Anatomy & Physiology I and II

Anatomy & Physiology Study Guide

©2018 Achieve Test Prep Page 65 of 367 is a brown, yellow-brown, or black pigment produced by melanocytes. The melanocytes involved are in the stratum germinativum. Melanocytes manufacture melanin from the amino acid tyrosine, and melanosomes store the melanin intracellularly. In people with large melanosomes, the skin pigmentation is darker and more persistent. Blood contains red blood cells filled with the pigment hemoglobin, which binds and transports oxygen in the bloodstream. When bound to oxygen, hemoglobin is bright red, giving capillaries in the dermis a reddish tint that is most apparent in lightly pigmented individuals. If those vessels are dilated, the red tones become much more pronounced. When body temperature rises, skin becomes flushed and red because the superficial blood vessels vasodilate to allow the skin to lose heat. When its blood supply temporarily drops, the skin becomes relatively pale; a light-skinned individual who is frightened may “turn white” as a result of a sudden drop in blood supply to the skin. Changes in skin appearance can be useful in diagnosing diseases that primarily affect other body systems. Pigmentation Carotene is an orange-yellow pigment that normally accumulates in epidermal cells. Carotene is in a variety of orange vegetables, such as carrots and squashes, and thus the skin of individuals with a fondness for carrots can turn orange from an overabundance of carotene. Melanin