Positive and Negative Feedback. Positive Feedback Designed to accelerate or enhance a response that has already started Pushes systems outside of their.
Post on 18-Jan-2016
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Positive and Negative Feedback
Positive Feedback
• Designed to accelerate or enhance a response that has already started
• Pushes systems outside of their normal range
Positive Feedback Example
• Childbirth– Pressure receptors encourage the release of
Oxytocin in the Pituitary Gland– Oxytocin causes contractions – Pressure increases on the pressure sensors– After the child is born, the pressure receptors
are no longer stimulated and Oxytocin production ceases
Pressure Sensors cause the release of oxytocin
Oxytocin causes contractions to intensify
More intense contractions cause more pressure
Positive Feedback Example
• Blood Clotting– A tear in the capillary wall exposes collagen– Exposed collagen encourages platelets to adhere– Platelets release chemicals to encourage platelet
production and to encourage constriction of the wound
– This constriction exposes more collagen– More platelets to adhere and release chemicals
encouraging the production of more platelets
Collagen is exposed in the damaged capillary
Platelets bind to the collagen
Platelets release chemicals into the blood
Chemicals increase platelet production and constrict the
capillaries exposing more collagen
Negative Feedback
• Designed to maintain the body systems within appropriate parameters
• Keeps delicate systems working ideally and preserves body function
Negative Feedback Examples
• Calcium Levels– If calcium levels in the blood are too low the
parathyroid releases parathyroid hormone– Parathyroid hormone causes the bones to
release calcium– Parathyroid hormone also causes intestines
to absorb more calcium– Blood calcium levels then return to normal
Negative Feedback Example
• Calcium Levels cont’d– If your calcium levels in your blood are too
high– The thyroid produces calcitonin– Calcitonin increases the uptake of calcium to
the bones– Calcium levels return to normal
Facebook Activity
• Create a Facebook Profile for a gland on paper– Profile picture of what the gland looks like– Where the gland is located in the body– The hormones the gland secretes– The tissues or hormones it interacts with, or
interact with it and the effects– Conditions that may result from a malfunction
of the gland
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