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endocrine S. Horvath > Calcium > Flashcards

Calcium Flashcards

1
Q

Why is Ca important?

A
  • nerve conduction
  • bone formation
  • muscle formation
  • blood coagulation
  • cerebral and cardiac function
  • capillary permeability
  • cell growth and division
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2
Q

the body contains ___kg of CA

A

1-2

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3
Q

How much Ca Is in the ionized (active) form?

A

50%

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4
Q

T/F: the ionized form is the most important form for calcium functions on heart, the nervous system, and bone formation

A

True

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5
Q

Of the non-ionized Ca, ___ is protein bound (primarily albumin) and ___ is combined with anions (diffusible)

A

41%, 9%

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6
Q

plasma calcium equilibrates with bone Ca++, but only ___ of bone Ca is readily exchangeable

A

0.5%

the rest is slowly exchangeable

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7
Q

T/F: Hypercalcemia causes nervous system excitement

A

FALSE - hypo

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8
Q

Hypocalcemia causes increased neuronal permeability to __, easy action potentials

A

Na

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9
Q

Chvostek’s sign is caused by ___ and is recognized how?

A

hypocalcemia, tapping facial nerve leads to twitching

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10
Q

T/F: Hypocalcemia leads to a prolonged QT

A

TRUE

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11
Q

Hypocalcemia leads to __ and ___. most common is in the ____, carpopedal spasm

A

tetany, seizures, hand

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12
Q

The chief manifestation of hypercalcemia is

A

skeletal muscle weakness

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13
Q

S/S that are a result of HYPERca –> nervous system depression include

A

short qt, long PR interval, constipation, anorexia

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14
Q

Treatment for HyperCa

A

maintain UOP, hydrate, administer mithramycin in severe cases

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15
Q

The body contains __kg of phosphorus, and it is located __ skeletal, __% muscle/tissue, and __% ECF

A

1, 85, 15, 1

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16
Q

__% of Phos circulates in plasma protein bound

A

12

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17
Q

T/F Phos levels fluctuate significantly more than Ca++ because Ph moves between ECF and bone as well as between ECF and ICF

A

TRUE

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18
Q

Phos enters ECF via what 3 routes

A

GI, ICF, bone

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19
Q

phos leaves via what 3 routes

A

urine, ICF, bone

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20
Q

T/F The major control site for phosphorus is the liver

A

FALSE - kidney

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21
Q

___ increases urinary excretion of phos

A

parathyroid. Calcitonin to a lesser extent

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22
Q

GI absorption of Phos is increased by

A

1,25 D3

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23
Q

Parathyroid consists of __ glands

A

4

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24
Q

where is the parathyroid located

A

behind the upper and lower poles of the thyroid

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25
Q

Parathyroid contain mainly ___ cells and ___ cells

A

chief, oxyphil

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26
Q

T/F Oxyphil cells secrete PTH

A

FALSE Chief cells

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27
Q

Synthesis and secretion of PTH is related to ____ concentrations in the blood.

A

Calcium

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28
Q

3 reasons for parathyroid enlargement?

A

prolonged stimulation, pregnancy, lactation

29
Q

calcium homeostasis slide???

30
Q

T/F PTH Increases reabsorption of Ca++ in the kidney’s proximal tubules

A

FALSE - distal tubules

31
Q

T/F PTH decreases reabsorption of phosphate in the renal tubules

32
Q

PTH increases ___ reabsorption to mobilize __ and ___

A

bone, ca, phos

33
Q

PTH increases the production of 1,25-dihydroxycholecalciferol which is a Vit D metabolite which enhances _____

A

intestinal Ca++ absorption

34
Q

the major stimulus for PTH is

A

low serum Ca++ level

35
Q

Bone resorption is the process by which

A

osteoclasts break down bone and release Ca from bone fluid to blood

36
Q

Rapid: activation of ____ for rapid reabsorption

37
Q

Delayed: activates/proliferates ___ for bone matrix break down

A

osteoclasts

38
Q

increases in PTH results in ___ ca and ____ phosphate in the serum

A

increased, decreased

39
Q

Increases in PTH results in increased excretion of ___, ____ and ___ by increasing ___ ___ and ____ reabsorption, largely in distal tubules and collecting ducts

A

phosphate, potassium, sodium, calcium, magnesium, hydrogen.

40
Q

Where is calcitonin produced

A

the parafollicular (clear or C cells) of the thyroid

41
Q

T/F Calcitonin has a similar affect of PTH

A

FALSE - opposite effect

42
Q

Functions of Calcitonin:

A

inhibits bone reabsorption, increases urinary excretion of calcium

immediate: decreases osteoclastic activity and osteolysis of osteocytes
delayed: decreases osteoclast formation

43
Q

calcitonin will cause ___ in serum ___ and ____ levels, and increased excretion of both

A

calcium, phosphate

44
Q

T/F Excess or deficiency of calcitonin leads to defects in bone or calcium metabolism

A

FALSE- effect is weak

45
Q

T/F Vitamin D has a potent effect to increase calcium absorption from the intestinal tract

46
Q

Vitamin D has important effects on both bone ____ and bone ____

A

deposition, absorption

47
Q

T/F Vitamin D is an active substance

A

FALSE - must be converted to its active product 1,25 dihydroxycholecalciferol

48
Q

Vitamin D3 is formed in the skin by _____

A

exposure to sunlight

49
Q

Vitamin D3 is converted to 1.25-dihydroxycholecalciferol by the ____

50
Q

GI absorption of Ca++ is increased by _____

51
Q

urinary excretion is _____ by PTH and _____ by calcitonin

A

decreased, increased

52
Q

bone resorption is increased by ____ and inhibited by ____

A

PTH, calcitonin

53
Q

____ is usually a result of a surgical damage to the glad during thyroid surgery

A

hypoparathyroidism

54
Q

Calcium levels fall below normal in 24-72h which results in 4 things:

A 
-tetany
(calcium ion interferes with membrane transport, interferes with the relaxation of the muscle)
-muscle cramps
-grand mal seizures
-cardiovascular collapse
55
Q

treatment of hypoparathyroidism

A

-PTH (expensive, short half life)
-high ca and Vit D intake
(occasionally 1/25-D3 necessary)

56
Q

T/F: hypomagnesemia can cause hypocalcemia resistant to calcium

A

TRUE - must treat first with magnesium. magnesium suppresses the release of PTH

57
Q

primary hyperparathyroidism is caused by?

A

inappropriate hyper secretion of PTH resulting in hypercalemia

58
Q

Primary hyperparathyroidism effects

A
  • hypercalcemia
  • hypercalciuria
  • hypophosphatemia
  • hyperphosphaturia
  • bone mineralization
  • shortened QT interval, depresses relaxation
  • causes kidney stone formation as Ca+++ mobilized from bone must eventually be excreted by kidneys
59
Q

most common cause of hyperparathyroidism is ____ hyperplasia or tumor

A

parathyriod

60
Q

T/F Pregnancy may stimulate the parathyroids

61
Q

Secondary hyperparathyroidism is caused by

A

hypersecretion of PTH in response to hypocalcemic stress

62
Q

secondary hyperparathyroidism results in

A

osteomalacia (inadequate mineralization of the bones)

63
Q

vitamin D deficiency is caused by

A
  • inadequate dietary syndrome - often due to fat malabsorption syndrome
  • inadequate sunlight
64
Q

Vit D deficiency results in ____ in adults and ____ in children

A

osteomalacia, rickets (bones fail to mineralize, epiphyses fail to fuse, epiphyseal plates widen and bowing and fractures occur)

65
Q

T/F Vitamin D deficiency causes decreased absorption of ca and phos, decreased serum calcium and phosphate, increased PTH and increased bone resorption

66
Q

1g of calcium chloride contains the equivalent amount of ionized calcium as __g of calcium gluconate

67
Q

Calcium therapy is indicated in patients with hypotension associated with either ___ or ___

A

CCB’s or beta adrengeric blockers

68
Q

calcium is indicated in causes of _____ as may occur in parturients being treated for preeclampsia

A

magnesium toxicity

69
Q

calcium is contraindicated in patients with ____ as it may cause lethal arrhythmias

A

digoxin toxicity

endocrine S. Horvath (6 decks)

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