Page 3 - Chapter 1 Introduction to the Human Body

 High blood CO2 levels (carbon dioxide) caused by intense
exercise � our body increases respiration and heart rate to
remove excess CO2 and deliver more oxygen rich blood to our
muscles

 High blood glucose levels causing by eating a candy bar � our

body releases insulin to remove the blood sugar into our cells

Negative Feedback

In negative feedback the body responds to an extreme condition by reversing
the current direction of change (thus the term negative feedback).

Negative feedback is the primary mechanism our bodies use for regulation. There
are always three components involved. They are the sensor, control center and
the effector.

 sensor - detects the change (body is getting too warm)

 control center - receives signal (usually the brain) from sensor

and sends message to effector

 effector - reverses the initial change (skin pores begin to
perspire and blood vessels dilate)

Positive Feedback

In positive feedback the body responds to an extreme condition by promoting the
current direction of change.

One positive feedback example event in the body is blood platelet accumulation, which, in
turn, causes blood clotting in response to a break or tear in the lining of blood vessels.

Another example is the release of oxytocin to intensify the contractions that take place during
childbirth. [5]

Homeostatic imbalance.- Much disease results from disturbance of homeostasis, a condition
known as homeostatic imbalance. As it ages, every organism will lose efficiency in its control
systems. The inefficiencies gradually result in an unstable internal environment that increases