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Physiology > 4.6 Endocrine Ca and PO4 > Flashcards

4.6 Endocrine Ca and PO4 Flashcards

1
Q

is calcium or phosphate regulation more important?

A

calcium

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2
Q

calcium regulation is specifically critical to?

A

1) neuronal excitaility (stabolize nueromuscular membranes)
2) cardiac muscle contraction (regulate release of sarcopplasmic reticulum)
3) hemostasis (blood clotting)
4) mineralization of tissues

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3
Q

low Ca levels make neuromuscular membranes?

A

hyperexcitable; leaky to Na causing partial depolarization

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4
Q

how do you get hypocalcemic tetany?

A

low plasma Ca =
plasma membranes leaky to Na=
partial depolarization=
hyperexcitable membranes= hypocalemic tetany

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5
Q

hypocalcemic tetany is characterized by?

Starts where?

A

skeletal muscle spasms

  • begin in extremities and progress to face and torso
  • die of spasms to larynx
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6
Q

ECF Ca is utilized for cardiac muscle?

A

contraction

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7
Q

low plasma Ca = ______ cardiac contraction

A

weak

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8
Q

Ca is reuqired for many of the reaction that lead to what important function of blood?

A

blood clotting

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9
Q

why is stating that low plasma Ca compromises clotting theoretical?

A

because it would require an extreme drop in Ca to adversely affect clotting; person would MOST LIKELYDIE of HYPOCALCEMIC tetany first!!!

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10
Q

Ca is required for the formation of bone and ____>

A

teeth

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11
Q

Ca + HPO4 =

why is this structure important?

A

CaHPO4 aka hydroxyapatite

*larger, stronger and more insoluble than smaller compounds

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12
Q

where is 90% of body calcium located?

A

in bones and teeth

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13
Q

strength of inorganic vs organic components of mineralized tissue

A
  • Inorganic= compressile strength

* Organic= tensile strength (collagen, elastin, glucopolysaccarharids

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14
Q

do we have more Ca or PO4 in blood? which one is more diffusable?

A
  • more Ca in blood

* PO4 is more diffusible, that’s why you don’t have to keep much in blood

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15
Q

describe plasma calcium? diffusible or not?

A
  • 10mg per day
  • 40% bound to plasma proteins= NONdiffusible
  • 50% free = Diffusible
  • 10% nonionic calcium in complexes with citrate, phosphate, and bicarbonate= Diffusible
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16
Q

describe plasma phosphate (PO4)? diffusible or not?

A
  • 4 mg per day
  • 10% bound to plasma proteins= NONdiffusible
  • 55% free= Diffusible
  • 35% bound to Ca and other ions = Diffusible
17
Q

we need ECF pyrophosphate to ______ of soft tissue

A

prevent mineralization

18
Q

what does alkaline phaohatase do?

secreted by?

A

hydrolyzes pyrophosphate so mineralization can occur

*secreted by osteoblasts

19
Q

most mineral exchange occurs between ____ and bone/teeth? which is diffusible and what isn’t?

A

ECF

  • Ca and CaHPO4 is Diffusible
  • hydroxyapatite is NONdiffusible (what we see in enamel)
20
Q

where do we see exchange of minerals in teeth?

A

cementum (some with dentin at CEJ or pulp vessels)

21
Q

what do osteoclasts do? derived from?

A
  • derived from fused monocytes (multinucleated)

* function in bone resorption

22
Q

osteoclasts secrete what 2 things to start resorption of bone?

A

1) hydrocholoric acid for demineralization of inorganic CaHPO4 to Ca and PO4
2) acid phosphatase enzyme to digest oragnic collagen matrix

23
Q

osteoblasts are derived from? function in?

A
  • derived from undifferentiated mesenchyme

* bone BUILDING/formation

24
Q

osteoblats synthesize and secrete?

what gets imbed in the collagen matrix?

A

collagen and alkaline phosphatase to promote mineralization

*Ca++ and PO4 3- ions get imbedded in collagen matrix

25
Q

osteoblasts become?

A

osteocytes

26
Q

osteocytes derived from? function?

A
  • derived from osteoblasts

* function in both bone resorption and bone formation

27
Q

minerals are mobilized (destruction of bone) by?

A

osteoclasts or osteocytes

= resorption

28
Q

minerals are deposited (formation of bone) by?

A

osteoblasts or osteocytes

= deposition

29
Q

what is bone modeling? stops when? occurs where?

A

growing

  • shapes bones during growth
  • stops at age 18-20
  • resorption and formation occur on different surfaces
30
Q

Why is resorption on inner side and deposition on outside for bone modeling?

A

both need to happen and happen simultaneously to grow. If not, you’d get thick and heavy bones

31
Q

what is bone remodeling? occurs when? occurs where?

A

repair or maturation of bone

  • continuously occuring to repair microfractures
  • resorption and formation occur sequentially at SAME SITE
32
Q

bone modeling vs remodeling?

A
  • modeling= resorption and formation occur sequentially on Opposite sides
  • REmodeling= resorption and formation occur sequentially at SAME SITE
33
Q

Remodeling cycle?

A

1) activation
- -osteoclasts formed by blood monocytes
2) resorption
- -dig hole via clasts
3) reversal
- -osteoclasts leaves and osteblasts comes in to form bone
4) formation
- -osteoblasts ONLY

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