report 代写 The Cardiovascular System Description Biology Essay

Blood Groups:

Blood groups were first identifies in 1900 by Karl Landsteiner at the university of Vienna to ascertain why deaths occurred after blood transfusions. The blood groups most widely known are A, B, AB and O.

Two antigens (an antigen is a substance that an antibody fixes to), one type of antigen attaches to one type of antibody similar to a lock and key. These two antigens and antibodies identify the A, B and O blood groups. The antibodies are called Anti A and Anti B

These antigens form on the surface of the red blood cells. A type blood cells will have the A blood antigen attached, and the body would not produce A blood antibodies. The reason for this is that if A blood antibodies were present, then these would attach and destroy the blood cells. However, should type B blood be inserted, B type antibodies are present. These antibodies would then attach to the antigens of the B blood and destroy the cell. The blood cells start to clump together that can cause a blockage in the blood vessel. This is called "agglutination".

O type blood do not produce any antigens for type A, B or O which makes this group universally accepted by any blood group therefor it is known as the "Universal Donor". AB Blood types have both Anti A and Anti B antibodies and therefore can receive blood from all groups safely. AB blood groups are known the "universal receiver".

Rhesus:

There are many other antigens on the red blood cell. The "Rhesus" antigen is another important factor. It was named rhesus after finding the antigen during research injecting Rhesus monkeys with rabbit's blood.

Not all blood has the antigen. Blood that does have the antigen is defined as RH+ and the Blood that does not is defined as RH-. There is rhesus negative (RH-) and rhesus positive (RH+). RH- does not already contain the RH antibodies and should RH+ blood come into contact with RH- blood, RH- then starts to produce the anti RH antibodies. This does not cause too much of a problem in the first instance as the process of producing the antibodies takes almost a week and the donated blood cells would have died. The major problem occurs should the RH- receives a further dose of RH+ blood as this causes the reaction much quicker due to the presence of the RH antibodies. This causes "Agglutination" and can be fatal. This is especially serious in pregnancy. Should a mother that is RH- has a foetus that is RH+. The mother receives the RH+ blood from the foetus and then starts to produce RH antibodies. These antibodies are then transferred back to the foetus via the placenta and into the foetus's circulation. In the first child, this is not generally a problem as the antibodies will not have been produced in sufficient numbers to do any damage. The huge issue is any subsequent pregnancy. If a following foetus is RH+ the RH- antibodies from the mother will transfer across to the unborn foetus causing a mass destruction of blood cells. This condition is known as "Haemolytic disease of the new born".

TASK 7 - (ASSESSMENT CRITERIA 4)

Explain the structure of the heart.

Label the diagram of the heart - Worksheet 1 below - and explain its structure

TASK 8 - (ASSESSMENT CRITERIA 5.1)

Explain the function of the heart

Concisely describe the function of the heart

The heart is the most vital organ in the body. Its function is to "pump" blood through the circulatory system via arteries and veins. It has what is known as a "double circulatory" system. The first system pumps blood to and from the lungs to expel waste gasses (CO2) and other waste products and to collect the vital oxygen needed to sustain life, provision on nutrients that are essential for growth and repair.

The second system pumps blood to the whole body. Oxygenated blood is pumped into the left atrium via the Pulmonary veins from the lungs. The flow is controlled by the mitral valve as it is passed through to the left ventricle where the heart muscle contraction pushes the oxygenated blood with its thick walls at high pressure through the aorta and into the body. Deoxygenated blood is returned to the heart via the inferior and superior vena cava into the right atrium where it is passed through the tricuspid valve into the right ventricle. Here, at low pressure, it is pumped through the pulmonary artery back into the lungs to expel the waste and to collect oxygen to be pumped around the body again. This function takes place continuously and the heart pumps approximately 7200 litres per 24 hours (based on an average heart rate of 72 bpm).

TASK 9 - (ASSESSMENT CRITERIA 5.2)umflhdzx

Explain coronary circulation

The heart muscle (Myocardium) requires a blood supply to enable it to function correctly. This supply allows the heart to be provided with the oxygen required along with the extraction of waste products, (CO2 etc). Coronary Circulation is the supply of this blood to the myocardium. The oxygenated blood is provided by the coronary Arteries which can either be epicardial (run along the surface of the heart) or Subendocardial which are the arteries that run deep within the myocardium. Epicardial arteries are self regulating providing a constant level of supply to the heart muscle. They are very narrow and are prone to blockage which can cause serious heart damage such as angina or a heart attack due to the arteries being the only source of blood to the myocardium. Deoxygenated blood is removed by the cardiac veins.

TASK 10 - (ASSESSMENT CRITERIA 6.1., 6.2 and 6.3)

Describe the major arteries and veins of the circulation system.

Explain the relationship between the structure and functions of arteries, veins and capillaries.

Explain the ways in which the body controls blood vessel size and blood flow.

Complete Blood Vessels sheet - class-based activity

Draw up a table to show how the structure and functions of arteries, veins and capillaries differ.

In bullet point format explain the ways in which blood vessel size and blood flow are controlled