Brainscape's Knowledge GenomeTM

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


See full index

RE > Calcium homeostasis > Flashcards

Calcium homeostasis Flashcards

1
Q

What physiological roles does calcium have in the body?

A

Muscle contraction
Bones and teeth
Blood coagulation
Hormone release

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

What cellular roles does calcium have in the body?

A

Exocytosis
Second messenger
Metabolism

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

What is the normal range of calcium?

A

2.2 - 2.7 mmol/L

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

Where is the majority of calcium found in the body?

A

99% in bones
1% in cells
0.1% in extracellular fluid

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

What is corrected calcium levels?

A

Levels corrected to the amount of protein in the patients body - as calcium attached to protein in blood, and amount of protein varies from person to person.

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

What percentage of dietary calcium is absorbed in the body?

A

10%

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

What factors can increase intestinal absorption of calcium?

A

Vitamin D
Low calcium uptake
Phosphate deficiency
Growth hormone
Oestrogens
Pregnancy and lactation
Furosemide

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

What factors can decrease intestinal absorption of calcium?

A

Age
High calcium uptake
glucocorticoids
Phosphate loading
Thyroid hormones
Thiazide diuretics

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

Vitamin D works in conjunction with which hormone?

A

PTH

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

Which hormone does the opposite of Vitamin D and PTH?

A

Calcitonin

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

Which gland secretes PTH?

A

The parathyroid

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

How are the levels of PTH and Calcium linked?

A

They are inversely proportional.
Higher PTH = lower Ca2+
Lower PTH = higher Ca2+

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

Which cells in the parathyroid gland synthesise and produce PTH?

A

Chief cells.

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

Which cells can be seen in secondary parathyroid hyperplasia, that synthesise and secrete PTH?

A

Oxyphil cells.

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

What is the main role of the parathyroid gland?

A

To monitor calcium concentration.

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

How long is the amino acid chain of PTH?

A

84 amino acids

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

The active part of PTH is in what part of the amino acid chain?

A

1-34

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

What part of the PTH amino acid chain is inactive?

A

35-84

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

The active part of the PTH (1-34) binds to which receptors?

A

PTH (Type 1) receptor - GPCR

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

Which receptor does calcium bind to, and that calcium is the agonist for?

A

Calcium sensing receptor (CaSR)

21
Q

What type of receptor is the Calcium sensing receptor?

A

GPCR

22
Q

Mutations to which receptor are correlated with hyper and hypocalcaemia?

A

Calcium sensing receptor (CaSR)

23
Q

Which cells monitor plasma calcium concentration?

A

Chief cells in the parathyroid gland via a g-protein calcium sensing system - this controls PTH release.

24
Q

Which ion is important for PTH to work?

A

Magnesium

25
Q

What is the half-life of PTH?

A

4 minutes

26
Q

Low levels of which ion inhibits the release of PTH?

A

Magnesium

27
Q

What factors stimulate PTH to be released?

A

Fall in plasma ionised calcium (acute)
Rise in plasma phosphate (chronic)

28
Q

What is parathyroid hormone released protein (PTHrP)?

A

Hormone secreted by tumours and contributes to the hypercalcaemia seen in malignancy.

29
Q

What role does parathyroid hormone related protein have in the foetus?

A

It acts as a calciotropic hormone and stimulates the transport of calcium across the placenta.

30
Q

Does a normal lab assay pick up PTHrP?

A

No, only PTH

31
Q

How does PTH affect bones?

A

PTH binds to osteoblasts –> cells express RANKL and M-CSF –> Interact with preosteoclast cells –> Form mature osteoclasts –> Release enzymes and acids to dissolve bone

32
Q

How does PTH affect the kidneys?

A

It binds to reduce Ca2+ excretion.
Causes increased absorption of calcium in the loop of henle, distal tubule and collecting ducts.
Reduces phosphate reabsorption in the proximal tubule.

33
Q

Where are PTH receptors found?

A

Bone
Kidneys
Intestine

34
Q

How does PTH affect the small intestine?

A

It binds and increases Ca2+ levels.

35
Q

What is the active form of Vitamin D called?

A

1,25-Dihydroxycholecalciferol

36
Q

Which hormone helps vitamin D be converted into it’s active form?

A

PTH

37
Q

Where does the hydroxylation of vitamin d occur in the body?

A

Liver
Kidneys - active conversion here

38
Q

Who do those with kidney problems need the active form of vitamin D?

A

Kidneys aren’t able to do the conversion to active vit D

39
Q

How does Vitamin D, Calcium and PTH have a negative feedback loop?

A

PTH helps the conversion of vit D into active Vit D.
Active vit D increases the intestinal absorption of calcium.
Higher calcium concentration inhibits PTH, thus reducing the amount of vit D converted into active vit D.

40
Q

How many amino acids are in calcitonin?

A

32

41
Q

Where is calcitonin produced?

A

In the thyroid gland by parafollicular C cells.

42
Q

What is calcitonin modulated by?

A

CaSR - Calcium Sensing Receptor
Also GI hormones e.g. Gastrin

43
Q

What stimulates the parafollicular C cells to secrete calcitonin? What inhibits it?

A

A rise in extracellular calcium
Inhibited by a fall in calcium.

44
Q

How does calcitonin affect bones?

A

It inhibits osteoclastic activity - therefore reducing bone resorption.

45
Q

How does calcitonin affect the kidneys?

A

It reduces tubular reabsorption of calcium and phosphate, therefore increasing their excretion and lowering their serum levels.

46
Q

Calcitonin is the major tumour marker of which cancer?

A

Medullary carcinoma of the thyroid gland.

47
Q

Which bone-derived hormone suppresses phosphate reabsorption and vitamin D synthesis in the kidneys?

A

FGF23 - Fibroblast growth factor-23

48
Q

What can an excess of FGF23 (Fibroblast growth factor-23) cause?

A

Hypophosphatemic rickets

RE (18 decks)

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