BIO SCI E182 Lecture Notes - Axon Terminal, Nernst Equation, Central Nervous System
2 Mar 2014
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Document Summary
Sensor: detects whether regulated variable is within desired range (thermometer is a sensor that detects temperature) Controller (or integrating center): compares regulated variable level (input from sensor) to set point or desired range, sends output to effector. Effector (or target): causes a change in a regulated variable. Sensor is constantly monitoring the changing stimulus (continuous loop) Sometimes, different types of effectors are needed for different responses. Negative feedback loop--response by effector returns regulated variable back to set point or range; homeostatic control. Positive feedback loop response by effector sends regulated variable to extreme (runaway process); not used in homeostatic control. Negative feedback controls the temperature to return to normal if it gets too high or too low. Positive feedback example: delivery of baby drives process to completion (delivery of baby) Controller: brain (when it gets oxytocin chemical signals, it sends output signal of uterine contractions) Set points for regulated variables can change with time of day/night (circadian rhythm) or season.
