Welcome to our nutrition class

This class is designed for 7th Intermediate students. You will find here many activities, announcements, and links to useful sites related to this course... Enjoy! :)

Junk Food busted

What you eat and Why?!

Our human body requires several types of nutrients that should be acquired mainly from our diets, in order for each of our bodies to be able to grow, maintain, and repair itself continuously. Our diet should be varied to contain foods from all the groups of the food pyramid in adequate amounts. Some nutrients called fuel nutrients are needed to obtain energy (such as carbohydrates, lipids, and proteins). This energy is measured in calories. Another kind of nutrients are regulatory nutrients that are required to regulate how our body uses energy from fuel nutrients (such as water, minerals, and vitamins).
Fuel Nutrients:
1-Carbohydrates: These are the main source of fuel and the foundation of a healthy diet, by which more than half of our body’s energy needs should come from. They are classified as starches and sugars. Glucose, for example, is a simple sugar that all of our body cells use for energy, and when combined into longer complex chains they constitute starches. We also have what is called fiber, sometimes called the seventh nutrient, but it doesn’t provide energy.
2-Lipids: These are very concentrated energy sources such as fats and oils. They have 3 main functions:
*form the bilayer foundation of cell membranes and organelles
*act as a solvent for fat-soluble vitamins and essential fatty acids
*gives satisfaction after eating because of the long time they take to get digested
3-Proteins: These are the only source of nitrogen, which the body needs to make small molecules called amino acids that are then carried out by most carrier molecules like enxymes, muscles, hormones,… The body makes most of them , but some should be taken from the diet and these are called essential amino acids.
Regulatory Nutrients:
1-Water: It’s the most vital nutrient. It acts as a lubricant, solvent, and coolant. The adequate amount is established when we drink one-half an ounce daily for each pound of body weight. To know if ur water intake is adequate, watch your urine for its color. If it was pale to almost clear, then ur intake is adequate, but if it was dark and concentrated, then you should drink more water.
2-Minerals: These are inorganic compounds, they aren’t made by living things, and they aren’t broken down within the body. Plants absorb them from the soil or water, and we in turn can get them from the plants or from plant-eating animals. They are needed for bones, nerve and muscle function, production of certain enzymes, etc…
3-Vitamins: They are needed in very small amounts. They mainly activate enzymes and regulate energy release. They are of two classes:
*Fat-soluble (A,D,E, and K) excessive amounts of these can be dangerous, for they can accumulate in body fat and liver.
*Water-soluble (B and C) easily dissolve in water rather than being stored in the body, and any excess wouldn’t be harmful because they will be excreted in the urine.

Questions:
a) What are the six nutrients that the body requires for good health?
b) What are the main functions of lipids in the body?
c) Name two kinds of vitamins and mention the difference between them

The Digestive System

Whenever we have a meal, it travels through our digestive system a journey of 8 meters. The meal undergoes a process by which it is crushed, nutrients are broken down, chemical reactions take place, and energy and building material are released. To summarize all this process by one word, we can say it gets “digested”.
The pathway of this process of digestion:
1- The mouth: It begins in the mouth, where the food is chewed to become accessible to digestive enzymes. Salivary glands found there secrete saliva that is used both to lubricate food making it easier to swallow and also begins breakdown of starch by a certain enzyme found in the saliva called Amylase.
2- Esophagus: After swallowing, by contractions called peristalsis, food is swallowed down the esophagus bypassing the trachea by a certain mechanism done by a flap of tissue acting as a “trapdoor”.
3- Stomach: food spends 4 hours in the stomach where they are reduced into liquid. The stomach is protected by a thick coating of mucus that protect it against the highly acidic pH (between 1.5 and 2.5) that is caused by hydrochloric acid (HCl) and pepsin that are responsible for the breaking down of proteins to small chains of amino acids. Lipase is also present, and thus a small amount of lipid digestion takes place in the stomach.
4- Small intestine: tightly coiled within abdomen and is six meters long. The remaining carbohydrates and proteins are digested here, and almost all lipids are too. The critical function of the small intestine is that it absorbs the nutrients released by digestion and then transfers them to the blood.
5- Pancreas and Liver: these two organs secrete chemicals and enzymes that cause additional food breakdown.
Pancreas has 3 roles:
*regulates blood sugar through the secretion of insulin and glucagon
*Secretes a variety of digestive enzymes
* Secretes bicarbonate which helps neutralize stomach acids so that lipid digestion can proceed and in order for the acids not to digest the walls of small intestine.
Liver on the other hand:
*Secretes bile that emulsifies fat globules in order to be broken down and absorbed
*Removes excess glucose from the blood, storing it as glycogen
*Detoxifies many substances, such as producing enzymes that break down alcohol and drugs.
6- Large intestine: stores the indigestible material and eliminates them with the help of water and fibers from the diet. Some vitamins such as B-vitamins and vitamin K are produced here by beneficial bacteria that play a role in nourishing the host and resisting disease.
7- Rectum and anus: The rest of the food, especially undigested food such as bacteria and cellulose, then pass out of the body in the form of feces through the rectum and anus.

Questions:
a) Define Digestion
b) What is the critical role of the small intestine?
c) What is the role of each of the pancreas and liver in the process of digestion?

The Excretory System

After being broken down, amino acids and ammonia which is the form of nitrogen metabolic wastes are released and made less poisonous by ammonia being combined with carbon dioxide to form urea which is eliminated from the body through either perspiration by skin or excreted in urine.
Kidneys, fist-sized organs in the back of the abdomen that receive about one-fourth of the blood being pumped by the heart and that are made out of nephrons, play a major function in this system by conserving homeostasis. 3 main functions of the kidneys:
*Remove urea and other wastes
*Regulate the amount of water in the blood
*Adjust the concentrations of various substances in the blood.
After urine is formed and filtered, the next step is reabsorption, the process which is regulated by the hypothalamus. When the hypothalamus senses the need of your body for water, it triggers secretion of antidiuretic hormone ADH which makes the end of the nephrons more permeable to water thus more reabsorption of water back, making urine more concentrated.
After urine formation, filtration, and reabsorption, urine flows to the ureters, stored in the bladder, and then leaves the body through the urethra.

a) What are the two mechanisms by which urea is eliminated from the body?
b) What is the amount of blood that the kidneys receive?
c) What are the roles of the kidneys?