Celeste and Miriam

The function of nutrition gives our cells energy and

oxygen. The digestive, respiratory ,circulatory and excretory system take part in nutrition.

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

·Te digestive tract : it is a long muscular tube about

eight metres long. Its parts are the mouth, pharynx, oesophagus, stomach, small intestine and large intestine.

· Glands : They release chemicals to the digestive tract to

help with digestion . They are the salivary glands, the liver and the pancreas.

Breathing is the process where the body takes in oxygen and releases carbon dioxide.

Lung ventilation: Inhaling is when air goes into lungs.

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

Respiratory tract: It is made made up of passages

throung which air enters and leaves the body. Lungs: They are two spongy organs made up of

millions of small bags called alveoli, where gases are exchanged.

Excretion is the elimination of the waste substances collected in the blood that cells have produced. The excretory system is in charge of excretion and it is made up of: Sweat glands They are in the skin and

produce sweat. Urinary system

_ Kidneys They take substances out of the

blood, mix it with some water and make urine._ Urinary tract It takes, stores and releases the urine.

Circulation is the transportation of blood throungh the circulatory system. Heart: It is a hollow, muscular organ that

pumps blood so that it reaches the entire body.

Blood It collects oxygen from the alveoli

And nutrients from the small intestine and transports them to all of the body. Blood vessels They are the tubes through

which blood circulates._ Arteries They are blood vessels that carry blood from the heart to the rest of the body._ Veins They are the blood vessels that carry

entire body back to the heart.

_ Capillaries They are very thin vessels that

reach all the cells of the body.

BLOOD

Blood is a read liquid tissue made up of cells that float the nutrition liquid called plasma. Blood cells There are different types

of cells._ Red blood cells: Most are of this type.

_ White blood cells: They are the body´s defence.

_ Platelets They form blood clots in blood vessels to stop blood form coming out when they are broken. Blood plasma It is a liquid made up of water

with dissolved salts and nutrients.

It is a muscular organ located in the chest.It is divided into two parts separated by a wall called the heart septum. Atrium It is the upper cavity. Ventricle The cavity is smaller. Systole: It is the movement of contraction. Diastole: It is the movement of relaxation.

Mammals have a closed circulation because blood full of oxygen or carbon dioxide do not mix.

Human circulation is double because it has a pulmonary or minor circulation and a general or major circulation.