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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
What occurs when OPGL/RANKL alone bind osteoclasts?
bone resorption
26
What happens if OPG is co-released with OPGL/RANKL?
it binds OPGL/RANKL, preventing sesorption
27
A mutation in which gene would decrease osteoblasts and bone ossification?
RUNX2
28
What condition occurs as an autosomal dominant mutation in RUNX2?
cleidocranial dysplasia
29
PTH has what two effects on the kidney?
increase calcium absorption decrease PO4 reabsorption
30
What enzyme does PTH stimulate, allowing activation of vitamin D?
1-alpha-hydroxylase
31
This hormone targets intestine, bone, kidney to regulate calbindin synthesis
vitamin d
32
Where is vitamin D first activated by hydroxylation of C25?
liver
33
Where does vitamin D receive its second hydroxylation on C1, leading to full activation to 1,25 dihydroxy?
kidney
34
How is vitamin d deactivatied?
hydroxylation on C24
35
What is the role of vitamin D in bone?
+ PTH stim. Resorption & Remodeling
36
What role does vitamin D have in the kidney?
Reabsorption of Ca2+ in DT and PO4 Reabsorption in PT
37
What role does vitamin D have in small intestine?
↑ Calbindin → ↑ Ca-ATPase Activity
38
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
Calcitonin
39
What role does calcitonin have, and where
bone and kidney inhibits bone resorption and tubular reabsorption
40
What Condition? ``` PTH: Increased Vit. D: Increased Plasma: Hypercalcemia, hyperphosphatemia Urine: ↑ Phosphate, cAMP, Ca2+ Bone Resorption: Increased ```
primary hyperPTH "stones, bones, groans"
41
What Condition? ``` PTH: Decreased Vit. D: Decreased Plasma: Hypocalcemia, Hyperphosphatemia Urine: Decreased PO4 & cAMP Bone Resorption: Decreased ```
hypoPTH, surgical
42
What condition? ``` PTH: Increased Vit. D: Decreased Plasma: Hypocalcemia, Hyperphosphatemia Urine: Decreased PO4 & cAMP Bone Resorption: Decreased (defective Gs) ```
Pseudohypoparathyroidism (Albright’s Heredetary Osteodystrophy)
43
What condition? ``` PTH: Decreased Vit. D: NC (no intestinal Fx) Plasma: Hypercalcemia, Hypophosphatemia Urine: Increased Ca, PO4 & cAMP Bone Resorption: Increased ```
Humoral Hypercalcemia of Malignancy
44
Which disease has the following S/S? Short stature, short neck Obesity Shortened 4th metatarsals and metacarpals
Pseudohypoparathyroidism (Albright’s Heredetary Osteodystrophy)
45
Which disease has the following S/S? Tetany Hyperreflexia, twitching, cramps Convulsions Trousseau sign
Hypoparathyroidism: Surgical
46
Which disease has the following S/S? Osteoporosis, osteomalacia Kidney stones Muscle weakness, decreased excitability
Primary Hyperparathyroidism: Stones, Bones, & Groans
47
Which disease has the following S/S? Tetany Muscle weakness Greenstick fractures Skeletal abnormality: bow legs, wrists
Rickets - Deficiency of Vitamin D in Childhood
48
Which disease has the following S/S? Soft, weak bones Frequent fx Hypocalcemic tetany hypocalcemia
Ostoemalacia: Deficiency of Vit. D in Adulthood

Physiology II (28 decks)

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