Photomicrograph of a
sectioned
sebaceous gland (220x)
Sebaceous
gland duct
Hair in
hair follicle
secretory
cells
Dermal
connective
tissue
Sebaceous
gland
Sweat
pore
Eccrine
gland
Chapter 5. The Integumentary System
●
Skin
●
Epidermis
●
Dermis
●
Appendages
●
Sweat glands -
eccrine,
apocrine,
●
Oil glands -
●
Hair, Nail
●
Integumentary system
functions
●
Integumentary system
Hair
●
Functions-
protection
●
alerting the body to presence of insects on the skin
●
guarding the
scalp
against physical trauma, heat loss,
and sunlight
●
Distribution
●
entire surface except palms, soles, lips, nipples, and
portions of external genitalia
●
Consists of dead
keratinized
cells
●
Contains hard keratin; more durable than soft keratin
of skin
●
Hair pigments:
melanins
(yellow, rust brown, black)
●
Gray/white hair: decreased melanin production,
increased air bubbles in shaft
Hair shaft
Hair Follicle
●
Extends from the epidermal surface into
dermis
●
Two-layered wall:
outer
connective
tissue root sheath,
inner
epithelial
root sheath
●
Hair bulb: expanded deep end
●
Hair follicle receptor (root hair plexus)
●
. sensory
nerve endings around each
hair bulb --- stimulated by bending a
hair
●
Arrector pili-smooth muscle
●
smooth muscle
attached to follicle
●
responsible for “goose bumps”
Hair
shaft
• Arrector pili
muscle
•
Sebaceous gland
•
Hair follicle
•
Hair root
Hair shaft
Arrector pili
Sebaceous gland
Hair root
Hair bulb
: formed by infolding of epidermis,
produce hair
Photomicrograph of a cross
section
of a hair and hair follicle (250x)
• Connective tissue
root sheath
Follicle wall
• Cuticle
• Glassy membrane
• Cortex
• Medulla
• Internal epithelial
root sheath
• External epithelial
root sheath
Hair
Hair shaft
Arrector pili
Sebaceous gland
Hair root
Hair bulb
Hair shaft
Arrector
pili
Sebaceous
gland
Hair root
Hair
bulb
•
Internal epithelial root sheath
•
External epithelial root sheath
•
Connective tissue root sheath
Follicle wall
Hair matrix
Melanocyte
Hair papilla
Subcutaneous adipose tissue
•
Medulla
•
Cortex
•
Cuticle
•
Glassy membrane
Hair root
Structure of a Nail
●
Scalelike modification of the
epidermis
on the distal,
dorsal surface of fingers and toes
Later
al
nail
fold
Lun
ule
Nail
mat
rix
Root of
nail
Proxi
mal
nail
fold
Hyponyc
hium
Nail
bed
Phalanx (bone of
fingertip)
Eponych
ium
(cuticle)
Bod
y
of
nail
Free
edge
of nail
(a
)
(
b
)
Integumentary System Functions
1.
Protection
—three types of barriers
●
Chemical
●
Low pH secretions &
defensins
retard
bacterial
activity
●
Physical/mechanical
●
Keratin
and
glycolipids
block water & water-soluble
substances
●
Limited penetration of skin by lipid-soluble substances,
plant oleoresins (e.g., poison ivy), organic solvents,
salts of heavy metals, some drugs
●
Biological
●
cells, macrophages
antimicrobial
peptide
by corneum
also sebaceous gland
