Nutrition

This section will introduce you to the structure and function of the digestive system. 
We  will compare mechanical and chemical digestion and we trace the food´s path through the disgestive tract. At the end of this term you will understand the importance of having a balance diet in order to stay healthy.

Why do we eat?
Human beings eat to growth, to get energy and to stay healthy.

Do you know why do you feel hungry? You feel hungry because your brain receives signals that your cells need energy. 

But, eating is the begining of the story. Your body changes the food into substances your cells can use for growth, tissue repair, metabolism, movement, etcetera. 

Your digestive system is a group of organs that work together to digest food so that it can be used by your body. 

DIGESTIVE SYSTEM

The most obvious part of the digestive system is a series of tubelike organs called the digestive tract, which includes your mouth, pharynx, oesophagus (gullet), stomach, small intestine, large intestine, rectum and anus.

Did you know that the digestive tract may be as long as 9 m!

The digestive system is composed of two sets of organs: those that made up the digestive tract and those that are called accesory organs. 
Accesory organs include the salivary glands, the gailbladder, the liver and the pancreas. 


Lets explore some of the functions of each of the digestive system´s organs.

digestive system´s organs´functions
http://www.musclesculpt.com/digestive.swf


DIGESTION is the process of breaking down food, such as your cheese sandwich into a form that can pass from the digestive tract unto the bloodstream

There are two types of dygestion: mechanical and chemical. The breaking, crushing and mashing of food is called mechanical digestion.
In chemical digestion, large molecules are broken down into nutrients. 
Nutrients are substances present in food (aliments) that the body needs for normal growth, maintenance and repair. So minerals, vitamins and roughage are nutrients present in a carrot (aliment) 

There are 7 major types of nutrients:
proteins: made of small units called amino acids
carbohydrates: sugars such as glucose
vitamins: 
minerals
fats: made of fatty acids and glycerol
fibre (roughage)
water

Substances called enzymes break some nutrients into smaller particles that the body can use: glucose, amino acids, fatty acids, glycerol, etc.  

For example proteins are chains of smaller molecules called amino acids. Proteins are too large to be absorbed into the bloodstream. So enzymes cut up the chain of amino acids. Amino acids are small enough to pass into the bloodstream. 

Enzymes act as chemical scissors to cut the long chains of amino acids into small chains.  

Examples of three different enzymes:
Pepsine is an enzime that acts on proteins to broken them down into amino acids.

Amilase is an enzyme that acts on starch to broken it down into sugars.

Lipase is an enzyme that acts on fats to broken it down into fatty acids and glycerol.

NUTRITION AND NUTRITIONAL DISORDERS ...

VISIT MY SITE AT GOOGLE

Norma´s Site at Google

https://sites.google.com/a/sagradocorazonmexico.edu.mx/biology-s-class/

2ND TERM VOCUABLARY

ALSO GO AND VISIT MY SITE AT GOOGLE

2nd Term Vocabulary at Norma Google´s Site


https://sites.google.com/a/sagradocorazonmexico.edu.mx/biology-s-class/vocabulary-2nd-term/vocabulary-2nd-term