Homeostasis What is it?

What is the definition of Homeostasis? A process or system that is in balance What are some examples of homeostasis? –You sweat when you get too hot or shiver when you get cold= maintain body temperature

What are some conditions in the body that need to be regulated? Temperature Blood pressure Salt concentration Changes in the body or one ’ s environment can sometimes cause these conditions to increase or decrease

Example 1 Notice your resting heart rate, breathing, and temperature … Do jumping jacks (quickly) for 2 minutes What has changed? oBreathing, heart rate, maybe sweating.

Explanation of Example 1 During exercise, muscles use large amounts of nutrients (such as sugar) and oxygen Waste products (such as CO 2 ) build up quickly Result = the body is temporarily out of balance so breathing and heart rate must increase –This brings the sugars and O 2 to the internal environment –Expelling unneeded compounds (such as CO 2 ) Exercise may also increase body temperature –Body sweats (perspires) to cool the body –The body temperature remains relatively constant during exercise (heat gain is balanced by heat loss)

Example 2 Note your resting heart rate and breathing patterns Relax for a moment, close your eyes, listen to the sounds … Notice your breathing as well as your heart rate

then… What has changed? –Breathing and heart rate have increased, you may have jumped. –How do you feel now?

Explanation of Example 2 Adrenaline and other chemicals are activated –increase heart rate, palpitations, increase in blood pressure –Were you ready to run or attack? This state of being is called the fight or flight mechanism

What would happen if you maintained this bodily state forever? Write down some thoughts to discuss. –You would wear out your body Overexertion of the muscles (including the heart) Overexertion of the lungs Overexertion of the endocrine system (releases adrenaline) Overexertion of the blood vessels (carrying needed nutrients to needed parts of the body)

How do we return to a normal state? How does homeostasis kick in? Sometimes it doesn ’ t … this is why people have panic attacks and chronic anxiety. –The body does not return to its normal state (may last a few hours or even days)

Monitoring and Controlling Homeostasis The brain monitors and controls homeostasis by generating a series of internal signals –Example: when you are hot and when you are cold Hot= brain signals activate perspirations and blood rushing to the skin Cold= brain signals activate muscle twitching (shivering) and lowering blood flow to the skin- generates heat quickly

Monitoring and Controlling Homeostasis Actions and reactions continue until the temperature is normal or balanced state is reached –Example: Acts much like a home heating and cooling system (model) When a house is too cool- heat comes on until desired temperature is reached and will continue to turn on if the temperature happens to fall When a house is too hot- air conditioning comes on until desired temperature is reached and will continue to turn on if the temperature gets to warm –Specialized cells in the brain act as the thermostat

Homeostasis Animations (Fluid balance/Dialysis Animation) php