3. Calcium Metabolism Flashcards

1
Q

7 calcium dependant processes

A

1) Bone formation
2) Muscle contraction
3) Nerve conduction
4) Hormone release
5) Blood coagulation
6) Cell signalling
7) Enzyme cofactor

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2
Q

3 hormones that control bone endocrinology

A

1) Parathyroid (PTH) 2) Vitamin D 3)Calcitonin

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3
Q

Hydroxyapatite

A

Major Mineral of bone complex of Ca2+ and PO43-

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4
Q

What cell Builds bones

A

OsteoBlasts

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5
Q

What cell is responsible for bone resorption/breakdown?

A

Osteoclasts

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6
Q

5 roles of Vitamin D

A

1) Increases serum Ca2+
2) Facilitates intestinal absorption of calcium and phosphates
3) Increases bone resorption
4) Enhances PTH to promote renal tubular calcium reabsorption

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7
Q

Parathyroid hormone (PTH)

A

When extra cellular calcium falls PTH restores calcium level

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8
Q

Action of PTH on bone

A

High levels of PTH in response to low serum Ca2+ = inhibits osteoblasts and stimulates osteoclasts ( bone resorption) Low levels of PTH in response to high serum Ca2+ stimulates osteoblasts and inhibits osteoclasts ( bone formation)

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9
Q

Action of Calcitonin

A

released when calcium levels rise

decreases osteoclast activity

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10
Q

Phosphate %

A

bone = 84.97%

intracellular = 5%

extracellular = 0.03%

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11
Q

Factors increasing bone production

A

1) Growth hormone
2) Insulin-like growth factor
3) Local growth factors
4) Testosterone
5) Vitamin D

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12
Q

Factors reducing bone production

A

1) Corticosteroids 2) Staying in bed

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13
Q

Factors causing bone breakdown

A

1) PTH 2) Thyroid hormones

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14
Q

Factors reducing bone breakdown

A

1) Calcitonin 2) Oestrogen

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15
Q

Hypercalcaemia (high Ca2+ levels in serum) Symptoms

A

“Bones, moans and abdominal groans”

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16
Q

Causes of hypercalcaemia

A

1) Hyperparathyroidism
2) Vitamin D excess
3) Kidney Failure (secondary Failure)
4) Sarcoidosis – vitamin D sensitivity

17
Q

Emergency management of hypercalcaemia

A

Calcium 2.6 to 2.9 mmol/L: - Send to outpatients If Calcium > 2.9 mmol/L - Urgent referral - Rehydrate with 0.9% saline - IV bisphosphonates*

18
Q

Hypocalcaemia symptoms

A

1) Tingling of fingers, toes, lips 2) Painful bones 3) Tetany (muscle spasm) 4) Seizures

19
Q

Causes of hypocalcaemia

A

1) Hypoparathyroidism
2) Vitamin D deficiency/ resistance
3) Magnesium deficiency
4) Pancreatitis
5) Hungry bone syndrome

20
Q

Causes of Hypoparathyroidism

A

1) Destruction of the glands 2) Surgical removal

21
Q

Treatment of hypocalcaemia

A

1) Calcium supplements
2) Vitamin D

22
Q

Changes in bone density

A
  • Increases until age 30 year - 10 % bone turnover per year - 0.5% bone loss per year - 1.5 % after menopause
23
Q

Treatment of Osteoporosis in Women

A
  • Bisphosphonate – first line - Oestrogen replacement - Calcitriol (Vit D) - Teriparatide
24
Q

Treatment of Osteoporosis in Men

A
  • Bisphosphonate – first line - Testosterone - Calcitriol
25
Q

Osteomalacia

A

softening of the bones

caused by impaired bone metabolism

26
Q

Causes of Osteomalacia

A

Vitamin D deficiency

Liver disease

Kidney disease

Malabsorption

Genetic causes

In children = RICKETS

In adults = OSTEOMALACIA

27
Q

Paget’s disease

A

excessive breakdown of bone

followed by disorganized bone remodelling

28
Q

Symptoms of Paget’s disease

A

Fractures

Bowed legs

Deformed skull

Deafness

29
Q

Osteogenesis imperfecta

A
  • a group of genetic disorders that mainly affect the bones
  • results in bones that break easily
  • white of the eye is blue! (bluish)
  • hypermobility (double jointed)
  • short height
  • problems with the teeth
30
Q

T-cell tolerance

A

T-cells that react with self too strongly in the thymus are eliminated

31
Q

B-cell tolerance

A

B-cells with an antibody (receptor) that reacts with self are deleted in the bone marrow

32
Q

Peripheral tolerance

A

results in non-responsiveness of B- and T- cells to peripheral antigens not expressed in the thymus/bone marrow

33
Q

Anergy

A

functional non-responsiveness of a lymphocyte to antigen

34
Q

Suppressor/Regulatory T-cells

A

CD4+

CD25+

35
Q
A

Ankylosing Spondylitis

36
Q

What secretes PTH

A

parathyroid glands

4 in the neck (primarily)

37
Q

What secretes Calcitonin?

A

perifollicular cells of the thyroid gland