3. Epidermal Derivatives (pg 6)
• Accessory structures of the skin include hair,
nails, and glands
• They are derived from the stratum basale of
the epidermis and are embedded in the
reticular layer of the dermis
5. Hair
• Found on nearly all body surfaces
• Made of dead, keratinized epithelial cells. No
blood vessels or nerves
6. Hair
• Found on nearly all body surfaces
• Made of dead, keratinized epithelial cells. No
blood vessels or nerves
• Consists of a shaft (portion above scalp) and a
root (portion below scalp)
7. Hair
• Found on nearly all body surfaces
• Made of dead, keratinized epithelial cells. No
blood vessels or nerves
• Consists of a shaft (portion above scalp) and a
root (portion below scalp)
• Root is surrounded by the hair follicle, which
contains stratum basale cells that divide to
produce the hair
8. Hair
• Found on nearly all body surfaces
• Made of dead, keratinized epithelial cells. No
blood vessels or nerves
• Consists of a shaft (portion above scalp) and a
root (portion below scalp)
• Root is surrounded by the hair follicle, which
contains stratum basale cells that divide to
produce the hair
• Hair color is determined by the type of melanin
produced (yellow, red, brown, or black). With
age, melanocytes become less active and melanin
is replaced with air bubbles, which appear white
9. Hair
• Found on nearly all body surfaces
• Made of dead, keratinized epithelial cells. No
blood vessels or nerves
• Consists of a shaft (portion above scalp) and a
root (portion below scalp)
• Root is surrounded by the hair follicle, which
contains stratum basale cells that divide to
produce the hair
• Hair color is determined by the type of melanin
produced (yellow, red, brown, or black). With
age, melanocytes become less active and melanin
is replaced with air bubbles, which appear white
• If shaft is round, hair is straight. If oval, wavy. If
flat, curly.
10. Nails
• Thin plates of stratum corneum that contain a
very hard type of keratin
11. Nails
• Thin plates of stratum corneum that contain a
very hard type of keratin
• Cover the distal ends of the phalanges
12. Nails
• Thin plates of stratum corneum that contain a
very hard type of keratin
• Cover the distal ends of the phalanges
• Stratum basale grows under the nail to form
the nail bed. Thickened at the proximal end to
form the matrix, which is responsible for nail
growth. Whitish, crescent shaped region of
nail above the matrix is called the lunula
14. Sebaceous glands
• Associated with hair follicles
• Sebum (oil) keeps skin and hair soft and
pliable. Also inhibits growth of bacteria on
skin
15. Sebaceous glands
• Associated with hair follicles
• Sebum (oil) keeps skin and hair soft and
pliable. Also inhibits growth of bacteria on
skin
• Stimulated by sex hormones, so become
highly active during puberty
16. Sweat glands
• Present everywhere except the lips and
nipples. Most numerous on the palms
17. Sweat glands
• Present everywhere except the lips and
nipples. Most numerous on the palms
• Merocrine sweat glands: widely distributed.
Secrete water and salts onto the surface of the
skin to decrease body temperature
18. Sweat glands
• Present everywhere except the lips and
nipples. Most numerous on the palms
• Merocrine sweat glands: widely distributed.
Secrete water and salts onto the surface of the
skin to decrease body temperature
• Apocrine sweat glands: present only on axillae
(armpits) and genitalia. Secretions contain
fatty acids and proteins, which are quickly
broken down by bacteria and cause body odor
