1. Notes: Homeostasis

2. Homeostasis Homeo=unchanging stasis-=standing
Keeping internal conditions the same despite changes in the outside environment.
Conditions within the body must remain within a narrow range
Blood pH= 7.41
Blood Sugar Level= mg/dL
Blood osmolality = 275 to 295 mosm/kg
Body Temperature=98.7 (F)
Blood Pressure= 120/ /90
BUT……..You live in constantly changing environment

3. How is this done?....FEEDBACK MECHANISMS
Parts of Feedback Mechanisms
Sensors: also called receptors, gather information about conditions inside and outside body
Control center- receives information from the sensors and responds (E.g. brain)
Communicate: controlled by nervous and endocrine system and carry messages to target.
Targets: any organ, tissue, or cell that changes its level of activity in response to message

4. Negative Feedback Mechanisms
Control system that counteracts any change in body that moves condition above or below set point
The last step (response) decreases the first step (receptor).
Examples: Glucose and Insulin, Body temperature and sweat

5. Positive Feedback Mechanisms
Uses information from sensors to increase rate of change
A secondary substance increases production or rate of the initial substance or receptor.
Not as common as negative feedback
Important when rapid change is needed
Example: Oxytocin and contractions during childbirth, Platelets during blood clotting