Homeostasis Flashcards
Homeostasis
A dynamic state of equilibrium, or a balance, in which internal conditions vary, but always within relatively narrow limits; when the body’s need are adequately met and functioning smoothly
Which two systems chiefly accomplish communication within the body to create homeostasis?
The nervous and endocrine systems using neural electoral impulses and blood borne hormones
The variable
The factor or event being regulated
The receptor
Some type of sensor that monitors the environment and responds to changes, called stimuli, by sending info (input) to the second component, the control center.
What is the afferent pathway?
The direction INPUT flows from the receptor and “approaches” the control center.
The control center
Determines the “set point”, which is the level of range at which a variable is to be maintained; analyzes the input it receives and determine the appropriate response
The effector
Provides the means for the control center’s response (output) to the stimulus
What is the efferent pathway?
The direction information, or OUTPUT, flows from the control center to the effector.
Feed back
The results of the response feeding backing to influence the effect of the stimulus, either reducing it to shut the process off, or enhancing it to continue it at a faster rate.
Negative feedback mechanisms
the majority of homeostatic control mechanisms, where the output shuts off the original effect of the stimulus or reduces its intensity; cause the variable to change in a direction OPPOSITE to that of the initial change, returning it to its “ideal” value (e.g. the control of blood sugar, or glucose, by insulin, p. 10)
Positive feedback mechanisms
The result or response the enhances the original stimulus so that the response is accelerated; the change that results proceeds in the SAME direction as the initial change, causing the variable to deviate further and further from its original value or range (e.g. blood clotting, labor contractions)
Homeostatic imbalance
Most disease can be regarded as a result of this; abnormal conditions caused by age (less reactive and efficient systems) or by an overwhelmed negative feedback mechanisms which then allows destructive positive feedback mechanisms to take over (e.g. heart failure)
