Studied by 0 people
Looks like no one added any tags here yet for you.
provitamin D3
starts as dehydrocholesterol (derrived from cholesterol) in the skin
Vitamin D3 activation pathway uv step
the UV step in the Vitamin D3 tells us that sunlight exposure is important and VD3 can be obtained in the diet as well
how are vitamin d3 metabolietes transported
transported in the blood bound to the vitamin D binding protein and serum albumin
what is the chemical for vitamin D3
1,25-(OH)2 D3 or calcitriol
what happens to your body with Rickets
softening of bones in immature/growing mammals due to deficiency or impaired metabolism of vitamin D, phosphorus or calcium. Leads to fracturs and deformities
there are two types
common childhood disease in many develop countries
Synthesis of vitamin D
Biologically active vitamin D3 is produced by two hydroxylation steps.
first occurs in the liver to form (25-OH-vitamin D3) which is the main circulatory form
the second occurs mainly in the kidney to form the active 1,25-(OH)2D3 (calcitroil =vitamin D3)
what does the PTH hormone do
regulates poisitively the expression of the 1-hydroxylase needed to form the 1,25-(OH)2D3 in the kidney
how does vitamin D3 mediate its effects
it mainly goes through an intracellular nuclear receptor
and some non genomic effects are thought to be mediated via a membrane receptor
what are the Physiological actions of active vitamin D3
it regulates the intestinal uptake or absorption of calcium ion(as nutrient) and as a cell pro-differentiation for skin and hair
serum calcium concentrations are maintained within a narrow range so as to facillitate normal mineralization of bone and teeth and for nerve transmission and for blood coagulation
what is the biochemical effects of rickets
due to defect in vitamin D 25-hydroxylation: CYP2R1 is gene encoding 25-hydroxylase
what is the biochemical effects of rickets type IIA
caused by an inactivating mutation in the nuclear vitamin D receptor
what is the biochemical effects of rickets type 2B with normal nuclear VDR
its unusual form caused by abnormal expression of a hormone response element binding protein that interferes with the normal function of the VDR. This leads to increased circulating 1,25-(OH)2-vitamin D3.
most patients will also display total alopecia in addition to rickets
what is vitamin D deficiency associated with
Cancer
cardiiovascular disease
hypertension
stroke
diabetes
multiple sclerosis
rhematoid arthritis
inflammatory bowel disease
osteoporosis
periodontal disease
macular degeneration
mental illness
chronic pain
Vitamin D receptor - VDR
mediates the nuclear actions of 1,25-(OH)2D3. This 1,25 has the highest affinity
Calcium and Vitamin D correlation
vitamin D3 allows for Ca2+ absorption in the gut
calmodulin helps absorb Ca2+
PTH and Calcitonin affects on Ca2+
acts to increase Ca2+ levels while calcitionin decreases Ca2+ levels
Calcium sensing receptor (CaSR)
regulates the release of PTH produced by the parathyroid
located in the kidney helps in the reabsoption of Ca2+, phosphate, Na+ and water
encoded in the membrane by the CASR gene and is a G-protein coupled receptor
what are the two key serum ion levels
serum calcium - oral tingling sensation in and around the mouth/lips and in the extremities
serum phosphate levels - inadequate intake (alcoholics), increased excretion(hyperparathyroidism, hypophosphatemic rickets) this is normally very difficult to attin hypophosphatemic status since we have abundant phophorus in our diet
Once deficient it starts taking Ca2+ out of the bone whch causes more issues
Plaque Psoriasis
immune mediated disease affecting skin
no cure but vitamin D3 can help with symptoms
Plaque Psoriasis treatment
Topical: ointments containing coal tar, corticosteroids, vitamin D3 and retinoids
Phototherapy: going out side
Biologics used: Enbrel and Remicade (they are TNF-alpha inhibitors = reduce inflammation) Stelara is also used and targets IL-12 and IL-23 to reduce inflammation
Hereditary Vitamin D Resistance - Rickets
mutations which affect DBD and LBD
osteomalacia
inadequete levels of Ca2+ and phosphate caused by Vit D3 deficiency causes soft bone
