Anaesthesia Fundamentals | Physiology | Control of Breathing

Control of Breathing
Session overview
Description
This session describes how breathing is controlled. It defines the physiological components involved in regulating breathing, and shows how they combine into an integrated system of control.

Learning objectives
By the end of this session you will be able to:

• Describe the anatomy of the components which control breathing
• Describe the physiology of these components
• Explain how these components are interrelated
• Describe changes to breathing under differing conditions

Breathing is tightly controlled by a complex regulatory system which has several aims:

• Achieving uninterrupted rhythmic breathing, of which the individual is unaware
• Regulating PaCO2, i.e. partial arterial pressure of carbon dioxide, and PaO2, i.e. partial arterial pressure of oxygen, within tight limits to maintain a constant homeostatic internal milieu. For example, just by doubling minute ventilation arterial pH increases by 0.2 points.
• Ensuring the individual breathes enough to get haemoglobin close to full saturation without wasting effort

However, the regulatory system also needs to be flexible enough that it can be overridden, both voluntarily, e.g. breath-holding in a smoke-filled room, and involuntarily, e.g. during exercise, coughing, sneezing, or talking. The system also needs to be adaptable, to allow other activities, such as talking and eating, which share anatomical structures with the lung.