Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

ibms: lipids and carbs > Vitamin D, Calcium homeostasis and biomineralisation > Flashcards

Vitamin D, Calcium homeostasis and biomineralisation Flashcards

1
Q

Where can vitamin D be made?

A

In the skin with the help of sunlight

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

What does public health England recommend to adults and children in regards to vitamin D?

A

Advises that adults and children over the age of one should consider taking a daily supplement painting 10 micrograms of Vit D

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

Name the most potentially toxic vitamin

A

Vitamin D

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

What can vitamin D cause in high doses?

A

Nausea
Muscle weakness

In very high doses can cause increased calcium absorption and bone resorption

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

What effect can increased calcium absorption and bone reparation have on the body

A

Increased calcium levels in body fluids can leaf to calcification of arteries and organs eventually leading to liver failure

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

Give some dietary sources of vitamin D

A
  1. Egg yolk
  2. Fish oil
  3. Some plants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name the vitamin D precursor

A

Ergosterol or vitamin D2

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

Is dietary intake of vitamin D usually enough?

A

No exposure to sunlight of consumption of supplements with vitamin D are necessary to prevent deficiencies

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

What is the first stage of vitamin D activation?

A

Ring cleavage

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

Name the inactive component of vitamin D found in plants

A

Ergosterol

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

What happens to Ergosterol when it is hit with UV?

A

It becomes ergocalciferol (vitamin D2)

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

Name the inactive form of vitamin D formed in our liver

A

7-Dehydrocholesterol

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

What happens to 7-Dehydrocholesterol when it is hit with UV

A

Cholecalciferol

Vitamin D3

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

Name the stages involved in vitamin D botsynthesis/activations

A
  1. Ring cleavage

2. Double hydroxylation

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

How is Cholecalciferol

(Vitamin D3) activated

A

It undergoes double hydroxylation

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

Go through the steps of the double hydroxylation of Cholecalciferol
(Vitamin D3)

A
  1. Cholecalciferol
    (Vitamin D3) is inactive in the liver
  2. First hydroxylation occurs by enzymes in the liver at position 25
  3. Second hydroxylation occurs in the kidneys at position 1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where does the double hydroxylation of vitamin D occur?

A

First hydroxylation occurs in the liver

Second hydroxylation occurs in the kidneys

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

Name the 2 precursors of vitamin D

A
  1. Ergosterol (provitamin D2)

2. 7- Dehydrocholesterol (provitamin D3)

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

Name the 3 intermediates of vitamin D

A
  1. Ergocalciferol (vitamin D2)
  2. Cholecalciferol (Vitamin D3)
  3. 25-Hydroxycholoecalciferol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Name the activated form of vitamin D3

A

Calcitriol or 1,25- Dihydroxyvitamin D3

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

Is vitamin D hydrophobic or hydrophilic?

A

Hydrophobic

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

How is vitamin D transported?

A

It is transported in blood bound vitamin D binding protein (DBP)

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

What is the half life of 25- hydroxycholecalciferol

A

several weeks

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

What is the half life of 1,25 dihydroxycholecalciferol

A

A few hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What can imbalances in calcium serum levels lead to?
Can lead to hypercalcaemia and hypocalcaemia
26
What is the normal range of calcium serum levels a person should be within?
2.2-2.7mmol/L
27
Which hormone is released when calcium levels are low?
The parathyroid hormone (PTH)
28
What does the parathyroid hormone (PTH) do?
1. Enhances bone resorption and increases efflux of Ca2+ from bone 2. Also decreases the loss of calcium from Turin
29
What response does the body have when it detects low calcium levels in the blood?
1. The parathyroid hormone is released (PTH) 2. This hormone enhances bone resorption and increases efflux of Ca2+ from bone 3. Also decreases the loss of calcium from urine
30
Which form of vitamin D is involved in controlling calcium serum levels?
Vitamin D3
31
How does vitamin D3 respond when low calcium levels are detected in the blood
It enhances absorption of calcium from the intestine
32
Where is vitamin D3 found?
In the kidneys
33
Name the glands involved in controlling serum calcium levels
1. Thyroid glands | 2. Parathyroid glands
34
What is the parathyroid hormone (PTH) secreted by?
Parathyroid glands
35
Does the parathyroid hormone (PTH) increase or decrease serum calcium?
Increases it
36
What does parathyroid hormone (PTH) activate indirectly?
Osteoclastogenesis
37
What effect does the parathyroid hormone (PTH) have on RANKL and OPG
Increases RANKL | Decreases OPG
38
What is calcitonin produced by?
Produced by the parafollicular cells in the thyroid
39
What effect does calcitonin have on parathyroid hormone (PTH)
It has an antagonistic effect
40
Does calcitonin increase or decrease serum calcium?
Decreases
41
What does calcitonin do?
It decreases serum Ca2+ by inhibiting osteoclasts
42
The parathyroid hormone (PTH) hormone stimulates the production of C__________
Calcitriol
43
What is calcitriol
1,25 Dihydroxy vitamin D3
44
What is the production of calcitriol stimulated by?
The parathyroid hormone (PTH)
45
What is calcitriol do?
It increases calcium absorption in the intestines
46
How does calcitriol increase calcium absorption in the intestine?
Vitamin D responsive elements (VDRE) directly regulate gene expression eg osteocalcin
47
Name the enzyme that catalyses the hydroxylation of C25 in the liver
25 hydroxylase enzyme
48
Does the 25 hydroxylase enzyme need to be activated?
No it is always active and ready to hydroxylate any cholecalciferol and ergocalciferol
49
What can the 25-hydroxylase enzyme be inhibited by?
25- hydroxyvitamin D3
50
Talk through when the Parathyroid Hormone (PTH) is released and what effect it has on the kidneys
1. Low serum calcium levels are detected 2. The Parathyroid Hormone is released by the parathyroid gland 3. Hormone travels to kidneys and activated the 1-hydroxylase enzyme 4. This enzyme then aids het reaction of 25-hydroxyvitamin D3 into 1,25-hydroxyvitamin D3
51
What are al steroid hormone the in body derived from?
Cholesterol
52
Where are steroid hormones secreted from?
Steroid glands
53
Are steroid hydrophobic or hydrophilic?
Hydrophobic (lipophilic)
54
What do steroid do?
They directly regulate the expression of certain responsive geneses in conjunction with additional factor
55
Name some common steroids found in the body
1. Cortisol 2. Testosterone 3. Vitamin D3 3. Retinoic acid
56
How are steroid hormones activated and what affect does their activation have?
Steroid receptors bind to cognate steroid hormones and become activated This then activates transcription of target genes
57
What is the human osteroclacin gene responsible for?
Biomineralisation and bone matrix synthesis
58
What is human Osteocalcin produced by?
Osteoblasts and odontoblasts
59
What does human Osteocalcin do?
1. Binds hydroxyapatite and calcium 2. Modulated mineralised matrix mechanical properties 3. It is a marker of matrix mineralising cells
60
What can a deficiency in human Osteocalcin lead to?
Osteopetrosis
61
What percentage of the bone matrix is composed of human Osteocalcin?
2%
62
How much vitamin D do adults require daily?
5-10 micrograms (200-400 iu)
63
State the normal serum levels of vitamin D in an adult
25-80ng/ml
64
What can deficiency of vitamin D3 lead to in children?
Skeletal mineral deficiencies such as rickets and osteomalacia
65
What can deficiency of vitamin D3 lead to in children?
Skeletal mineral deficiencies such as kidney insufficiency and liver cirrhosis
66
What affect can vitamin D3 deficiency has orally?
1. Can increase a patients risk of developing dental caries and periodontal disease 2. Can lead to enamel and dentine hypoplasia or incomplete/delated development 3. Can have effects on the alveolar bone
67
What is the significance of vitamin D3 in the mouth?
It is necessary for the mineralisation of oral hard tissues including bone an d teeth
68
What does the 25 hydroxylase enzyme do?
Ut catalyses the hydroxylation of C25 in the liver (Vitamin D activation)

ibms: lipids and carbs (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions