Bicuspid valve - is in the left side of the heart; it separates the left atrium form the left ventricle. Its job is to stop the blood form flowing back into the left atrium when the left ventricle contracts.
Semilunar valve- Stop the blood from flowing back to the heart from the arteries.
Aorta- Takes the oxygenated blood away from the heart to the body.
Vena cava- Brings deoxygenated blood back to the heart from the body.
Pulmonary artery- Takes deoxygenated blood to the lungs from the heart to pick up oxygen.
Pulmonary vein- Takes oxygenated blood back to the heart from the lungs.
A Double Pump
All fast moving creatures like mammals and birds have a double circulation system, but what does this mean? Well, it’s pretty simple, what it simply means is that the heart of these creatures has two sides, (right, which contains deoxygenated blood and left, which contains oxygenated blood) so the blood is pumped to the body through two stages. Stage one begins when the cardiac muscle contracts letting the blood in through vena cava and after going through the right atrium and the right ventricle the blood is pumped to the lungs through pulmonary artery to pick up oxygen. Stage two starts by blood coming back to the left atrium through pulmonary vein, after going through the left atrium the blood goes to the left ventricle where it is then pumped out of the heart to the body.
How well does your heart pump?
To be able to answer this question you need to know a few different terms, that tell you the output and the strength of your heart.
Heart rate- the number of times the heart, beats a minute. With exercise the number of heart beats increase because more blood is needed around the body.
Stroke volume- is the amount of blood that leaves a ventricle each time the heart, beats. Exercise also increases the amount of blood leaving the heat mainly because the body requires more blood.
Cardiac output- is the amount of blood that leaves the left ventricle in one minute, to be pumped around the body. In other words: Cardiac output= Stroke volume x Heart rate
Exercise also increases the cardiac output because more blood is needed around the body so the heart rate increases this in term increases the stroke volume therefore there is more blood leaving the heart in one minute during exercises because the body requires more blood.
Different types of blood vessels
Arteries- are the blood vessels that contain oxygenated blood and carry that blood to body organs. Arteries have got the thickest outer layer because blood with high pressure is pumped into them from the heart. The arteries also pump the blood themselves because they contain an elastic tissue and muscle. The blood stretches the walls then the walls contract and force the blood along. The small branches of the arteries are called arterioles.
Veins- the veins contain deoxygenated blood they go from the body to the heart. Their walls are not as thick as the artery’s walls, because the blood in them is low pressured. The deoxygenated blood in the vein is pumped back to the heart with the help of the contracting muscles.
The internal diameter of the vein is bigger than the artery because the blood in the vein does not need to be in a high-pressure form. The presence of the valves in the vein are vital as the blood pressure is down and blood can flow backwards if the valves are not there, this is unlike the arteries as they don’t need to have any valves because there is pressure behind the blood to ensure that the blood doesn’t flow backwards.
Capillaries- the capillaries are the smallest blood vessel; their walls only contain one cell to allow the exchange of nutrients and other things. The capillaries are connected to both veins and arteries.
What is blood?
Blood is a liquid called plasma with red cells, white cells and platelets floating in it. The body contain 5 litres of blood.
Plasma- plasma is a yellowish liquid. It is mostly water, with different things dissolved in it, the dissolved substances include: glucose, and other nutrient from digested food, hormones, carbon dioxide and other waste from cells.
Red cells- red cells are the body’s oxygen carriers. They contain a red substance called haemoglobin, which combines readily with oxygen. Haemoglobin gives cells its red colour.
White cells- white cells defend your body against disease. They are larger than red cells and have a nucleus. There are several different kinds of white cells all doing different jobs. Blood cells defend your body in two different ways
- They make antibodies to destroy germs.
- They surround the germ and produce enzymes to kill and digest the germs.
Platelets- are fragments from special cells made in red bone marrow. Their job is to stop you body losing blood.
A fit and an unfit person’s circulatory system
The heart of an unfit person can not pump as much blood as a heart of a fit person because the cardiac muscle of a fit person has more fibres therefore it is stronger as a result of this the heart can pump more blood out of itself therefore the stroke volume goes up this leads to the cardiac output going up in a fit person’s heart, because the heart has more muscles and is stronger the chambers of the heart are also bigger as a result, so more blood enters and leaves a fit person’s heart. This huge amount of blood can get food and oxygen to the working muscles and the waste and carbon dioxide away this is why fit people don’t get cramp and last longer in sports.
The unfit person’s heart is not as strong so when the unfit person’s working muscles require blood the heart rate of the unfit person goes up but little amount of blood leaves the heart so the heart wears itself out by pumping too much to try to supply adequate amount of blood to the muscles, the cardiac output of an unfit person is considerably less than a fit person’s cardiac output.
My pulse rate during a normal day
Conclusion
The circulatory system has a very important job in the body because this system pumps blood to the body through the heart. The heartbeat and the cardiac output depend on the fitness of the person. Exercise alters the heartbeat within each person.
