1. Homeostasis is the maintenance and regulation of the internal environment within the body through feedback mechanisms that keep conditions within a narrow range. 2. Feedback mechanisms can be negative, which counteracts changes away from normal conditions, or positive, which increases the rate of change away from normal. Negative feedback is more common in the body. 3. When homeostasis is disrupted in the short term by things like exercise or illness, the body uses feedback mechanisms to return conditions to normal; however, long term disruptions like diabetes can cause lasting damage throughout the body if not regulated.

1. Investigating
Homeostasis
Nutrition Standard 1: Plan and
conduct an investigation to provide
evidence that feedback mechanisms
maintain homeostasis.

2. What is Homeostasis?
 Homeostasis is the maintenance and regulation of
the internal environment within the body.
 The body is not maintaining a constant environment
but rather a narrow range of conditions
 The body is organized so that it has many controls in
place to maintain a healthy environment

3. Homeostasis Song
From: http://www.youtube.com/watch?v=1iPndNB7mjw

4. Levels of
organization
1. Cells – Each type is specialized
2.
3.
4.
5.
to perform specific functions.
Tissues – Groups of similar cells
that work together.
Organs – Groups of different
tissues working together.
Organ Systems – Different
organs working together.
Organism – Organ systems
working together to maintain
life.

6. Feedback Mechanisms
Negative Feedback Loop
Positive feedback Loop
Negative feedback mechanisms Positive feedback loops
counteract or reverse changes
increase the rate of change
within the body if conditions
away from the normal
move above or below the
range
narrow range of conditions
Very Common in the body
Not very common in the body

7. Negative feedback: Body Temperature

8. Positive Feedback: Oxytocin Production during labor

9. What happens when
you exercise?
Heart Rate?
Temperature?
Breathing?
Anything else?

10. Disruptions in
Homeostasis
What happens when
you get a virus?
These are short term
effects that generally
have no lasting impact

11. Long Term Effects
 Long term disruption of homeostasis can cause lasting
damage.
 Example: Diabetes
 If the body fails to regulate blood glucose levels properly it
can affect the entire body
 Kidneys excrete excess glucose and water
 Fat used as energy causes increased blood acidity
 Normal cellular function is compromised throughout the body