Breathing in and breathing out
Lungs do not have any muscles, so they cannot move air on their own. Instead, muscles in the chest make the lungsexpand, or blow up like a balloon, as air is sucked in. Most of the work of breathing is done by muscles that raise the ribs, but if you breath out hard, for example when blowing a trumpet, you use muscles on the front of your belly as well. This pushes your insides upwards, squeezing the air out of your lungs more forcefully.
Big breathers
People take, on average, more than half a billion breaths during a lifetime. Each person's lungs move about 250 000 m3 (8 million cu ft) of air, a quantity that would fill the biggest airship ever built.
Saturday, November 24, 2007
Friday, November 23, 2007
How do lungs work?
When you breath in, air flows through the bronchi and bronchioles in your lungs, and comes to a halt in millions of air pockets, known as alveoli. These pockets are surrounded by blood vessels that are so tiny they can be seen only under a microscope. The blood vessels are so thin that gases can pass straight through them. As blood flows around the air pockets, oxygen passes into the blood, while carbon dioxide waste in the blood passes into the pockets to be breathed out.
Inside a lung
The trachea branches off to the right and left lung. Each lung is made up of a mass of subdividing airways.
When you breath in, air flows through the bronchi and bronchioles in your lungs, and comes to a halt in millions of air pockets, known as alveoli. These pockets are surrounded by blood vessels that are so tiny they can be seen only under a microscope. The blood vessels are so thin that gases can pass straight through them. As blood flows around the air pockets, oxygen passes into the blood, while carbon dioxide waste in the blood passes into the pockets to be breathed out.
Inside a lung
The trachea branches off to the right and left lung. Each lung is made up of a mass of subdividing airways.
LUNGS AND BREATHING
Human need oxygen to survive. Each time you take a breath, air rushes into your lungs and oxygen passes from the air into your blood. To get enough oxygen into your body your lungs need a very large surface area in contact with the air. If your lungs could be unpacked and laid out flat, they could wrap up your body at least 25 times.
What do lungs look like?
Lungs are like air-filled sponges. Air flows into the lungs through a tube called the windpipe. This tube divides into many smaller tubes called bronchi, and these subdivide again into even smaller tubes called bronchioles. Each bronchiole ends in a cluster of tiny air pockets called alveoli, which are buried deep inside the lungs. You can also find the diagram of lungs at www.mydr.com.au
What do lungs look like?
Lungs are like air-filled sponges. Air flows into the lungs through a tube called the windpipe. This tube divides into many smaller tubes called bronchi, and these subdivide again into even smaller tubes called bronchioles. Each bronchiole ends in a cluster of tiny air pockets called alveoli, which are buried deep inside the lungs. You can also find the diagram of lungs at www.mydr.com.au
Thursday, November 22, 2007
How does the heart work?
Your heart is made of muscle, and has two chambers, called the atrium and the ventricle, on each side. About 100 000 times a day, the heart fills with blood and then contracts to pump the blood out again. This contraction is called a heartbeat. Deoxygenated blood from your body flows into the right side of your body flows into the right side of your heart, and is pumped to the lungs, where it takes in oxygen. The oxygenated blood returns to the left side, which pumps the blood returns to the left side, which pumps the blood out through a large artery called the aorta and around your body. Each side of your heart has two valve. These are flaps that stop blood flowing backwards after each beat.
Your heart is made of muscle, and has two chambers, called the atrium and the ventricle, on each side. About 100 000 times a day, the heart fills with blood and then contracts to pump the blood out again. This contraction is called a heartbeat. Deoxygenated blood from your body flows into the right side of your body flows into the right side of your heart, and is pumped to the lungs, where it takes in oxygen. The oxygenated blood returns to the left side, which pumps the blood returns to the left side, which pumps the blood out through a large artery called the aorta and around your body. Each side of your heart has two valve. These are flaps that stop blood flowing backwards after each beat.
Why do scabs form?
If blood was like water, it would drain away through cuts and grazes. Instead, small leaks are quickly plugged, bringing bleeding to a halt. This happens because blood contains chemical called fibrinogen. When a blood vessel is cut, the fibrinogen turn into another chemical, called fibrin, which creates a maze of sticky strands. Blood cells get trapped in the strands, making a solid plug called a clot. Once a clot has formed, the skin underneath starts to heal. Eventually, the clot dries out to form a scab, which later falls off. By this time, the injury has been fully repaired.
If blood was like water, it would drain away through cuts and grazes. Instead, small leaks are quickly plugged, bringing bleeding to a halt. This happens because blood contains chemical called fibrinogen. When a blood vessel is cut, the fibrinogen turn into another chemical, called fibrin, which creates a maze of sticky strands. Blood cells get trapped in the strands, making a solid plug called a clot. Once a clot has formed, the skin underneath starts to heal. Eventually, the clot dries out to form a scab, which later falls off. By this time, the injury has been fully repaired.
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