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BAMS > Calcium > Flashcards

Calcium Flashcards

1
Q

What are the functions of calcium

A
  • bone and tooth structure
  • mineral store
  • action potentials (cardiac muscle)
  • membrane excitability
  • 2nd messenger
  • co-factor in metabolic pathways
  • blood clotting
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2
Q

Give examples of how calcium acts as a second messenger

A
  • muscle excitation-contraction coupling
  • gland secretion
  • non-steroid hormone action
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3
Q

Describe parathyroid secretion

A

Secreted from parathyroid glands in response to low plasma (Ca2+)

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4
Q

Acts to increase plasma calcium by:

A
  • increase bone (osteoclasts)
  • increase calcium response in kidney (with decreased oxygen reabsorption)
  • increased uptake of Ca 2+ from the intestines
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5
Q

When is parathyroid hormone secreted

A

Secreted from parathyroid glands in response to low plasma Ca2+

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6
Q

How does calcitonin act to lower plasma calcium

A

Increased formation of bone (osteoblasts)
Decreased calcium resorption in kidney

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7
Q

Describe diffusible calcium concentration

A

Ionised calcium 1.2mmol/l
Bound to citrate 0.2mmol/l

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8
Q

What is the calcium concentration of non diffusible calcium

A

1.2mmol/l

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9
Q

What is the calcium concentration of blood plasma

A

2.6mmol/l

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10
Q

Name some functions of calcium

A
  • bone and tooth structure
  • mineral store
  • action potentials (cardiac muscles)
  • membrane excitability
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11
Q

What is the role of calcium in muscles

A

Responsible for excitation contraction coupling

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12
Q

What are some ways calcium can be obtained in the body

A
  • diet
  • kidneys
  • exchangeable bone
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13
Q

What hormones control calcium homestasis

A
  • parathyroid hormone
  • calcitonin
  • vitamin D
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14
Q

What is the role of parathyroid hormone in calcium secretion

A
  • secreted from parathyroid glands in response to low plasma (Ca2+)
  • acts to increase plasma calcium by - increasing osteoclastogenesis, increasing calcium Reabsorption by kidney and increasing uptake of calcium from the intestines (assisted by vitamin D)
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15
Q

What is the role of calcitonin

A
  • secreted from the thyroid glands in response to high plasma (Ca2+)
  • acts to lower plasma calcium by increased osteoblastogenesis, decreased calcium resabsorption by the kidneys

Does not seem to play a massive role, no pathological effects

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16
Q

What ways can vitamin D3 be obtained

A
  • diet
  • 7-dehydrocholestrol synthesised in the skin
17
Q

What is cholecalciferol

A

Vitamin D3 essential for the deposition of calcium in the bones and formed by the action of sunlight on the de hydro Cholestrol in the skin

18
Q

What happens to cholecalciferol in the kidney

A

Cholecalciferol converted into calcitrol in the kidney, this is regulated by PTH

19
Q

What effect does calcitrol have on the intestine

A

Increased calcium absorption

20
Q

What effect does calcitrol have on the kidney

A

Ca retention and PO4 retention of the kidney

21
Q

What effect does calcitrol have on bone

A

Ca release and PO4 release

22
Q

What overall effect does calcitrol have on the body

A

Increased levels of calcium and phosphate in the plama

23
Q

Name some hormones that increase bone formation and bone mass

A
  • calcitonin
  • growth hormone
  • insulin
  • IGF-1
  • Oestrogen
  • Testosterone
24
Q

Name some hormones that increase bone reabsorption and decrease bone mass

A
  • cortisol
  • parathyroid hormone
  • thyroid hormones
25
Q

Where do osteoclasts lie in the bone

A

Lie in depressions known as howships lacunae

26
Q

What is hypercalcaemia

A

Raised calcium levels

27
Q

What is hypocalcemia

A

Reduced calcium levels

28
Q

What is hypocalcemia caused by

A
  • decreased calcium intake
  • excessive calcium loss
  • alkalosis (low Ca2+)

A panic attack could cause this, excessive blowing off of CO2, rebreathing air from a bag can solve this

29
Q

What are the effects of low calcium concentration

A

Increased nerve excitabity
- pins and needles, muscle spasms
- trousseaus sign, chvosteks sign

30
Q

What can hyperparathyrodism cause

A

Osteitis fibrosa - areas of demineralisation in the skull and legs

31
Q

What can hyperparathyroidism cause in the teeth

A

Defective mineralisation of teeth due to low blood calcium levels due to undersecretion of PTH

32
Q

What can vitamin D deficiency cause

A

Rickets (children)
Osteomalacia (adults)

33
Q

What is osteoporosis

A

Decreased bone mass and density, fractures are common, more common in elderly

34
Q

What is osteopetrosis

A

Increased bone mass and density
Results in -
Reduced blood supply, fracture, chronic inflammation

35
Q

What can osteopetrosis cause in terms of dentistry

A

Difficult tooth extraction

36
Q

What is the term used to describe low calcium levels in the body

A

Alkalosis

BAMS (41 decks)

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