Homeostasis

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Homeostasis
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Homeostasis

• Definition the maintenance of equilibrium in
  bodily processes.
• Example the maintenance of the volume of bodily
  fluid and the specific composition of the
  different bodily fluids.

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Components of Feedback Systems

• Receptorssensory receptors, chemical receptors,
  oxygen receptors, etc.
• Control centerevaluates input and regulates
  output of nerve impulses or release of chemical
  signals.
• Effectora body structure that receives output
  from the control center and produces a response.

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Negative Feedback System

• Receptorsbaroreceptors in the blood vessels
  sense change in blood pressure.
• Control centerevaluates input from baroreceptors
  and releases chemical signals.
• Effectorsthe heart receives chemical signals and
  adjusts blood pressure.

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Positive Feedback System

• Receptorsstretch sensitive nerves in cervix send
  signals to the brain.
• Control centerthe brain evaluates the signal and
  releases oxytocin.
• Effectorsthe muscles in the uterine wall
  contract more forcefully, which increases signals
  to the brain.

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Bones role in calcium homeostasis

• The importance of calcium
• Proper functioning of muscle and nerve tissue
• Blood clotting
• Cofactor in many enzymatic reactions
• Blood levels of calcium need to be maintained at
  around 9-11mg/100mL.
• Ca2 levels too high can lead to cardiac arrest.
• Ca2 levels too low may halt respiration.

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Homeostasis
stimulus
Stimulus decreases calcium
Controlled condition
Calcium gt 9mg/100mL andlt 11 mg/ML
Disrupted condition
Calcium lt 9mg/100mL
Parathythroid gland cells detect lowered Ca2
PTH gene turned on
Osteoclast activity increases and kidneys retain
Ca2 and produce calcitriol
Response altering condition
Ca2 gt 9mg/100mL
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Homeostasis Hypercalcemia
stimulus
Controlled condition
Disrupted condition
Response altering condition
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Homeostasis Osteoporosis I
stimulus
Controlled condition
Disrupted condition
Response altering condition
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Homeostasis Osteoporosis II
stimulus
Controlled condition
Disrupted condition
Response altering condition
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Homeostasis Rickets
stimulus
Controlled condition
Disrupted condition
Response altering condition