Key Points
Key Points
- Homeostasis is important for maintaining optimal internal conditions to promote survival. Maintaining homeostasis requires that the body continuously monitor its internal conditions and respond to internal and external stimuli. Each physiological condition within the body has a particular set point for optimal health and stability, around which the normal range fluctuates. The set point for human body temperature, for example, is approximately 37°C. While small fluctuations above or below the set point of body temperature is normal, substantial deviations from this set point activate negative feedback mechanisms that reverse the deviations and return body temperature to homeostasis.
- Physiological values are measured by sensors/receptors which report these values to the control centre. The control centre compares this value to the normal range and if a significant difference is identified the control centre activates an effector that triggers a physiological change to reverse the situation and returns the value to homeostasis.
- Positive feedback mechanisms intensify changes in a physiological condition, rather than reversing it. This moves the physiological value further from the set point, though these mechanisms have a definite end point. Childbirth at the end of a pregnancy requires significant changes to support delivery and once begun must progress rapidly to a conclusion for the health and wellbeing of the mother and child.
- Circadian rhythms are important for regulating sleep and wakefulness and are influenced by external stimuli such as light. In the absence of light melatonin in released by the pineal gland which indicates to the body that it is time for sleep. Dysregulation of the circadian rhythm can occur when this rhythm is not aligned with the external environment, such as traveling to a different time zone resulting in jet lag.
