What is homeostasis and why is it important to life?

Define Homeostasis

The state of balance within all physical systems needed for a body to function properly and survive is homeostasis. In a state of homeostasis, body levels are constantly adjusting in response to changes outside and inside the body. Some of the systems that constantly adjust to stay at normal levels are:

• blood sugar
• blood pressure
• energy
• acid levels
• oxygen
• proteins
• temperature
• hormones
• electrolytes

Example of Homeostasis

Any bodily system in dynamic equilibrium reaches a steady state or balance that can withstand external forces of change. When this system is disturbed, regulating devices built into the body respond to create a new balance. 

One process is called feedback control. All processes of implementation and coordination of function are examples of homeostasis. This occurs whether facilitated by the nervous system, hormonal system, or electrical currents.

An easy example of regulation via homeostasis is a mechanical system of action that controls the temperature in the room: i.e., a thermostat. The center of the thermostat is a metallic strip that can sense temperature changes and react by controlling an electric circuit. 

When the room is cold, the furnace is activated by the thermostat, and the temperature will then go up. At the time when the preset level of the thermostat circuit is reached, the furnace stops, and the temperature will remain the same or go back down. 

Biological systems are a lot more complex but can achieve similar results. These systems have regulators that are comparable to mechanical devices, and the two are alike in goals: that is, to regulate a system and keep conditions within a normal range. This is the goal whether regulating room temperature or leveling pressure in the circulatory system.

How Does Feedback Regulation Work?

A vital feature of homeostasis is that the organism's internal environment is maintained via the thin range of values of a self-regulating system. Both feedback and feedforward are ways that homeostasis is maintained. A feedback system is defined as a closed-loop structure that controls future actions by feeding the past changes in the internal environment into the system. The system then changes its behavior to adapt to external conditions.

There are two types of feedback systems. They are negative and positive. Negative feedback seeks a goal and responds to any failures to meet that goal. It maintains a steady range of values. 

Positive feedback produces processes of growth where actions capitalize on the results that in turn would build greater actions. These systems of feedback are subject to levels of higher control and may be counteracted by negative feedback. 

The operation range encompasses variables that are regulated and can respond to stimuli from the environment. The result of these complex interactions and the competing negative and positive feedback systems results in homeostasis, which is the foundation of physiological regulation. 

Why Is Homeostasis Important?

Homeostasis is the central uniting concept of physiology and self-regulation performed to maintain internal stability. Homeostasis is not constant. It is a dynamic process that changes internal conditions to promote survival. 

Regulation via homeostasis is not a singular feedback cycle. It reflects the complex interaction of many feedback systems controlled by nerves and hormones. This feedback results in a precise level of control and flexibility that allows an organism to acclimate to changes in environmental conditions.

The life and health of an organism are the end result of regulation via homeostasis. The disruption of homeostasis is what causes disease. 

Proper treatment and therapy must be aimed at reestablishing conditions of homeostasis. Otherwise, severe disease or death could be imminent.  

How Does the Body Maintain Homeostasis?

Body temperature control is a good overall example of how the body maintains homeostasis in a biological system. In humans, 98.6 degrees Fahrenheit is the average body temperature. Various factors could affect this number, though, including:

• exposure
• metabolic rate 
• hormones
• disease

All of these factors can lead to extremely low or high temperatures. The body temperature is then regulated by the brain, though, in an area called the hypothalamus. Body temperature feedback is carried via the nervous system to the brain. This results in adjustments in blood sugar levels, breathing rate, and metabolic rate in an attempt to return to homeostasis.

Heat loss in the body is affected by sweating, decreasing activity, and heat exchange functions that allow large blood amounts to circulate at the skin's surface. Heat loss is reduced by decreased skin circulation, insulation, and outside adjustments. Examples include seeking shelter, clothing, and external sources of heat. 

The difference between low and high body temperatures is a homeostatic plateau. This is the normal range that allows life to continue. As temperature, levels approach either extreme, correction via negative feedback helps the system to return to a normal range.

The body also maintains homeostasis via the circulatory system and baroreceptors. Baroreceptors are pressure-sensitive areas in the blood vessels that react to stretching. They send blood pressure information to the brain, which sends hormones produced by the thyroid gland and the hypothalamus to regulate metabolism in the body.

Where Else Is Homeostasis Applied?

Homeostasis has also been utilized in ecological settings. First introduced by ecologist Robert MacArthur, an understanding of homeostasis in ecosystems is produced by combining biodiversity and interactions between different species. It was believed that the concept could explain stability in the ecosystem. It has evolved over the years to include non-living parts and is seen by some as controversial.