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

The Structure and Function Of Arteries, Veins and Capillaries.

Extracts from this document...


Sarah English The Structure and Function Of Arteries, Veins and Capillaries In its route from the heart to the tissues, the blood passes through channels of six foremost types: elastic arteries, muscular arteries, arterioles, capillaries, venules and veins. I intend to explore the structure and function of arteries, veins and capillaries. When an artery branches into smaller and smaller vessels, eventually the blood vessel is too small to see with the naked eye. At that point, it is called an arteriole. Likewise, a venule is a microscopic vein. Arteries All arteries are comprised of three different layers but the proportion and structure of each varies with the size and function of the particular artery. A large artery, like the aorta, is comprised of the following layers, going from the inner to the most external layers: (1) The innermost narrow layer consists of a layer of endothelial cells separated from the inner layer by a thin layer of connective tissue that anchors the cells to the wall. ...read more.


Since it would be unworkable to get all the blood back to the heart as quickly as it left the heart (because there is no pumping mechanism to do so); veins have to be able to hold more blood than arteries. The veins provide a "storage area" for our blood, which is why the diameter of the veins is larger than the artery diameter. At any given time, the majority of our blood is within our veins. Veins have a thinner smooth muscle layer that allows for the expansion of the vessels and minimize resistance by reducing friction to the flow of blood. Because blood pressure is lower in veins, since the blood has had to travel some distance through the many capillaries, the diameter of muscle walls are needed to contain blood within the veins. Since the blood pressure is lower, the blood has to be pushed towards the heart via skeletal muscles and venous valves. ...read more.


From a functional point of view, the two most important parts of the circulatory system are the heart and capillaries. The heart is obviously important because it is responsible for pumping blood around the body. Capillaries represent the place where exchange of materials takes place, which is the principal function of the circulatory system. The structural differences between arteries and veins are all based in their relationship to the heart. Since arteries receive blood from the heart, the blood they receive is under a lot of pressure. At the same time, this pressure helps the blood move through the arteries- even when the arteries are opposing gravity (like the carotid artery running towards the head). In conclusion, the arteries carry oxygenated blood away from the heart, and due to the high pressure of this blood the arteries have thick wall, which contain many muscle fibres. The veins carry deoxygenated blood to the heart and because blood is of a lower pressure, have thinner walls consisting of less muscle fibres. Capillaries are the principal part of the circulatory system; they allow substance exchange. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Humans as Organisms section.

Found what you're looking for?

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

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 GCSE Humans as Organisms essays

  1. Stem Cell Research

    because it is making the embryos seem much more lifelike and vulnerable. This is very effectively portraying the idea of how the innocent, possibly human lives are being destroyed. However, in my opinion, not only is this picture biased, it is also inaccurate.

  2. Should the cloning of humans be allowed?

    So it would be very unlikely that genetic diversity would be reduced. Arguments against Human Cloning Existing cloning of animals is fraught with many developmental problems and the cloning itself isn't very exact, with it taking many tries before a clone is created.

  1. The cardiovascular system is made up of the heart and the blood vessels, such ...

    The heart walls are made of three layers: Endocardium- the innermost layer. It is made of epithelial tissue and forms the lining of the entire circulatory system. Myocardium- the middle layer. This layer is the thickest of the three and is made up of cardiac muscle. Epicardium- the outer layer.

  2. Describe how the structure of arteries, veins and capillaries enables them to fulfil their ...

    These arteries aren't permeable and are capable of constriction due to the fact they have a large quantity of elastic fibres around the endothelium. The blood moves through the arteries rapidly and in pulses, they expand to accept the blood being forced into them from the heart, then when the

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