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A&P_Exam2
Anatomy & Physiology Exam 2
| Question | Answer |
|---|---|
| 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 |
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