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.
Wednesday, November 21, 2007
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.
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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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