Epidermis & Dermis (Layers, Structure, and Function)

Epidermis

superficial region

Epidermis consists of _______ tissue

Avascular epithelial tissue

Dermis

underlies epidermis

Dermis consists of ______ tissue

Fibrous connective tissue

Hypodermis

subcutaneous layer

Hypodermis consists of _______ Tissue

Adipose tissue

(absorbs shock and insulates)

Specific tissue type in epidermis

keratinized stratified squamous epithelium

Keratinocytes produces

keratin

What is keratin

tough fibrous protein

How are Keratinocytes connected?

desmosomes

Melanocytes

spider-shaped

Melanocytes produces

melanin

Melanocytes location

stratum basale

Melanosomes

Pigment carrying granules

Dendritic Cells

star-shaped

Dendritic Cells function

macrophages that patrol deep epidermis (activates immune system)

Dendritic Cells location

stratum spinosum and stratum granulosum

Tactile Cells function

sensory detection

tactile cells location

stratum basale

Layers of the epidermis

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

Epidermis Mnemonic

Can Lucy Give Some Blood

Stratum Basale

Deepest layer & single row of stem cells

Stratum Basale contains

Melanocytes and tactile cells

Stratum Spinosum

Several layers of prekeratin filaments

Strata Spinosum contains

dendritic cells and melanosomes

Stratum Grandulosum

Flatten cells w/ deteriorating organelles

keratohyaline granules

help to form keratin in the upper layers

Lamellar granules

creates hydrophobic layer

Stratum Lucidum

2 to 3 rows of clear, flat, dead keratinocytes

Strata Lucidum is only found in

thick skin

Thick Skin

Palms and Soles

Five layers of keratinocytes

Stratum Corneum

Outermost layer with 20-30 flat, anucleate, keratinized dead cells

Strata Corneum functions to

Protect deeper cells

Prevent water loss

Protect from abrasion and penetration

Biological, Chemical, Physical barrier

Keratinization

process in which the outermost cells of the epidermis are replaced by dead cells containing keratin

The Dermis is a

strong, flexible CT

Fibroblasts

cells that secrete the proteins of the fibers.

Macrophages

phagocytize foreign substances and help activate T cells

Mast Cells

Cells that release chemicals to promote inflammation.

Leukocytes

white blood cells

Papillary Layer

Outermost layer of the dermis, directly underneath the epidermis

Papillary Layer is made of

Areolar CT

Dermal Papillae

fingerlike projections

Dermal Papillae contains

Capillary loops

Meissner's corpuscles

Free nerve endings

Friction Ridges

epidermal ridges that lie on top of dermal ridges

Friction Ridges functions

enchance gripping, sense of touch, sweat pores create fingerprint pattern

Reticular Layer

deepest skin layer

Reticular layer consists of

Dense irregular CT

Cutaneous Plexus

network of blood vessels between reticular layer and hypodermis

Cleavage (tension) lines

elastic and collagen fibers oriented in some directions more than in others

Striae

Stretch Marks

Blisters

acute, short-term trauma

fluid-filled pockets