Homeostasis is the control of internal conditions, be it temperature, specific blood conditions or other variables within living organisms. The term ‘Homeostasis’ was first defined by the French physiologist, Claude Bernard, in 1865.

The purpose of homeostasis is to provide a consistent internal environment for set processes to occur. Each process, or reaction, has a desirable peak environment called the norm. Influences, such as an external influence, can cause deviation away from this norm level and the body will correct this change – this is called negative feedback.

Examples of negative feedback:

• When blood pressure rises the heart will slow.
• If glucose levels are too high the pancreas secretes insulin to stimulate the absorption of glucose.

Negative feedback is the most common type of reaction, because it is only natural to rectify a potential problem, but there is also positive feedback. This is when the body will push itself further away from the norm level. An example of this:

• During hypothermia – if a human’s body temperature falls and is being lost quicker than it can be produced the metabolic rate will also drop. This causes a positive feedback and the body temperature will fall further from the norm.

Temperature Control

Many of the body’s enzymes are sensitive to temperature change, even by a few degrees difference, which then affects their reactions. This is because humans are endotherms, or warm blooded creatures, and are depend on creating their own heat.

Ways to change temperature:

• Radiation – The transfer of heat between two objects through the air.
• Conduction – The transfer of heat from direct contact between two objects.
• Convection – The transfer of heat through moving air.
• Evaporation – The loss of heat (and energy) through changing a liquid into a vapour.

The hypothalamus, located in the central brain, controls:

• Body temperature.
• Hunger and thirst.
• Sleep.

It regulates body temperature by detecting change in blood temperature and sending relevant signals through the nervous system to the body’s organs to rectify this.

Frequently Asked Questions

What is Homeostasis?

Homeostasis is maintaining a uniform internal environment in the human body despite changes in the external environment. For example, the internal body temperature of the human body stays at the same level despite fluctuations in the environmental temperature.

How is Homeostasis maintained?

Homeostasis is maintained by a series of control mechanisms functioning in our body at the cell, tissue, or organ level that ensures that the internal body environment stays the same in contradiction to external changes.

Why is Homeostasis so important?

Our body cells require a stable internal environment to work. Fluctuations in the internal environment alter the functional capacity of cells. Moreover, enzymes also become inactive in changing the body’s internal environment.

How is the temperature of the body maintained?

If the heat supply to the body is increased, sweating and other heat loss mechanisms become active to maintain the temperature. Similarly, if the heat supply is depressed, as in winter, shivering and non-shivering thermogenesis starts to maintain temperature.