Introduction

This is my report about the circulatory system. It includes all of the organs involved and what they do. It also has what can go wrong with the circulatory system. I picked the circulatory system because I find it very interesting and I wanted to find out more about it.

Heart

Your heart is a big muscle. It is placed in the middle of your chest but a bit to  left. Its purpose is to pump your blood around your body. The heart is made up of four chambers two upper and two lower. The upper chambers are called atria and the lower chambers are called ventricles, which are bigger than the atria. The muscle wall on the left side is thicker than the right side because the left side has to work a lot harder to pump the blood all round the body, where as the right side just pumps blood to the lungs. Here is a picture of a heart,

When you feel your heart beat it is actually contracting to pump blood out, for children it pumps out 25 to 80ml per beat. The more exercise you do results in your heart being more stronger and it finds it more easy to pump out blood. When you feel your heart beat it is actually made up of two beats, this is because the top half of your heart (atria) contracts first and then the bottom parts contract (ventricles). The blood on the left and right side never mixes and the valves help stop blood go backwards.

Arteries

Most arteries carry blood away from your heart and carry oxygenated blood, except the pulmonary artery carries deoxygenated blood. Another big artery is the aorta. Arteries are very deep in your body and they carry a lot of blood quickly at high pressure. This means arteries need very thick walls so they don’t burst. If you cut an artery blood sprays out.

Veins

Veins mostly carry deoxygenated blood to the heart, except the pulmonary vein carries oxygenated blood. Veins are a lot higher up in the skin than arteries. Veins carry blood at low speeds and at low pressure which means they have a lot thinner walls.

Capillaries

Capillaries are tiny and very close to the surface. They are designed to transfer important substances with cells: oxygen, carbon dioxide and glucose.

What can go wrong

Some common problems with the circulatory system:

• Heart attacks, this is when blood can’t get to certain parts of the heart.
• Blocked blood vessels, blood can’t pass through, this can lead to a heart attack.
• Stroke, this is when blood vessels burst in the brain.
• Heart failure, this is when the heart is not pumping very well.

Respiration

There are seven life processes that all life forms can do. These are:

• Moving
• Respiration
• Sensitivity
• Grow
• Reproduce
• Excrete
• Nutrition

The circulatory system plays a big part in respiration because the blood, which contains oxygen and glucose, is pumped by the heart.