Brainscape's Knowledge GenomeTM

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


See full index

MEH > Calcium Metabolism > Flashcards

Calcium Metabolism Flashcards

1
Q

What is Calcium vital for?

A

Bone formation
Nerve and muscle function

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

How is calcium important for nerve and muscle function?

A

Ca2+ stimulates synaptic vesicles to release neurotransmitter into synaptic cleft

Calcium released from sarcoplasmic reticulum binds to Troponin at the TnC part of this 3 complex protein. This causes a conformational change pulling the protective Troponin-tropomyosin complex away exposing the actins active sites to the myosin heads

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

What can happen as a result of a sudden change in calcium levels?

A

Seizures and palpitations due to changes in Ca2+ levels in nerves

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

Which gland is responsible for regulating Calcium levels?

A

Parathyroid glands

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

What is the hormone that the parathyroid glands synthesise and secrete?

A

Parathyroid hormone (PTH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which 3 parts of the body does PTH act on regulating Ca2+ levels?

A

Bone
Kidney
Gut

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

Where are the parathyroid glands located?

A

Posterior to the thyroid gland
They are completely separate in structure and function

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

How many parathyroid gland tissues are there in the parathyroid and how are they distributed?

A

There are 4
2 in each lobe
Each lobe has an upper parathyroid and lower parathyroid

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

What is the embryological origin of the lower left and right parathyroids?

A

The III Brachial arch

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

What is the embryological Origin of the left and right upper parathyroids?

A

The IV Brachial Arch

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

What are the cells called that secrete PTH in the Parathyroid gland?

A

Chief cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of hormone is PTH?

A

Peptide hormone

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

What form is PTH first produced in?

A

PreproPTH

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

How is preproPTH processed to its active form?

A

Signal sequence cleaved out of PreproPTH forming proPTH in ENdoplasmic reticulum
ProPTH enters Golgi and is cleaved to active PTH form

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

Generally what does PTH do to the:
-Gut/intestines
-Bone
-Kidney
In terms of calcium levels

A

Increases Ca2+ absorption in gut
Increases Ca2+ resorption from bone
Increases Ca2+ retention in kidney

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

What do receptors on chief cells detect?

A

Ca2+ levels

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

What affect does PTH have on Phosphate?

A

Causes phosphate loss

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

What does a patient with low phosphate levels indicate in terms of PTH?

A

Indicates phosphate loss so high PTH levels

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

What does a patient with high phosphate levels indicate in terms of PTH levels?

A

Indicates low phosphate loss so low PTH

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

What protein actually causes the phosphate loss as a result of high PTH?

A

FGF23

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

What type of molecule is Vitamin D?

A

A steroid hormone

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

How does vitamin D work inside a cell?

A

Works in nucleus affecting gene expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is required to synthesise inactive Vitamin D3 in the skin?

A

UV light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the name of the inactive Vitamin D3 synthesised in the skin?

A

Cholecalciferol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How is the Inactive Vitamin D3 (cholecalciferol) converted into Active Vitamin D3?

A

Hydroxylation in the LIVER
Then Hydroxylation in the KIDNEY
Molecule is now ACTIVE VITAMIN D (Calcitriol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How is vitamin D2 and Vitamin D3 obtained?

A

Vitamin D2 = diet
Vitamin D3 (cholecalciferol) = diet fish and made in skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What must happen to vitamin D2 before it can become activated Vitamin D

A

Must be converted to inactive vitamin D3 (cholecalciferol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the role of Active Vitamin D3?

A

Increases Ca2+ levels in the body

29
Q

How does activated Vitamin D3 increase calcium levels?

A

Stimulates kidney to produce enzymes (C-1 Hydroxylase) to convert cholecalciferol into active vitamin D3
Vitamin D3 stimulates kidney to re absorb more Ca2+
Stimulates gut to absorb more Ca2+

30
Q

How does PTH increase resorption of Ca2+ from bone into the blood?

A

Increases osteoclast activity so more bone is broken down and Ca2+ and phosphate released into blood

31
Q

What is the definition of Hypercalcaemia?

A

Serum calcium> 2.51mmol/L

So higher than normal range of serum calcium

32
Q

What are the 4 main symptoms of Hypercalcaemia?

A

-Polydipsia and polyuria (Nephrogenic diabetes Insipidus)
-Constipation
-Kidney stones
-Confusion

33
Q

Why does high calcium levels cause Nephrogenic Diabetes Insipidus?

A

Calcium reduces nephrons sensitivity to ADH by degrading aquaporins so less water is reabsorbed

34
Q

To remember symptoms of Hypercalcaemia what pneumonic should I remember?

A

Bones, stones, groans and psychic moans

35
Q

What are being referred to in remembering the symptoms of Hypercalcaemia in Bones, groans, stones and psychic moans?

A

Bones = painful bones due to HIGH PTH causing abnormally high bone resorption/remodelling
Groans = abdominal pain from constipation
Stones= kidney stones (normally made of calcium)
Psychic moans = confusion

36
Q

What are the 2 causes of Hypercalcaemia?

A

PTH Independant
PTH dependant

37
Q

What does it mean I terms of PTH levels if the cause of Hypercalcaemia is PTH independent?

A

PTH LOW

38
Q

What does it mean in terms of PTH levels if the cause of Hypercalcaemia is PTH dependent?

A

PTH HIGH

39
Q

Describe what happens in PTH Independent Hypercalcaemia:

A

PTH levels are actually low
But PTH related peptides are being made (PTHrp)
These PTHrp act on PTH receptors stimulating the actions that PTH would cause like:
-increased bone resorption
-increased re absorption of Ca2+ in kidneys
-increased Ca2+ absorption in gut

40
Q

What is the most likely explanation if somebody has a PTH independent Hypercalcaemia?
So PTH levels are low but Serum Ca2+ > 2.6

A

Cancers producing PTH related peptides

41
Q

What cancers cause high calcium?

A

Myeloma = cancer of blood cells (plasma cells)
Bone metastases = cancer has spread to bone activating more osteoclasts increasing bone resorption

42
Q

PTH independant Hypercalcaemia can also be caused be things that affect/ increase Vitamin D

A

TB
Granulomas

43
Q

What is primary hyperparathyroidism?

A

When there is a problem with the parathyroid gland itself causing over production of PTH
Leads to Hypercalcaemia

44
Q

Why is a PTH Dependant Hypercalcaemia (Primary Hyperparathyroidism) better than a PTH independant Hypercalcaemia?

A

If Ca2+ levels are high and PTH levels are high it indicates that the high calcium is being cause by the parathyroid glands and not a Cancer /malignancy

45
Q

So what normally causes Primary hyperparathyroidism?

A

A benign parathyroid adenoma

Produces more PTH

46
Q

What are the effects of Primary Hyperparathyroidism on a patient?

A

-Hypercalcaemia symptoms (Think Bones, stones, groans, psychic moans)
-High calcium and low phosphate
-Signs of increased bone turnover (bone pain)

47
Q

What is Alkaline Phosphatase a marker of?

A

Bone resorption rate
Increased ALP = increase bone resorption

48
Q

How to treat Acute severe Hypercalcaemia?
So over 3 or 4mmol/L
Normal 2.2 - 2.6

A

Give IV fluids quick due to dehydration
Then treat underlying cause

49
Q

What is Hypocalcaemia?

A

Low serum calcium
Below normal 2.2 -2.6 range

50
Q

What are the Symptoms of Hypocalcaemia?

A

Numbness
Muscle cramps
Palpitations
Seizures

Due to neuromuscular junctions being affected

51
Q

What can cause Hypocalcaemia?

A

Vitamin D deficiency
Hypoparathyroidism

52
Q

Why does Vitamin D deficiency cause Hypocalcaemia?

A

Vit D needed to:
-absorb Ca2+ from gut
-reabsorb Ca2+ from urine in kidneys

53
Q

What happens biochemically when vitamin D is low?

A

Low calcium (Hypocalcaemia)
Body stimulates PTH production causing high PTH to try and increase vitamin D synthesis and bone resorption to increase serum Ca2+
High PTH causes low Phosphate due to PTH causing production of FGF23

54
Q

What causes Vitamin D deficiency?

A

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

55
Q

What condition does severe Vitamin D deficiency cause in Kids?

A

Rickets

56
Q

What condition does serve Vitamin D deficiency cause in Adults?

A

Osteomalacia

57
Q

Why does Rickets happen with Vitamin D deficiency?

A

Low Ca2+ in the body
Ca2+ and phosphate needed to mineralised bone to form strong hydroxyapatite crystals

58
Q

Symptoms of Rickets

A

Bowed legs
Neonatal seizures

59
Q

Why does Vitamin D deficiency lead to Osteomalacia?

A

Bone is soft due to low Ca2+ in body
Ca2+ not available to mineralised bone with phosphate

60
Q

What symptoms does osteomalacia present?

A

Gluteal muscle weakness causing waddling gait
Multiple fractures possible

61
Q

In rickets and osteomalacia is the bone structure normal?

A

Yes it’s just under-mineralised making it soft

62
Q

What happens in the chief cells during Hypoparathyroidism?

A

Cell not producing PTH so:
Ca2+ not reabsorbed in kidney
Ca2+ not resorted from bone
Ca2+ not absorbed in gut

63
Q

Why would phosphate levels be high in Hypoparathyroidism?

A

Low PTH means less phosphate loss due to less FGF23 made

64
Q

What can cause Hypoparathyroidism?

A

Parathyroid damaged or removed in SURGERY
Pathology of parathyroid
Failed embryological development of 3rd or 4th brachial arch

65
Q

How do you treat Acute Severe Hypocalcaemia

A

Give intravenous calcium and monitor them and their heart (ECG)

66
Q

What occurs in Osteoporosis?

A

Cortical bone is broken down reducing bone density making bones brittle and easily broken

67
Q

What is the cause of Primary Type 1 osteoporosis?

A

Occurs mainly in post menopausal women
Lack of oestrogen overly stimulates osteoclast activity causing more bone to be resorped/broken down than is reformed

68
Q

What is the cause of Primary Type 2 osteoporosis?

A

Occurs in elderly men and women
Caused by reduced osteoblast function as patient ages

69
Q

What are the risk factors for osteoporosis?

A

Post menopausal females
Family history of osteoporosis
Smoking and sedentary lifestyle
Endocrine disease

MEH (33 decks)

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