UNIT 5: NUTRITION

THE FUNCTION OF NUTRITION

INDEX
1.- The function of nutrition.
1.1 Nutrition

1.2 Digestion and the digestive system
 



2.- BREATHING AND EXCRETION
 2.1.- Breathing and the respiratory system.

2.2.- Excretion and the excretory system.



 1. THE FUNCTION OF NUTRITION

1.1 Nutrition
The function of nutrition gives our cells all the energy they need to perform their life. The body systems which carry out the function of nutrition are:
  Digestive system. It is in charge of digestion, which transforms the food we eat into the nutrients our cells need.

 Respiratory system. It is in charge of breathing, which takes oxygen from the air to help cells get energy.

 Circulatory system. It transports nutrients and oxygen to all the cells in the body and it collects waste substances produced by cells.

 Excretory system. It filters the blood, takes out waste substances, and transports them to take them outside the body through excretion.



1.2 Digestion and the digestive system
 
 Digestion is the process in which food changes into nutrients. It takes place in the digestive system, which has two parts:

a) The digestive tract. It is a long muscular tube about eight metres long.. Its parts are the mouth, the pharynx, the oesophagus, the stomach, the small intestine and the large intestine.

b)Glands. They release chemicals to the digestive tract to help with digestion. They are the salivary glands, the liver and the pancreas.

 The digestive system

ACTIVITIES.

1.- What are the two parts of the dygestive system? What do they do?

2.- Fill the gaps about the four body systems that carry out the function of nutrition.
 ___________ system. It is in charge of _________, which takes oxygen from the air to help cells get energy.

 Circulatory system. It transports ________ and _________ to all the cells in the body and it collects waste substances produced by cells.

 ________ system. It filters the blood, takes out _______ substances, and transports them to take them outside the body through excretion.

 ___________ system. It is in charge of digestion, which transforms the food we eat into the _________our cells need.


2.- BREATHING AND EXCRETION.
2.1.- Breathing and the respiratory system.

Breathing this is the process where the body takes in oxygen and releases carbon dioxide. Two processes take place when we breathe:

- Lung ventilation. Inhaling is when air goes into the lungs. Exhaling sends out of the lungs.

- Exchange of gases. The oxygen goes to the blood and the carbon dioxide from the blood moves to the lungs where it is released outside the body.

The respiratory system carries out breathing. It consists of:
- Respiratory tract: It has passages through which air enters and leaves the body. These passages are the nostrils, larynx, trachea, bronchi and bronchioles.



- Lungs. They are two spongy organs made up of millions of small bags called alveoli, where gases are exchanged.

2.2.- Excretion and the excretory system.
 Excretion is the elimination of the waste substances collected in the blood that cells  
have produced.

It is made up of:

- Sweat glands: They are in the skin and produce sweat.

- Urinary system: It is made up of:

a) Kidneys: They take waste substance out of the blood, mix it with some water and make urine.

b) Urinary tact: It takes, stores and releases the urine. It has got several parts: the ureters, the bladder and the urethra.

The respiratory system also takes part in the function of excretion, because it releases

carbondioxide outside the body.

ACTIVITIES.

1.- Define:

a) Breathing

b) Excretion:

2.- Name the two processes that take place when we breathe.

3.- The respiratory tract is made up of passages. Name them.