Vitamin A_ vitamin

Vitamin A_ vitamin

Unsaturated yuan alcohol, belong to lipid-soluble vitamin. Because the human body or mammal is apt to present dry eyes while lacking vitamin A, so also called axerophthol. Known vitamin A is A1 and A2 two kinds, A1 exists in animal's liver, blood and eyeball
In the retina, also called retinol, natural vitamin A mainly exists in the form of this. A2 mainly exists in the liver of the fresh-water fishes. Vitamin A1 is faint yellow flaky crystallization of a lipid solubility, melting point is 64 , vitamin A2 melting point is 17- 19 , it is usually golden yellow oil. Vitamin A is much alkene alcohol with - ketone ring of Radix Angelicae Dahuricae. Vitamin chemical constitution and difference of A1 of A2, just in - the intersection of Radix Angelicae Dahuricae and the intersection of ketone and 3 of ring, many one pairs of key at the 4. There are unsaturated keys in the vitamin A molecule, the chemical property is lively, it is easy to be oxidized in the air, or is shone and destroyed by the ultraviolet ray, lose physiological function, so preparation of vitamin A should be put and kept in the brown bottle in shade. No matter A1 or A2,can and three chlorine antimony function,appear dark blue, can last bases to determine vitamin A quantitative the property. A lot of plants such as carrot, tomato, green leaves vegetables, corn include the carotenoid material, such as , , - carrotene, latent yellow quality, xanthophyll,etc.. It has ring structure the same as vitamin A1 that among them carotenoid a bit, can be changed into vitamin A in the body, so it is original to call vitamin A, - carrotene contains the ring structure of two vitamins A1, conversion ratio is the highest. A molecule beta carotene, can turn into two molecule vitamin A1 while adding two molecule water. In animal's body, this kind of watering oxidizing process is plain by the trailing plants card of 's moustache - 15, 15 ' - add oxygen enzyme to catalyze, mainly go on in animal's mucous membrane of small intestine. In the food, combine with fatty acid into ester in the intersection of small intestine and mucomembranous cell by - the intersection of carrotene and cracked vitamin A that turn into, then mix the chyle particle and enter body through lymphocytic absorption. The liver of the animal is in order to store the main place of vitamin A. When the organism needs, and then release into the blood. In the blood, retinol (R) With the conjugated proteln of retinol (RBP) And albumin (PA) before the blood plasma Combine, produce R-RBP-PA complex and transship to every organization.
It was 1913 Taiwan, chemist of United States of America, linked Sri Lankan and was extracted from cod's liver. It is yellow powder, insoluble in water, apt to be soluble in organic solvents such as the fat, oil,etc.. The chemical property is more steady, but apt to destroy for the ultraviolet ray, should store in the brown bottle. Vitamin A is raw materials of visual purple in eyes, it is essential materials of skin tissue too, people will catch dry eyes, nyctalopia,etc. if people lack it. Should take in vitamin A2- 4.5mgs per person per day usually, can't take in too many. Relevant research indicate, it has anticancer function in recent years. Include a lot of vitamin A in animal's liver, secondly it is cream and egg,etc..
The main function of vitamin A is: Maintain all epithelial tissue to need sound. At the time of the shortage, the epithelial tissue dries, hyperplasia, excessive horn, resist the ability that microorganisms are infected with to reduce. For example the cover is secreted and stopped on the lachrymal gland, can dehumidify cornea, conjunctiva, inflammation, even soften and punch. When sebaceous gland and the intersection of sweat gland and corner take, apt to take place dry skin the intersection of hair follicle and papule and hair loss. Promote growth, development and breed. While lacking vitamin A, children grow bad, the skeleton is grown up bad, the reproduction function fails. Form the composition of sensitization material in visual cells. Vitamin A can be oxidized and produced retinene, retinene and mere receptor (look at pole cells and look at awl cells) under taking off the enzymolysis of hydrogen Different opsin in China combines and produces all kinds of to absorb looking at the pigment of spectrum, such as rhodopsin, visual purple,etc.. Regard pigment as the sensitization material, they will cause a succession of physical chemical changes while absorbing the photon, produce the receptor potential. This kind of receptor potential changes the nerve impulse in the form of pulse through various nerve cells on retina, reach the brain, produce the vision. It is known that, may be decomposing and regenerating and forming dynamic equilibrium constantly in sensitization depending on rhodopsin in the omentum. While looking at the pigment in the dark place, retinene among them is by 11 - exist along the configuration, claim to 11 - arrange retinene, but change after sensitization into the whole retinene instead type rapidly. The change with the configuration, depend on the pigment fades and reacts, and resolve into type retinene and opsin. Shone by the shimmer against type retinene, can change into 11 - arrange retinene again, and bind with opsin, form rhodopsin, thus guarantee, can look at pole cell lasting sensitization, appear sootopic vision, may see the outlines and shapes of thing under the faint light while being only. However, opsin and retinene which makes up rhodopsin carries on the catabolism constantly, so need to supplement protein and vitamin A constantly. If vitamin A is insufficient in supply, visual purple is formated and reduced in the rod, will cause dark visual disorder - -Nyctalopia.
The demand of every day:
Women need 0.8 milligrams. Namely 80 grams of eels and 65 grams of chicken's liver, 75 grams of carrot, 125 grams wrinkle wild cabbage of leaf or 200 grams of tunas.
Efficiency: Strengthen the immune system, help cell regeneration, protects cell against the infringement of the free radical that can cause many kinds of diseases. It can make the mucous membrane of organs such as respiratory tract, oral cavity, stomach and intestine,etc. not damaged, vitamin A can also make eyes bright.
Side effect: Take in 3 milligrams of vitamin A every day, there is a danger which cause osteoporosis. Will make losing the appetite, skin drying, hair lossing, skeleton and joint pain to take in 33 milligrams of vitamin A long-term every day, even cause abortion.
( 2) Vitamins B B clan vitamin are contain rich amount of in food such as animal's liver, red meat, poultry egg, milk, soyfood, grain, carrot, fish, vegetablesed. It is a kind of water soluble vitamin, the majority is coenzyme in the human body, mainly has the following aspects.


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