Introduction to Homeostasis PDF

Introduction to Homeostasis Feedback Mechanisms How do thermostats work? HOMEOSTASIS... … is like your body’s thermostat  Homeostasis The process by which a constant internal environment is mai...

Introduction to Homeostasis Feedback Mechanisms How do thermostats work? HOMEOSTASIS... … is like your body’s thermostat  Homeostasis The process by which a constant internal environment is maintained despite changes in the external environment. Brainstorm What things in your body need to be kept in a particular range?  Examples of Homeostasis Blood Glucose is kept at 0.1% Temperature is kept at 37°C Systolic Blood Pressure is kept at 120mmHg Blood pH is kept at 7.35 These numbers do deviate slightly, but too much change and you cannot survive The body maintains a constant balance (steady state) through a Homeostasis series of monitored adjustments. All homeostatic control systems have 3 parts: ○ Sensor (receptor) ○ Integrator (control center) ○ Effector Sensor (receptors) Detects the change and Integrator - Processes the sends the message to the control center message and sends a response to the effector Effectors: work to bring the system back to the set point The whole idea is to keep it at a fixed point!!! Body Temperature is usually the first to pop into peoples minds….. Are we warm or cold blooded? (endothermic or ectothermic?) So what happens at the other end of the spectrum? https://www.youtube.com/watch?v=TyBKz1wdK0M Article on Raining Iguanas if you want it! What did we learn from that video?? Mammals and Birds are warm-blooded (endothermic) These organisms have internal feedback systems to regulate their body temperature. Amphibians, Reptiles and Fish are cold blooded (ectothermic) These organisms rely on the external environment to regulate their body temperature. If it’s hot, they’ll move into the shade where it is cooler If it’s cold, they’ll move into the sun where it is warmer There is a whole section on this in your textbook Positive Feedback Sometimes there is a need to enhance the output of a stimulus. Example: Childbirth Stimulus Your work for today: Draw 5 negative feedback loops using the info. on this activity sheet Ensure you identify the: Stimulus Receptor Control Centre Effector Response Define Negative and Positive feedback loops (try writing it as a GIE) Find a second example of positive feedback and add it to your notes. (this often shows up on a test - hint, hint, wink, wink!) This should be a body example not fruit ripening) Try this for fun!