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32 Cards in this Set

  • Front
  • Back
Why is dietary calcium absorption poor?
B/c it is in divalent form
Vitamin D aids in absorption of what?
Dietary calcium
Where does the body get vitamin D from?

UV light (via skin)
What does the liver do in vitamin D processing?
Converts vitamin D into 25-hydroxycholecalciferol
What does the kidney do in vitamin D processing?
Converts 25-hydroxycholecalciferol into the active or inactive form.
What is the active form of vitamin D?
1,25 dihydroxycholecalciferol
What is the inactive form of vitamin D?
What circumstances would promote the formation of 1,25 dihydroxycholecalciferol? x3
Phosphate deficiency
Vitamin D deficiency
Calcium deficiency
What circumstances would promote the formation of 24,25 dihydroxycholecalciferol? x3
Phosphate excess
Active form present
Calcium excess

- duration of effect
- activates what? x3
Several weeks of CBP

Alkaline Phosphate
Calcium ATPase
What inhibits the conversion of 25-hydroxycholecalciferol and where?
It will inhibit itself if there is enough

In the liver
What hormone activates the conversion of 1,25-dihydroxycholecalciferol in the kidney?
Parathyroid hormone
A high increase in plasma calcium ion concentration will inhibit what hormone?
Parathyroid hormone
50% of plasma calcium is in what form?

41% of plasma calcium is in what form?

9% of plasma calcium is in what form?
Divalent form

Bound to protein

Bound to X
Stress on bones will stimulate what?
Bone remodeling
What would promote PTH secretion?
Low plasma calcium concentration
What would inhibit PTH secretion?
High plasma calcium concentration
Parathyroid gland:

- where is it
- how many are there
- how many needed for normal function
Behind thyroid


What are the two cells in the parathyroid that differentiates it from the thyroid?
Chief cells

Oxyphil cells
PTH responds to what?
Low calcium levels in plasma
What is the MAIN hormone essential for calcium homeostasis?
What is the normal levels for calcium?
9 - 10 mg/dl
What hormone works in opposition to PTH?
Parathyroid hypertrophy can result in what? x3
Parathyroid atrophy can result in what? x3
Vitamin D excess
Calcium excess
Bone absorption
PTH plateaus in how many hours
4 hours
Calitonin plateaus in how many hours
2 hours
What are the direct effects of an increase in PTH secretion? x5
1. Increase in Bone resorption
2. Increase in Active D vitamin
3. Increase in Urine Phosphate
4. Decrease in Urine Calcium
5. Decrease in Plasma Phosphate

- osteoclasts
- dangers x2
- treatment x2
Becomes almost dormant

Paralysis of laryngeal muscles
(possibly lethal if resp. effected)

PTH administration ($$)
Vitamin D and Calcium administration

- osteoclasts
- dangers x2
- treatment
Elevated activity

Weak bones
Cystic areas of osteoclastic giant cell tumors

Surgical removal of tumors

- Source
- Effective strength
- Mechanism x2
Parafollicular cells of thyroid


Quick -> inhibits osteoclast activity

Slow -> inhibits osteoclast formation