Dermal Layers
Chapter 6
Dermal Layers
Skin is a m________
membrane and is made of
epithelial tissue and c_________
e__________
connective tissue.
epithelial
The
e______ layer is called the e__________.
epidermis
The c_________
connective tissue layer is called the
d________.
dermis Below these two layers is another
layer which is not part of the skin, but is still vital
to the skin’s function. This layer is called the
subcutaneous
s_______
____ layer, or the h___________.
hypodermis This
layer consists of adipose tissue.
Epidermis
• Outermost layer of the skin
• 4 or 5 layers
– Stratum corneum
– (Stratum lucidum)
– Stratum granulosum
– Stratum spinosum
– Stratum basale
• Stratified squamous epithelial tissue
– Avascular
Epidermis
Epidermis
• Functions
– Prevents water loss (keratinized cells of stratum
corneum)
– Keeps out disease-causing microorganisms
Stratum Basale
•
•
•
•
Deepest epidermal layer
Closest to dermis
1-cell thick
Cell division
– Pushes older cells toward surface of the skin
• Basement membrane is deep to stratum
basale
Stratum Spinosum
•
•
•
•
•
Superficial to stratum basale
Several cells thick
Less cell divison
Flattened/irregular cells
Spinelike projections from cells
Stratum Germinativum
• Stratum basale + Stratum spinosum = Stratum
germinativum
• Growing layers
– Where cell division occurs
Stratum Granulosum
• Superficial to stratum spinosum
• Very thin, 2-3 cells thick
• As cells move up from the stratum basale,
they die and become flatter
• Keratinization
– Older cells harden
– Keratin protein
Stratum Lucidum
• Bonus layer
• Thickened skin of palms and soles
Stratum Corneum
• Most superficial layer of epidermis
• Many layers of tough, tightly packed dead
epidermal cells
– Thickest layer of the epidermis (20-30 cells thick)
• Dead cells completely filled with keratin
– Water resistant
• 30-40 days from creation in stratum basale
until flake off at stratum corneum
Epidermis
Cells of the Epidermis
• Stem cells – undifferentiated cells found only in
stratum basale
• Keratinocytes – cells that make keratin (most cells
in epidermis)
• Melanocytes – make melanin, found only in
stratum basale
• Merkel cells – touch receptors, attached to nerve
cells
• Dentritic cells (Langerhans cells) – macrophages
that guard against foreign microbes/pathogens,
alert immune system
Dermis
• Deep to epidermis
• Binds epidermis to underlying tissues
• Blood vessels in the dermis supply nutrients to
all layers of the skin
• Dense connective tissue
• 2 layers
– Papillary layer
– Reticular layer
Papillary Layer
• Areolar connective tissue
• Lots of blood vessels
• Dermal papillae
– Capillary loops
– Sensory cells
– Fingerprints
Reticular Layer
• Dense connective tissue
• Stretch marks
– Dermal tearing
Hypodermis
• Subcutaneous layer
– Sub- = below
– Cut- = skin
• Deep to the dermis
• Adipose, loose connective tissues
– Insulation
– Major blood vessels
• Infants/elderly have less, more sensitive to
cold
HOMEWORK
• pg. 116 #1-2
• pg. 117 #1-3
• Daily Quiz #12 tomorrow!