Why do you get out of breath?
The amount of oxygen you need depends on how hard your body is working. If you are resting, you need only a small amount. If you are running or playing badminton, you use up oxygen more quickly producing enough energy. An area in your brain automatically adjusts your breathing rate to make sure you get the oxygen you need, by breathing faster and more deeply.
Gasping for air
At rest, a 10-years-old takes in about 0.25 litre (15 cu in) of air with each breath. If you take deep breaths, you will take in seven times more air than this. If you work hard, you will force more air out of your lungs and take in ten time more air.
Saturday, November 24, 2007
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.
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.
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.
Wednesday, November 21, 2007
Why is blood red?
Blood gets its colour from a red chemical called haemoglobin, which is stored in red blood cells. When blood flows through the lung, the haemoglobin collects oxygen and carries it to other parts of the body. Haemoglobin that is carrying oxygen is bright red, but it has released its oxygen into the body's cells as it flows past them, it becomes much darker. As a result, the blood flowing in your arteries is brighter red than the blood flowing in your veins.
Blood gets its colour from a red chemical called haemoglobin, which is stored in red blood cells. When blood flows through the lung, the haemoglobin collects oxygen and carries it to other parts of the body. Haemoglobin that is carrying oxygen is bright red, but it has released its oxygen into the body's cells as it flows past them, it becomes much darker. As a result, the blood flowing in your arteries is brighter red than the blood flowing in your veins.
Where does blood go?
Bloods travels around your body in a network of pipes called blood vessels. The blood vessels that carry blood away from the heart are called arteries, the one that carry it back again are called veins. Arteries and veins are connected to each other by more than 80 000 km (50 000 miles) of capillaries, tiny vessels much thinner than a hair. Arteries expand every time your heart beats. In places such as the wrist, this creates a 'pulse' you can feel.
replacement service
A single drop of blood contains about 250 million red cells and over 300 000 white cells. Red cells wear out quickly, and every day the blood makes about 2.5 billion new ones to replace them.
Bloods travels around your body in a network of pipes called blood vessels. The blood vessels that carry blood away from the heart are called arteries, the one that carry it back again are called veins. Arteries and veins are connected to each other by more than 80 000 km (50 000 miles) of capillaries, tiny vessels much thinner than a hair. Arteries expand every time your heart beats. In places such as the wrist, this creates a 'pulse' you can feel.
replacement service
A single drop of blood contains about 250 million red cells and over 300 000 white cells. Red cells wear out quickly, and every day the blood makes about 2.5 billion new ones to replace them.
Tuesday, November 20, 2007
What is blood made of?
Blood is a complicated mixture of liquids, chemicals and cells. If you could separate out the ingredients in a single drop of blood, you would find that just over half of it is made of liquid called plasma. Plasmas consists mainly of water, but it also contains many dissolved chemicals. One of these is glucose, the substance that your body uses to make energy. The rest of the drop of blood would consist of millions of cells so tiny that they can only be seen under a microscope. Most of these cells are the red blood cells, which carry oxygen. Scattered among them are transparent cells called white cells, which are involved in fighting disease. Red blood cells are shape like tiny coins. White blood cells are bigger, and many can move about by changing shape.
Blood is a complicated mixture of liquids, chemicals and cells. If you could separate out the ingredients in a single drop of blood, you would find that just over half of it is made of liquid called plasma. Plasmas consists mainly of water, but it also contains many dissolved chemicals. One of these is glucose, the substance that your body uses to make energy. The rest of the drop of blood would consist of millions of cells so tiny that they can only be seen under a microscope. Most of these cells are the red blood cells, which carry oxygen. Scattered among them are transparent cells called white cells, which are involved in fighting disease. Red blood cells are shape like tiny coins. White blood cells are bigger, and many can move about by changing shape.
Monday, November 19, 2007
BLOOD AND CIRCULATION
Blood is pumped to every part of your body by your heart. In an adult, up to 5 litres (8 pints) hurtle through arteries and veins, completing a double loop around the body in less than one minute. During this endless high-speed journey, blood delivers oxygen, collects waste, and supplies the substance that all your body's cells need to survive. Blood also helps the body to fight diseases, and it spreads warmth from one part of the body to another.
Sunday, November 18, 2007
Muscles ache
Muscle need energy to work. They get it by using oxygen to break down a chemical fuel called glucose, a form of sugar, which is delivered to them by the blood. If a muscle is working hard, it starts to run short of oxygen and it cannot break down glucose in the normal way. Instead, glucose is turned into lactic acid. The acid builds up inside the muscle and makes it ache. If the muscle is allowed to rest, the acid is broken down and the ache disappears.
Muscle need energy to work. They get it by using oxygen to break down a chemical fuel called glucose, a form of sugar, which is delivered to them by the blood. If a muscle is working hard, it starts to run short of oxygen and it cannot break down glucose in the normal way. Instead, glucose is turned into lactic acid. The acid builds up inside the muscle and makes it ache. If the muscle is allowed to rest, the acid is broken down and the ache disappears.
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