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

Structure Related to Function of the Heart.

Extracts from this document...


Felicity Roussak 05/10/87 Structure Related to Function of the Heart The heart is the pumping station of the body. It is infact two completely seperate pumps, one pushing deoxygenated blood to the lungs to oxygenate it through diffusion through the alvoli in the lungs, the other to pump the freshly oxygenated blood around the body. The two pumps consist of an atrium and a ventricle, and are seperated by the septrum, a thick muscular wall down the middle of the heart, which prevents oxygenated and deoxygenated blood from mixing, and also aids contraction of the heart- more detail on this later. The two sides of the heart differ slightly because of their different fuctions. At the top of the heart, both have a thin walled atrium, which collects blood from the main veins of the body, the pulmonary vein on the left and the anterior and posterior vena cava on the right. ...read more.


- if there was as much then the capillaries in the surrouding tissue of the lungs would burst and drown the alveoli in blood. The left ventricle has a very thick muscular wall because it pushes blood around the body, and so needs a high pressure to move blood in arteries in the furthest regions of the body. When the ventricles are full, they then contract at the same time, starting from the bottom, pushing the blood upwards, through the semi-lunar valves - one on each side of the septrum. The right ventricle pumps blood into the pulmonary artery to the lungs, the left into the aorta which swells, then branches off to various parts of the body. This is called ventricular systole. When there is no blood left in the ventricles and therefore little pressure, and a high pressure in the arteries, the semi-lunar valves in the middle of the heart close to prevent backflow of blood (this makes a sound which can be heard by a stethoscope as the second thump of a heartbeat - 'Dub'). ...read more.


This sends an electrical wave of excitation spreading across both atria meaning they contract at the same time and push blood into the ventricles. The same wave of excitation will then reach and stimulate the Atrio-Ventricular node (or AV node) which causes ventricular contraction. However, blood from the ventricles needs to be pushed upwards to allow it to flow more easily into the arteries. Therefore, the new wave of excitation initiated by the AV node travels down special fibres in the septrum (mentioned before in aiding heartbeat) called Purkinje fibres, which collectively make up an insulating electrical conducting passage called the 'Bundle of His'. When it reaches the bottom of the heart, called the apex, the same wave of excitation then spreads upwards across the ventricle walls causing them to contract from the bottom up and push the blood towards the arteries. This process is called the cardiac cycle. In conclusion, the size of the muscular walls in the heart, the existance and positioning of valves and the conduction of electrical waves of excitation make the heart perfect for the job as a pump of blood around the body. ...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. The Structure and Function Of Arteries, Veins and Capillaries.

    The capillary wall is formed of a single layer of endothelial cells resting on a membrane. The wall of the capillary is only one cell thick and has a large surface area, thereby facilitating rapid diffusion of respiratory gases and soluble food materials between blood and tissues.

  2. Work related report

    If a nurse confidently answers questions then the patient will feel ease at heart because he/she knows the nurse wants to help. Working as a team - Nurses will work as part of a multi-disciplinary team. They will work with doctors, physiotherapists, anaesthetist, pharmacists, dieticians and many more.

  1. Caffeine and health related issues

    All of these changes vary considerably among people and may depend upon the individual's sensitivity to the caffeine, his/her metabolism, or upon whether the consumer habitually uses or rarely uses caffeine. (5) Level of caffeine for the average adult is approximately 200 mg daily.

  2. Governing AIDS.

    Immunodefieciency is a compound word. The first word is immuno. This word refers to a person's immune system, the part that fights off infectious diseases. When a person is immune to a disease that means their immune system will fight off an infection before it makes one sick.

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