Integumentary
System
Integumentary System
 Epidermis (epithelial tissue)
 Dermis (connective tissue)
 Hypodermis (not part of the skin)
Hypodermis
 subcutaneous layer (underneath the
skin)
Hypodermis
contains areolar and adipose tissue
Hypodermis
 attaches skin to underlying tissues and
organs
Hypodermis
 Conatains pacinian corpuscles (
sensitive to pressure / looks like an
onion)
Epidermis
 Stratified Squamous epithelium
 4 different types of cells
 5 layers
Types of Cells in
Epidermis
1.
2.
3.
4.
Keratinocytes
Melanocytes
Langerhans
Merkel
Keratinocytes
 90% of epidermal cells
Keratinocytes
 produce the protein keratin which
protects the skin and underlying tissues
from heat, microbes, and chemicals
Keratinocytes
produce lamellar granules which produce
a water repellant sealant
Melanocytes
 8 % of epidermal cells
Melanocytes
Produces the pigment melanin
Melanocytes
 Transfers melanin granules to
keratinocytes
Melanocytes
In keratinocytes the melanin granules
acts like an umbrella over the DNA in
order to protect it from UV light
Langerhans
 migrate from red bone marrow to
epidermis
Langerhans
 involved in immune response
Merkel
 sensitive to touch
Merkel
 located in stratum basale
Merkel
 Have contact with the flattened process
of a sensory neuron (Merkel disc)
5 layers of Epidermis
1.
2.
3.
4.
5.
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
Stratum Basale
 Deepest layer of the epidermis
Stratum Basale
Single layer of cuboidal or columnar
keratinocytes
Stratum Basale
Nuclei large
Stratum Basale
Also contains some melanocytes, merkel
cells, and langerhans cells
Stratum Spinosum
 8 to 10 layers of squamous shaped
keratinocytes
Stratum Spinosum
Has a large nucleus
Stratum Spinosum
Appear spiny underneath microscope
Stratum Spinosum
 Some langerhans cells and
melanocytes
Stratum Granulosum
 3 to five layer of squamous
keratinocytes
Stratum Granulosum
Undergoing apoptosis (cell death)
Stratum Granulosum
Nuclei disappearing
Stratum Granulosum
Contains protein keratohyalin which
converts tonofilaments into keratin
Stratum Granulosum
 Secretes lamellar granules which fills the
spaces between stratum granulousum,
stratum lucidum, and stratum corneum
Stratum Lucidum
 Only in thick skin
Stratum Lucidum
3 to 5 layers of clear, dead, squamous
keratinocytes
Stratum Lucidum
Contain keratin
Stratum Corneum
 25 to 30 layers
Stratum Corneum
 Dead squamous keratinocytes
Stratum Corneum
Contain keratin
Stratum Corneum
Sometimes forms callus (the stratum
corneum is abnormally thick)
Dermis
 Two Regions
 Papillary Region
 Reticular Region
Papillary Region
 Contains areolar connective tissue with
fine elastic fibers
Papillary Region
 20 percent or one fifth of dermis
Papillary Region
 Contains Meisner corpuscles ( sensitive
to touch)
Papillary Region
 Contains dermal papillae
(small,fingerlike projections that indent
the epidermis and some contain capillary
loops)
Reticular Region
 Contains dense irregular connective
tissue with collagen fibers and course
elastic fibers
Reticular Region
 Contain some adipocytes, hair follicles,
nerves, sebaceous glands, and sweat
glands
Skin Color
 Melanin
 Carotene
 Hemoglobin
Melanin
 Number of melanocytes doesn’t vary
among people
Melanin
 Differences in skin color can be
attributed to the amount that these
melanocytes produce
Melanin
 Melanocytes most commonly found in
the epidermis of the penis, nipples, face
and limbs
Melanin
 Freckles and age spot (accumulations of
melanin)
Carotene
 Yellow-orange pigment
 Precursor to vitamin A
Carotene
 Found in stratum corneum, fatty areas of
dermis, and hypodermis
Hemoglobin
 Protein in rbc’s that carries oxygen
 Found in capillaries in blood
Albinos
 Contain melanocytes, but are unable to
produce melanin
 Inherited
 Melanin is absent in hair, eyes, and skin
Vitiligo
 Irregular white spots
 Due to loss of melanocytes
 Antibodies in body attack melanocytes
Types of Skin
1. Thin Skin
2. Thick Skin
Thin Skin
 Covers all surfaces except palms,
fingertips, and soles
Thin Skin
 Lacks stratum lucidum
 Thin stratum spinosum and corneum
Thin Skin
 Lack epidermal ridges (fingerprints)
Thin Skin
 Fewer sweat glands
 Fewer sensory receptors
Thin Skin
 Contains hair follicles, arrector pili
muscles, and sebaceous (oil) gland
Thick Skin
 Located on palms, fingertips, and soles
Thick Skin
 Stratum Lucidum
 Thicker stratum spinosum and corneum
Thick Skin
 Contains epidermal ridges
 Contains more sweat glands
Thick Skin
 Lacks hair follicles, sebaceous glands,
and arector pili muscles
Accessory Structures
1. Hair
2. Glands
3. Nails
Hair
 Shaft
Superficial portion of hair
Hair
 Root
Penetrates into dermis
Hair
 Root and Shaft contain three layers
Inner medulla(may lack in thin hair), cortex
(contains pigment granules), and cuticle
Hair
 Hair Follicle
Surrounds the root of the hair
Contains an external root sheath
(continuation of epidermis) and internal
root sheath (produced by the matrix)
Hair
 Bulb
Contains papilla of hair (areolar connective
tissue and blood vessels to nourish hair)
Contains matrix (produce new hairs)
Hair
 Sebaceous glands and arrector pili
muscle associated with hairs
Hair
 Arrector pili muscle responsible for
“goose bumps”