-largest organ

-also called cutaneous membrane or integument

-2 main parts-epidermis(epithelial); dermis(connective tissue)

-Deeper thicker connective tissue

-Deep to dermis but not part of the skin

-consists of areolar andadipose tissues

-contains nerve endings that are sensitive to pressure cld pacinian(lamellated) corpuscles

-composed of keratinized stratified squamos epithelium

-4 types of cells:keratinocytes 90%, melanocytes 8%, langerhans cells, merkel cells

keratin, fibrous proteins, protects skin, underlying tissues from heat, microbes, and chemicals

-produce lamellar granules-water-repellent  sealant

-produce the pigment melanin

-contributes color

-absorbs damaging uv rays or light

-susceptible to damage by uv light

-arise from red bone marrow

-help other cells recognize the invading microbe and destroy it.

-lease numerous

-located in deepest layer of the epidermis

-detect touch sensations merkel disc flattened process of a sensory neuron

palms, soles

-srtaum basale, stratum spinosum, stratum granulosum, stratum lucidum, thick stratum corneum

most inner layer

-made up of 1 or 2 layers

-stem cells

-also known as the stratum germinativum

-superficial to the strautum basale

-spiny, arranged in 8-10 layers of keratinocytes

-langerhans and melanocytes present

keratinocytes that are undegoing apoptosis(cells dying)

-Granules of keratin

-fingertips palms and soles

-dead keratinocytes w large amounts of keratin

25-30 dead keratinocyte layers

-contain mostly keratin

composed of strong connective tissue containing collagen and elastic fibers

-2 regions; papillary & reticular

-dense irregular connective tissue

-extensibility & elasticity

-attached to the subcutaneous layer

-liberating sweat & adjusting the flow of blood

-homostatic regulation of body temperature