Notes

Homeostasis and Disease
Homeostasis is the body’s ability to maintain a stable internal environment when faced with a changing external environment. For example, the body maintains a stable core body temperature of about 98.6 degrees F (37 degrees C). The core temperature stays the same, even though the temperature outside may be frigid cold or sweltering hot. Similarly, the heart begins to pump faster and your lungs breathe faster when you are running. The action of the heart and the lungs provides nutrients and oxygen to your muscles. The body maintains homeostasis in the following three steps: A sensor monitors the body’s condition. Several different sensors detect changes both inside and outside the body.
Next, the sensor sends its messages to a control center. This part of the body interprets all of the data it receives. Then, it decides what action is necessary to return the body to homeostasis. In many cases, the brain is the control center. In the next step, an effector causes an action that returns the body back to homeostasis. The effector acts only when the control center decides to take action. Once the effector takes action, the body returns to a stable condition (homeostasis). The sensor no longer detects an abnormality. When the body undergoes a change and homeostasis cannot return to normal conditions, the body might experience a disease. A disease is an abnormal condition that affects all or part of the body. The study of diseases is called pathology. A related term, pathophysiology, is the study of how the disease affects the body’s functions. When disease occurs, you often look or feel ill. These indicators are called signs and symptoms. Signs of illness are visible or measureable changes. Some changes are swelling, soreness, breathing difficulties, elevated blood pressure, or fast heart rate. Symptoms are feelings that someone experiencing the disease expresses. They are not precisely measureable or even visible. Pain, dizziness, and cramping are common symptoms. Both signs and symptoms are important to healthcare professionals. These factors help in determining the cause or severity of a disease. Determining the cause and nature of a disease is called diagnosis. There are many ways to classify disease. The most common way is to group diseases by body systems and organs.