Parathyroid Flashcards
(31 cards)
In what species of animals is calcitonin and excretion of calcium most important and why?
Fish. They live in an environment where there is a higher amount of calcium so it was a bigger challenge for them to get rid of the calcium
Where is the most of calcium stored?
In the bone as hydroxyapatite
What is the role of the kidney in calcium regulation?
It resorbs the calcium to be reabsorbed by the body and a small amount of it is excreted out
What is the function of calcium?
- Structural integrity
- Messenger or regulator ion
Abnormal Ca can lead to what?
- Calcification of soft tissues
- Osteoporosis
- Repro disorders
- Muscle tetany
Where is the parathyroid?
4 glands
: 2 craniolateral and 2 caudomedial
What are the two main cells type?
- Chief cells-make PTH clear
- Oxyphil- dont know what they do
What type of hormone is PTH?
Peptide
What is the function of PTH?
- Increase plasma Ca and decrease phosphate in ECF
- Effect bone and kidney metabolism of Ca
- indirect effect on GI tract
What is the effect of Ca on PTH?
Inhibits vesicle release of PTH so it can not be released
What is the effect of PTH on bone?
- Increase osteoclastic activity
- Resorption
- Release Ca from bones
- Release phosphate from bones
- inhibit bone formation
What is the effect of PTH on the kidney?
- Increase reabsorption of Ca and decrease reabsorption of P
- Formation of Calcitriol (1, 25 vitamin D)
- Excrete phosphate in the urine
What is PPARgamma?
this is a gene that is responsible for balancing bone metabolism. It inhibits osteoblast differentiation and causes them to become osteoclasts to release calcium from the bones
What is the most important pool of calcium?
50% in ECF is ionized and freely diffusible
What prevents precipitation of hydroxyapatite?
Inhibitors that stabilize more soluble salts by osteocalcin or pyrophosphate
Why is there such a hige buffering capacity in BLood ca?
- Other calcium salts which is more soluble than hydroxyapatite
- Rapid infusion of calcium salts
What is the purpose of amorphous crystals of calcium?
During rapid loss of calcium get a rapid release of calcium to buffer through these crystals
Do acute changes in P have profound effects on the body?
No not really
What is the effect of hypocalcemia?
- Excites CNS
- Tetany
- Affects blood clotting
What is the effect of hypercalcemia?
- Depress CNS
- Lengthens QT interval
- Calcium phosphate deposition
What is the role of vitamin D?
Cause more absorption of Ca in GI tract
What do osteoclasts release when they eat bones?
Ca and Phosphate
In bones what is the more diffusible form of calcium?
Amorphous crystals because the hydroxyapatite is less accessible and more stable
What type of bones are first used to release more Ca?
Cancellous bones: it is more accessible has high surface area and a greater amount of amorphous calcium phosphate
