Fundamentals of Anatomy and Physiology

The Integumentary System (^121)
(A) (B) (^) Medulla (^)
Cortex (^) Hair root
Cuticle^
Hair shaft
(of hair) (^)
(^) Cuticle of (^)
internal root sheath Internal (^)
Medulla Granular layer^ sheathroot^
Pallid layer^
Epidermis Cortex Hair (^)
Hair root^ Cuticle^ External root sheath^
(^) Arrector (^)
(^) pili muscle (^) Papilla of hair (^)
(^) Sebaceous in bulb (^)
gland (^)
Dermis Dermal root sheath^
Blood vessels^
External epithelial
Hair bulb root sheath Hair (^)
(base of (^) Internal epithelial follicle (^)
hair root)^ root sheath^ Matrix
Artery Matrix (^)
Vein
Dermal papilla
(^)
(^)
Fat (^)
(C) (^)
Dermal root sheath (^)
(^) External epithelial (^)
(^) root sheath Hair follicle (^)
(^) Internal epithelial (^)
root sheath (^)
(^) Medulla (^)
(^) Cortex Hair (^)
(^) Cuticle (^)
(^) ®
Learning
Cengage ©
Figure 6- 4 (A) The anatomy of an individual hair. (B) Longitudinal section. (C) Cross sectional anatomy of a hair in a hair follicle.
men suffer a permanent loss of hair because the hair
follicles are also lost. This occurs because male sex hor-
mones affect the hair follicles of men with this genetic trait
and they become bald.
Hair Texture
We classify hair texture as straight, curly, or tightly curly
sometimes referred to as kinky. This is due to genetic
factors controlling the nature of the keratin of the hair. The
keratin of the cortex of the hair is polymerized and cross-
linked chemically in a characteristic folded configuration
called alpha keratin, making the fibers elastic. The alpha
keratin chain in some individuals produces straight hair, in
others curly, and in still oth-ers tightly curled. When
stretched, the keratin chain gets drawn or pulled out into a
more linear form called