Homeostasis

=** __BIG IDEA__ **= =**1. Homeostasis facilitates a balanced internal/inter-cellular environment **=

 Introduction interactive on: [] ACTIVITY :

Students themselves demonstrate the role of homeostasis in our bodies

Set up a small desk fan a couple of feet in front of one of the students (at least 2-3 feet out of arm's reach). Turn the fan on --- one click, to LOW power --- and when the student feels the breeze. Some of them will say it feels nice, while others will be too chilly almost immediately. It may take a second click --- to MEDIUM power --- to get the kids who liked LOW power to feel chilly. A few will require HIGH power to feel chilly. (If all you have is a low-high fan, you may have to move the fan a foot or two closer [when it's on "high"]to get the necessary responses.

This demonstration should show that different people have different homeostatic ranges of personal comfort --- something everyone has already seen in real life, since in almost any air-conditioned room, there are still some hot, sweating people, with others cold enough to put a sweater on

This website combines both the prac with heating or cooling a person, and the comparison of heating a house: [] The desired level or concentration of one of the six factors which are regulated. ||  Thermostat set at 70 degrees Fahrenheit  || Desired level of blood pressure is 80/120 || Cells and areas of the body that are constantly monitoring the current conditions. || Metal components within the thermostat expand and contract according to the current temperature. Current temp.=65 degrees  ||  Sensory cells within the walls of the blood vessels detect the pressure of the blood flowing through the vessels. Current pressure is 100/160  || A comparison made by the nervous system between the set point and the sensor’s reading of current conditions. || The heating system detects the room temp. as too low when the metal component contracts and closes a circuit. Room temp. is lower than the set point. || Messages are sent to the brain from the sensory cells, indicating the pressure of the blood vessels. Brain makes a decision to lower blood pressure. || Parts of the body which make physical adjustments to the body, returning conditions to the desired level (set point). || The heater turns on and begins to blow out warm air. This continues until the sensor and integrator detect the desired 70 degree temp. || Arteries in the body dilate, so the space in which the blood flows is larger. This effectively lowers the blood pressure, returning to the set point level of 80/120. || ref http://www.coldwater.k12.mi.us/nicholsk/courses/chs/Phys/homeo.htm
 * **There are 4 components to homeostasis: ** || **Heating System ** || **Human System** ||
 * **Set Point-**
 * **Sensor-**
 * ** Integrator- **
 * ** Effector- **

Now work through the following two powerpoints in order





And review with the word search below:



Further review with pages 59-64, 67, 71, 76, 79 from Biozone 2009 Year 12 Biology Student Workbook

// These notes are for your reference. They contain most of the terms used in this topic: //



ACTIVITY :

Choose to demonstrate one of the following options via a presentation to the class: work in groups How homeostatic mechanisms operate under the demands of
 * 1) exercise
 * 2) pregnancy
 * 3) outer space

Use diagrams, flowcharts and illustrate with examples. Your presentation may be oral, poster or multi media.

__Assessing knowledge:__ Student learning can be assessed at the end of this Big Idea by asking them to describe the structures involved in the regulation of body temperature, blood pressure, blood glucose and water and salt in the body. Importantly, students need to be able to relate the structures involved to the functions they perform in the processs of homeostasis.

Complete this table:
 * Regulation of: || Structures involved || Specific functions ||~  ||
 * body temperature ||  ||   ||~   ||
 * blood pressure ||  ||   ||~   ||
 * blood glucose ||  ||   ||~   ||
 * Water and salt balance ||  ||   ||~   ||


 * Key Knowledge (Table of Contents)**