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The Heart, Structure and Function

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Introduction

Heart Structure and Function Mammals have a double circulation Pulmonary Circulation- Takes blood on the relatively short return journey to the lungs, where blood is oxygenated Systemic Circulation- Takes blood around the rest of the body The human heart is covered by a double layer of tough inelastic membranes which form the pericardium. A fluid (pericardial fluid) is secreted between the membranes, allowing them to move easily over each other. The pericardium protects the heart from over-expansion caused by elastic recoil when it is beating very fast. The walls of the heart consist mainly of cardiac muscle, a special type of muscle only found in the heart. ...read more.

Middle

Deoxygenated blood from the systemic veins enter the right atrium and is passed through the tricuspid valve into the right ventricle. This contracts and pumps blood through the pulmonary artery into the lungs. Oxygenated blood returns through the pulmonary vein into the left atrium and then, through the bicuspid valve , into the left ventricle. This has a very thick muscular wall which enables it to contract strongly and exert sufficient pressure to pump blood into the aorta and all the way around the body. The role of the valves Tricuspid Valve - This valve is between the right atrium and right ventricle. It has 3 flaps which allow blood to flow freely from atria to ventricles, but when the blood pressure in the ventricles exceed that in the atria, the valves prevent backflow from ventricles to atria. ...read more.

Conclusion

prevent the valves from turning inside out. The papillary muscles do not move the valves, they just increase the tension of the tendinous chords so that they can resist the powerful back pressure of blood Semi Lunar Valves- Half moon shaped valves, they prevent backflow in the pulmonary artery and dorsal artery. The vena cava constricts during each hear beat so that blood does not flow back into the veins The Heart's Blood Supply The heart is a very active organ with a high demand for oxygen and nutrient. Some of the oxygenated blood leaving the left ventricle goes directly to the heart through the coronary arteries, of which there are usually 3. These arteries branch out to supply the thick heart muscle with nutrients and oxygen. Disease of these arteries can lead to them become blocked and resulting in a heart attack. ...read more.

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Response to the question

This essay has no clear introduction, the candidate just starts listing various information about the heart. An introduction should set out what you plan to discuss, it also gives you a chance to catch the reader’s attention. In addition the ...

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Response to the question

This essay has no clear introduction, the candidate just starts listing various information about the heart. An introduction should set out what you plan to discuss, it also gives you a chance to catch the reader’s attention. In addition the candidate’s response to the question is vague, for the most part they simply discuss the heart, they don’t clearly mention the heart’s overall function. It is essential to make sure that whatever you're discussing, you always come back to the main question.

Level of analysis

he candidate has clearly undergone independent research, as the information provided is more detailed than that required for this level of qualification. This shows the candidate’s interest in this particular subject and makes the essay more enjoyable to read. The candidate gives suitable detail for each topic and all of the information provided is scientifically correct. However they could have provided more information, for example they don’t talk about the different arteries and veins of the heart, neither do they discuss how the heartbeat is generated. To obtain a higher grade, it is often necessary to go beyond the set topic and link together other key ideas, in this case it would appropriate to go on to discuss heart disease and prevention or even mention how nerve impulses from the brain are transmitted to the senatorial node of the heart in order to control heart rate. In addition I think it would be appropriate in this case to add a diagram, which you could refer to when talking about the different valves of the heart etc. This visualisation helps the reader understand what you are talking about and can make key points a little clearer. Finally there is no real conclusion to this essay. A conclusion should answer the initial question and summarise your key points. This is important as it brings the essay to a close and gives you a chance to leave the reader with a good impression.

Quality of writing

The candidate presents the information given in an unstructured manner. At this level of qualification I would expect the candidate to be able to write a well structured essay. An essay should have a clear introduction and conclusion, and the information given should be in the form of paragraphs, in which a new paragraph is started for each new topic of discussion. On a positive note the candidate describes scientific terms accurately and there is no issue with spelling, punctuation or grammar. Overall this is a good piece of writing, though it lacks structure, it is fluent, easy to read and accurate. The candidate clearly has a good subject knowledge.


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Reviewed by PicturePerfect 25/03/2012

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