DK - WOW! The Visual Encyclopedia of Everything

BODY SYSTEMSThe body’s trillions of cells are highly organized. Cells of the same type are grouped together in tissues. Two or more types of tissue are used to build organs that perform specific roles. Linked organs form different systems that each carry out an essential job, such as digestion. There are 12 body systems that cooperate and interact with each other to form the human body. The organs of six body systems are shown here. The other six systems are the integumental (skin), skeletal (bones), muscular, endocrine (hormones), immune (defence), and reproductive systems.

LUNGS

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The respiratory system

consists of the two lungs and the air passages that carry air from the outside. Each lung

contains a network of

branching tubes that end in millions of tiny air bags. It is from these bags that oxygen

in the air passes into the

bloodstream. It is carried to

all body cells where it is

used to release life-giving

energy from food.

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HEARTThe cardiovascular system moves blood around the body to deliver oxygen and food to all the body’s cells, and to remove their wastes. Located

between the lungs, the heart is the centre

of this system – a hollow, muscular pump that contracts without tiring more than 70 times a minute to

force the blood around the

body along blood vessels.

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Brain

The brain is the centre of the nervous system, which is responsible for controlling body activities. It is dominated by the folded cerebrum that enables us to feel, think, and remember, and instructs the body to move. Other brain parts are the cerebellum, tucked under the cerebrum, and the brain stem, which automatically controls breathing and heart rate and links the brain to the spinal cord.◀

SPINAL CORD

An extension of the brain that runs down the back, the spinal cord relays signals between brain and body through the spinal nerves connected to it. It also controls many of the body’s automatic reflex actions, such as pulling the hand back if it touches something sharp. Together the brain, spinal cord, and nerves form the nervous system.

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SPLEEN

The spleen is part of the lymphatic system, the body’s drainage network. It contains white blood cells, which fight infection by

destroying bacteria,

and also removes

worn-out red blood cells from the blood.

Air travels from the nose and mouth along the trachea to the lungs

The cerebellum is tucked under the cerebrum and

coordinates balance

and movement

Blood travels to and

from the heart via arteries and veins

Breathing moves air in and out of the lungs

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