43

2. You are what you eat
Food is your body’s fuel. When you eat, your body breaks down food and the nutrients it contains into simpler elements.
Energy is released and nutrients are used to help build, repair, and maintain body cells. Then your body discards the by-products of this process as waste.

3. Food, Nutrients, and Energy
There are 6 groups of nutrients your body needs;
Carbohydrates
Fats
Proteins
Vitamins
Minerals
Water
Each of the nutrients has a specific job to do in the body.
Each nutrient has a recommended daily allowance.

4. The Function of Nutrients
Essential nutrients from food are used to;
Build and repair body tissues
Regulate all body processes
Provide energy.

5. Build and repair body tissues
From the time you are born until the time you die, cells are dividing in your body. This cell division accounts for your physical growth. All of these cells are formed from the materials that come from the food you eat.
Nutrient needs during periods of rapid growth are greater than at any other time. Such periods are;
Prenatal
Infancy
Adolescence
Every cell in your body contains genes. Genes carry hereditary information you received from your parents. Height, gender, skin color, and other details. Your parents might be tall but if you don’t meet your nutritional needs you might not reach your full height potential.

6. THE LONG AND SHORT OF IT

7. Regulate Body Processes
A second function of nutrients is to keep body processes running smoothly. For instance, the circulation of body fluids requires a balance of essential nutrients. Maintaining the correct acid-base level in the blood is a function of nutrients. Digestion, adsorption, and metabolism are also processes that rely on proper amounts of nutrients.

8. Provide energy
A third key function of nutrients is to provide energy. Food is to your body what gasoline is to a car. The quality of the food you eat affects how well your body will run. Your body needs energy every minute of every day for everything you do, like breathing, pumping blood, moving muscles, and providing heat. Carbohydrates and fat are the two main nutrients used for energy. Protein may also be used but the body prefers to save proteins for other vital functions.

9. Energy being burned

10. Energy Value of food
The energy value of food is measured in units called kilocalories. A kilocalorie is the amount of heat required to raise one kilogram of water one degree Celsius. Kilocalories may also be called calories. As mentioned earlier, only certain nutrients provide energy. Each gram of carbohydrate in a food product supplies the body with 4 kilocalories. Fats provide 9 kilocalories per gram. Proteins yield 4 kilocalories per gram.

11. The process of digestion
Digestion is the process by which your body breaks down food, and nutrients in the food, into simpler substances. The blood can then carry these simple substances to cells for use in growth, repair and maintenance.
Digestion occurs through mechanical and chemical means throughout the digestive system.
Mechanical digestion occurs when food is chewed and crushed
Chemical digestion happens as food is mixed with powerful acids and enzymes.

12. The GI tract (gastrointestinal)
Food enters the GI tract through the mouth where mastication (chewing) occurs. The teeth and tongue prepare the food and move it into position so it can be swallowed.

13. The Esophagus
As you swallow, food passes from the mouth to the stomach through the esophagus. The esophagus is about 10 inches long. It is one of two tubes in the throat. The other is the trachea, sometimes called the windpipe.
When you swallow a flap of skin called the epiglottis covers the trachea to stop food from entering.

14. In the stomach
When you eat, the stomach produces gastric juices to prepare for digesting the oncoming food. Gastric juices contain hydrochloric acid, digestive enzymes, and mucus. The mixture of gastric juices and chewed food in the stomach is called chyme.
The acid in the stomach is almost as strong as battery acid in a car. The stomach wall has a think lining called mucosa. These mucosa secrete mucus to help lubricate the food and protect from the strong acidic juices.

15. The GI Tract

16. The small intestine
About 95% of digestion occurs in the small intestine. The small intestine is coiled in the abdomen in circular folds. It has three sections: the duodenum, the jejunum, and the ileum.
Duodenum is the first section and is 12 inches long
Jejunum is the second section and is 4 feet long
Ileum is the third section and is 5 feet long
When stretched out the small intestine is about 20 feet long.

17. More small intestine
It takes about 5 to 14 hours for food to travel from the mouth through the small intestine.
The small intestine needs a less acidic environment than the stomach to perform its work.
The pancreas, an elongated gland behind the stomach secretes bicarbonate, which neutralizes hydrochloric acid that has come from the stomach.
The pancreas also produces digestive enzymes that aid in the chemical digestion that takes place in the small intestine.

18. Work of the Small intestine
With the help of the pancreas protein, fat and carbohydrate are broken down into their basic parts.
Protease breaks protein into amino acids
Lipases break fats into fatty acids, glycerol and monoglycerides
Saccharidases break carbohydrates into monosaccharides

19. The liver
The liver plays a roll in digestion as well. The liver produces bile, a digestive juice that aids in the digestion of fat. Bile is stored in the gallbladder until it is needed by the small intestine. At which point it is secreted into the first section of the small intestine (duodenum).

20. In the large intestine
The small intestine connects to the large intestine which is sometimes referred to as the colon. The large intestine stretches to about 5 or 6 feet outside the body.
Very little digestion occurs in the large intestine, its main job is to reabsorb water. As chyme inters from the small intestine it is still very liquid.

21. Absorption of Nutrients
Absorption is the passage of nutrients from the digestive tract into the circulatory or lymphatic system.
The inside surface area of the small intestine is 600 time larger than a smooth tube. This is because the wall of the small intestine is pleated with thousands of folds. The folds are covered with villi, which are tiny finger-like projections that great increase the overall surface are of the small intestine. The villi are covered with microvilli which trap the nutrient particles as they pass by.

22. Cross section of small intestine

23. Metabolism
Once nutrients are digested and absorbed the circulatory system carries the nutrients and oxygen to individual cells. All chemical changes that occur as the cells produce energy and materials needed to sustain life are known as metabolism.
During metabolism, cells make some compounds. They use some of these compounds for energy and save others for later.
Cells will also make new proteins in order to make new cells so that old cells can be discarded and replaced.

24. Factors Affecting Digestion and absorption
Eating Habits – If you eat too little food or your diet lacks variety, you may be missing important nutrients.
Emotions – fear, anger, and tension can lead to digestive problems.
Food allergies – this is a reaction of the immune system to certain proteins found in food.
Physical activity – It can aid digestion and metabolism. Physical activity stimulates a healthy appetite and strengthens the muscles and internal organs.

25. Digestive Disorders
Most people experience digestive disorders from time to time. Some of the most common include;
Diarrhea
Constipation
Indigestion
Heartburn
Ulcer
Gallstones
Diverticulosis