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MD1 Locomotor > Physiology of Bone and Calcium Homeostasis > Flashcards

Physiology of Bone and Calcium Homeostasis Flashcards

1
Q

How is soft tissue growth measured?

A

Weight

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2
Q

How is bone growth measured?

A

Height

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3
Q

What are growth hormone and insulin-like growth factors needed for in tissue and bone growth?

A

Protein and cell division

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4
Q

What is thyroid hormone’s role in growth?

A

Permissive role

Directly contributes to nervous system development

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5
Q

What is the role of insulin in growth?

A

Supports growth

Provides glucose energy

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6
Q

Of what adequate dietary requirements needed for bone growth?

A

Calcium

Protein

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7
Q

What happens to long bones as they grow in length?

A

Bone diameter increases as matrix deposits on outer surface

Epiphyseal plate site of linear growth of long bones

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8
Q

When is the epiphyseal plate active?

A

Childhood and adolescence

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9
Q

Between what does hormonal control exchange calcium?

A

ECF and bone, kidneys, and intestine

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10
Q

What is calcium important in?

A

Intracellular signalling
Structural
- Physical strength to bone matrix
- Helps hold cells together at tight junctions
Cofactor in blood coagulation
Normal excitability of neurons and muscle

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11
Q

What are the three pools of calcium, and what proportion of total body calcium do they store?

A

Bone matrix = 99%
Extracellular fluid = 0.1%
Intracellular fluid = 0.9%

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12
Q

Which pool of calcium can move to other locations?

A

That in extracellular fluid

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13
Q

How much calcium is absorbed from the small intestine?

A

1/3

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14
Q

What regulates calcium absorption?

A

Hormones

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15
Q

How is calcium excreted?

A

Most through urine

Some through faeces

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16
Q

Where in the nephron is calcium reabsorbed?

A

Distal tubule

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17
Q

What regulates calcium excretion?

A

Hormones

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18
Q

What secretes parathyroid hormone?

A

Parathyroid glands

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19
Q

Is parathyroid hormone essential for life?

A

Yes

20
Q

In response to what is parathyroid hormone secreted?

A

Decreased plasma calcium

21
Q

What effect does parathyroid hormone have on the plasma?

A

Increases calcium

Decreases phosphate

22
Q

What are parathyroid hormone’s actions on bone?

A

Increases calcium and phosphate release from bone into plasma
Favours bone resorption via indirect action on osteoclasts

23
Q

What are parathyroid hormone’s actions on the distal nephron?

A

Increases calcium reabsorptuon

Decreases phosphate reabsorption

24
Q

What are parathyroid hormone’s actions on the intestine?

A

Indirectly increases calcium and phosphate reabsorption by activating vitamin D

25
Q

What is the chemical nature of parathyroid hormone?

A

Peptide

26
Q

What is the half-life of parathyroid hormone?

A

Less than 20 min

27
Q

What is the onset of action of parathyroid hormone?

A

2-3 hours for bone
- Increased osteoclast activity in 1-2 hours
1-2 days for intestinal absorption
Minutes for kidney transport

28
Q

What produces calcitonin?

A

C cells of thyroid gland

29
Q

When is calcitonin released?

A

Plasma calcium is high

30
Q

What does calcitonin do?

A

Decreases plasma calcium and phosphate

31
Q

What effect does calcitonin have on bone?

A

Decreases release of calcium from bone

Decreases bone resorption

32
Q

What effect does calcitonin have on the kidneys?

A

Increases calcium excretion

33
Q

When is calcitonin physiologically useful?

A

No role normally

Only works with extreme hypercalcaemia

34
Q

What is the effect of calcitonin on the gut?

A

None

35
Q

What is the chemical nature of calcitriol?

A

Steroid

36
Q

How is calcitriol transported in circulation?

A

Bound to plasma proteins

37
Q

What is the stimulus for synthesis of calcitriol?

A

Decreased calcium
Indirectly via parathyroid hormone
Prolactin

38
Q

Where is the target receptor for calcitriol?

A

Nuclear

39
Q

What are the roles of phosphate?

A 
Energy transfer and storage
- ATP
- cAMP
Control of
- Enzymes
- Transporters
- Ion channels
Part of DNA and RNA backbone
40
Q

What can cause hyperparathyroidism?

A

Tumour

41
Q

What can cause hypoparathyroidism?

A

Rare
Autoimmune attack of glands
Inadvertent parathyroidectomy during thyroid surgery

42
Q

What happens to calcium and phosphate levels in hyperparathyroidism?

A

Hypercalcaemia

Hypophosphataemia

43
Q

What happens to calcium and phosphate levels in hypoparathyroidism?

A

Hypocalcaemia

Hyperphosphataemia

44
Q

What can a vitamin D deficiency cause?

A

Impaired intestinal calcium absorption
Parathyroid hormone maintains calcium levels at expense of bones
Bone demineralisation

45
Q

What is bone demineralisation due to a vitamin D deficiency in children called?

A

Rickets

46
Q

What is bone demineralisation due to a vitamin D deficiency in adults called?

A

Osteomalacia

47
Q

What are the preventable risk factors for osteoporosis?

A

Low dietary calcium
Lack of exercise
Smoking

MD1 Locomotor (17 decks)

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