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Calcium Flashcards

1
Q

In which 2 ways can calcium be carried around in the body

A

Ionised or unionised

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2
Q

What ion binds to albumin in the same way as calcium

A

Hydrogen

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3
Q

Describe the binding of hydrogen/ calcium in acidosis

A

Increased ionised calcium as less binding to albumin

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4
Q

Describe the binding of hydrogen/ calcium in alkalosis

A

Decreased in ionised calcium because more bound to albumin

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5
Q

Why do some people experience tinging in their lips and extremities when they hyperventilate

A

Reduction in ionised calcium- symptoms of hypocalciumia

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6
Q

2 main roles of calcium

A

Structural role

Intracellular signalling

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7
Q

Is calcium higher inside or outside the cell

A

Outside

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8
Q

Which channels are responsible for firing of action potential

A

Fast sodium channels

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9
Q

What happens if you reduce calcium in the blood

A

Nerves are more likely to fire- tachyarrythmias, fibrillation, cardiac arrest

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10
Q

What does calcium do the fast sodium channels

A

Stabilises them

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11
Q

What % of body phosphate is mineralised in the bone

A

85%

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12
Q

What is released by parathyroid gland

A

Parathyroid hormone

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13
Q

What type of hormone is PTH

A

Peptide hormone

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14
Q

What are the pharyngeal arches made of

A

Bone and cartilage

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15
Q

What 2 cell types are present in the parathyroid

A

Oxyphilic and chief cells

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16
Q

Which cells release PTH

A

Chief cells in the parathyroid gland

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17
Q

When do oxyphil cells appear

A

Puberty

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18
Q

Describe the order that different organs process parathyroid hormone in

A

Rough ER–> golgi–> vesicles

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19
Q

What is the biggest trigger to PTH released

A

Low levels of serum calcium

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20
Q

What is represented by the maximal secretory rate of PTH

A

Parathyroid reserve

Capacity to repsond to hypocalcaemia

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21
Q

What receptor senses low levels of calcium

A

Calcium sensing receptor

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22
Q

What kind of receptor is the calcium sensing receptor

A

G protein coupled receptor

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23
Q

What happens if calcium sensing receptor is activated

A
  • Reduces PTH secretion
  • Increases breakdown of stored PTH
  • Suppresses transcription of PTH gene
  • Blocks stimulation of cAMP
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24
Q

Other than calcium, what else activates calcium sensing receptor

A

Magnesium, certain amino acids

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25
Other than calcium, what else may determine PTH secretion
Activated vitamin D (calcitriol) suppresses PTH | Phosphate stimulates
26
What is the action of PTH in the kidney
Decreases calcium excretion | Increases phosphate excretion
27
What is the action of PTH on bone
Increases calcium and phosphate resorption
28
What is the action of PTH in the intestine
Increases absorption of calcium and phosphate | Some evidence for direct effects but mainly indirectly through calcitriol
29
How much calcium resorption occurs in the proximal tubule
65%
30
What drives calcium resorption in the proximal tubule
Voltage gradient
31
How much resorption occurs in the loop of Henle
20%
32
What inhibits calcium resorption in the loop of Henle
Loop diuretics
33
What % of calcium is absorbed in the distal tubule
10%
34
Which area of the kidney is PTH dependent in terms of calcium resorption
Distal tubule
35
What calcium channels are found in the distal tubule
TRPV calcium channels
36
What is the action of PTH in the distal tubule
Upregulate: - TRPV calcium channels - Calcium ATPase channels - Na/Ca exchanger
37
What does PTH downregulate in the kidney, and what is the effect of this
- Downregulation of NaPi transporters= reduced phosphate reabsorption
38
PTH stimulates gluconeogenesis in which area of the kidney
Proximal tubule
39
PTH inhibits the reabsorption of what in the kidney
Sodium, water, bicarbonate
40
What is the effect of PTH and calcitriol on the bone
- Stimulate RANKL production, signalling for bone resorption | - Downregulation of osteoprotegerin
41
What is the relationship beween bone resorption and formation
They are equal
42
What is the relationship between bone remodelling and formation in menopausal women
Resorption> formation
43
What is the effect of PTH on IGFI and IL 1
Increases
44
What is the effect of glucocorticoids on bone remodelling
- Reduce osteoblast numbers | - Increase RANKL
45
What is the effect of oestrogen on bone remodelling
Inhibiits bone remodelling
46
What are some radiological signs of primary hyperparathyroidism
Terminal tuft erosion Rugger jersey spine Brown tumour Subperiosteal erosion
47
What kind of receptor is the vitamin D receptor
Nuclear and membrane bound
48
What is the effect of vitamin D in the bone
- Reduces type 1 collagen expression - Increases osteocalcin and RANKL - Facilitates osteoclast differentiation
49
What is the effect of vitamin D on phosphate
- Increases gut absorption | - Increases levels of GFG23 to remove it via renal excretion
50
What is the effect of vitamin D on cellular proliferation
Reduces it
51
What is the effect of vitamin D on amino acid uptake
Deficiency--> myopathy
52
What is FGF 23
A phosphatonin- a hormone that reduces serum phosphate levels
53
What happens if there is an activating mutation if FGF23
Autosomal dominant hypophosphataemic rickets
54
What do you call a tumour induced osteomalacia
Paraneoplastic FGF23
55
What may happen if there are low levels GFG23
Familial tumoral calcinosis
56
Where is calcitonin released from
Thyroid C cells
57
What is primary hyperparathyroidism
Absence of hypocalcaemia | May be caused by parathyroid adenoma, carcinoma, hyperplasia
58
What does primary hyperparathyroidism lead to
Hypercalcaemia
59
What is secondary hyperparathyroidism
Compensation for hypocalcaemia
60
When should asymptomatic primary hyperparathyroidism be treated
``` Low BMD Renal calculi Renal impairment Calcium >3.0 Age <50 ```
61
What scan should be used to localise an adenoma
MIBI scan
62
What happens in hypocalcaemia
Convulsion Arrythmia Tetany Paraesthesia
63
What can lead to hypocalcaemia
Chronic kidney disease | Vit D deficiency
64
How is hypoparathyroidism treated acutely
IV or oral calcium supplement
65
How is hypoparathyroidism treated chronically
VIt D orally
66
What is familial hypocalciuric hypercalcaemia
Inactivating mutations of CaSR - parathyroid can't sense high calcium - PTH not suppressed by high calcium - CaSR in kidney not activated - PTH-calcium curve shifts to the right
67
What serum results would be seen in familial hypocalciuris hypercalcaemia
High serum Ca Low urine Ca High serum Mg

MET 2 (32 decks)

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