Human Anatomy and Physiology an Introduction to Respiration Essays

3654 Words Aug 13th, 2011 15 Pages
In this essay we will consider a few major aspects of respiration. We shall first consider the interesting history of the study of respiration before moving on to our modern understanding of respiration. We will look at the structure and function of the respiratory system including the upper and lower respiratory tracts with a note on the control system. Secondly we will consider the physiology of respiration. Thirdly we will discuss some of the major common disorders and diseases which affect the system with a special focus on asthma. A BRIEF HISTORY OF THE STUDY OF RESPIRATION Hippocrates "counted air as an instrument of the body" just as food was eaten. Galen (129-200) felt
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The epiglottis prevents both openings being open simultaneously. The larynx is located between the pharynx and the trachea. This is commonly known as the voice box. The trachea is a tube which extends from the larynx and divides to form the bronchi. It is lined with cilia with further warms and filters the air. The bronchi lead to the lungs. The lungs are a pair of organs located on either

side of the thoracic cavity and enclosed in double membranes or pleura. The bronchi enter the lungs at a point known as the helium. They divide into smaller and smaller branches known as bronchioles and finally alveolar ducts and alveoli. These are sack like structures and this is the site of gas exchange. Their total surface area is approximately 70 square meters. Lets us consider the actual mechanism of breathing for a moment. Inspiration involves movement of the diaphragm and the internal and external intercostal muscles. On inspiration the diaphragm contracts pulling downwards on the lung and drawing air into the lungs. The ribs move upwards and outwards at the same time. Expiration is said to be a passive event which arises from the relaxation of the diaphragm and intercostals. The volume of air breathed in and out is known as the tidal volume and is normally about half a litre. However total lung capacity includes inspiratory reserve volume, expiratory reserve

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