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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
l i k e an oni on)
Epidermis
 Stratified Squamous epithelium
 4 different types of cells
 5 layers
Types of Cells in Epidermis
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Keratinocytes
Melanocytes
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Langerhans
Merkel
Keratinocytes
 90 % o f e p i d e r m a l c e l l s
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
s ea l a n t
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
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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
c el l s
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
th i c k )
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
 M el ani n
 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
p en i s , n i p p l e s , f a c e a n d l i m b s
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
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Thin Skin
Thick Skin
Types of 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
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Hair
Glands
Nails
Hair
 S h a ft
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
 B ul b
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”