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Musculoskeletal case > Healthy bones and metabolism > Flashcards

Healthy bones and metabolism Flashcards

1
Q

How much calcium does the body contain?

A

~ 1kg (25mol)

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2
Q

What is the percentage of calcuim in our body that is in our bones?

A

99%

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3
Q

How much calcium travels in the body and from and to where?

A

approximately 500mmo1/240 moves between bone and ECF

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4
Q

What forms are calcium in the body

A

Diffusible (ion complexed to lots of proteins, slows it and able to diffuse as it is bigger)- which can be spilt into
‘Free’ calcium- physiologically active(ionised calcium)
Complexed to proteins
Protein bound

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5
Q

Which form of calcium is homeostatically managed?

A

‘Free’ calcium

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6
Q

How is calcium used around the body? Describe calcium cycle in body

A 
From bone to ECF- Bone resorption and exchange
From ECF to bone- 
Bone formation and exchange
Formation and resorption in balance
Kidney to ECF - Reabsorption
Plasma to kidney-
Glomellular filtration
Gut to Plasma- Absorption
Plasma to Gut - 
Secretion
Food to gut
gut to faeces
Plasma to skin thorugh sweating
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7
Q

What is bone resorption?

A

Bone broken down and calcium and phosphate taken back into ECF
Otherwise known as reuptake

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8
Q

What is reabsorption?

A

Not breaking down anything but taking up ions

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9
Q

What regulates calcium ? 3

A

Parathyroid hormone
Vitamin D
Calcitonin

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10
Q

Where is Parathyroid hormone secreted from? Where is that?

A

Parathyroid glands which sit on four corners of the thyroid gland on the neck

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11
Q

The process of secreting Parathyroid hormone-Size of each form

A

First- Pre pro PTH- 115 amino acids

  • > Pro PTH- 90 amino acids
  • > Mature PTH- 84 amino acids
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12
Q

What does PTH do and where?

A

In Kidney:
Increases calcium resorption/ reuptake in distal tubules
Increases phosphate excretion
Increases formation of active vitamin D

In Bone:
Stimulates bone resorption

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13
Q

How does PTH regulate calcium when it is at a low level?

A

Hypocalcemia- stimulus detected
Trigger Calcium Sensing Receptor in Parathyroid gland (CaSR)
Increases PTH

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14
Q

What is hypocalcemia

A

Low calcium

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15
Q

What does increasing bone resorption do?

A

Increases calcium and phosphate

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16
Q

What does Increasing calcium resorption

Increasing formation of active vitamin D do?

A

Decreases phosphate resorption

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17
Q

How would you describe results of measurements that are abnormal? why?

A

NOT abnormal
SAY Appropiate
Because if someone has a low level of calcuim, it would be expected to see high levels of PTH therefore better to say appropiate than high or low

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18
Q

What are the common forms of Vitamin D?

A

Most common are Vitamin D2 and Vitamin D3

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19
Q

What is Vitamin D derived from? How can you tell from the structures?

A

Cholesterol

Steroid backbone

20
Q

Where is most Vitamin D derived from?

A

UV light on skin

21
Q

What is Vitamin D2 used as?

A

Food additive

22
Q

What food source contains Vitamin D?

A

Oily fish

23
Q

How is vitamin D overally sythesised

A

dehydrocholesterol in skin turned into Vitamin D3 Cholecalciferol by UV light

24
Q

Is Vitamin D3 (cholecalciferol) biologically active?

A

No

25
Q

Activation of Vitamin D? Where?

A

In liver
Vitamin D3 (Cholecalciferol) undergoes hydroxylation so becomes Calcidol/ 25(OH)D / 25-hydroxycholecalciferol
Reaction is dependent upon availability of substrate (Vitamin D)
In kidney
25(OH)D undergoes enzymatic reaction
Enzyme- 1α hydroxylase
Which changes 25(OH)D into 1,25-dihydroxycholecaIciferol

26
Q

Is Calcidol/ 25(OH)D / 25-hyclroxycholecalciferol biologically active?

A

No

27
Q

How is the activation of Vitamin D in kidney regulated?

A

decreased phosphate
decreased 1,25-OHD
increased PTH

28
Q

Is 1,25(OH)D biologically active?

A

yes

29
Q

What does activated Vitamin D do?

A

In bone-
Stimulates bone resorption

In Intestine-
Stimulates calcium absorption
Stimulates phosphate absorption

30
Q

When do we look at abonormal Vitamin D Levels and PTH levels?

A

Calcium and ohosphate levels
If in same direction- Vitamin D
If in different directions- PTH

31
Q

What is Vitamin Deficiency called in adults

A

Osteomalacia

32
Q

What is Vitamin Deficiency called in chilldren

A

Rickets

33
Q

What is calcitonin?

A

32 amino acids protein

34
Q

What secretes calcitonin and from where?

A

parafollicular cells of the parathyroid gland

35
Q

What does calcitonin do?

A

Opposes the effect of PTH

36
Q

What happens if there are high levels of calcium

A

Thyroid gland releases calcitonin ->

Inhibit osteoclast activity and Calcium reabsorption on the kidney decreased-> calcium levels dropped

37
Q

What is bone density?

A

A measure of the amount of mineral present in the bone

38
Q

Why is bone density measured

A

Used to diagnose osteoporosis

39
Q

What is it a factor for?

A

A contributing factor to the fracture risk

40
Q

What is a DEXA scan?

A

Scans for bone density

41
Q

What can affect bone density- 8

A

Calcium intake
Calcium absorption — Vitamin D (sun exposure and dietary factors)
Functionality of PTH — Magnesium deficiency
Weight bearing exercise
Smoking — affects bone turnover
BMI
Healthy diet — oily fish, whole grains, cut down on fat and sugar
Hormones
Steroid hormones, oestrogen, thyroid hormones

42
Q

What is osteopaenia?

A

Lower bone density

43
Q

What do vegans eat to supplement calcium

A

need leafy green vegetables, almonds, sesame seeds.Pulses, tofu

44
Q

What do people with lactose intolerance eat to supplement calcium

A
  • pilchards, curly kale, watercress, sesame seeds
45
Q

Factors that contributes to fracture risk? 6

A 
Age
Previous fracture
Alcohol intake
Smoking status 
Medication (steroids)
Bone density
46
Q

What happens to bone density in women over time? Why?

A

Bone density in women decreases after the menopause

decreasing oestrogen levels

Musculoskeletal case (8 decks)

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