Whenever a blood vessels is damage, its precious liquid pours out: in great rhythmic spurts from an artery, in a slow but steady stream from a vein, in smaller amounts from a capillary. If the spillage, technically termed a hemorrhage, continues, the volume of blood circulating in the body will drop enough to lower blood pressure drastically.

Shock leading to possible cardiac arrest and death can follow. In the case of smaller wounds, two safety mechanisms are activated as soon as hemorrhaging begins, which rapidly help to decrease bleeding.

The first mechanism is the formation of a blood clot. Clotting, a very complex process, begins when platelets in the spilled blood flow over the jagged edges of torn tissue. The contact stimulates the platelets to burst open. They then release protein substances, called blood platelet factors, that initiate a series of chemical reactions. Ultimately, the plasma protein fibrinogen is converted to its solid form, fibrin. Fibrin strands form a tangle of threads over the wound. As blood flows through the threads, red and white corpuscles and platelets are trapped and bleeding ceases.

At the same time, the second safety mechanism serves to reduce the volume of blood flow locally. This happens when substances are released at the wound that cause the muscles in the blood vessels to squeeze shut. In cases where the bleeding is very extensive, and there is also low blood pressure, the substances send signals to the brain that cause a reduction in blood flow.

When Bleeding Doesn’t Stop, What Can be Done?

sometimes injuries are so severe that they overwhelm normal protective mechanisms. There are some people – hemophiliacs, for example – in whom the blood lacks one or more clotting factors, so that even minor cuts bleeding long and hard.

When, for whatever reason, bleeding continues beyond the normal few minutes or when it is abnormally heavy, medical help should be called, and the patient must receive emergency first aid treatment in the meantime. Pressure applied to the wound may be sufficient, but if there is heavy bleeding, an arterial pressure point between the wound and the heart should be located and firm pressure exerted there.

If the patient’s blood pressure drops precipitously, the physician will administer a transfusion. When whole blood of the right type is not available, a plasma substitute can restore blood volume until a suitable donor is found.

How and When Does Healing Begin?

After any flow of blood, the mechanisms of healing take over as soon as bleeding stops. Knowing why the uncomfortable sensations occur may help you endure them.

The essential first step in that process is inflammation, with its redness, heat, swelling, and pain. The redness and heat of inflammation occur because blood vessels in the area become abnormally enlarged, flooding the damaged tissue with fresh blood. Capillary walls become thinner, and water from the blood plasma seeps through into the surrounding tissues, causing swelling. Pain develops when the swollen tissues put pressure on sensitive nerves, and the nerves send pain signals to the brain.

When the flow of blood slows, white blood cells called leukocytes enter the inflamed tissue. They clean up the debris left by the injury and kill bacteria that enter the wound through the ruptured skin. The leukocytes also release chemicals that attract other white cells to the injured area.

Once inflammation subsides, the constructive phases of healing begin. In some cases, this means the regeneration of identical new cells to replace those that were lost; in others, scar tissue forms to take the place of tissue that cannot regenerate.

What Causes Pus to From?

When an infection results from an injury, millions of white blood cells are drawn to the damaged area to combat bacteria. Pus is the yellowish, semisolid mixture of those cells, as well as bacterial and other debris. In most situations, pus rises to the surface of the skin and discharges naturally under pressure.

Why Do Some People Heal More Quickly Than Others?

Just as no two people are born with identical fingerprints, so no two people’s natural defense and repair systems are precisely the same. Each of us is born with a unique set of biological potentials, including clotting tendencies and the capacity for tissue regeneration, that influence the rate of healing.

As people age, healing takes longer. But age is not the only factor that influences healing. In ways that medical researchers are only beginning to understand, the general health of a person can also promote, or slow down, the healing process. Nutrition, and even emotional and environmental stress, are important, too. Lastly, some people are simply more prudent in caring for injuries than others: they use medications precisely as called for, and they keep their wounds clean and well-aired. Healing needs a certain degree of cooperation from the victim if it is to proceed smoothly and quickly. But cooperation does not entirely explain it; healing is always a small miracle.