Layers of the Epidermis Quiz

Structure of the Skin

• The skin is composed of two main layers: the epidermis and the dermis.
• The epidermis is the outer layer, capable of being hard and tough, and is made up of stratified squamous epithelium.
• The epidermis is avascular, meaning it lacks blood vessels, and is composed of five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

Epidermis Layers

• Stratum basale (stratum germinativum): the deepest layer of the epidermis, where cells undergo mitosis and daughter cells are pushed upward to become the more superficial layers.
• Stratum spinosum: cells become increasingly flatter and more keratinized.
• Stratum granulosum: cells contain granules and are dying.
• Stratum lucidum: a thin, clear layer found only in thick, hairless skin of the palms of hands and soles of feet.
• Stratum corneum: the outermost layer of the epidermis, composed of dead cells filled with keratin, which prevents water loss from the skin.

Dermis

• The dermis is the layer of connective tissue that underlies the epidermis.
• It has two layers: the papillary layer and the reticular layer.
• The papillary layer is the upper dermal region, containing projections called dermal papillae that indent the epidermis above.
• The reticular layer is the deepest skin layer, containing blood vessels, sweat and oil glands, and deep pressure receptors.

Cells of the Epidermis

• Keratinocytes: the most common cell type in the epidermis, producing a fibrous protein called keratin.
• Melanocytes: cells that produce melanin, found mostly in the stratum basale.
• Epidermal dendritic cells: cells that alert and activate immune cells to a threat.
• Merkel cells: cells associated with sensory nerve endings, serving as touch receptors.

Integumentary System

• The integumentary system includes the skin, hair, nails, and associated glands.
• Body membranes are classified into epithelial membranes, connective tissue membranes, and synovial membranes.
• Epithelial membranes, including the cutaneous membrane (skin), mucous membranes, and serous membranes, cover body surfaces, line body cavities, and form protective sheets around organs.

Test your knowledge on the layers of the epidermis including stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. Learn about the characteristics and functions of each layer.