CHAPTER TWO

The human body& first aid

The human physique is both incredibly strong and intensely vulnerable. Life is sustained around the efficient functioning of three major body systems — circulatory, respiratory and nervous — and knowing how they work forms the basis of much of your emergency first aid treatment.

First aid is primarily about immediate and practical treatments, so advanced medical knowledge is not a pre-requisite. However, it is advantageous if the first aider comprehends the biological cornerstones of human life, for without an understanding of the body’s basic mechanisms, it is difficult to adapt treatments to meet unexpected developments in the illness or injury. Furthermore, without understanding or appreciating the reason for your actions, it can be more difficult to best apply yourself.

We begin this chapter with a look at the three biological systems responsible for maintaining human life – the respiratory, circulatory, and nervous systems. From there, we move onto the fundamentals of first aid practice – diagnosis, assessment, and treatments when one or more of the major body systems is in acute failure.

THE BODY’S SYSTEMS

For a first aider, the essential principle to remember is that the oxygenation of the human body must be maintained at all times. All human tissue, but especially the major organs of the body, will quickly die if deprived of oxygen. It is the respiratory system’s job to draw air from the outside world, extract the oxygen and pass it into the blood. It is the job of the circulatory system to pump this blood around the body, and deliver oxygen to the body tissue while extracting waste products. Finally, the nervous system regulates the pace and efficiency of the whole process.

When a first aider is faced with a casualty, their attention is (initially) totally given over to supporting the efficient function of all three systems if need be. For if any system fails, the result is hypoxia, or low levels of blood-borne oxygen. For example, a patient has an obstructed windpipe, then the respiratory system cannot draw air into the lungs, and the blood receives no new oxygen. This in turn means that the circulatory system does not contain enough oxygen in the blood to perform full-body oxygenation properly (a condition known as ischemia).

Hypoxia, if not corrected, leads to infarction, the death of body tissue and organs. The brain is one of the most vulnerable organs to ischemic problems. Brain cells begin to die after only three minutes of deprivation, and if completely deprived of oxygen for more than five minutes, brain damage or brain death will almost certainly ensue. Consequently, in life-threatening emergencies the combating of ischemia is the first aider’s absolute priority. That involves the effective support of all three body systems, and we shall now look at each in more detail.

Respiratory System

The respiratory system consists of the mouth, nose, trachea, and lungs, and includes the network of pulmonary arteries that take oxygen from the