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Homeostasis: Negative Feedback Pathways in the human body

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Kevin Sparaco

on 9 October 2012

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Transcript of Homeostasis: Negative Feedback Pathways in the human body

Negative feedback pathways for the Human Body Homeostasis In what context have you heard the term "feedback" used before? (ie. "I've heard people say "feedback" when they talk about….)

What are some examples of "feedback"? (think about situations in school, home, jobs, sports, etc)

Write a definition of what you think "feedback" means, using 8-12 words - no more, no less! You can discuss as a group, but don't look up the meaning of the word!
Another example of a negative feedback system is a thermostat connected to a furnace and an air conditioner.

If the temperature in the room is below the temperature set on the thermostat, the thermostat signals the furnace to send warmer air into the room.
Humans also have many feedback systems/feedback loops, to maintain homeostasis. There are a variety of mechanisms and vital functions that are maintained through homeostasis; blood glucose, blood pH, blood pressure, body temperature, O2 and CO2 levels, etc.

Each feedback system has three key features:
1. A receptor that can evaluate the stimulus (change in environment) and sends a message to
2. An integrating center (Brain) that processes the information and sends a message to
3. An effector that acts on the stimulus and causes a response (reaction) in the organism.
Homeostasis in Humans: Humans maintain a temp close to 37 C (98.6 F).

To keep this constant --->shivering and sweating are homeostatic mechanisms.

--If the body temp the automatic response from the body is to shiver to maintain temperature.

In some systems, all changes are resisted. This resistance is called "negative feedback".

Negative doesn't mean "bad", it means "opposite". For example, if you want to keep a pencil in the middle of your desk, you will do what it takes to stop it from rolling off. If the pencil starts to roll to the left, you will push it back to the right. If the pencil rolls to the right, you push it back to the left. Any time the pencil starts rolling from the center, you push in the opposite (or negative) direction.

Do Now: Negative Feedback
In the event that the temperature in the room got too HIGH, the thermostat would send a message to the air conditioner to turn on. The air conditioner would push cool air into the room until the temperature drops to the set temperature. Once that temperature is reached, the thermostat stops the air conditioner would turn off. Define: Stimulus:
integrating center:

Create a flow chart

Your group has been assigned a human function/process.
1. Read the description of your process
2. Identify the stimulus, receptor, integrating center, effector, and response and write these on paper in a list.
3. Make a flow chart of the process, showing the cyclical pattern.
4. Be prepared to share your findings and flow chart with the class.

Group 2: Blood Pressure
In the example of blood pressure increasing, receptors in the carotid arteries detect the change in blood pressure and send a message to the brain. The brain will cause the heart to beat slower and thus decrease the blood pressure. Decreasing heart rate has a negative effect on blood pressure.

Group 1: Carbon Dioxide
When we exercise our muscles give off carbon dioxide as a waste product. This increase in the level of carbon dioxide in the blood. Receptors in the carotid arteries sense the change in carbon dioxide and send a message to the brain. The brain will stimulate the lungs to increase respiration. This will lower the amount of carbon dioxide in the blood Flow Chart --If the body temperature starts to rise and get too warm, (due to hot air or water, or the muscles are moving), our sweat glands respond by release water (sweating), and our skin cools from that water evaporating into the air.
What would you consider normal or acceptable range for your grades?

What feedback do you get when your grades fall BELOW that range? Who gives you that feedback?

What actions do you need to take when your grades fall BELOW that range?

What actions might you take if your grades ABOVE that range?
What's a flow chart? Example Flow Chart A flowchart is a type of diagram That represents a process showing the simple steps as shapes When the air in the room becomes warmer than the desired temperature, the thermostat signals the furnace to turn off. When the air temperature drops below that set temperature, the furnace switches on. Muscles generate heat while moving, ---> prevents our temp from falling. No, wait...
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