Dermal Layers Chapter 6

Dermal Layers Skin is a m________ and is made of e__________ tissue and c_________ tissue. The e______ layer is called the e__________. The c_________ tissue layer is called the d________. 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 s_______ ____ layer, or the h___________. This layer consists of adipose tissue. membrane epithelial connective epithelial epidermis connective dermis subcutaneous hypodermis

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 below Deep to the dermis skin Adipose, loose connective tissues Insulation Major blood vessels Infants/elderly have less, more sensitive to cold below skin

HOMEWORK pg. 116 #1-2 pg. 117 #1-3 Daily Quiz #12 tomorrow!