HSS 2342 Lecture Notes - Lecture 12: Vitamin A Deficiency, Retinol, Beta-Carotene

• School: University of Ottawa
• Department: Health Sciences
• Course: HSS 2342
• Professor: Keir J Menzies

Document Summary

Vitamin a and beta-carotene: vitamin a was the first fat-soluble vitamin to be recognized, there are three different forms of vitamin a: retinol, retinal, and retinoic acid. These are known as the retinoids: beta-carotene is a vitamin a precursor. Movement of vitamin a in the body: vitamin a, once absorbed, travels in the lymph (it is fat-soluble) and eventually arrives at the liver, to travel to other tissues, retinal-binding protein is needed. Cells take up vitamin a by receptors on its surface. Vitamin a: roles in the body: regulation and/or expression of genes. Major transport and storage form of vitamin a: vitamin a helps maintain the cornea and participates in the conversion of light energy into nerve impulses at the retina. Light converts retinal from its cis conformation to the trans conformation. This releases the retinal from opsin and causes an electrical impulse that then sends messages to the brain. Rhodopsin is then regenerated and can be used again.