Chapter 1.2 - Homeostasis and Feedback Control

homeostasis

state of relative constancy in the internal environment, maintained by negative feedback loops

basic pathway of homeostatic feedback

sensor to integrating sensor to effector

set point

normal value of a physiological variable (ex: normal blood pH)

negative feedback loop

system of sensor, integrating center, and effector that works together to produce a change in the opposite direction of a physiological variable

dynamic constancy

when physiological variables fluctuate over time, but maintain an average of the set point

positive feedback

when the effectors amplify the changes that stimulated the effectors (ex: thermostat increasing temperature in response to rising temperature)

how do positive and negative feedback loops work together?

positive feedback loops amplify the negative feedback response

intrinsic regulatory mechanisms

regulatory mechanisms built into the organ

extrinsic regulatory mechanisms

regulation of an organ by the nervous or endocrine systems

negative feedback inhibition

the ability for a negative feedback loop to reduce its own activity (ex: insulin decreases blood glucose and also inhibits its own production in order to prevent blood glucose from falling too far)