Lecture 61 - Endocrine 3 Flashcards

(31 cards)

1
Q

what are the 4 functions of calcium?

A
  1. bone and teeth structure
  2. muscle function
  3. nerve transmission
  4. hemostasis
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2
Q

what two blood tubes contain chelating agents? What does this mean?

A

purple top (EDTA) and blue top (citrate)

chelate calcium so clots are unable to form

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3
Q

what role does calcium play in protein hormone synthesis

A

exocytosis - helps secretory vesicles bind with the plasma membrane

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4
Q

Ionized calcium

A

non-protein bound (biologically active)

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5
Q

total calcium

A

ionized and protein-bound calcium (albumin)

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6
Q

what are the 5 functions of phosphate

A
  1. bone and teeth structure
  2. muscle function
  3. acid-base balance
  4. energy provision
  5. nucleic acids
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7
Q

inorganic phosphate

A

simple form found in bone and teeth

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8
Q

organic phosphate

A

contain phosphate and carbon
found in ATP, DNA, etc.

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9
Q

T/F: protein-bound Ca is biologically active

A

FALSE

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10
Q

what is the distribution of calcium in the body? list from most stores to the least

A
  1. hydroxyapatite in bone
  2. intracellular
  3. extracellular
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11
Q

what are the 3 hormones involved in calcium homeostasis

A
  1. parathyroid hormone
  2. calcitonin
  3. vitamin D
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12
Q

what 3 organs play a role in calcium homeostasis

A
  1. bone (reservoir)
  2. GI (in)
  3. kidneys (out)
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13
Q

the parathyroid hormone works to

A

increase calcium

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14
Q

how does PTH increase blood calcium

A

increase resorption by kidneys, stimulate release from bone

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15
Q

summarize vitamin D metabolism in 5 steps

A
  1. UVB hits skin
  2. supports conversion of pre-vitamin D to vitamin D3
  3. vitamin D3 hydroxylated in the liver
  4. 25-hydroxyvitamin D (calcidiol) hydroxylated in the kidneys
  5. 1,25-hydroxyvitamin D (calcitriol) is ACTIVE
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16
Q

what enzyme coverts calcidiol to calcitriol

A

1a-hydroxylase

17
Q

PTH ____ the activity of 1a-hydroxylase

18
Q

PTH ____ tubular resorption of calcium

19
Q

PTH ____ tubular resorption of phosphate

20
Q

what two hormones increase osteoclastic activity

A

PTH and calcitriol

21
Q

describe how metabolic bone disease correlates to calcium homeostasis

A
  • inappropriate diet (low Ca/high P)
  • bone resorption and production of fibrous tissue (swollen, weak bones)
22
Q

an 8y/o castrated male labrador comes into the clinic with PU/PD. Diagnostic tests identify high calcium and low phosphate. what may cause this?

A

primary hyperparathyroidism (excessive PTH from mass continues to raise calcium)

23
Q

what is the function of calcitonin

A
  1. functionally oppose PTH
  2. decrease bone resorption and osteoclastic activity
  3. increased renal excretion of Ca and P
24
Q

calcitonin ___ blood calcium

25
what effect does PTH have on Ca and P?
increase Ca and decrease P
26
T/F: PTH enhances P loss via the kidney
TRUE
27
what produces calcitonin
parafollicular ("C") cells
28
what do "C" cells look like on histology
pale staining, large ovoid nuclei
29
calcitonin exerts its effect mostly by affecting which organ
bone
30
which hormone would increase in a cow with mild fever (hypocalcemic tetany)?
PTH
31
what are the 3 steps to protein-based hormone synthesis
1. synthesis (pre-pro-) 2. packaging (pro-) 3. storage (target hormone)