Epidermal Derivatives (pg 6)

Epidermal Derivatives (pg 6)

• Accessory structures of the skin include hair, nails, and glands

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

Hair• Found on nearly all body surfaces

Hair• Found on nearly all body surfaces• Made of dead, keratinized epithelial cells. No

blood vessels or nerves

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)

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• 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

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.

Nails

• Thin plates of stratum corneum that contain a very hard type of keratin

Nails

• Thin plates of stratum corneum that contain a very hard type of keratin

• Cover the distal ends of the phalanges

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

Sebaceous glands

• Associated with hair follicles

Sebaceous glands

• Associated with hair follicles• Sebum (oil) keeps skin and hair soft and

pliable. Also inhibits growth of bacteria on skin

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

Sweat glands

• Present everywhere except the lips and nipples. Most numerous on the palms

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

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

Ceruminous Glands

• Modified sweat glands found only in the ear canal

Ceruminous Glands

• Modified sweat glands found only in the ear canal

• Produce cerumen (earwax)

Ceruminous Glands

• Modified sweat glands found only in the ear canal

• Produce cerumen (earwax)• Repels insects and traps foreign material