The Basic Mechanisms of Homeostasis
The Basic Mechanisms of Homeostasis
Overview of homeostasis
The term homeostasis was first coined by Walter Cannon in 1929 to literally mean ‘steady state’. It describes the dynamic equilibrium by which internal constancy is maintained within set limits by regulation and control. There are many examples of homeostatic control throughout the human body and in other living organisms, such as pH, pressure, and temperature.
A concept important to homeostasis is the process of feedback circuits; involving a receptor, an effector, and a control centre. A receptor is responsible for detecting a change in the body, while the effector corrects this. The control centre organises these two together to elicit the response. The most common form of control in homeostasis is known as negative feedback, in which an excess or deficit in a homeostatic system triggers its own regulation. The diagram below illustrates this concept in reference to the control of temperature (Figure 1).
Figure 1 is a simple representation of a rather complicated process. Here, the several types of negative feedback circuits involved in temperature control have been summarised into one. The hypothalamus is a combined receptor and control centre, both recognising extremes of temperature change, and triggering bodily effectors to correct the changes. Figure 1 shows the responses to a decrease in body temperature, which directs organs to increase metabolism, thus causing shivering. Another effect would be causing hair cells on the skin to force up their hairs, creating a trapped layer of air across the body surface. Such effects should then cause the body temperature to rise to the optimal 37°C again, causing feedback to switch the circuit ‘off’. If this does not occur, the circuit will continue to direct effectors to warm the body because the feedback will not be switched ‘off’.
Recent research, however has added another dimension to the accepted definition of homeostasis. Scientists studying
Overview of homeostasis
The term homeostasis was first coined by Walter Cannon in 1929 to literally mean ‘steady state’. It describes the dynamic equilibrium by which internal constancy is maintained within set limits by regulation and control. There are many examples of homeostatic control throughout the human body and in other living organisms, such as pH, pressure, and temperature.
A concept important to homeostasis is the process of feedback circuits; involving a receptor, an effector, and a control centre. A receptor is responsible for detecting a change in the body, while the effector corrects this. The control centre organises these two together to elicit the response. The most common form of control in homeostasis is known as negative feedback, in which an excess or deficit in a homeostatic system triggers its own regulation. The diagram below illustrates this concept in reference to the control of temperature (Figure 1).
Figure 1 is a simple representation of a rather complicated process. Here, the several types of negative feedback circuits involved in temperature control have been summarised into one. The hypothalamus is a combined receptor and control centre, both recognising extremes of temperature change, and triggering bodily effectors to correct the changes. Figure 1 shows the responses to a decrease in body temperature, which directs organs to increase metabolism, thus causing shivering. Another effect would be causing hair cells on the skin to force up their hairs, creating a trapped layer of air across the body surface. Such effects should then cause the body temperature to rise to the optimal 37°C again, causing feedback to switch the circuit ‘off’. If this does not occur, the circuit will continue to direct effectors to warm the body because the feedback will not be switched ‘off’.
Recent research, however has added another dimension to the accepted definition of homeostasis. Scientists studying
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