integumentary system

skin functions

1. maintain homeostasis

2. acts as a physical barrier

3. protects against pathogens

4. produces vitamin D

5. sensory functions

keratin

a protein in keratinocytes that enhances water resistance and toughness in cells

keratinocyte

a common cell in the epidermis

originate from the basal layer and rise to the superficial layer where they become dead corned cells

epidermal layers (top to bottom)

Come Let’s Get Sun Burnt

1. stratum corneum

2. stratum lucidum

3. stratum granulosum

4. stratum spinosum

5. stratum basale

stratum corneum

most superficial layer of the epidermis

made of dead corned cells that are sloughed off and replaced by cells from the layers below

stratum lucidum

transparent layer of cornified cells found on thick-skinned areas

(palms of hands and soles of feet)

stratum granulosum

layer of granulated cells

water-proofing

stratum spinosum

contain keratinocytes and langerhan cells

stratum basale

single layer of basal cells that produce new keratinocytes

site of melanin production

contains merkel cells

dermis

beneath the epidermis

contains blood vessels, sweat glands, and hair follicles

made of proteins collagen and elastin

collagen

protein that provides skin structure

found in dermis

elastin

protein in skin that provides elasticity

found in dermis

dermis layers

1. papillary

2. reticular

keloid

irregular fibrous tissue formed at scar site due to increased collagen

hypodermis

deepest layer of the skin

connects the skin to bones and muscles

composed of adipose tissue

sweat glands

regulate body temperature by perspiration

thermoregulation — blood vessels

vasoconstriction — retains heat when cold

vasodilation — releases heat when hot

sebaceous glands

produce oil that waterproof the skin and hair

basal cell carcinoma

uncontrolled growth of basal cells in the epidermis

melanoma

tumor formed from melanocytes

melanocyte

skin cell that produces melanin

squamous cell carcinoma

cancer growth in the most outer layers of the skin due to UV radiation

first degree burn

damage to the epidermis

second degree burns

damage to the epidermis and upper dermis

third degree burn

damage that fully penetrates the epidermis and dermis

fourth degree burn

damage that extends to the hypodermis, bones, and tissues