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Endocrine > Calcium and Phosphate > Flashcards

Calcium and Phosphate Flashcards

1
Q

About 50% of Ca is free and

A

50% is bound to protein

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2
Q

Ca is mostly bound to

A

albumin

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3
Q

Chvostek and trousseau sign indicate

A

hypocalemia, alkalosis, or high albumin (twitching, hyperexcitable)

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4
Q

Acidosis

A

hypercalemia (H+ binds albumin) decreased excitability and muscle weakness

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5
Q

Phosphate is the major anion, hypophsophatemia

A

85% is unbound, cellular ATP production is impaired

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6
Q

What modulates phosphate metabolism?

A

vitamin D3

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7
Q

What modulates Mg exchange?

A

Vitsamin D3 and PTH

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8
Q

Amorphous crystals

A

labile crystals of Calcium phosphate

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9
Q

Osteocytic osteolysis

A

fats exchange of Calcium in the crystals with the ECF compartment (NOT bone resorption)

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10
Q

Hydroxyapatite crystals

A

within the matrix of the bone, slow exchange of Ca

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11
Q

BONE resorption

A

Ca exchange from hydroxyapatite crystals

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12
Q

Osteoblasts

A

surface of bone, secrete alkaline phosphatase to precipitate Ca and produce bone collagen

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13
Q

Osteoclasts

A

multinucleated, precursor cells, dissolve hydrxyapatite by secreting collagenase to degrade the collagen matrix

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14
Q

Alkaline phosphatase for _________ and collagenase for _________

A

bone production; bone resorption

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15
Q

Osteocytes

A

inactive, within matrix, conduit for Ca retrieval from amorphous crystals and delivery of Ca to ECF

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16
Q

bone remodeling

A

osteoblastic and osteoclastic activity for normal bone growth and adaptation to mechanical load

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17
Q

Bone remodeling occurs at the

A

resorption at ENDOSTEAL and deposition at PERIOSTEAL

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18
Q

Bone remodeling

A

quiescence, activation, resorption, reversal, and formation

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19
Q

quiescence

A

osteoblast inactivity

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20
Q

activation

A

osteoblast precursor stimulate collagenase release

21
Q

Resorption

A

recruitment of osteoclasts and binding to integrins, form ruffled membrane and secrete H+ and enzymes to degrade the collagenase, collagen, and hydroxyapatite

22
Q

Resorption results in

A

Ca and Po delivery to ECF

23
Q

Reversal

A

Macrophages appear on resorbing surface

24
Q

Formation

A

osteoblasts secrete collagen type I and hydroxyapatite crystals mineralize

25
Q

Even though more Ca is contained in the cortical bone (shaft) Ca is replaced more often in the

A

trabecular bone (ends)

26
Q

PTH production

A

peptide, chief cells in parathyroid gland

27
Q

PTH secretion

A

PTH in inverse to [Ca] 3.5-5.5 and vitamin D is permissive

28
Q

Estrogen and testosterone effect on PTH

A

inhibits PTH

29
Q

What inhibits PTH?

A

GH, IGF-1, Insulin

30
Q

What activated PTH?

A

Cortisol, T3 and T4, and

31
Q

The only example where an increase in [Ca] inhibits excretion

A

PTH

32
Q

Reciprocal relationship between Ca and Po

A

an increase in PO can impair mobilization of Ca

33
Q

What if you cannot excrete PO due to renal failure?

A

high levels of PO would result in low levels of Ca due to their reciprocal relationship

34
Q

Vitamin D3

A

Made in the dermis (isomerized by light waves)

35
Q

Vitamin D3 metabolism

A

highly regulated hydroxylations

36
Q

Vitamin D3 is activated in response to

A

low plasma Ca, low PO in plasma, D3 deficiency, or HIGH PTH

37
Q

Vitamine D3 inactivated by

A

normocalcemia or hypercalemia, normophosphatemia or hyperphosphatemia

38
Q

Vitamin D mechanism

A

bound to gc-globulin transport acts like steroid hormone with intracellular receptors

39
Q

Vitamin D action

A

increase Ca and PO, increased absorption, increased resorption

40
Q

Calcitonin secretion

A

parafollicular cells of thyroid gland

41
Q

Calcitonin mechanism

A

INHIBIT BONE RESORPTION no evidence of bone formation

42
Q

Hypocalcemia

A

stimulated PTH, renal resorption of Ca, Ca release from bone, vitamin D3 production, increased intestinal Ca absorption (promote renal excretion of PO)

43
Q

Renal Failure

A

Hypocalcemia due to inability to excrete PO and low Vitamin D3 which will alter PO and Ca concentrations

44
Q

Hypocalcemia

A

deficient PTH, deficient VitaminD, renal failure

45
Q

Hypercalcemia

A

reverse effects by lowering PTH and secreting Calcitonin (decreases resorption)

46
Q

Hypophosphatemia

A

could be related to hypercalcemia; stimulates Vitamin D3 which will increased both PO and Ca, but hypercalcemia will inhibit PTH decreasing the Ca reabsorption (increased urine excretion of Ca)

47
Q

Aging and its effect on Bone

A

decreased Vitamin D and decreased Ca and PO absorption from GI

48
Q

Menopause and decreased estrogen

A

increased sensitivity of bone to PTH INCREASED RESORPTION

49
Q

Immobilization

A

bone resorption

Endocrine (9 decks)

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