• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The Heart, Structure and Function

Extracts from this document...

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.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a star student thought of this essay

3 star(s)

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 ...

Read full review

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.


Did you find this review helpful? Join our team of reviewers and help other students learn

Reviewed by PicturePerfect 25/03/2012

Read less
Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Biology coursework planning - the effect of lead chloride on the growth of cress ...

    5 star(s)

    The closure of stomata (which may have resulted because there is less uptake of water and so water moves out of guard cells by osmosis) may deprive the cells of carbon dioxide and the lack of chlorophyll means that enough light energy may not be obtained.

  2. Marked by a teacher

    Describe the molecular structure of starch (amylase), glycogen and cellulose, and relate these structures ...

    4 star(s)

    Even though human digestion cannot break down cellulose for use as a food, animals such as cattle and termites rely on the energy content of cellulose. They have protozoa and bacteria with the necessary enzymes in their digestive systems. Cellulose in the human diet is needed for fiber.

  1. Marked by a teacher

    What is Type 1 diabetes

    3 star(s)

    But learning about how the body functions, giving insulin injections, controlling diet and measuring the blood glucose levels, will help to restore family life and the child's life, back to normal. The healthcare teams at the children's wards can teach you about these areas.

  2. Marked by a teacher

    Effect of temperature on membranes

    3 star(s)

    Passive transport which does not require energy is classified into three types - simple diffusion which occurs through the phospholipid bilayer, facilitated diffusion which involves channel proteins and carrier proteins and osmosis which occurs through the phospholipid bilayer. Active transport on the other hand requires the use of energy provided by adenosine triphosphate (ATP)

  1. Peer reviewed

    Effect of Caffeine on the Heart Rate of Daphnia

    3 star(s)

    Thus, an alternative is to use a model organism to represent human. The results of the experiment can then be used as a reference to the effect of caffeine on human. Daphnia are selected as the model as they can be easily handled in many ways in the investigation.

  2. Kidney Function.

    This is called selective reabsorption since only certain molecules are reabsorbed. The structure of the cells making up the wall of the proximal convoluted tubule has many of the adaptations associated with active transport: * Microvilli provide a large surface area for absorption.

  1. Effect of Caffeine on the Heart Rate of Daphnia

    Caffeine is also an addictive substance and is associated with many withdrawal symptoms. Typical withdrawal symptoms include headache, fatigue and muscle pain. These symptoms can occur within 24 hours after the last dose of caffeine. This is because without caffeine, the blood vessels of the head to dilate, leading to

  2. Describe the structure and purpose of the lymphatic system .

    These lymph nodes produce lymphocytes that actively help in the defence system of the body by filtering microorganisms and keep foreign substances out the body. Lymph nodes are a bean shaped that are enclosed by fibrous capsules. These lymph nodes are on the lymph ducts.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work