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50 Cards in this Set
- Front
- Back
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what are the 3 overlying functions of the skin? |
protection regulation sensation |
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what are the protective mechanisms of the integumentary system? |
-mechanical impacts -variations in temp -micro-organisms -radiation + chemicals -immunological organ |
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where are langerhans cells and macrophages (both involved immunologically) found, in the epidermis or the dermis? |
langerhans cells - epidermis macrophages - dermis |
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explain the role of melanocytes in the skin |
-melanocytes produce melanin -melanin protects against UV light -gives skin colour
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what are the 6 umbrella areas of regulation in the skin? |
-temperature -peripheral circulation -vitamin D3 -absorption -excretion -water resistance |
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explain temperature regulation in the skin? |
-vasoconstriction/vasodilation -release of sweat from eccrine glands followed by evaporation of sweat -erector pili muscles - erect hair and trap it- blood flow to capillaries is decreased |
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explain how peripheral circulation is regulated in skin |
the peripheral circulation and fluid balance are changed via sweat this prevents loss of moisture |
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explain how the skin acts as a reservoir for the synthesis of previtamin D3 (cholecalciferol) |
-7-dehydrocholesterol reacts with UVB light -D3 is produced in the s. spinosum and s. basale -the liver and kidneys convert the D3 to vitamin D3 |
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in which epidermal layer of the skin is D3 produced |
stratum spinosum and stratum basale |
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what are the absorbed and excreted substances by the skin |
absorbed: -O2, N2, CO2 + ANY lipid soluble substance excreted: -water (H2O) -urea -uric acid -Ammonia these are released form the surface of the skin via sweat |
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what are the 2 mechanisms by which the skin is water repellant/resistant |
-sebum secreted from the sebaceous gland -keratinocytes produce lamellar granules- these secrete a lipid rich water repellant |
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what are the sensation aspects of the skin? |
-it has an extensive network of nerve cells -there are receptors for HEAT, COLD, TOUCH + PAIN (these are the Merkel cells and the tactile discs) -there is also subcutaneous adipose tissue which provides insulation against heat loss |
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what are the 5 layers of the epidermis and what is the layer that is only present in "thick skin"? |
-s. corneum -s. lucidium (only present in THICK SKIN) -s. granulosum -s. spinosum -s. basale |
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what is the process that occurs as cell go from the s. basale to s. corneum? |
terminal differentiation |
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how many layers of cells in s. corneum? |
25-30 |
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how many layers of cells in s. lucidium? |
4-6 |
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how many layers of cells in s. granulosum? |
3-5 |
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how many layers of cells in s. spinosum? |
8-10 |
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how many layers of cells in s. basale |
a SINGLE ROW of cells |
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describe s. corneum |
-flattened dead keratinocytes- contain mostly keratin -keratinocytes in corner are final product of keratinocyte differentiation |
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describe the structure of a keratinocyte |
-no nucleus -no internal organelles -dead |
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describe the structure of cells in s. lucidium |
clear flat keratinocytes |
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which layer of epidermis present only in thick skin? |
stratum lucidium |
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describe the structure of cells in the stratum granulosum |
flattened dead keratinocytes - undergoing APOPTOSIS |
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which layer is described as the transitional layer between the deeper active strata and the dead superficial strata? |
stratum granulosum |
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what 2 things does the s. granulosum contain?
hint: one which serves as a water repellant and the other which converts keratin intermediate filaments (tonofilaments) to keratin |
contain lamellar granules - secrete lipid rich water repellent sealant keratinocytes contain keratohyalin which converts keratin intermediate filaments (tonofilaments) to keratin |
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describe the structure of cells in the s. spinosum |
many sided keratinocytes they contain bundles of tonofilaments (keratin intermediate filaments) |
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describe the structure of cells in stratum basale |
cuboidal/columnar cells with scattered tonofilaments |
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describe the structures and cells present in the stratum basale and explain their function |
-STEM CELLS- undergo cell division to produce new keratinocytes -keratinocytes contain TONOFILAMENTS -MELANOCYTES and MERKEL CELLS (which are associated with merkel discs) are scattered among keratinocytes -DESMOSOMES link cells (regardless of layer) to each other -HEMIDESMOSOMES bind keratinocytes to the basement? membrane |
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what are the 2 layers of the dermis and what are the respective proportions that each layer takes up of the dermis |
papillary - 1/5th reticular - 4/5th |
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what are the structures which project from the undersurface of of the dermis into the epidermis |
dermal papillae |
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do epidermal cells have polarity? |
yes......yes they do |
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describe the function of keratinocytes |
-produce keratin (protein which is tough and fibrous) -protects from heat microbes and chemicals -produce lamellar granules which secrete lipid rich water repellent (in s. granulosum) |
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describe the functions of melanocytes |
-do not regenerate easily -develop from ectoderm of developing embryo -produce melanin -arm like extensions extend between keratinocytes and transfer melanin --> the melanin granules cover the surface of the keratinocyte nucleus on the side facing the skin surface and so protecting it form UV damage -melanocytes susceptible to UV damage (irony) |
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describe the function of langerhans cells |
-present in all layers of epidermis - especially spinosum -ensure other cells of immune system recognise foreign antigen and destroy it -easily damaged by UV light |
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describe the structure of merkel cells |
work with merkel discs to detect touch sensations |
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describe the 2 types of wound healing and explain their difference |
epidermal wound healing - affects only epidermis e.g. abrasion/minor burn dermal wound healing - a wound which penetrates the dermis |
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what are the 3 main phases of deep wound healing |
-inflammation -migration -remodelling |
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describe what happens in the inflammatory phase of deep wound healing |
-blood clot forms and loosely joins wound edges -the inflammation which is occurring helps to eliminate microbes, foreign material and dying tissue in preparation for repair -vasodilation and increased permeability of the blood vessels occur which help the delivery of helpful cells e.g. phagocytic W.B.Cs --> eg neutrophils and macrophages --> mesenchymal cells --> develop into fibroblasts |
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what type of cells develop into fibroblasts? |
mesenchymal cells (please note they can also turn into bones and cartilage too) |
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describe the migratory phase of deep wound healing |
-clot becomes scab -epithelial cells go beneath wound to bridge it -fibroblasts migrate along fibrin threads and begin synthesising scar tissue -scar tissue that is formed is: collagen fibres + glycoproteins -damaged blood vessels begin to regrow -the tissue filling the wound is called the Granulation tissue
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what is the temporary tissue which fills a wound called? |
granulation tissue |
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describe the proliferative and maturation phase of deep wound healing |
Proliferative phase: -excessive growth of epithelial cells below scab -fibroblasts deposit collagen fibres in a random pattern -continued growth of blood vessels Maturation phase: -scab sloughs off since epidermis has been restored to normal thickness 1. collagen fibres become more organsied 2. fibroblasts decrease in number 3. blood vessels are restored to normal |
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at what point does the scab 'slough off' from the skin? |
when the epidermis has been restored to normal thickness this occurs in the maturation phase of deep wound healing |
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define autonomy |
The ability to be self-determining, self governing and to make competent decisions about oneself on the basis of reason.
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define informed consent |
A voluntary decision and agreement to authorise someone to do something. Requires understandable relevant info disclosure, understanding, capacity, not coerced or manipulated. Not once and for all, not transferable from one medical intervention to another, only for a specific intervention. |
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define proxy consent |
Under the adults with incapacity (Scotland) act 2000, a nominated welfare guardian can make decision on behalf of a patient that lacks capacity to undertake a treatment that will benefit the patient. Appointed by the Public Guardian once the patient is issued with a certificate of incapacity. |
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define implied consent |
Agreement that is presumed. Can be due to the patients actions and behaviour, e.g. rolling up sleeves when taking blood pressure/attending A&E service |
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define capacity |
The ability to act, understand, retain memory of decision and base on information to make reasoned decisions and communicate it. This varies in degrees and judged by doctor; it is not an all-or-nothing category=may have capacity to make some decision but not others; fluctuates throughout the day. Lack capacity= Cognitive impairment, poor mental state, memory deficit or unconcious |
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what are the factors affecting wound healing |
-size of wound -age of patient -blood supply to area/wound -drugs patient is taking -nutritional status of patient -presence of foreign bodies |
