Barber State Board Exam Complete Practice Test

Melanin is the primary pigment responsible for the coloration of the skin, but the color also significantly depends on blood supply. Blood vessels in the skin can give it a reddish hue, particularly in areas where blood flow is increased, such as during physical exertion or emotional reactions. The amount of blood circulating close to the surface of the skin impacts its overall tone, leading to variations in color that can be observed in different individuals or under varying conditions.

While skin thickness and environmental conditions can influence the appearance of the skin to some extent, they are not direct determinants of skin color like blood supply is. Skin thickness may affect the skin's overall texture and how light interacts with it, while environmental conditions can alter the skin's appearance without changing its inherent color.

Exposure to sunlight can increase melanin production and may lead to tanning, but this effect operates through a mechanism of changing melanin levels rather than serving as a primary factor in base coloration. Therefore, blood supply is the most relevant additional factor determining skin color alongside melanin.