Flashcards in Calcium Regulation and Pharmacology Deck (66)
What is calcium?
- major EXTRACELLULAR divalent cation (Ca2+)
- 45% ionized Ca2+ exerts physiologic effects
Where is 99% of calcium stored?
- in BONE
How do we get calcium?
- in the diet.
Do men have more calcium than women?
- YES by a little bit.
*** For what is calcium needed?
- neuronal excitability
- neurotransmitter release
- cardiac function (PHASE 2 of cardiac action potential as calcium enters).
- muscle contractions
- membrane integrity
- blood coagulation
Does calcium use a second messenger system?
What does endocrine regulation of extracellular calcium affect?
- entry at the intestines
- secretion/reabsorption at the kidney
- storage/release (bone absorption/release of Ca2+)
What regulates calcium absorption/excretion?
- kidneys and bones
What are osteoCLASTS?
- break down (reabsorb) bone to INCREASE serum calcium
What are osteoBLASTS?
- build up bone thus DECREASING serum calcium
How is calcium absorbed?
- ACTIVE vit. D-dependent transport in PROXIMAL DUODENUM.
- FACILITATED DIFFUSION in small intestines
- efficiency is inversely related to Ca2+ intake.
Does calcium intestinal absorption increase or decrease with age?
Is vitamin D a fat or water-soluble vitamin?
*remember A, D, E, and K are fat soluble.
What happens to the QT with HYPOcalcemia?
- WIDENS the QT
What happens to the QT with HYPERcalcemia?
- NARROWS the QT
What depresses intestinal calcium transport?
- phenytoin (used for seizures)
What do disease states do to calcium?
- lead to fecal loss of calcium
What regulates urinary excretion of Ca2+?
- PARATHYROID HORMONE (PTH)
*urinary calcium loss is influenced by filtered Na2+ and presence of non-reabsorbed anions.
Can lactation and sweat affect loss of calcium?
Can some diuretics increase urinary loss of Ca2+?
- YES, furosimide
*thiazides will reabsorb calcium!
How often is your entire bone mass modified?
every 6 months via osteoclasts and osteoblasts
What regulates blood calcium levels?
- PARATHYROID hormone by regulating osteoclasts and osteoblasts.
What factors influence bone remodeling?
INCREASE in the activation of remodeling units:
- hypervitaminosis D
What is the etiology of impaired osteoBLASTIC function?
- high dose CORTICOSTEROIDS
- high dose ETHANOL
What will augment osteoCLASTIC resorptive capacity?
- decreased estrogen
What promotes HYPOcalcemia?
- deprivation of Ca2+ and vitamin D
What stimulates PTH release?
What are the signs of symptoms of HYPOcalcemia?
- increased neuromuscular excitability
- muscle cramps
- tonic-clonic convulsions (GRAND MAL)
If a patient is having a seizure what should you not forget to check?