exam 3 Flashcards
what are the important forms of vitamin a?
retinol, carotenoids, b-carotene
what are sources of vitamin a
retinol esters, liver, egg yolk, carotenoids
structure of vitamin a
sperm - like with two heads
vitamin a absorption tracing
micelles absorbed along with other lipids -> carotenoids converted to vitamin A in enterocytes -> enters circulation in chylomicrons -> transported thru body by various RBP
what does excess vitamin a decrease ?
vitamin k absorption as it competes with chylomicrons in enterocytes
if there is a high intake of b-carotene, what does it decrease?
vitamin e levels
what is needed with protein for retinol binding proteins?
zinc
if vitamin a deficiency decreases what else decreases?
iron in rbcs
what are the functions of vitamin a?
vision, cell differentiation, growth, immune function, bone growth, reproductive systems, antioxidant
how does vitamin a affect vision
it is used to produce rhodopsin which allows light detection
the role of vitamin a in vision tracing
the light be hittin that retina -> rhod be in da cell -> brain be like oh heyy -> the ops and cis people get stabbed-> cis people turn trans -> they detransition -> the detrasitioned new cis people reattach to rhod their ex
SYMPTOMS OF VITAMIN A DEFICIENCY
night blindness, bitot’s/white spots, xerophthalmia/dry eyess, poor growth
who is at risk for vitamin a deficiency
those who have fat malabsorption, alcoholism, or zinc deficiency
vitamin a toxicity causes?
anorexia, skin discomfort, alopecia, headache
hypercarotenosis
when the skin yellows from excess b-carotene
what is calcitriol ?
active vitamin d3/hormone
sources of vitamin D
fish liver oil, butter, eggs
what is the structure of vitamin d
4 rings with a tail
how is vitamin D synthesized
sunlight -> converted to -dehydrocholesterol -> previtamin D -> cholecalciferol
Vitamin D absorption tracing
absorbed from micelle -> gets in circ as chylomicron
-> Cholecalciferol converts to the 25-OH version in the liver -> In the kidneys, 25-PH CHOLE is converted from the parathyroid hormone (PTH) into 1,25-OH cholecalciferol
why is vitamin d important for calcium absorption?
because the parathyroid hormone that is stimulated with low levels of calcium calls upon components of vitamin D such as calcitrol (the active form of cholecalciferol)
Does calcitrol, the active form of cholecalciferol, inhibit cancer growth?
yes
how does vitamin d function in calcium mobilization
When calcium levels are low, calcitrol is stimulated by pth, which will then stimulate osteoclasts and increase calcium serum
how is vitamin d useful in calcium retention?
When calcium levels are low, calcitrol levels are stimulated by pth and this process will increase renal calcium reabsorption
