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Physiology II > Lecture 17 - Ca & PO4 > Flashcards

Lecture 17 - Ca & PO4 Flashcards

1
Q

plasma calcium is regulated by

A

parathyroid hormone (PTH)
vitamin D

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2
Q

calcium can bind to

A

nerve axons - affecting action potential frequency

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3
Q

when plasma acidosis occurs, there are less Ca than H bound to albumin

A

increase free Ca on the nerve axon
decrease # of neuronal AP
decrease muscle contraction
WEAKNESS

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4
Q

when plasma alkalosis occurs, there are more Ca than H bound to albumin

A

decrease free Ca on the nerve axon
increase # of neuronal AP
increase muscle contraction
twitching

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5
Q

hypocelcemic tetany: carpopedal spasm

A

hyperventilation
low plasma CO2
respiratory alkalosis
decreased free Ca
increased freq. of motor neuron action potentials
skeletal muscle contraction
tetany

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6
Q

physiological role of phosphorus

A

major intracellular anion, ATP, co-factor, modifies proteins and/or enzyme activity
intracellular buffer in acid-base balance
DNA, RNA, membrane phospholipids

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7
Q

bone remodeling

A

calcified matrix: hydroxyapatite crystals within osteoid
osteoid: collagen-based matrix
resportion = formation (is good)

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8
Q

amorphous crystals
1st bone pool

A

4-5 g
liquid solution on surface of newly formed bone
fast exchange with ECF
osteolysis: initial burst of Ca

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9
Q

hydroxyapatite crystals
2nd bone pool

A

1000 g
mineralized bone
slow exchange with ECF
bone resorption: release Ca and PO4 into plasma

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10
Q

osteoblasts

A

build bone

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11
Q

osteocytes

A

detect worn-out bone

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12
Q

osteoclasts

A

chew up bone

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13
Q

PTH stimulates osteoblasts to

A

secrete M-CSF and osteoprotegerin which can bind to RANKL

secrete collagen and osteocalcin -> osteoid

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14
Q

after binding of RANKL and M-CSF,

A

preosteoclasts mature to osteoclasts (chew)

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15
Q

Osteoclasts chew the bone and released

A

Ca and P enter plasma

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16
Q

osteocytes detect worn out bone,

A

secrete RANKL, and attract osteoclasts

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17
Q

PTH favors bone

A

breakdown

18
Q

Vitamin D favors bone

A

formation

19
Q

PTH fxn

A

acute regulation of plasma ionized calcum

20
Q

vitamin D fxn

A

long-term maintenance of strong bones

21
Q

Calcium sensing receptors (CaSR) on PTH cheif cells sense

A

extracellular free Ca conc

22
Q

decrease in plasma Ca…

A

increases plasma PTH

23
Q

plasma Ca primary stimulus

A

decreased ionized ca stimulates PTH secretion
increased ionized Ca inhibits PTH secretion

24
Q

Lithium stimulates…

A

PTH secretion: right-shift of curve

25
Q

1,25(OH2)- vitamin D3 inhibits gene expression to

A

increase synthesis of CaSR
decrease synthesis of PTH

26
Q

Vitamin D3 is synthesized from 7-dehydrocholesterole

A

to previtamin D3

27
Q

melanin can impede converstion because it

A

absorbs the same uv wavelengths in sunlight

28
Q

previtamin D3 is converted to

A

Vitamin D3

29
Q

vitamin D3 is converted to

A

25-OH-vitamin D3 in the liver

amt of vitamin D3 due to diet

little biological activity
long half-life
indicator of vitamin D status
synthesis not regulated

30
Q

25-OH-vitamin D3 is converted to

A

1,25(OH)2-D3 (active) and 24,25-(OH)2-D3 (inactive) in the kidney

31
Q

when converting to 1,25(OH)2-D3 (active)

A

vitamin D def
1,25(OH)2-D3 def
Ca def
hypocalcemia
increase PTH secretion
hypophosphatemia
phosphate def

32
Q

when converting 24,25(OH)2D3 (inactive)

A

vitamin D sufficiency
1,25(OH)2-D3
normocalcemia
hypercalcemia
normophosphatemia
hyperphosphatemia

33
Q

Vitamin D3 physiological effects

A

increase phosphate absorption and calcium absorption in intestine and Ca and PO4 reabsorption in kidneys
the Ca and P go to plasma

34
Q

hormones that favor bone formation and bone mass

A

insulin
GH
IGF-1
estrogen
testosterone
calcitonin

35
Q

hormones that favor increased bone resorption and decreased bone mass

A

parathyroid hormone
plasma cortisol above normal range
plama thyroid hormone above normal

36
Q

hyperparathyroidism:
due to tumor: high PTH, high Ca, low phosphate
due to persistent hypocalcemia: high PTH, low or normal ca, low phosphate

A

increase bone resportion
increase renal Ca reabsorption
increase intestinal Ca absorption
decrease renal P reabsorption
increase urinary Ca and P

37
Q

hyperparathyroidism with chronic renal failure

A

high PTH and low or normal Ca

38
Q

hypoparathyroidism

A
  1. hypocalcemia:
    decrease bone resorption
    decrease renal Ca reabsorption
    decrease intestinal Ca absorption
  2. hyperphosphatemia:
    increased renal P reabsorption
39
Q

when plasma albumin is above normal range, plasma free calcium is

A

within the normal range

40
Q

when plasma free calcium is below normal range, plasma free calcium is

A

within the normal range

41
Q

when plasma albumin is above the normal range, plasma total calcium is

A

above the normal range

42
Q

when plasma albumin is below the normal range, plasma total calcium is

A

below the normal range

Physiology II (9 decks)

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