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Anatomy & Physiology Exam 2

what are the layers of the skin? epidermis, dermis, hypodermis
what is the main function of the integumentary system? protection
what are the sublayers of the dermis? papillary layer and reticular layer
what is found in the dermis? nervous structures and appendages of skin
which layer of the skin is vascularized? dermis
what is the hypodermis also called? superficial fascia
what is the purpose of hypodermis tissue? storing fat, anchor the skin to underlying structures (mostly muscle) but also loosely enough for skin to slide, shock absorber and an insulator
what is the purpose of sliding skin? to protect us by ensuring that many blows just glance off our bodies.
define EPIDERMIS keratinized stratified squamous epithelium consisting of four distinct cell types and four or five distinct layers.
what are the 4 cell types of the epidermis? keratinocytes, melanocytes, dendritic cells, and tactile cells
main function of keratinocytes? to produce keratin
define KERATIN the fibrous protein that helps give the epidermis its protective properties
epidermis has which type of cells most? keratinocytes
how are keratinocytes tightly connected to one another? by desmosomes
where do keratinocytes arise from? deepest part of the epidermis, the stratum basale layer
keratinocytes continuously undergo what? mitosis
what happens to keratinocyes? pushed upward by the production of new cells beneath them
what happens to keratinocytes when they reach the surface? they are dead, scalelike structures that are little more than keratin-filled plasma membranes
how often do humans have a completely new epidermis? 25 to 45 days
where are cell production and keratin formation accelerated? in body areas subjected to friction such as the hands and feet
define CALLUS persistent friction causing thickening of the epidermis
what is the main function of melanocytes? production of melanin
define MELANOCYTES the spider-shaped epithelial cells that synthesize the pigment melanin
where are melanocytes found? in the deepest layer of the epidermis, stratum basale
what are melanosomes? membrane-bound granules that motor proteins move along actin filaments to the ends of the melanocyte's process
what do melanin granules do? accumulate on the superficial side of the keratinocyte nucleus, forming a pigment shield that protects the nucleus from damaging effects of ultraviolet radiation
what is the main function of dendritic cells? ingest foreign substances and are key activators of our immune system
define DENDRITIC CELLS star-shaped cells raised from bone marrow and migrate to the epidermis
where do dendritic cells come from? bone marrow
what are dendritic cells also called? langerhans cells
what does the processes of dendritic cells do? slender processes extend among the surrounding keratinocytes, forming continuous network
what is the main function of tactile cells? sensory receptor for touch
define TACTILE CELLS spiky hemisphere shaped, present at the epidermal-dermal junction, associated with a disclike sensory nerve ending
where are tactile cells found? epidermal-dermal junction
what are the layers of the epidermis? Can Little Girls Skate Board Corneum, Lucidum, Granulosum, Spinosum, Basale
how many layers does thick and thin skin have? thick - 5 thin - 4
where is thick and thin skin found? thick - palms and soles thin - rest of body
where is the thickest skin in the body? the upper back
what is the deepest epidermal layer? stratum basale
what does stratum basale consist of? a single row of stem cells
what is stratum basale attached to? underlying dermis along wavy borderline
what does stratum basale represent? the youngest keratinocytes
what do stem cells do? continually renewing cell population
what is stratum basale also called? stratum germinativum
why is stratum basale also called stratum germinativum? many mitotic nuclei seen in this layer reflect the rapid division of these cells
what happens every time a basal cell divides? one daughter cell is pushed into the cell layer just above to begin its specialization into a mature keratinocyte. the other daughter cell remains in layer to continue process of producing new keratinocytes.
how many cells in the stratum basale are melanocytes? 10-25%
what is the stratum spinosum known as? prickly layer
how thick is stratum spinosum? several layers thick of keratinocytes unified by desmosomes
what do the cells in stratum spinosum contain? thick bundles of intermediate filaments made of pre-keratin
what does stratum spinosum look like? spiked iron balls used in medieval warfare
what is found in stratum spinosum? melanin granules and dendritic cells
what is stratum granulosum known as? granular layer
how many layers does stratum granulosum have? 4 to 6, typically 5
how are the cells in stratum granulosum? flattened
what happens in stratum granulosum? keratinocyte appearance changes drastically and the process of keratinization begins
define KERATINIZATION when cells fill with the protein keratin
what happens to the cells in stratum granulosum? the cells flatten, nuclei and organelles begin to disintegrate and accumulate two types of granules
what are the two types of granules in stratum granulosum? keratohyaline granules and lamellar granules
what are keratohyaline granules? help form keratin in the upper layers
what are lamellar granules? contain water-resistant glycolipid
what is the purpose of keratinocytes? to toughen up to make the outer strata the strongest skin region
whats wrong with the epidermal cells of the stratum granulosum? the cells are too far from the dermal capillaries so they die.
what is the stratum lucidum known as? clear layer
where is stratum lucidum found? only in thick skin
whats wrong with the epidermal cells of the stratum granulosum? the cells are too far from the dermal capillaries so they die.
what are the intermediate filaments in stratum lucidum called? tonofilaments
what is the stratum lucidum known as? clear layer
what is stratum corneum known as? horny layer
where is stratum lucidum found? only in thick skin
what are the intermediate filaments in stratum lucidum called? tonofilaments
what is stratum corneum known as? horny layer
where is the stratum coreum? outermost layer
how thick is the stratum corneum? 20 to 30 cell layers thick
how much of the epidermis is made up of the stratum corneum? three quarters
what protects the skin from abrasion and penetration in the stratum corneum? keratin and thickened plasma membranes
what does the stratum corneum do? provide a durable overcoat for the body, protecting from hostile environment, waterloss, biological, chemical, and physical assults
define APOPTOSIS when the cell commits suicide
what is statum corneum familiarized as? dandruff that sheds from scalp and dander that sheds off dry skin
define DERMIS strong, flexible connective tissue
what kind of cells are found in the dermis? fibroblasts, macrophages, mast cells and white blood cells
what does the semifluid matrix in the dermis do? binds the entire body together with fibers
define PAPILLARY LAYER areolar connective tissue in which fine interlacing collagen and elastic fibers form a loosely woven mat that is heavily invested with small blood vessels.
what is the purpose of the looseness in the papillary layer? allows phagocytes and other defensive cells to wander freely as they patrol the area for bacteria
what are touch receptors called? tactile or Meissner's corpuscles
define DERMAL PAPILLAE peglike projections from the surface of the papillary layer
define FRICTION RIDGES skin ridges, enhance the gripping ability of fingers and feet
what do recent studies say about friction ridges? contribute to our sense of touch by amplyfing vibrations
what are lamellar corpuscles? sense of touch and vibration receptors
what are friction ridges also known as? fingerprints
what is unique about friction ridges? the patterns are genetically determined and different for everyone
define RETICULAR LAYER coarse, irregularly arranged, dense fibrous connective tissue
what is the cutaneous plexus? network of blood vessels that nourishes the reticular layer
how is the extracellular matrix of the reticular layer? contains pockets of adipose cells and thick bundles of interlacing collagen fibers
how do the collagen fibers run? parallel to the skin surface
define CLEAVAGE (tension) LINES separations, or less dense regions between bundles of interlacing collagen fibers
why are cleavage lines important to surgeons? when incision is made parallel to these lines, the skin gapes less and heals more readily
what does collagen fibers of the dermis do? give skin strength and resiliency that prevent most jabs and scrapes from penetrating and keeps skin hydrated
what do elastic fibers do? provide the stretch-recoil properties of skin
define FLEXURE LINES type of skin marking, dermal folds that occur at or near joints, where the dermis is tightly texured to deeper structures
what happens to the dermis in regards to flexure lines? since the skin cannot slide easily to accomodate joint movement, the dermis folds and deep skin creases form.
where are friction ridges found? fingertips
where are cleavage lines found? the entire body
where are flexure lines found? palms, wrists, fingers, soles and toes
what are stretch marks called? striae
define STRIAE tear of the dermis, silvery white scars
define BLISTER a fluid-filled pocket that separates the epidermal and dermal layers
what is a blister? short-term but acute trauma
Created by: vnsa