9/13/13
Calcium Homeostasis
Calcium :
•  Normal level of calcium in
blood:
8.5 – 11 mg/dl
»
Need to have enough for bones,
muscles, and nerves.
If there is too much calcium in
blood:
•
Thyroid gland – produces the hormone –
calcitonin -
Calcitonin causes:
1. Increased excretion of calcium
by the kidneys into the urine
2. Calcium is stored in the bones
3. Inhibits the production of the
parathyroid hormone by the
parathyroid gland.
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9/13/13
If there is too little calcium in
the blood..
•  Parathyroid
gland releases
parathyroid
hormone:
Calcium rich foods:
Parathyroid hormone causes:
1.  More calcium is reabsorbed back into
the blood, not allowed to be excreted
in urine – by kidneys
2.  Calcium is released from the bones
where it has been stored into the
blood
3.  More calcium is absorbed by the small
intestine – into the blood - from our
food
Effectors:
Receptor
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Picture view of entire process:
Bones - if blood is low in
calcium
Picture view of bones portion
of it:
Can you :
1.  Identify the set point, receptors, and
effectors for calcium homeostasis?
2.  Can you show a diagram or picture of
what happens when calcium is low in
the blood?
3.  Can you show a diagram or picture of
what happens when calcium is high in
the blood?
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