Skin Anatomy and Function

Flashcards covering the structure and function of the skin, including the epidermis, dermis, and associated glands and structures.

Skin

Part of the integumentary system with functions including protection, insulation, storage, regulation of body temperature, sensation, synthesis of Vitamin D, and excretion.

Epidermis

Outer portion of the skin comprised of keratinized stratified squamous epithelium.

Dermis

Connective tissue layer of the skin.

Hypodermis

Superficial fascia; not technically part of the skin.

Keratinocytes

Produce keratin; a major cell type in the epidermis.

Melanocytes

Produce melanin; a major cell type in the epidermis.

Langerhans cells

Play a role in the immune system; a major cell type in the epidermis.

Merkel cells

Involved in the sense of touch; a major cell type in the epidermis.

Stratum basale (germinativum)

Deepest layer of the epidermis; exhibits mitotic activity and contains melanocytes.

Stratum spinosum

Several layers of keratinocytes in the epidermis.

Stratum granulosum

3-5 layers of keratinocytes with keratohyaline granules in the epidermis.

Stratum lucidum

Only in thick skin; 2-3 rows of cells in the epidermis.

Stratum corneum

Outermost 20-30 layers of dead cells filled with keratin in the epidermis.

Papillary region

Upper 20% of the dermis; consists of areolar connective tissue and dermal papillae.

Dermal papillae

Fingerprints formed by dermal papillae.

Reticular region

Lower 80% of the dermis; contains blood vessels.

Epidermis Functions: Protection

Provide layers of protection against harmful chemicals, toxins, microbes, and excessive heat or cold.

Epidermis Functions: Prevention of water loss and water gain

Water resistant and keeps water from either exiting or entering the skin easily.

Epidermis Metabolic Regulation

Produce vitamin D upon exposure to UV rays.

Epidermis Functions: Secretion and Absorption

Materials (e.g.. sebum, sodium, water, urea) secreted by dermal structures are released onto the epidermal surface. Selectively permeable because some materials (e.g., certain drugs, like nicotine and estrogen within transdermal patches) may be absorbed while others are blocked.

Epidermis Functions: Immune Function

Engulf and destroy pathogens, alert the immune system to the presence of pathogens, and initiate an immune response.

Dermis Functions: Temperature Regulation

Dilating blood vessels in the dermis release heat; constricting vessels conserve heat. Sweat glands release fluid onto the skin surface, and the body cools off by evaporation of the sweat.

Dermis Functions: Sensory Reception

Detect and relay pain, heat, cold, touch, pressure, and vibration.

Dermis Functions: Secretion and Absorption

Secrete sodium, water, and urea onto the epidermal surface, and in so doing help maintain electrolyte homeostasis. Secrete sebum, which lubricates the skin and hair, and helps make the integument water resistant.

Sweat (sudoriferous) Eccrine (merocrine) glands

Simple coiled tubular gland

Sweat (sudoriferous) Apocrine glands

in axillary and genital areas

Sebaceous (oil) glands

Holocrine; secrete sebum; Most associated with hair follicles

Hair Shaft

Complete keratinization; projects from skin

Hair Root

Hair follicle: hair bulb; vascular and nerve supply

Arector pili

Muscles attached to follicle and pull on follicles to produce goosebumps