Integumentary System Overview, Epidermis, and Dermis

Integument functions

Protect, prevent water loss, regulate temperature, metabolic regulation, immune defense, sensory receptors, and excretion via secretion

Integument structures

Skin, nails, hair, sweat glands, sebaceous glands

3 basic layers of skin

Epidermis, dermis, hypodermis (subcutaneous)

5 layers of epidermis

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

Stratum corneum structure and location

Top layer, 20-30 layers of keratonized cells

Stratum Lucidum structure and location

Second layer in thick skin, 2-3 layers of flat keratonized cells

Stratum granulosum structure and location

Third (thick) or second layer (thin), 3-5 layers of keratinocytes, 2 types of granules, keratohyalin granules and lamellar granules

Keratohyalin granules

Involved in the keratinization process

Lamellar granules

Fuse with the plasma membrane and expell lipids

Stratum spinosum structure and location

Second to last layer, specialized non-dividing keratinocytes, epidermal dendritic cells, and desmosomes connecting the cells

Stratum basale structure and location

Last layer, cuboidal and low columnar cells, large keratinocyte stem cells, melanocytes, and tactile (merkel) cells, attaches to the basement membrane

Keratinocyte function

Give strength and make water resistant

Melanocyte function

Produce and store melanin pigment

Epidermal dendritic cell function

Immune cells that fight infection in epidermis

Tactile (Merkel) cell function

Release chemicals when compressed to stimulate sensory nerve endings

3 things that create skin color

Hemoglobin, melanin, carotene

Hemoglobin skin color contribution

Red

Carotene skin color contribution

Orange-yellow

Melanin skin color contribution

Eumelanin: black/brown

Pheomelanin: tan, yellow, red

Dermis structures

Papillary layer and reticular layer

Papillary layer structures and functions

Made of areolar connective tissue, connects epidermis to reticular layer of dermis, sensation (nerve endings), and nutrients (blood vessels)

Reticular layer structures and functions

Dense irregular connective tissue, place for hair follicles, sebaceous glands, sweat glands, nerves, and blood vessels, stretches and resists stress in all directions

Dermal papillae

The ridges at the top of the papillary layer of the dermis

Epidermal ridges

The ridges at the bottom of the epidermis