Structure and Function of Skin Flashcards
Layers of skin
-epidermis
-dermis
-subcutaneous tissue
epidermis
-protects underlying tissue from infection, dehydration, chemicals, and mechanical stress
-relatively waterproof
-prevents most bacteria, viruses, other foreign substances from entering the body
-produces pigment melanin that gives human skin, hair, eyes their color
dermis
-contains tough connective tissue as well as different types of cells and glands
-nerve endings- sense pain, touch, pressure, temperature
-sweat glands- produce sweat in response to heat and stress
-sebaceous glands- secrete sebum into hair follicles (sebum is oil that keeps skin moist and soft)
subcutaneous tissue
-made up of fat and connective tissue
-plays many important roles in body
-helps insulate body from heat and cold
-provides protective passing and serves as energy storage area
layers of epidermis
-stratum lucidum
-stratum corneum
-stratum basale
stratum lucidum
-formed from dead cells of deeper strata
-occurs only in thick, hairless skin of the palms and hands and soles of feets
-2nd layer of epidermis
stratum corneum**
-outermost layer of epidermis
-shingle like dead cells are filled with keratin (protective protein prevents water loss from skin)
-all cells here are dead
-25-30 layers of flat dead cells filled with keratin and surrounded by lipids
-continuously shed
-BARRIER to light, heat, water, chemicals, and bacteria
-friction stimulates callus formation
-first thing infilatrated
stratum basale
-lower layer of epidermis
-mitosis takes place here
epidermal function of layers
-barrier protection against the environment -> infection, heat loss, UV damage, foreign matter
-epidermal layer replaced every 28 days moving from basal layer to stratum corneum****
-14 days to reach stratum corneum
-another 14 days to desquamate (peel, sheds off)*
-epithelial cells are the first line of defense to the environment
-vitamin D
-sensation through 3 types of nerve fibers
-temperature regulation- heat loss and heat conservation through sweat glands and capillaries
-blood flow through skin is approx 5% of CO (normally) -> can drop to 0 in cold temps
-extreme heat can cause CO to rise to 60%
melanocytes
-10% of cells found in basal cell layer
-produce melanin
-protection from UV light
-exposure to UV light stimualtes production of melanin and then is packaged into melanosomes
-melanosomes move to surface to protect cells from UV light
dermis
-1-4 mm thickness
-cushion of protection
-where you find collagen- makes up 75% of dermis
-hair follicles originate here
-oil glands, eccrine glands
-nerve fibers run through it
skin microbiome
-diverse symbionts- microbes that populate skin
-bacteria, fungi, viruses
-changes in this microbiome can cause pathology
-acne- cutibacterium acnes
-atopic dermatitis- staph aureus and s. epidermis
-diabetic ulcers- staphylococal species and fungi
-skin can be window to all organs as well as general age and overall health
papule
-<1cm
-solid
-raised
-proliferation of cells in epidermis or superficial dermis
-ex. allergic eczema
macule
-<1cm
-flat
-only epidermis
-color change
-ex. freckle
plaque
-larger papule
-raised (cast shadow with side lighting)
->1cm
-proliferation of cells in epidermis or superficial dermis
-skin or mucous membrane
-ex. thrush
