NTDT200 Lecture Notes - Lecture 10: Vitamin D Deficiency, Vitamin A Deficiency, Beta-Carotene
5 May 2016
School
Department
Course
Professor
Document Summary
Excess stored in liver and adipose tissue. Not readily excreted (risk of toxicity is greater) Regulates cell differentiation, growth and embryonic development. Major transport and storage form (liver to blood) Helps convert light energy to nerve impulses in the retina. Change in shape and size of epithelial cells. Disrupts normal digestion and absorption of nutrients from gi tract. Weakens defenses in respiratory tract, vagina, inner ear and urinary tract. Two hydroxylation reactions ( liver and kidneys) Active form of vitamin d is a hormone. Binding proteins carries it to target organs. Other roles: enhances or suppresses gene activity. Contributory factors: dark skin, breastfeeding without supplementation, lack of sunlight, not drinking fortified milk. Vitamin d deficiency in children leads to bowed legs. Rickets: bones fail to calcify normally, bones bend, affects children. Poor mineralization of bones: affects adults, bones are soft, flexible, brittle, and deformed. Osteoporosis: loss of calcium from bones, results in fractures.
