HomeostasisWhat is Homeostasis?Homeostasis can be directly defined as the maintenance of a constant internal environment in the body. External conditions are constantly changing while body cells have an unchanging job and thus must work in the same way in a vast range o conditions. Internal conditions of the body,however, are kept constant so the inernal conditions remains the same independent of external changes so cells must be maintained in the same conditions. Homeostasis allows living systems to correct for some disturbances and the organism is able to adapt to changing circumstances, it is the maintenance of a desired state in the face of disturbances. Even unicellular organisms have some homeostatic abilities. In animals, individual cells also have homeostatic abilities.
Most physiological functions or variables fluctuate within a predictable and often narrow range so while variables, such as blood glucose, may vary in the short term, the average is fairly constant. Hence if one system becomes dramatically out of balance so do other systems in the body become nonhomeostatic and out of balance. An animal is said to be in good health if all the majr organ systems are operating in a homeostatic manner.
The French Physiologist Claude Bernard developed the concept of ‘milieu interieur’ or the internal environment and that physiological regulatory mechanisms have the sole purpose of maintenance while Walter Cannon later coined theterm ‘homeostasis’ and explained the importance of the autonomic nervous system in maintaining a constant internal environment.
The internal environment is very important and is produced and controlled by the organisms which may become more independent from changes in the external environment by maintaining constant internal environments. The internal fluid environment bathes the cells with nutrients and inorganic and organic ions of critical importance to normal cell functioning. Homeostatic mechanisms will help to have a very stringent control over the concentration of glucose, calcium and sodium and other constituents of body fluid. Body fluid can be broken down to two compartments, the intracellular fluid (ICF) and extracellular fluid (ECF)
Homeostatic Control SystemsMulticellular organisms maintain the composition of ECF within a relatively narrow range which may vary with the time of day and other conditions. Regulated variables are kept within a normal range by control mechanisms and control systems.
With regards to internal regulation, some of the physiological conditions requiring homeostasis include temperature, blood gases, blood pressure and water and blood volume. Any changes in fluid, electrolytes and metabolic substrate levels in the ECF must be constantly monitored. To be able to achieve homeostasis the human body attempts to kep the concentration of regulated substances within a relatively narrow range of normal values.
In animals, there are two evolutionary paths for homeostasis, regulation and conformation. Regulators are animals that use internal body mechanisms to defend a relatively constant state. Conformers are animals in which the internal state varies with that of the environment.
There are 3 major components of a homeostatic system which are detectors/sensors which recognise deviation, the integrating unit or control centre which receives the message from detectors and finally effectors which transmit the information from the control centre.
Negative and Positive Feedback loopsA feedback mechanism is a process whereby an initial change will either reinforce the process such as the snowball effect (‘it just keeps going and going…’) or weaken the process. These two types are known as positive and negative feedback mechanisms respectively.
Negative feedback is a response that diminishes the original stimulus and either negates or eliminates the stimulus and is the most common one in biological systems such as regulation of body temperature or blood glucose. Positive feedback is a response that enhances the original stimulus and reinforces the initial change, movement away from a starting point elicits even more movement away from the starting point, and this feedback mechanism is less common exemplified by the milk ejection reflex and contraction of uterus during labour.
Homeostasis can be disrupted when one or more of an animal’s systems fail to function and thus cells are damaged with the loss of homeostatic function. Just one nonhomeostatic variable among the man that can be described, can have life-threatening consequences. Various pathophysiological states ensue with homeostatic disruption.
Learn More
Big Bang Theory: Homeostasis
Mr Ford's Class: Homeostasis
Homeostasis Quiz
Questions
Most physiological functions or variables fluctuate within a predictable and often narrow range so while variables, such as blood glucose, may vary in the short term, the average is fairly constant. Hence if one system becomes dramatically out of balance so do other systems in the body become nonhomeostatic and out of balance. An animal is said to be in good health if all the majr organ systems are operating in a homeostatic manner.
The French Physiologist Claude Bernard developed the concept of ‘milieu interieur’ or the internal environment and that physiological regulatory mechanisms have the sole purpose of maintenance while Walter Cannon later coined theterm ‘homeostasis’ and explained the importance of the autonomic nervous system in maintaining a constant internal environment.
The internal environment is very important and is produced and controlled by the organisms which may become more independent from changes in the external environment by maintaining constant internal environments. The internal fluid environment bathes the cells with nutrients and inorganic and organic ions of critical importance to normal cell functioning. Homeostatic mechanisms will help to have a very stringent control over the concentration of glucose, calcium and sodium and other constituents of body fluid. Body fluid can be broken down to two compartments, the intracellular fluid (ICF) and extracellular fluid (ECF)
Homeostatic Control SystemsMulticellular organisms maintain the composition of ECF within a relatively narrow range which may vary with the time of day and other conditions. Regulated variables are kept within a normal range by control mechanisms and control systems.
With regards to internal regulation, some of the physiological conditions requiring homeostasis include temperature, blood gases, blood pressure and water and blood volume. Any changes in fluid, electrolytes and metabolic substrate levels in the ECF must be constantly monitored. To be able to achieve homeostasis the human body attempts to kep the concentration of regulated substances within a relatively narrow range of normal values.
In animals, there are two evolutionary paths for homeostasis, regulation and conformation. Regulators are animals that use internal body mechanisms to defend a relatively constant state. Conformers are animals in which the internal state varies with that of the environment.
There are 3 major components of a homeostatic system which are detectors/sensors which recognise deviation, the integrating unit or control centre which receives the message from detectors and finally effectors which transmit the information from the control centre.
Negative and Positive Feedback loopsA feedback mechanism is a process whereby an initial change will either reinforce the process such as the snowball effect (‘it just keeps going and going…’) or weaken the process. These two types are known as positive and negative feedback mechanisms respectively.
Negative feedback is a response that diminishes the original stimulus and either negates or eliminates the stimulus and is the most common one in biological systems such as regulation of body temperature or blood glucose. Positive feedback is a response that enhances the original stimulus and reinforces the initial change, movement away from a starting point elicits even more movement away from the starting point, and this feedback mechanism is less common exemplified by the milk ejection reflex and contraction of uterus during labour.
Homeostasis can be disrupted when one or more of an animal’s systems fail to function and thus cells are damaged with the loss of homeostatic function. Just one nonhomeostatic variable among the man that can be described, can have life-threatening consequences. Various pathophysiological states ensue with homeostatic disruption.
Learn More
Big Bang Theory: Homeostasis
Mr Ford's Class: Homeostasis
Homeostasis Quiz
Questions
- Why do we need homeostasis?
- Distinguish between positive and negative feedback
- Explain why a large mammal such as an elephant might be expected to experience difficulties in regulating its body temperature in a hot climate.