Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MEH > 13 Calcium Metabolism > Flashcards

13 Calcium Metabolism Flashcards

1
Q

What is calcium vital for?

A
  • Nerve and muscle function - neuromuscular junction
  • Bone formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Three organs important in calcium metabolism

A

Bone
Kidney
Gut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where is the parathyroid gland?

A

Behind the thyroid
Completely different to thyroid gland
4 of them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Relationship between main organs and calcium.

A

Gut - vitamin D activation absorption
Bone- resorption
Kidney- retention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain the role of PTH in regulating serum calcium levels

A
  • Increase bone resorption + Ca release into circulation
  • Increase kidney Ca retention + excretion of phosphate
  • Stimulation to make active vitamin D - calcitriol > indirectly acts on GI tract
  • decreases plasma phosphate
  • increases plasma calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does calcium cause in relation to phosphate?

A

Phosphate loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What molecule causes phosphate loss?

A

FGF23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is needed to vitamin D synthesis?

A

Sunlight
Present in diet too

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Vitamin D synthesis

A

Vitamin D3 + sunlight
25-hydroxylation
1-hydroxylation
Active form of vitamin D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where do you get vitamin D2 and D3 from?

A

D2 - mushrooms
D3 - oily fish e.g. salmon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Action of vitamin D

A
  • Kidney - increased Ca reabsorption
  • Parathyroid- decreased PTH production + parathyroid growth
  • Bone- promotes formation and growth
  • Gut - increased absorption of Ca2+ and PO4 3-
  • increases plasma calcium and phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is hypercalcaemia?

A

High calcium
>2.51mmol/L
>3mmol/L severe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Symptoms of hypercalcaemia

A

Polydipsia
Polyuria
Moans - tried, depressed
Groans - constipation, pancreatitis
Stones - kidney stones, polyuria
Bones - bone and muscle aches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Causes of hypercalcaemia

A

PTH independent - PTH low
PTH dependent - PTH high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Outline the negative feedback regulation of serum calcium when there is an increase in plasma calcium

A

Decreased PTH secretion
Less calcitriol made
Less Ca2+ reabsorption in kidneys
Less bone breakdown, more bone building
Less Ca2+ absorbed in gut
Plasma Ca2+ levels decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Outline the negative feedback regulation of serum calcium levels when plasma calcium decreases

A

Increased PTH secretion
More calcitriol made
More Ca2+ reabsorption in kidneys
More bone breakdown, less bone building
More Ca2+ absorbed in gut
Plasma Ca2+ levels increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Explanation of high Ca and low PTH

A

High calcium form somewhere else
Most likely cancer
Cancer produced PTH-like peptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Cancers with high calcium

A
  • Myeloma-cancer of blood cells
  • Bone metastases -typical tumours that go to the bone: bronchus, thyroid, breast, kidney

NOT prostate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Causes of high Ca, low PTH that’s not cancer

A

Tuberculosis
Sarcoidosis
Granulomas
Produce vit D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is sarcoidosis?

A

Condition which causes small patches of swollen tissues (granulomas) to develop in organs
No necrosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are granulomas?

A

Small patches of swollen tissue

Epithelial histiocyte with surrounding lymphocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Primary hyperparathyroidism

A

High Ca due to high PTH levels
Due to benign parathyroid adenoma

23
Q

Effects of primary hyperparathyroidism

A

Causes hypercalcaemia:
Moans - tried, depressed
Groans - constipation, pancreatitis
Stones - kidney stones, polyuria
Bones - bone and muscle aches

24
Q

What do you need to do in acute severe hypercalcaemia?

A

Medical emergency
Severe dehydration
Fluid into vein quickly
Treat underlying cause

25
Q

Hypocalcaemia

A

Low calcium levels
<1.9mmol/L

26
Q

Symptoms of hypocalcaemia

A

Numbness
Muscle cramps
Palpitations
Seizures
Severe symptoms if sudden drop

27
Q

Signs of hypocalcaemia

A

Convulsions
Prolonged Q-T interval on ECG
Hyperreflexia- over responsive reflexes
Trousseau’s sign
Chvostek’s sign
Swelling of optic disk

28
Q

What is trousseau’s sign?

A

Involuntary contraction of muscle in hand and wrist

29
Q

What is chvotek’s sign?

A

Contraction of ipsilateral face muscles after percussion over facial nerve

30
Q

Causes of hypocalcaemia

A

Vitamin D deficiency
Hypoparathyroidism

31
Q

Biochemistry of vitamin D deficiency

A

Low vit D
Low Ca
High PTH
Low phosphate

32
Q

Causes of vitamin D deficiency

A

Lack of sunlight
Pigmented or covered skin
Dietary deficiency
GI disease
Kidney disease

33
Q

What can severe vitamin D deficiency cause?

A

Rickets in children
Osteomalacia in adults

34
Q

What is osteomalacia/rickets?

A

Demineralisation of bones
Soft and weak bones
Bend and break more easily
Bowed kegs

35
Q

Biochemistry of hypoparathyroidism

A

Low Ca
Low PTH levels
High phosphate

36
Q

Causes of hypoparathyroidism

A

Surgical damage or removal
Pathology of parathyroid gland
Failure of 3rd or 4th branchial arch

Look for scar in neck from surgery

37
Q

What is needed in acute severe hypocalcaemia?

A

Medical emergency
Assess airway and conscious level
ECG monitor to check heart
Intravenous calcium and monitor

38
Q

What is osteoporosis?

A

Demineralised bone
Brittle, fragile bones
Break easily
Looks like an areo bar

39
Q

Risk factors for osteoporosis

A
  • Post menopausal women
  • Family history
  • Smoking
  • Immobility
  • Endocrine diseases- hyperparathyroidism, hyperthyroidism, low testosterone in men, premature ovarian failure
40
Q

Classic places for osteoporotic fractures

A

Vertebra
Hip
Wrist

41
Q

Symptoms of osteoporosis

A

No symptoms
Not painful until break

42
Q

How is calcium transported in the blood?

A

Free ionised Ca2+
Bound to plasma protein
Complexed with citrate

43
Q

Explain the role of calcitonin in regulating serum calcium levels

A
  • Released from thyroid gland from parafollicular cells
  • Opposes PTH action
  • Decreases plasma calcium levels
44
Q

What cells are found in the parathyroid gland?

A

Chief cells - synthesis PTH
Oxyphil cells

45
Q

How does calcium regulate PTH synthesis?

A

Low serum calcium up-regulates gene transcription of PTH
High serum calcium down-regulates gene transcription of PTH

46
Q

Outline the action of PTH on the bone

A

1- PTH induces osteoblasts to secrete cytokines
2- cytokines stimulate differentiation + activity of osteoclasts
3- PTH decreases osteoblast activity
4- reabsorption of mineralised bone > releases Pi and Ca2+

47
Q

How is vitamin D3 transported?

A

Found to transcalciferin

48
Q

What is the half life of calcitriol

A

6hours

49
Q

How much calcium is present in the adult human body in kg?

A

1kg

50
Q

How do parathyroid glands sense plasma calcium conc.

A

By GPCR that are activated by calcium

51
Q

Storage of calcium

A

In bones as hydroxyapatite crystals

52
Q

What hormones are involved in calcium regulation?

A

Parathyroid hormone
Calcitriol
Calcitonin

53
Q

What is released if calcium levels are high vs low?

A
  • high: calcitonin to decreased plasma [Ca2+]
  • low: PTH to increased plasma [Ca2+]
54
Q

Action of calcitriol on serum calcium

A

Raises calcium levels where there has been prolonged reduction

MEH (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions