維生素a的介紹ppt課件(完整版)
【正文】 dry itchy) ? Alopecia ? Coarsening of hair ? Nausea ? Bone pain ? Anorexia ? 七、維生素 A在保健食品中的應(yīng)用 用維生素 A強(qiáng)化面粉 用維生素 A強(qiáng)化奶粉 維生素 A、維生素 C和維生素 E在 100克奶粉中的含量分別達(dá)到 2022IU, 40mg和。 2/3可為β胡蘿卜素 ,應(yīng)為 534?6=3204 ?g. 中國(guó)居民膳食維生素 A推薦攝入量 (RNI) 年齡（歲） RNI*(?gRE) 年齡（歲） RNI*(?gRE) 0~ 400 14~ 男 800 女 700 ~ 400 18~ 800 700 1~ 500 孕婦： 初期 800 4~ 600 中期 900 7~ 700 晚期 900 11~ 700 乳母 1200 注： * 建議兒童及成人膳食維生素 A約 1/3~1/2以上來自動(dòng)物性食物；但孕婦膳食維生素 A來源應(yīng)以植物性食物為主。 Retinol is transported to the retina via the circulation, where it moves into retinal pigment epithelial cells. There, retinol is esterified to form a retinyl ester that can be stored. When needed, retinyl esters are broken apart (hydrolyzed) and isomerized to form 11cis retinol, which can be oxidized to form 11cis retinal. 11cis Retinal can be shuttled to the rod cell, where it binds to a protein called opsin to form the visual pigment, rhodopsin (visual purple). Absorption of a photon of light Night blindness is also an early symptom Xerophtalmia This is a range of disorders that affect the eye and that can lead to blindness. The symptoms of xerophthalmia occur in approximately the following order: Nightblindness: The child can not see in the dim light, making child to fall over things and can not see to eat. Bitot180。 暗適應(yīng)按上述相反方式進(jìn)行，又形成視紫紅質(zhì)。 維生素 A與視覺的關(guān)系 視網(wǎng)膜上有兩種視細(xì)胞，即視桿細(xì)胞與視錐細(xì)胞， 人類前者數(shù)量多，與暗視覺有關(guān) ；后者數(shù)量少，與明視覺及色覺有關(guān)，他們都有視色素，由視蛋白與生色團(tuán)組成。 維生素 A的氧化代謝的可能途徑 維生素 A的氧化代謝的可能途徑 胡蘿卜素的吸收 胡蘿卜素的微膠粒溶液在小腸內(nèi)吸收。經(jīng)血流入靶組織。 對(duì)堿較穩(wěn)定 ,但對(duì)酸不穩(wěn)定 ,使其脫氫或?qū)㈦p鍵重新排列。它的衍生物具有特殊的生理功能，如視黃醛 (Retinyl Aldehyde VA醛 )對(duì)暗適應(yīng)有效；甘露糖視黃醇磷酸 (Mannosyl Retiny Phosphate MRP)也具有某些生理功能 。 酯式水解進(jìn)入肝 ,然后又再酯化為棕櫚酸酯。 Vitamin A, which circulates in the plasma as a plex with retinolbinding protein (RBP) leaves the binding protein, when the plex binds the cell surface receptor. The liberated retinol crosses the cell membrane via the receptor and is transferred to an intracellular binding protein, known as cellular retinol binding protein (CRBP). CRBP then seems to deliver retinol to the target proteins that bring about the ultimate function. 4. 維生素 A的分解代謝及排出 視黃醇通過氧化轉(zhuǎn)變?yōu)榫S生素 A酸，其中一部分異構(gòu)為 β順式。 血漿中的類胡蘿卜素可分為 β胡蘿卜素、葉黃素，番茄紅素及其他類胡蘿卜素，視攝入情況而定。 Vitamin A is almost exactly the same as one half of the yellow pigment in carrots, betacarotene. Light causes vitamin A to change shape from the bend cis form to the straight trans form. Our eyes sense light by 39。
教學(xué)課件相關(guān)推薦
鄂ICP備17016276號(hào)-1