UNIT 1: THE NUTRITION

VOCABULARY

Bolus

Digestion

Digestive system

Food pyramid

Ingestion

Respiratory system

Saliva

Urine

Balance diet

Plasma

CONTENTS

1 Understand the process of nutrition.

2 Recognize what is a healthy diet and the different foods.

3 Create a food pyramid and a healthy diet.

4 Explain and understand the four systems: digestive,respiratory,circulatory and excretory

WHAT IS NUTRITION?

Nutrition is a combination of processes which supply our body with the building materials and energy we need to live.

NUTRIENTS

Food contains simple substances called nutrients, which provide the building materials and energy our body needs to grow and work. Nutrients are classified into groups:

• Carbohydrates: provide a fast supply of energy. We can find it in cereals, potatoes, bread, pasta...
•  Fats: provide a slower supply of energy. They are mainly found in oils and butter.
• Proteins: provide building materials for growth and to repair our body. They are mainly found in meat, fish, eggs, milk...
• Vitamins and minerals: are necessary for our body to function properly. They are mainly found in fruit, vegetables and dairy products.
• Water: transport other nutrients and waste around the body.

HOW NUTRITION WORKS

There are 4 processes involved in nutrition:

• DIGESTION
• RESPIRATION
• CIRCULATION
• EXCRETION

DIGESTION: THE DIGESTIVE SYSTEM

Digestion is the process of breaking down food into nutrients that our body can use. It normally takes our body 24 to 48 hours to digest food. Digestion takes place in the digestive system.

The digestive system consists of one long tube, called the digestive tube, and the helper glands. These are the stages of digestion:

• It begins in the mouth, where our teeth break down food. While we chew, the food mixes with saliva produced by salivary glands. This mixture is called bolus. When we swallow, the bolus is pushed into the pharynx and down the oesophagus. 
• Then, the bolus reaches the stomach, which produces gastric juices. These juices break down food even further, forming a thick mixture calle chyme.
• The chyme travels to the small intestine, which produces intestinal juices. These juices combine with bile, produced in the liver, and pancreatic juice, produced in pancreas. The chyme turns into a milky liquid called chyle.
• Nutrients are absorbed into the blood in the small intestine. The inside of small intestine is covered with tiny finger-like projections, called vili, which help to absorb the nutrients.
• In the large intestine, water is absorbed and the remaining undigested food parts turn into solid faeces. Faeces leave the body through the anus.

HEALTHY HABITS IN RELATION TO DIGESTION

• Have a variety and healthy diet.
• Avoid fats and sugar.
• We need to eat 5 times a day.
• We need to drink 2 liters of water per day.
• Eat 5 pieces of fruit per day.

THE RESPIRATORY SYSTEM

Respiration is the process by which we breathe in, or inhale, to obtain the oxygen our body needs, and we breathe out, or exhale, to expel the carbon dioxide our body produces. Respiration takes place in the respiratory system.

The respiratory system consists of the air passageways and the lungs. 

When we inhale, air enters through the nostrils, goes to the pharynx, then travels down the larynx and the trachea. The trachea is divided into two branches called the bronchi. The bronchi take the air to each lung.

Inside the lungs, the bronchi are divided into smaller branches called bronchioles. The bronchioles lead to the air sacs. Air sacs are most surfaces in the lungs where gas exchange takes place.

GAS EXCHANGE

The air sacs in the lungs are surrounded by tiny blood vessels. Both the air sacs and the blood vessels have very thin walls. This allows oxygen and carbon dioxide to pass between the lungs and the blood.

• The oxygen in the air we inhale passes from the air sacs into the blood. The blood caries the oxygen to all the cells in our body.
• The carbon dioxide produced by all the body cells travels through the blood and passes into the air sacs. The air sacs expel the carbon dioxide when we exhale.

HEALTHY HABITS IN RELATION TO RESPIRATION

• Do exercise regularly.
• Eat vitamins and minerals.
• Breathe with your nose.
• Do not smoke.
• Avoid places with high levels of air pollution.

CIRCULATORY SYSTEM

Circulation is one of the four processes involved in nutrition, along with digestion, reparation and excretion. Circulation involves transporting nutrients, oxygen and waste products throughout the body.

THE CIRCULATORY SYSTEM

Circulation is the movement of blood through the circulatory system. Blood carries nutrients and oxygen to all parts of the body. It also collects carbon dioxide and other waste products which need to be eliminated.

The circulatory system is made up of blood, blood vessels and the heart.

• BLOOD: is a liquid substance in our body that reaches all the body cells. It is made up of:
• PLASMA: this is a clear fluid which transports nutrients and waste around the body.
• RED BLOOD CELLS: these carry oxygen from lungs to all body cells.
• WHITE BLOOD CELLS: these protect the body from germs and disease.
• PLATELETS: these are fragments of old cells. They help to stop bleeding from wounds.

• BLOOD VESSELS: are tubes which transport blood throughout the body. There are three types:
• ARTERIES: these carry blood away from the heart towards all body tissues.
• VEINS: these carry blood back to the heart from all body tissues.
• CAPILLARIES: these have very thin walls. This allows for nutrients and oxygen to pass into the body cells, and for carbon dioxide and other waste products to leave the cells.

• THE HEART: is a special type of muscle. It acts as a pump to send blood around the body through the blood vessels. The heart has four chambers:
• The right and left atria, where blood enters the heart.
• The right and left ventricles, where blood leaves the heart.

• Excretion is the elimination of waste products from the blood. Excretion takes place in the excretory system, the respiratory system and the sweet glands.

EXCRETORY SYSTEM

• The excretory system is also called the urinary system, because it is the system that produces and expels urine. It consists of the kidneys, the ureters, the bladder and the urethra.
  
  
  In the excretory system, excretion happens when blood reaches the kidneys. The kidneys filter the blood, retain waste products and use them to produce urine. Then, the ureters carry urine from the kidneys to the bladder. Urine is stores in the bladder until it leaves the body through the urethra.
• The respiratory system is involved in both nutrition and excretion. It obtains the oxygen we need to live when we breathe in. When we breathe out, it eliminates carbon dioxide, a waste substance produced in our body.
• Sweat glands are long, coiled tubes that are located inside the skin. Each sweat gland connects to a pore on the surface of the skin. Sweat leaves the skin through the pores. Sweat is formed in the sweat glands. It consists mainly of water, but it also contains mineral salts and waste product.

Interesting activities to learn

1.  What is Nutrition? 
2. How does nutrition works?
3. Which are the different types of nutrients? Provide an example of each one.
4. Explain, how does digestion work? (Stages)
5. What is respiration?
6. Explain briefly, how does respiration work? (The process) 
7. How is waste eliminated at the end of digestion?
8. What is gas exchange?
9. What can we do to keep our digestive system healthy? (HEALTHY HABITS IN REATION TO NUTRITION)
10. What should we do to keep our respiratory system healthy? (HEALTHY HABITS IN REATION TO RESPIRATION
11.  Explain the components of BLOOD.
    What is the HEART?
12. DRAW and COLOUR the excretory system and NAME its parts.
13. Explain how sweat is formed and expelled by the SWEAT GLANDS.
14. Use your words to explain the EXCRETORY system.
15. What is excretion? where does it take place?
16.  What happens to BLOOD in the lungs? How the Circulatory  and the Respiratory systems are connected?
17.  Use your words to explain the SYSTEMIC circulation.
18. How can we take care of our circulatory system?
19. Use your words to explain the PULMONARY circulation.
20. What is circulation? How many types of circuits are there?
21. Draw a heart using different colours and name its parts.
22.  Define the following concepts: ARTERIES, CAPILLARIES and VEINS.