The actual word homeostasis means "steady state". Homeostasis describes how the body regulates its process to keep its internal conditions as stable as possible. Homeostasis is necessary because human cells are efficient but very demanding. The phrase "steady state" is a bit confusing; the conditions inside our bodies are not constant but are kept within a narrow range. Some factors such as core temperature and blood pH change slightly while others such as blood glucose vary considerably throughout a normal day without producing any harmful effects.
A very brief description of homeostasis is that it is the maintenance of a constant internal environment in response to a change in external environment.
Negative feedback as a regulatory mechanism – Negative feedback arises when an important transformation, sometimes known as a key transformation, such as the pH of blood and tissue liquid, deviates from the accepted range or limits, and activates responses that returned transformation to within the normal range. In other words, deflection produces a negative response to counter or annul the deflection. It is a feeding back of the interference to the status quo.
Example of a negative feedback system – Digestive system, when blood glucose levels fall, the liver glycogen is converted into glucose in order to top up those crucial energy levels in cells. The brain and nervous system play a crucial role in controlling homeostatic mechanisms and they also help us to expect when key transformation able degrees or fall beyond the accepted range.
For example – If it is several hours since your last meal and you are beginning to feel tired and cold, you will try to eat a warm, energy-giving meal frustrate these feelings.
Negative feedback systems demand –
• Receptors to detect change
• A control centre to receive the information and process the response
• Effectors to reverse the change and re-establish the original state.
Most control centres are located in the brain.
Internal environment - The internal environment refers to the internal milieu of a multicellular organism. Every cell of a multicellular organism must regulate its surroundings to help keep a relatively stable internal environment.
Homeostatic mechanisms for regulation of heart rate:
The heart is controlled by two branches, which are called the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system starts to work when our body muscles are working, fear or stress. When this happens it increases heartbeat and heart rate, on the other hand the parasympathetic nervous system works when our body is resting, and it calms the body and makes the environment peace. The main aim of the homeostatic is to maintain good environment for internal organs, so to keep the heart rate in good level the receptors sends messages to the brain and the brain then sends responds to the cardiac centres by nerve impulses. By this activity the nerve slows the heart rate down and deceases BP back to normal.
The body is mainly automatic for the rate of ventilation and does not notice minor variations that are the result of homeostatic regulations. An individual is only controlling their own breathing when holding their breath, speaking or taking deep breathes. When the body's metabolism produces extra carbon dioxide breathing rates increase slightly until it is blown out of the body in expiration. If a period of forced ventilation such as gasping is presented to the body it will lower the carbon dioxide levels in the body and homeostatic mechanisms will slow or stop breathing until levels return to normal.
Roles of internal receptors – Internal receptors can be expanse receptors in muscles and tissues that convey nervous impulses to the brain about the status of ventilation