Transcript Ch.19Pt.4_000

Vitamins "vital amine," are organic molecules (C, H, N, or O)
that are needed in trace amounts to help catalyze
many of the biochemical reactions in the body.
Generally obtained from dietary sources.
Thirteen vitamins have
been shown to be
essential for normal
growth and health in
humans
What are the important differences between
fat and water soluble vitamins?
Fat-soluble vitamins that we need include
vitamins A, D, E and K. Fat-soluble vitamins
dissolve in fat and therefore can be stored in the
fatty tissues of the body.
As a consequence, we do not need to ingest fatsoluble vitamins daily.
The body can use these stores when the intake
of fat-soluble vitamins is low.
Vitamin D is necessary for the proper formation of bones
A metabolic bone disease from vitamin D deficiency.
It is called rickets in children and osteomalacia in adults.
Both cause softening and weakening of bones because of
defective or inadequate bone mineralization.
Cholesterol
(a sterol)
Testosterone
(a steroid hormone)
Vitamin D3
(cholecalciferol)
Cholesterol is produced by the liver –
found in all body tissues –
Helps organize cell membranes & control their permeability.
Cholesterol derivatives in the skin are converted to vitamin
D when the skin is exposed to sunlight.
Vitamin D3 mediates intestinal calcium absorption and bone
calcium metabolism
Beta-carotene is the provitamin for vitamin A,
that is, it can be converted to vitamin A.
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Vitamin A (also called retinol) is fat-soluble, and as such, can be
stored in the fatty tissues of the body.
We obtain vitamin A either directly from foods that are substantial in
vitamin A (beef liver, fish liver oils, egg yolks and butter, for
example) or by converting a substance called beta-carotene into
vitamin A.
Vitamin A is an unsaturated alcohol, which
maintains good eyesight. A deficiency in the diet
leads to a degeneration of the structure of the eye.
Physiological Aspects of Vitamin E
Vitamin E is absorbed in the intestines.
The majority of the absorbed vitamin E is delivered to
the liver, where it is then secreted into the circulation for
delivery to tissues.
Anti-oxidant activity of Vitamin E:
H on the hydroxyl group of the Vitamin E ring can be
donated to neutralize a free radical
(creating a more stabile tocopheroxyl radical).
Polar ring stays near edges of plasma membrane.
When a phospholipid tail becomes peroxidized by a free
radical, the tail becomes more polar and migrates to the
edge where it gets neutralized by the vitamin E.
Vitamin E is present in animal fats, cereal
grains and nuts.
Alpha-tocopherol is found in a number of oils,
including safflower and sunflower.
It is also found in wheat germ. Soybean and
corn oils contain mainly gamma-tocopherol.
The Anti-Hemorrhagic Vitamin:
Vitamin K
Present in green leafy vegetables was required for
normal coagulation of the blood.
The "K" in vitamin K comes from the German
word "koagulation" (coagulation).
Vitamin K is essential for the functioning of several
proteins involved in normal blood clotting.
When a cut occurs,
complex series of
events acts to stop
the bleeding.
Blood clotting is
body's response to
tissue injury.
Constriction of ruptured vessel - proteins soon start "coagulation
cascade:"
Interaction of coagulation factors, platelets and the damaged vessel
itself.
Clot forms = protective barrier.
Clot breaks down as wound heals
There are several forms of vitamin K, namely:
1. Vitamin K1 (phylloquinone)
2. Vitamin K2 (menaquinone)
3. Vitamin K3 (menadione)
Vitamin K1 or "phylloquinone”
Major dietary source of vitamin K:
Green leafy vegetables like lettuce, kale, parsley,
spinach and various greens (turnip, beet and
mustard). Broccoli is also a good source of
vitamin K1 as are certain vegetable oils
(soybean, cottonseed, canola, and olive).
Vitamin K2 is actually a group of compounds
called the "menaquinones" distinguished by the
# of isoprene residues in side chain of the
vitamin K2 molecule or by # of C in the side
chain.
e.g.
menaquinone-8 (MK-8) has 8 isoprene units in side chain