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LET'S EXPLORE The human body

How do we breathe?

Trachea and lungsTrachea and lungsYour lungs breathe in air, and take oxygen from it. Oxygen is needed by every cell in your body, to give it energy and stay alive. After the oxygen enters the lungs, it passes into your blood. Your heart pumps blood through the tubes called blood vessels all around your body. The blood delivers oxygen to every cell, picking up waste, including carbon dioxide, at the same time. This is returned to the lungs, which breathe it out into the air. You breathe in and out about 23,000 times a day.

Breathing inBreathing in

Breathing in

Breathing muscles stretch your lungs to make them larger and suck in air. These muscles are the diaphragm below the lungs, and the muscles between the ribs. With each breath, your lungs suck in air through your nose and mouth, and down your trachea (windpipe). The air travels along branching air tubes deep into your lungs. These tubes are called bronchi. They divide many times and become thinner and thinner as they do so. The thinnest tubes, called bronchioles, are no wider than a hair.

A person may breathe in on average about 18 kg (40 lb) of dust during their lifetime.

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