Book contents
- Frontmatter
- Contents
- List of contributors
- Preface to the first edition
- Preface to the second edition
- Preface to the third edition
- How to use this book
- Acknowledgements
- List of abbreviations
- Section 1 Clinical anaesthesia
- Section 2 Physiology
- 1 Cellular physiology
- 2 Body fluids
- 3 Haematology and immunology
- 4 Muscle physiology
- 5 Cardiac physiology
- 6 Physiology of the circulation
- 7 Renal physiology
- 8 Respiratory physiology
- 9 Physiology of the nervous system
- 10 Physiology of pain
- 11 Gastrointestinal physiology
- 12 Metabolism and temperature regulation
- 13 Endocrinology
- 14 Physiology of pregnancy
- 15 Fetal and newborn physiology
- Section 3 Pharmacology
- Section 4 Physics, clinical measurement and statistics
- Appendix: Primary FRCA syllabus
- Index
8 - Respiratory physiology
from Section 2 - Physiology
- Frontmatter
- Contents
- List of contributors
- Preface to the first edition
- Preface to the second edition
- Preface to the third edition
- How to use this book
- Acknowledgements
- List of abbreviations
- Section 1 Clinical anaesthesia
- Section 2 Physiology
- 1 Cellular physiology
- 2 Body fluids
- 3 Haematology and immunology
- 4 Muscle physiology
- 5 Cardiac physiology
- 6 Physiology of the circulation
- 7 Renal physiology
- 8 Respiratory physiology
- 9 Physiology of the nervous system
- 10 Physiology of pain
- 11 Gastrointestinal physiology
- 12 Metabolism and temperature regulation
- 13 Endocrinology
- 14 Physiology of pregnancy
- 15 Fetal and newborn physiology
- Section 3 Pharmacology
- Section 4 Physics, clinical measurement and statistics
- Appendix: Primary FRCA syllabus
- Index
Summary
Functional anatomy
The primary function of the respiratory system is the exchange of oxygen and carbon dioxide between the body and the environment. In addition, the lungs also have a metabolic role, act as a filter for small emboli in the circulation, play a part in acid–base balance and contribute to the immune defences of the body. These functions are all reflected in the anatomy of the components of the respiratory system.
Upper airway and larynx
In respiration, the function of the nose, mouth and pharynx is to conduct fresh gas to the larynx, which marks the entrance to the conducting airways. These structures also warm, humidify and filter the gases.
During quiet nasal breathing this section of the airway can provide two-thirds of the total resistance to airflow of the respiratory system. Since the pharynx is a muscular tube without rigid structures to maintain its patency, it can increase the flow resistance considerably, even to the point of total obstruction, depending on the tone of its muscular wall, the associated muscles and the transmural pressure.
The larynx has three main functions:
Regulation of expiratory airflow (expiratory braking). This is important for vocalisation, coughing and control of end-expiratory lung volume.
Protection of the lower airway. Vocal cord closure prevents aspiration of foreign material or objects and expiratory braking enables the cough reflex to expel foreign material and secretions.
Vocalisation.
Conducting airways
The respiratory system is traditionally divided into gas-conducting and gas-exchanging components.
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- Fundamentals of Anaesthesia , pp. 358 - 387Publisher: Cambridge University PressPrint publication year: 2009
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