Body covering {skin}| has epidermis and dermis layers. Skin glands make oil and water and eliminate salt wastes. Most animals have drier skins than humans.
skin color
Skin color depends on epidermis yellow tinge, epidermis translucence, and skin-cell pigment amount and type: yellow, brown, or red. Melanin absorbs ultraviolet light and scavenges free radicals. Ultraviolet-B light causes melanocyte increase.
Chimpanzee skin is light colored, with pink skin at face, hands, and feet. Homo ergaster probably had little or no hair and had many more sweat glands.
High ultraviolet-A light reduces blood folic-acid concentration, needed for spermatogenesis and avoiding neural-tube defects. Ultraviolet-B light starts skin vitamin-D production. Vitamin D is for calcium absorption and for skeleton and immune-system development. Skin color balances these, with women having slightly lighter skin to absorb more calcium.
Biological Sciences>Zoology>Organ>Skin
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0224