Summary

In study session II you have learnt

• The goals of respiration are to provide oxygen to the tissues and to remove carbon dioxide. Normal lung function requires a balanced interrelationship between the respiratory (the upper and lower airway), nervous, and cardiovascular systems.
• Mechanisms to achieve the goal of respiration are pulmonary ventilation, diffusion of oxygen and carbon dioxide between the alveoli and the blood, transport of oxygen and carbon dioxide in the blood and body fluid to and from the body's tissue cells; and regulation of ventilation and other facets of respiration by the respiratory centre.
• Normal quiet breathing is accomplished almost entirely by movement of the diaphragm.
• The venous blood arrives in the lung (from the tissues) with an O2 pressure of 40 mmHg. Because of the difference in pressure (103 – 40 mmHg), O2 passes from the alveoli into the blood stream. This transfer occurs by the process of diffusion.
• The venous blood arriving in the lung is rich in CO2. The pressure of CO2 in the venous blood is 46 mmHg. The alveolar pressure is 40 mmHg. The CO2 diffuses from the venous blood to the alveoli. The arterial blood leaves the lung with an oxygen tension of 100 mmHg and a CO2 tension of 40 mmHg.
• The gases in the alveoli pass into the blood in the capillaries by the process of diffusion. Diffusion of oxygen from the alveolus into the red blood cell and diffusion of carbon dioxide in the opposite direction occur in the respiratory membrane. The overall thickness of the respiratory membrane in some areas is as little as 0.2 micrometer, and it averages about 0.6 micrometer.
• The respiratory unit is composed of a respiratory bronchiole, alveolar ducts, atria, and alveoli.
• Oxygen is carried in combination with the hemoglobin in the red blood cells (1 gm of hemoglobin can carry 1.34 ml of O2) and carried in solution (0.3 ml of oxygen per 100ml of blood).
• The respiratory center is composed of several groups of neurons located bilaterally in the medulla oblongata and pons of the brain stem.
• Compliance is a measure of distensibility of the lung by change in pressure. Airway resistance denotes the measure of obstruction to the flow of gas in the air passages.
• Common problems of oxygenation and ventilation include hypoxia, lack of oxygen in the tissue and hypercapnia. excess of carboondioxide in the tissue. Treatment of hypoxia and hypercapnia is removal of the cause and administration of oxygen.
• The overall effects of anesthesia on respiratory system is depression by central depression, air way obstruction, decreasing muscular activity and decreasing lung volumes
• A comprehensive respiratory assessment includes history, physical examination and diagnostic tests that provide information about respiratory function
• Physical examination of respiratory system can be done by inspection, palpation, percussion and auscultation
• Whenever there is abnormal finding during auscultations inform and discus with the operating physician or if it is elective consult medical side