Skin - Dermis and Appendages Flashcards
What layer of the dermis is stained darkly?
The reticular dermis because of dense collagen with eosin
Composition of dermis
Mostly keratinocytes with multiple epidermal sublayers
Papillary dermis - thin collagen and elastic fibers, fibroblasts, rich with capillaries to nourish avascular epidermis and regulate temp
Reticular dermis - thick collagen and elastic fibers, fibroblasts, glands, hair follicles, smooth muscle
What is the function of dermal papillae?
Prevent tearing and separation that results from friction. Skin integrity. Also called epidermal-dermal interdigitations. Also rich with capillaries
What controls blood flow to the dermal interdigitatons?
Autonomic nervous system to control body heat loss/retention. Causes the flush or pale look of skin.
Where are sweat glands most often found? Function?
In the dermis and hypodermis. Cools via evaporation of secreted sweat.
Epidermal and dermal junctions are characterized by?
Epidermal ridges and dermal papillae interdigitating. Make up fingerprints and footprints
What are cleavage lines?
Orientations of collagen fibers making up the reticular dermis. Characteristic in different areas of the body. Surgeons cutting along these allow skin to heal faster and with less scarring.
What are the two types of sweat glands?
Eccrine and Apocrine
Name the appendages of the skin
Sweat glands, sebaceous glands, hair follicles, nails, specialized mechanosensory receptors
Sweat glands have what morphology?
Simple tubular
Where are apocrine glands found?
In the axilla and perineal region
Apocrine glands release?
Sweat, but also bits of cytoplasm along with the watery sweat
T or F: Apocrine sweat gland lumens tend to be wider than eccrine glands
T
Describe eccrine glands
Most numerous and produce true sweat
Describe apocrine glands
Confined to axillary and perineal areas
Secrete sweat with bits of cytoplasm into hair follicle
Tubular glandular lumens wider than those of eccrine glands
What is sweat?
Blood filtrate that is 99% water with some salts.
Contains traces of metabolic waste (urea)
What is the function of myoepithelial cells along sweat glands?
Contract to move sweat along the tubes
Sweat ducts have what cell morphology?
Stratified cuboidal epithelium (2 layers)
Describe the morphology of apocrine glands?
Much larger lumens than eccrine glands
Contain viscous secretory product that produces distinctive odor after being metabolized by bacteria
Secretion is mediated by hormones
Describe the structure of a hair follicle
Invagination in the sruface epithelium into the underlying dermis or hypodermis. Keratinous hair shaft produced by hair bulb epithelial cells in the same way that keratinocytes make keratin. Typically has a sebaceous gland and small smooth muscle bundle that connects the tissue around the hair shaft to the basement membrane. Under autonomic control - goose bumps/hair stand
What is the arrector pilli?
Smooth muscle bundle associated with the hair shaft. Under autonomic control
T or F: Sebaceous glands are commonly associated with hair follicles
T
Nail matrix is composed of?
Keratinized epithelial cells arranged into plates of hard keratin. Can be used clinically by examining color, rigidity and texture.
What are nails derived from? Function?
Develop from cells in the nail matrix that proliferate and become keratinized. The nail plate occupies the function and position of the stratum corneum
