KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment.

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KEY CONCEPT Homeostasis is the regulation and
maintenance of the internal environment.
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Conditions within the body must remain within a
narrow range.

• Homeostasis involves keeping the internal
  environment within set ranges.

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• Control systems help maintain homeostasis like
  ...

• Sensors gather data
• ?senses
• B. Control Center receives data, interprets
  info, sends messages out.
• ? brain
• C. Communication System delivers messages to
  target organs, tissues
• ?PNS (e.g. motor neurons)
• D. Targets respond to change.
• ?muscles, glands (release hormones)

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Negative feedback loops are necessary for
homeostasis.

• Feedback compares current conditions to the
  bodys comfort levels (Set Ranges).
• Negative feedback counteracts change and brings
  the body back to homeostasis.

Negative Feedback Loop
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• Positive feedback increases change away from the
  set points. Needed for rapid change in the body.

Ex. 1 Torn blood vessels stimulates the
release of clotting factors to stop blood flow.
Ex. 2 Growth hormones stimulate cell division
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• Thermoregulation The process of maintaining a
  steady
• body temperature under a variety of conditions.
• Systems Involved
• Muscular
• Integument (skin)
• Respiratory
• Circulatory
• Nervous (hypothalamus in brain)
• Endocrine (hormones, feedback)

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A disruption of homeostasis can be harmful.

• Homeostasis can be disrupted for several reasons.
  
• sensors fail (dont detect changes)
• targets do not receive messages (nerve issues)
• injury (overwhelm homeostatic controls)
• illness (viruses or bacteria)
• Disruption of homeostasis can begin in one organ
  and cause a chain reaction in the others
  therefore causing a major body disturbance.

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• Organ systems must also work together to keep the
  organism healthy.

• Organ systems work together to produce Vitamin D.
• Thermoregulation maintains a steady body
  temperature.

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Stimulus Body Temp. Sensors
Body Temperature Regulation
Target Muscles/Glands
Commun.Syst Nerve Receptors
Control Syst. Brain