The human body is a vastly complex biochemical organism, finely tuned and adaptable. It contains many diffe...
The human body is a vastly complex biochemical organism, finely tuned and adaptable. It contains many different regulatory systems to make sure that things work properly in response to external conditions. When it becomes too warm inside the body, the water cooling system is turned up, and more sweat is secreted by the skin. The sweat evaporates, cools the blood underneath the skin, which in turn cools the body core. The sensors in the brain detect that things are back within normal limits, and turn off the sweat glands. This type of regulation (known as homeostasis) occurs for all bodily processes, and usually without any awareness or thought on our part.
When external circumstances (like extreme heat or cold) or internal conditions (disease or poisoning) cannot be adjusted by normal mechanisms, the signs of discomfort and disease appear. The types of physical effects seen or felt (signs and symptoms) depend on the type of stress to which the body has been exposed. Because there are so many complex interrelationships between the systems within the body, a single change in any one system may result in numerous effects in other systems. In addition, the types of response to disease are limited, thus signs and symptoms of disease are often quite similar for different diseases. For example, headache, fever, nausea, vomiting and diarrhea are very common non-specific symptoms of disease, produced by many, many conditions. Because of the generality of most physiological responses to disease, many other methods have been developed to help diagnose the actual causes of disease. These methods include physical, biochemical and immunological techniques upon which modern clinical medicine is based.
A body's homeostasis can be upset by physical, chemical and/or biological agents which put stress on the body. The body's reaction to prolonged stress depends on the nature of the agent, the degree of stress, and the duration of stress. When the stress is too strong or too long, and