Quick Orientation
Section
Definition
- Objective
- Understand the core idea
- Keywords
- Vitamin A, carotenes, 20 to 50 μg/dl
Chemistry and Forms
- Objective
- Learn the main facts and relationships
- Keywords
- vitamin A, retinoids, retinol
Absorption, Transport and Storage
- Objective
- Learn the main facts and relationships
- Keywords
- retinyl esters, carotenes, beta-carotene 15,15'-dioxygenase
Biochemical Functions
- Objective
- Learn the main facts and relationships
- Keywords
- vision
Vitamin A and Vision: Wald's Visual Cycle
- Objective
- Follow the sequence and key control points
- Keywords
- 11-cis retinal, all-trans retinal, retinal isomerase
Clinical Correlation
- Objective
- Connect the mechanism to clinical findings
- Keywords
- Night blindness (nyctalopia), Xerophthalmia, Bitot's spots
Definition
Vitamin A is a fat soluble vitamin present preformed only in foods of animal origin; its provitamins, the carotenes, occur in plants.