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People breathe in oxygen and breathe out carbon dioxide. All tissue in the human body requires oxygen on an ongoing basis, and even a temporary lack of oxygen can cause damage. A loss of oxygen to brain tissue can result in damage in as little as three minutes. The air that we normally breathe contains approximately 21% oxygen. Here is bought into the body through the mouth and nose, close down a windpipe into the lungs, which are located behind the ribs in the chest. Oxygen in the lungs passes across a membrane into the blood.


It is the red fluid that flows out of a cut. Blood is pumped around the body by the heart. It leaves the heart in large pipes called arteries and traveled through the body in pipes that get smaller and smaller until they become very small pipes called capillaries which transfer oxygen and other substances to the cells. The capillaries pick up waste products such as carbon dioxide and continue to flow into larger pipes called veins which return to the heart. Some of the cells in the blood are specially designed to steal over a cut or wound to prevent the loss of blood or the entry of infection.


Bones are hard and white and form the foundation of the structure of the human body. Bones are living tissue, with blood vessels and nerves. The hard white part of the bone is covered by a membrane that interacts with the surrounding tissue and inside the hard white part of the bone is a fragile honeycomb.


The lymph system is the filtering system of the body. Small pipes called lymph capillaries pick up the waste product and excess fluid from body tissue. These fluids are forced through the lymph system using the action of surrounding muscles. The lymph capillaries drain into lymph nodes which filter the fluid into the bloodstream.

  1. Sign

A sign is something that you as a first aider can see. E.g. pale, shaking, uncoordinated

  1. Symptom

A symptom is something that the casualty feels e.g. headache, nausea, dizziness.


Skin color is different in every person. When blood is flowing normally under the skin, the skin is warm and pink. The color of fingernails is an indicator if you are unsure, as is the inside lining of the lips.

Regardless of the normal colour of a person’s skin, the colour in these areas will give you an indication of their colour.

  1. PULSE 

The pulse is the feeling of the blood pumping through the arteries on the way around the body. Each pulse is a heartbeat. A normal adult pulse rate is 60 to 100 beats per minute. This fluctuates with physical condition, age, and other factors. Children and babies normally have a faster pulse rate.


 A normally healthy adult will take between 10 and 20 breaths per minute. This varies depending on the size, fitness, and history of the person. Normal breathing is without noise, regular, and without tension. Children and infants normally have a faster respiration rate.


Normal body temperature is around 37degree Celcius. The body temperature of a person fluctuates up or down in the normal course of the day.


The body cannot function without adequate fluids. Dehydration causes the body to heat up, the skin to become dry, the mouth to be dry and the casualty thirsty.


There are three levels of consciousness:

  • Fully conscious The casualty responds normally to questions.
  • Semi-conscious Confused, disoriented, slurred speech
  • Unconscious The casualty is unresponsive.

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M. P. Khan