Skin
Integument  Body’s outer covering
Body’s largest organ (over 9 pounds)
Skin Functions
•Prevents dehydration; infection
•Produces Vitamin D
•Regulates Body Temperature
•Dermis has 10% of body’s blood vessels
Blood vessels in dermis
Layers of Skin
Epidermis
•Made of keratinocytes; produce the protein keratin
•Outer skin cells are dead & flattened
•Deeper layer of epidermis contains melanocytes,
contain pigments
Layers of the Skin
Dermis
•Protects internal structures in the body
•Made of Dense Irregular Connective Tissue
•Some epithelial cells (hair follicles)
•Nervous Tissue (receptors)
•Blood vessels
•Nutrients diffuse through
bloodstream through dermis
•Glands, fingernails & hair follicles
originate in dermal tissue
Accessory Organs of the Skin
•Hair follicles: rooted in the dermis, extend
through epidermis
•Arrector Pili muscles give us goose
bumps
•Pigment: melanin gives our skin its color
Accessory Organs of the Skin
Merocrine Glands (Sweat Glands)
Found in armpits, palms of hands, and forehead
Originate in dermis
Used to regulate body temperature
Accessory Organs of the Skin
Sebaceous Glands (Oil Glands)
Found everywhere on the body (except on palms
and feet)
Oil softens hair follicles & kills bacteria
In acne, oil glands become infected with bacteria,
skin becomes inflamed
Accessory Organs of the Skin
Apocrine Glands (A Type of Sweat Gland)
Glands that connect into the ducts of hair
follicles
Secreted in response to stress and emotion
Odorous secretions
Found in armpits and groin
Regulation of Body Temperature
When body temperature is low
•Hypothalamus signals glands on skin to decrease
sweat production
•If body temperature is still low
•Hypothalamus signals muscles of the skin to
shiver
•This brings blood to surface
of skin, warming the body
Regulation of Body Temperature
If body temperature is high
•Hypothalamus signals glands on skin to increase
sweat production
•That water must be replaced!
•If not, heat exhaustion/heat stroke