Calcium Regulation and Pharmacology Flashcards Preview

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Flashcards in Calcium Regulation and Pharmacology Deck (66):
1

What is calcium?

- major EXTRACELLULAR divalent cation (Ca2+)
- 45% ionized Ca2+ exerts physiologic effects

2

Where is 99% of calcium stored?

- in BONE

3

How do we get calcium?

- in the diet.

4

Do men have more calcium than women?

- YES by a little bit.

5

*** 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

6

Does calcium use a second messenger system?

- YES

7

What does endocrine regulation of extracellular calcium affect?

- entry at the intestines
- secretion/reabsorption at the kidney
- storage/release (bone absorption/release of Ca2+)

8

What regulates calcium absorption/excretion?

- kidneys and bones

9

What are osteoCLASTS?

- break down (reabsorb) bone to INCREASE serum calcium

10

What are osteoBLASTS?

- build up bone thus DECREASING serum calcium

11

How is calcium absorbed?

- ACTIVE vit. D-dependent transport in PROXIMAL DUODENUM.
- FACILITATED DIFFUSION in small intestines
- efficiency is inversely related to Ca2+ intake.

12

Does calcium intestinal absorption increase or decrease with age?

- decrease

13

Is vitamin D a fat or water-soluble vitamin?

- FAT-soluble.
*remember A, D, E, and K are fat soluble.

14

What happens to the QT with HYPOcalcemia?

- WIDENS the QT

15

What happens to the QT with HYPERcalcemia?

- NARROWS the QT

16

What depresses intestinal calcium transport?

- glucocorticoids
- phenytoin (used for seizures)

17

What do disease states do to calcium?

- lead to fecal loss of calcium

18

What regulates urinary excretion of Ca2+?

- PARATHYROID HORMONE (PTH)
*urinary calcium loss is influenced by filtered Na2+ and presence of non-reabsorbed anions.

19

Can lactation and sweat affect loss of calcium?

- YES

20

Can some diuretics increase urinary loss of Ca2+?

- YES, furosimide
*thiazides will reabsorb calcium!

21

How often is your entire bone mass modified?

every 6 months via osteoclasts and osteoblasts

22

What regulates blood calcium levels?

- PARATHYROID hormone by regulating osteoclasts and osteoblasts.

23

What factors influence bone remodeling?

INCREASE in the activation of remodeling units:
- hyperthyroidism
- hypervitaminosis D
- hyperparathyroidism

24

What is the etiology of impaired osteoBLASTIC function?

- high dose CORTICOSTEROIDS
- high dose ETHANOL

25

What will augment osteoCLASTIC resorptive capacity?

- decreased estrogen

26

What promotes HYPOcalcemia?

- deprivation of Ca2+ and vitamin D

27

What stimulates PTH release?

- HYPOcalcemia

28

What are the signs of symptoms of HYPOcalcemia?

- tetany
- paresthesias
- increased neuromuscular excitability
- laryngospasm
- muscle cramps
- tonic-clonic convulsions (GRAND MAL)

29

If a patient is having a seizure what should you not forget to check?

- CALCIUM

30

What are some hypocalcemic states?

- hypoparathyroidism
- advance renal insufficiency
- excessive use of K+ phosphate in the tx of DKA
- sodium fluoride (large quantities)
- massive transfusions with CITRATED BLOOD.

31

How do we treat HYPOcalcemia?

- REPLACEMENT (dietary Ca2+ or IV calcium chloride)
- oral supplements often in combination with vitamin D

32

What can cause HYPERcalcemic states?

- very high ingestion of Ca2+ (rare except in hypothyroidism)
- milk alkali syndrome
- hyperparathyroidism (MOST COMMON)
- systemic malignancy (looks like holes in the bones)
- vitamin D excess

33

How do we treat HYPERcalcemia?

- fluids
- increased Ca2+ EXCRETION (loop diuretics)
- corticosteroids
- calcitonin
- sodium phosphate
- EDTA

34

What substances are involved with calcium regulation?

- phosphate= binds ca2+
- PTH
- vitamin D
- calcitonin (tones the bones), lowering serum calcium levels

35

What does phosphate do to calcium?

- causes precipitation, thus lowering calcium

36

What does PTH do to phosphate?

- increases urinary excretion of phosphate by preventing its reabsorption in the kidney.

37

What does vitamin D do to phosphate absorption in the DCT?

- increases it

38

What are some pathologic states of phosphate?

- RICKETS= vitamin D deficiency
- osteomalacia
- chronic renal failure

39

What does PTH do to intestinal Ca2+ absorption?

- increases it

40

What does PTH do to calcium in the bone?

- mobilizes it by activating osteoCLASTS to break down bone.
*aka increases overall bone resorption.

41

Where is Vitamin D (calcitriol) synthesized?

- in the skin

42

What stimulates calcitonin?

- hypercalcemia, to lower blood calcium.

43

What can stimulate calcitonin release?

- glucagon
- gastrin
- serotonin

44

What does calcitonin do?

- causes direct inhibition of osteoclastic bone resorption, which results in HYPOcalcemia and HYPOphosphatemia.
- lowers calcium and phosphate in the blood

45

What is Alendronate?

- inhibits osteoclast-mediated bone resorption

46

What is Raloxifene?

- reduces bone turnover
- decreases LDL levels (no change on HDL)
- no increase in triglycerides

47

What are the 2 parts of the adrenal glands?

- cortex (outer part)
- medulla (inner part)

48

What does the adrenal cortex produce?

- minearlocorticoids= aldosterone (N+/K+ balance)
- glucocorticoids= cortisol (raises glucose and suppresses inflammatory response).
- adrenal androgens

49

What does aldosterone do?

- causes the DCT to reabsorb Na+ and thus water

50

What are the 3 levels of the adrenal cortex?

- zona GLOMERULOSA= produces ALDOSTERONE
- zona FASCICULATA= produces CORTISOL
- Zona RITICULARIS= DHEA, androstenidione

51

What does the adrenal medulla?

- EPINEPHRINE= increased chronotropy and inotropy, bronchodilation, increased glucose
- NOREPINEPHRINE= ditto

52

What is needed for synthesizing adrenal hormones?

- CHOLESTEROL

53

What is prednisone?

- glucocorticoid that is 4x as potent as cortisol, used to suppress the inflammatory response.

54

What is mehtylprednisolone?

- synthetic glucocorticoid that is 5x as potent as cortisol.

55

What is dexamethasone?

- glucocorticoid that is 30x as potent as cortisol

56

Do plasma proteins bind adrenocortical hormones?

- YES

57

Where are adrenal hormones metabolized?

- liver

58

What electrolyte problems can we see with low levels of mineralocorticoids?

- sodium chloride wasting and high potassium in the blood.

59

What can HYPOkalemia lead to?

- muscle weakness
- cardiac conduction issues

60

What acid base issue can elevated aldosterone cause?

- METABOLIC ALKALOSIS
*remember H+ follows K+

61

What do glucocorticoids do?

- stimulate GLUCONEOGENESIS in the liver
- decreased glucose utilization by cells
- STEROID INDUCED DM
- reduction of cellular protein
- increased liver and plasma proteins

62

How does cortisol mitigate stress and inflammation?

- stabilize lysosomes
- decreases eosinophils and lymphocytes

63

What is Addison's disease?

- hypoadrenalism (mineralocorticoid deficiency)= loss of NaCl and water, hyponatremia, hyperkalemia, mild acidosis, increased RBC concentration, decreased CO, and death.

64

What will glucocorticoid deficiency lead to?

- low glucose
- muscle weakness
- respiratory difficulties

65

Do the adrenal glands contribute to precursors of melanin pigmentation?

- YES

66

How do we treat loss of glucocorticoids or mineralocorticoids?

- replace them