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Physiology II > Endo: Calcium & Phosphate > Flashcards

Endo: Calcium & Phosphate Flashcards

1
Q

What percent of calcium is stored in bone and as what type?

A

99% as crystalline form, bone and teeth

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2
Q

Resorption of bone/Ca is stimulated by ____ and inhibited by ____

A

stim: PTH, Vit. D

Inhib: Calcitonin

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3
Q

How much calcium is stored in bone?

A

4000 mg

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4
Q

What percent of calcium is absorbed in the GI?

A

20%

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5
Q

how much calcium is in the ECF?

A

10 mg/dl, 1%

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6
Q

Of the free calcium, what percent is ionized and active?

A

50%

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7
Q

0.9% of ECF calcium is stored in…

A

soft tissue, ER, mitochondria, membranes

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8
Q

0.1% of ECF calcium is stored in

A

1/2 bound: bicarb, albumin, phosphate

1/2 free

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9
Q

Kidneys filter ____ mg of Ca per day, making up ___% of filtered load

A

10,000 mg filtered

98% of filtered load

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10
Q

how much calcium is free and bound in blood?

A

8.6-10.6 mg/dl

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11
Q

what hormone increases intestinal absorption of calcium?

A

vitamin d (1,25 dihydroxy)

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12
Q

PO4 represents ___ % of filtered load. The kidney can reabsorb ____% of PO4 when needed…

A

10% of FL

70-100% can be reabsorbed

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13
Q

What percent of phsophate can be found in bone/teeth, and what percent in muscle?

A

85% bone/teeth

15% muscle

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14
Q

In cells ___% of phosphate is in mitochondria

A

80%

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15
Q

Calcium and PO4 are regulated by which two hormones?

A

Vitamin D and PTH

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16
Q

calcium and PO4 levels require coordinated action of what 3 tissue types?

A

bone, intestine, kidney

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17
Q

PTH is released by what cell type of the parathyroid gland?

A

chief cells

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18
Q

What inhibits the activity of PTH?

A

rising Ca levels

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19
Q

Mechanism of PTH secretion from chief cells?

A

Hypocalcemia →

Parathyroid Stimulation →

PTH Release →

PTH Acts on Bone, Intestine, Kidney →

↑ Ca

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20
Q

Which pool of calcium in bone?

  • mature mineralized
  • hydroxyapatite
  • reabsorption, slow breakdown into ECF
A

Stable pool

21
Q

Which pool of calcium in bone?

  • bone fluid in canaliculi
  • amorphous crystals
  • osteolytic osteolysis, fast release of ca and po4
A

labile pool

22
Q

What separates bone from plasma within the canals?

A

osteocytic-osteoblastic membrane

23
Q

In the labile pool, what moves calcium and po4 into the plasma in the central canal?

A

PTH activated calcium pump in osteocytic-osteoblastic membrane

24
Q

PTH targets osteoblasts which regulate osteoclast activity by releasing what two substances?

A

OPG and RANKL/OPGL

25
Q

What occurs when OPGL/RANKL alone bind osteoclasts?

A

bone resorption

26
Q

What happens if OPG is co-released with OPGL/RANKL?

A

it binds OPGL/RANKL, preventing sesorption

27
Q

A mutation in which gene would decrease osteoblasts and bone ossification?

A

RUNX2

28
Q

What condition occurs as an autosomal dominant mutation in RUNX2?

A

cleidocranial dysplasia

29
Q

PTH has what two effects on the kidney?

A

increase calcium absorption

decrease PO4 reabsorption

30
Q

What enzyme does PTH stimulate, allowing activation of vitamin D?

A

1-alpha-hydroxylase

31
Q

This hormone targets intestine, bone, kidney to regulate calbindin synthesis

A

vitamin d

32
Q

Where is vitamin D first activated by hydroxylation of C25?

A

liver

33
Q

Where does vitamin D receive its second hydroxylation on C1, leading to full activation to 1,25 dihydroxy?

A

kidney

34
Q

How is vitamin d deactivatied?

A

hydroxylation on C24

35
Q

What is the role of vitamin D in bone?

A

+ PTH stim. Resorption & Remodeling

36
Q

What role does vitamin D have in the kidney?

A

Reabsorption of Ca2+ in DT and PO4 Reabsorption in PT

37
Q

What role does vitamin D have in small intestine?

A

↑ Calbindin → ↑ Ca-ATPase Activity

38
Q

What hormone has the following characteristics?

May prevent postprandial hypercalcemia

Deficiency idoes not lead to hypercalcemia

Excess does not produce hypocalcemia

May protect against excessive bone resportion

A

Calcitonin

39
Q

What role does calcitonin have, and where

A

bone and kidney

inhibits bone resorption and tubular reabsorption

40
Q

What Condition?

PTH: Increased
Vit. D: Increased
Plasma: Hypercalcemia, hyperphosphatemia
Urine: ↑ Phosphate, cAMP, Ca2+
Bone Resorption: Increased
A

primary hyperPTH

“stones, bones, groans”

41
Q

What Condition?

PTH: Decreased
Vit. D: Decreased
Plasma: Hypocalcemia, Hyperphosphatemia
Urine: Decreased PO4 & cAMP
Bone Resorption: Decreased
A

hypoPTH, surgical

42
Q

What condition?

PTH: Increased
Vit. D: Decreased
Plasma: Hypocalcemia, Hyperphosphatemia
Urine: Decreased PO4 & cAMP
Bone Resorption: Decreased (defective Gs)
A

Pseudohypoparathyroidism (Albright’s Heredetary Osteodystrophy)

43
Q

What condition?

PTH: Decreased
Vit. D: NC (no intestinal Fx)
Plasma: Hypercalcemia, Hypophosphatemia
Urine: Increased Ca, PO4 & cAMP
Bone Resorption: Increased
A

Humoral Hypercalcemia of Malignancy

44
Q

Which disease has the following S/S?

Short stature, short neck

Obesity

Shortened 4th metatarsals and metacarpals

A

Pseudohypoparathyroidism (Albright’s Heredetary Osteodystrophy)

45
Q

Which disease has the following S/S?

Tetany
Hyperreflexia, twitching, cramps
Convulsions
Trousseau sign

A

Hypoparathyroidism: Surgical

46
Q

Which disease has the following S/S?

Osteoporosis, osteomalacia
Kidney stones
Muscle weakness, decreased excitability

A

Primary Hyperparathyroidism: Stones, Bones, & Groans

47
Q

Which disease has the following S/S?

Tetany
Muscle weakness
Greenstick fractures
Skeletal abnormality: bow legs, wrists

A

Rickets - Deficiency of Vitamin D in Childhood

48
Q

Which disease has the following S/S?

Soft, weak bones
Frequent fx
Hypocalcemic tetany
hypocalcemia

A

Ostoemalacia: Deficiency of Vit. D in Adulthood

Physiology II (28 decks)

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