Homeostasis is defined by the Oxford Concise Medical Dictionary as “the physiological process by which the internal systems of the body (e.g. blood pressure, body temperature, acid-base balance) are maintained at equilibrium, despite variations in the external conditions”. Essentially this means that our bodies have internal processes that are designed to react to circumstances beyond the body’s direct control which may have an impact on it. By reacting and changing how it behaves, the human body is able to maintain a balancing act that keeps it functioning.
Why is Homeostasis Important?
Homeostasis is what makes human beings able to withstand different types of conditions and maintain a constant internal environment. Homeostasis is a healthy condition, a middle ground where the body can function effectively. In order to stay in this normal range, there is a constant adjustment process going on inside all of is. The body monitors and makes adjustments in order to regulate how the body is functioning.
How the body achieves homeostasis is through using what we call negative feedback. The phrase negative feedback doesn’t mean negative in the conventional sense of the word but rather it means to cancel something out. So, this basically means that the body monitors levels within the body, and if the level is too high, it acts to reduce it. When a level is too low, it acts to raise it. In order to do this, it uses the nervous system and chemical messengers such as hormones which can be secreted by glands in order to have the desired effect on the appropriate organs. The body continually monitors levels of certain substances in order to react quickly and proportionally whenever action is required to return the body to a state of homeostasis.
Examples of Homeostasis
Body temperature is one of the best examples of how homeostasis works through negative feedback. The body functions best when a steady temperature of around 98.6 degrees Fahrenheit is maintained. In order to maintain this, the body does a number of things, many of which we can see and feel happening. When the body temperature is too high, we sweat to cool the skin through moisture evaporation. The skin may also become flushed, which is the body’s attempt to cool the blood by bringing it to the surface of the skin. When body temperature is too high, we may also shiver to create more heat. Blood is moved away from the surface of the skin, resulting in paler skin and the body will stop sweating. Hairs on the surface may raise to trap air and help the body to warm up. Through this series of small but effective adjustments, the human body seeks a state of homeostasis. This results in the human body temperature rarely increasing or decreasing in a healthy individual, even when we ‘feel’ hot or cold, and despite the environmental temperature.
In order to maintain homeostasis, the body makes many small adjustments to the cardiovascular system. Baroreceptors monitor how the blood stretches the vessels, and this enables adjustments to be made that regulate blood pressure and keep it within a normal healthy range. This happens to offset the impact of environmental changes, such as pressure, temperature etc., activity levels such as rest and exercise and changes that occur to the blood pressure depending on the position the body is in. For example, to maintain blood pressure homeostasis regardless of whether a person is lying down, standing up or even upside down (for brief periods!). Keeping the blood pressure regular through homeostasis means there is less pressure on the cardiovascular system, and this is extremely important for people of all ages.
The water content of cells must be controlled so that they don’t gain or lose too much water. In order to achieve a state of homeostasis, the body monitors fluid levels and purposely loses water through urination, by sweating and by breathing out (exhaling) when it needs to.
Blood glucose levels are maintained through the action of insulin, a hormone secreted by the pancreas in response to the level of glucose in the blood. When the blood glucose level is high, it signals to the pancreas to secrete insulin which turns glucose into another substance, glycogen. If the glucose level in the blood is low, no insulin is secreted, and this allows the blood glucose level to rise. The disease diabetes is an example of what can happen when the blood glucose homeostasis cannot be maintained.
Homeostasis is one of the central concepts in the study of physiology. For more information about the processes involved in physiology, check out what WebMD has to say.
The processes that result in homeostasis are some of the most important in the human body, and it is responsible for the fact that humans are remarkably resilient despite the fact that we rely upon thousands of incredibly nuanced and complex interactions between the various physiological systems within the body. We are capable of enduring different external circumstances such as changes in temperature, altitude, and pressure. We can cope with stress. We can adapt to different diets and endure periods of hardship. A lot of this ability is down to the body’s ability to maintain homeostasis. It is amazing that we do not have to think about the many adjustments our bodies make as we go about our daily lives. We can rely on the internal monitoring systems inside us to evaluate various levels. We can trust that countless bodily systems come together to work in harmony in order to make the adjustments that are necessary in order to keep us functioning as best we can.