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Structure and function of the lungs.

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Structure and Function of the Lungs Mat Simpkins (500words approx.) The main function of the lungs is (rapid) gaseous exchange. This is accomplished by a well-co-ordinated interaction of the lungs with the central nervous system, the diaphragm and chest wall muscle, and the circulatory system. The gas exchange surface of a mammal is the alveolus. There are numerous alveoli (air sacs) supplied with gases via a system of tubes (trachea, splitting into two bronchi (one for each lung) and numerous bronchioles, overall connected to the outside by the mouth and nose. These alveoli provide a massive surface area through which gases can diffuse. ...read more.


Smooth muscle tone: Controls the diameter of the conducting passages and controls resistance to the passage of air within the respiratory system. Creating pressure differences for breathing. (contraction and relaxation) There is no smooth muscle present in the alveoli, due to the fact that this would take up space, therefore minimising the rate of gaseous exchange. (the elastic fibres within the alveoli tend to do the contracting and relaxing.) Goblet cells is a form of defence, attacking the germs/bacteria, before they enter the alveoli. They are only found in the bronchus and the trachea lining, secreting mucus, to prevent germs/bacteria which would lead to infection. ...read more.


This means that carbon dioxide is got out of the body as quickly as possible and more oxygen comes in. Other Components of Lung Structure, is the actual environment in which the lungs are situated. The blood supply is extensive, which means that oxygen is carried away to the cells as soon as it has diffused into the blood. The lung has a dual blood supply: pulmonary (venous blood) and systemic (arterial blood). The pulmonary circulation delivers deoxygenated blood from the right side of the heart and returns oxygenated blood to the left side of the heart. The pulmonary circulation consists of larger elastic and smaller muscular arteries, as it is handing less pressure. This environment is perfect for breathing. ...read more.

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