Feedback Control

three types of receptor regulation

down regulation, up regulation, and desensitization

down regulation of a receptor is caused by

too much hormone acting on a cell leads to a decreased number of receptors

up regulation of a receptor is caused by

too little hormone acting on a cell leads to an increased number of receptors

desensitization of a receptor is caused by

too much hormone acting on the cell decreases receptor response

difference between receptor down regulation and desensitization

in response to too much hormone, down regulation decreases number of receptors and desensitization decreases receptor response

feedback control

system output controls the system

controlled variable

aspect that is controlled

setpoint

value that control variable should be at

controller

makes control variable go up or down

sensor

measures level of control variable

integrator

compares control variable with the setpoint

control signs

(+) or (-)

(+)

greater input causes greater output, less input causes less output

(-)

greater input causes less output, less input causes greater output

(-) is also called

an inversion

negative feedback will have how many inversions

an odd number

negative feedback affect on homeostasis

maintains it

positive feedback will have how many inversions

an even number or none

positive feedback has what effect on homeostasis

disrupts it

how is positive feedback usually terminated

by an endpoint

in a feedback problem where everything is normal, where should you start?

at the control variable that the system works to maintain

in a feedback problem with a specific problem/interruption of the loop, where should you start

at the interruption

how does a tumor work in a feedback problem

a tumor will always produce excess hormone, no matter what feedback it receives

tumor response to negative feedback

continual increase in hormone production/concentration