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Human Anatomy and Physiology an Introduction to Respiration

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HUMAN ANATOMY AND PHYSIOLOGY
AN INTRODUCTION TO RESPIRATION
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 …show more content…

THE CONTROL SYSTEM FOR RESPIRATION The control unit of ventilation consists of a processor or breathing centre in the brain which integrates emotional, chemical and physical stimuli inputs and controls an effector - in this case the lungs via motor nerves from the spinal cord. Ventilation is normally autonomic with a limited voluntary override. Ondine's curse is the exception to this where the autonomic control is lost. The mechanism of generation is not completely understood but involves the integration of neural signals by respiratory control centres in the medulla and pons. In the medulla we have the ventral respiratory group i.e. nucleus retroambigualis, nucleus ambiguus, nucleus parambigualis and the pre-Botzinger complex. This group controls voluntary forced exhalation and also works to increase the force of inspiration. The medulla also contains the dorsal respiratory group consisting mainly of the nucleus tractus solitarius and this controls mostly inspiratory movements and their timing. The pons contains the pneumotaxic centre which is involved with the fine tuning of the respiration rate and the apneustic centre. In addition there is further integration in the anterior horn cells of the spinal cord. The actual breathing rate of a human is controlled in the following way. Chemoreceptors detect the levels of carbon dioxide in the blood by monitoring

the number of hydrogen ions in the blood, which decreases the pH of the blood. This is as a direct consequence

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