Chapter 5
Introduction to Skin
 Most accessible but often least appreciated organ
system.
 The skin, or simply integument, accounts for
approximately 16% of your total body weight.
 The skin’s surface, 1.5 - 2.0 m2, is constantly worn
away, attacked by micro-organisms, irradiated by
sunlight, and exposed to environmental
chemicals.
 Skin is composed of two major components:
Two Components of Skin
Functions of Skin
The epidermis is composed primarily of keratinocytes
arranged into layers called strata.
Thin Skin versus Thick Skin
Thin Skin versus Thick Skin
 Thin skin, which covers most of the body surface,
contains four strata and is about as thick as the wall
of a plastic sandwich bag (roughly 0.08 mm).
 Thick skin, which occurs on the palms of the hands
and soles of the feet, possesses five strata. It is about
as thick as a standard paper towel (roughly 0.50
mm).
 Note that the terms “thick” and “thin” refer to the
relative thickness of the epidermis, not the
integument as a whole.
Strata of the Epidermis
 Stratum Basale = the “basement layer”; innermost layer
 Stratum Spinosum = the “spiny layer”
 Stratum Granulosum = the “grainy layer”
 Stratum Lucidum = the “clear layer”
 Stratum Corneum = the “horny layer”; outermost layer
Strata of the Epidermis
Ridges of the Skin
Dermal Papillae
The dermis supports the epidermis and the hypodermis
connects the dermis to the rest of the body.
Layers of the Dermis
Dermis versus Hypodermis
Cleavage Lines
Factors influencing skin color include
epidermal pigmentation and dermal circulation.
Pigmentation
Dermal Circulation
Skin Cancers
Nerve fibers and corpuscles
Hair follicles, hair shafts, and arrector pili muscles
Oil glands and sweat glands
Arteries, veins, and lymph vessels
Accessory Organs of Skin
Sensory Receptors in the Skin
Hairs and their Associated
Structures
Hair Structure
Sebaceous Glands
Sweat Glands
Nails and their
Associated Structures
Nail Changes
The integumentary system is physically and functionally tied to
all other body systems and as a result, the state of the skin can
be an indication of the health of an individual.
Hormones and Endocrine
Functions of Skin
Vitamin D
Vitamin D
Age-Related Changes in Skin