1. Mechanisms of Homeostasis

2. Homeostasis
Defined: Process where the body maintains a constant internal environment
Reactions & enzymes work best in specific conditions
Control systems adjust to changes
pH, temp, fluids
Hypothalamus senses you are cold
Thermostat turns heater off
Thermostat senses cold room
Hypothalamus turns off
Room gets back to normal
Body temp returns to normal
Hypothalamus activates muscles to shiver
Heater is activated
Heat is generated
Warm air released

3. Control Systems Sensors (aka: receptors)
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Sensors (aka: receptors)
Gather information about the body
Ex: skin senses pressure from bowling ball
Communication Center
Messages sent throughout the body
Ex: Impulse travels through your nerves
Control Center
Receives information from the sensors
Ex: Brain receives the impulse
Targets
Body part changes its activity
Ex: Brain tells foot muscles to pull away

4. Negative Feedback Loops
Regulates most of the body
Reverses the change
Ex: if your temp drops…you will shiver to reverse that
Ex: If your temp rises…you will sweat to reverse that

5. How Negative Feedback Makes You Breathe

6. Positive Feedback Loop
Does not stop the change, but…
Speeds up the change
Ex: Birth Contractions
Contractions of a pregnant woman start slow
Oxytocin released
Contractions speed up to push out baby

7. Thermoregulation Defined: Maintenance of body temperature
Example of homeostasis
Many organ systems working together
Skin: sensors provide feedback to brain
Nervous & Endocrine system: send messages to/from brain
Muscles: Start to shiver

8. Homeostasis disruption
Some changes can be too great for your body to control
Examples:
Frost bite: Sensors are destroyed
Paralysis: Messages from brain doesn’t reach target
Infection: fever, sore throat, soreness

9. Long Term: Diabetes Normally (good) Glucose in blood rises after meals
Pancreas releases insulin
Cells remove the glucose
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10. Long Term: Diabetes Normally (good) Glucose in blood rises after meals
Pancreas releases insulin
Cells remove the glucose
Type 1 (bad)
Immune system destroys pancreas cells
Pancreas unable to make insulin
Blood pH decreases as glucose builds up
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11. Long Term: Diabetes Normally (good) Glucose in blood rises after meals
Pancreas releases insulin
Cells remove the glucose
Type 1 (bad)
Immune system destroys pancreas cells
Pancreas unable to make insulin
Blood pH decreases as glucose builds up
Type 2 (bad)
Pancreas does not make enough insulin
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12. Kobe Kuiz Define homeostasis.
Name and describe the four parts of the “control system.”
What is negative feedback?
What is positive feedback?
Is the following example positive or negative feedback?
During heavy exercise your body loses water when you sweat. As a result of water loss, your body redirects the remaining water inside your body to vital parts of your body to replenish these vital organs.
What is diabetes?
How does Type I and Type II diabetes differ?