vitamin D ,calcium homestasis and biomierlasiton Flashcards
what type or roman is vitamin D
steroid hormones
how much vitamin D derived by ultraviolet B rays
80%
what is vitamin D essential for
calcium homeostasis,
bone and teeth health,
cardiovascular ehealth and immune function
prevention of cancer
what ar normal Vitamin D levels NOT be less than or more than
Normal vitamin D levels should not be less than 50 nmol/L (20ng/mL)
Or more than 125 nmol/L (50 ng/mL)
how much supplement doe public health England advise
10 ug
name dietary sources of vitamin D
egg yolk,
oily fish,
fish oil
and a number of plants
name the first step of activation of vitamin D
VITAMIN d3 - CHOLECALCIFEROL GENERATED IN SKIN OF ANIMALS WHEN LIGHT ENERGY IS ABSORBED BY 7 DEHYDROCHOLESTEROL
name the second step of activation of thiamine D
UVB activated or hydroxylates 7 dehydrocholesterol to cholecalciferol - vitamin D3
Within the liver ,Then cholecalciferol goes through hydroxylation by D’25 hydroxyls to create
25-hydroxycholecalcierol
where does the double hydroxylation the occur
Within the kidney -To be activated completely goes through another hydroxylation using 25-1 alpha hydroxylase to form 1-25 dihydroxycholecalciferol - active form of vitamin D which is circulated in blood and body to perform required role of body of
what’s the name for provitamin D2 found In plant cells
Ergosterol
what is the half life of 25 hydroxychoelcalfierol
and 1-25 dihydroxychoelcciferol
- weeks
- Hours
how much balance in calcium serum levels is required fro functions
(2.2-2.7nmol/L)
what does vitamin D do when tis acitvated
enhances the absorption of calcium from intestine and moves it to the bone
Stimulated PTH and enhanced bone resorption and act on kidneys to prevent calcium loss and enhance absorption
Low calcium levels - vitamin D enhance absorption of calcium from the intestine and act augmenting the PTH to decrease calcium loss in urine
Normal calcium levels - enhance mobilisation of calcium to the bone via absorption form interesting
how are serum calcium levels controlled -
thyroid and pTH influencing release of stored calcium in bone tissue through regulation of bone resorption
describe properties of PTH
- secreted by PT glands
- Short half life r
- Rapid response
- PTH receptor 1 in bone
- Increases RANKL and decreases OPG
- Indirectly activates Osteoclastogenesis and increase serum calcium
what does cacitonin do
Produced by parafollicular cells in thyroid
Antagonises PTH effects and decreases serum calcium
I
nhibits osteoclasts indirectly
what does calcitrol do
aka 1-25 dihydroxyvitamin D3
- Production stimulated by PTH in kidney
Increases calcium absorption in intestine
Vitamin D response elements
Directly regulates gene expression bone matrix proteins
how is vitamin D gene transcription regulated
- When PTH stimulates vitamin D in skin or by viable supplemented
- The vitamin D binds to vitamin d binding proteins and circulates tot the target cells
- These target cells have specific receptors called Vitamin d receptors that uptake the vitamin D ligand and enter the specific target cells
- In the target cells the vitamin b receptor and vitamin D form homo dimers with another receptor called retinoid X receptor
These form complexes that enter nucleus and affect vitamin D elements which are DNA sequences of specific genes that will response to interactions with vitamin D receptor vitamin D RXR combination - Target specific gene transcription to fulfil spice functions in bone]
what happened when the vitamin D dimers enter OB
Stimulation ECM proteins such as OPN - osteopontin ,OCN- osteocalcin and collagen type 1 - enhancing bone formation
Also triggers RANK of OB which stimulates OC leading to bone reoption and turnover
Vitamin D can lead to anabolic and catabolic activities mainonta health of bone
If one takes over - leads to stiffness or bone or osteoporosis
list cause son vitamin D deficiency
- DECREASED EXPOSURE TO SUNLIGHT
- Impaired photosynthesis in skin
- Inadequate diet
Impaired intestinal absorption - Impaired conversion of vitamin D into active metabolites owing to liver or renal disease
- Resistance to biological effects of 1,25 OHc
- Accelerated inactivation of vitamin D metabolites ( barbiturates, phenytoin,rifampin)
- Medications (anticonvulsants,systemic glucocorticoids, ketoconazole or antiretrovirals)
SPF than8 - block synthesis of vitamin D in skin
what are normal vitamin D levels
75-125 Nmol/l
what can vitamin D defieicny lead to
ecessary for mineralisation of oral hard tissues including bone and teeth (enamel,dentin,cementum)
Inadequate levels of vitamin D3 leads to hypomineralization and increases risk for developing dental caries
Increase risk of periodontal disease
In canada soem schools have ful spectrum lighting - less caries in children with normal lights
Vitamin D deficiency in pregnant mothers- enamel and dentine hypoplasia or incomplete/delayed development
Orthodontic and tooth movement
Oral pathology ; cancer and osteonecrosis of the ajw
Maternal imbalance - affect deciduous states< 15ng/ml has 14% of hypomineralisation
Vitamin D deficiency - reduced sliabe - increased inflammatory markers IL-35 AND IL-17A
When vitamin D supplemented - IL markers reduced
Reduced p gingivalis too and in animal experimental studies - reduce MMPs that disrupt PDL matrix
Orthodontics - vitamin D during tooth movement enhances tooth movement
Compression- boen regeneration , tension- boen reospion
Allos tooth to move in socket
ORAL PATHOLOGY - VDD increased incidence of oral cancer such as squamous cell carcinoma
Vitamin D reduced proliferation of keratinocytes and reduce angiogenesis associated with cancer invasion
Increased incidence of these types of cancer - vitamin D supplements during cancer treatment reduce toxicity related to chemotherapy and improves survival rates after surgery
what does vitamin D toxicity aka
how it starts
consequences and treatment
Hypervitaminosis D
Rare
Serious
Large doses of vitamin D supplements not by diet or sun
Taking 60,000 UNITS A DAY OF VITAMIN d - TOXICITY
MAIN Consequence- buildup of calcium in blood - hypercalcemia-
Cause nausea and vomiting,weakness, frequent urination
Vtiamin D toxicity might progress to bone pain and imbalance as well as kdiey problems suhc as formation of calcium stones
Treatment - stop supplements for period of tiem
