Heads have 100,000 hairs {hair, human}. Hairs grow several years, five inches a year. Follicles then become dormant, and hairs fall out. Later, new hair grows. Humans have less hair, because they have many more sweat glands with which to stay cool.
Hair holders {hair follicle}| have growing and non-growing phases. Dermal papilla are deep in dermis, organize hair follicles, and start hair matrix. Wnt signaling proteins induce hair follicles and control hair-growing cycle. Hairs fall out after bottom cells die.
region
Hairs have inner and outer sheathes. Hair follicles have attached muscles, which can form goosebumps, and nearby sebaceous glands.
curl
Flat follicles make curly hair.
color
Hair, fur, and feathers are dead skin cells. Pigments, air bubbles, and rough or smooth surfaces cause color.
Head hair {cowlick}| can grow in another direction than other hair.
Hair {forelock}| can grow from or fall over forehead. Horse manes typically have forelocks.
fur {pelt}.
short unshaven facial hair {stubble}.
woman's long hair {tress}.
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Date Modified: 2022.0225