Exsc 223 Ch5 notes
Exsc 223 Ch5 notes EXSC 223
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This 8 page Bundle was uploaded by ashvipatel120696 on Thursday October 6, 2016. The Bundle belongs to EXSC 223 at University of South Carolina taught by Dr. Raymond Thompson in Fall 2016. Since its upload, it has received 3 views. For similar materials see Anatomy and Physiology I in exercise science at University of South Carolina.
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Date Created: 10/06/16
Chapter 5- Integumentary System What has your skin done for you lately? Functions of the skin: 1. protection- chemical, physical, biological 2. body temperature regulation 4 mechanisms 3. Cutaneous sensation 4. Metabolic function- chemical conversion sunlight 5. Blood reservoir cold env- withdraw blood from skin hot environment- more blood to skin 6. Secretion/excretion sweat glands-secreation urea from sweat- excretion sebaceous glands- release oil onto the skin 2 distinct layers outer layer- epidermis stratiﬁed squamous epithelium keratinized - tough ﬁbrous protein makes skin cells tough dermis- 2 layers of connective tissue between both layers- foldings- interdigatation hypodermis- layer of adipose connective tissue below the dermis not part of the skin epidermis composed of 4 diﬀerent types of cells keratinocytes produce keratin connected by desosomes arise from a deeper mitotically active layer dead at surface- turnover 25-45 days catabolic protein in the basal layer are capable of going through mitotic phase langerhans cells macrophage cells activate immune system macrophage that lives and resides in the epidermis they stay there resident macrophages alter the body in case the skin breakes merkel cells epidermal-dermal junction associated with sensory nerve endings receptor for touch sensory cell communicate with neurons in the dermis not mitotically capable melonocytes synthesize melanin found in deepest layers give skin color basal skin color responsible for giving us a tan protein called melanin- melanozome move and get picked up by keratinocytes keratinocytes will use these to protect their cells from UV radiation protect nucleus from the sunlight/UV may have 4/5 layers stratum corneum 20-30 layers thick glycolipids between cells cells are dead here function- abrasion provides a tough outer layer/coating stratum granulosum 3-5 layers thick nuclei and organelles disintegrate accumulate keratohyaline granules granules contain keratin cells dying or already dead going through apoptosis stratum spinosum several layers thick ﬂat irregular shaped keratinocytes desmosome attachments produce desmosomes and protein keratin and melanin stratum basale deepest layer, attached to dermis single row of youngest keratinocytes melanocyte cell no source of nutrients dermis provides them with that 5 layers only at soles and palms stratum lucidam only in thick skin clear calusus dead skin cells layer between corneum and granulosum Dermis has 2 layers of CT which includes other cell types and structures top layers dermal papillae ( papillary layer of dermis) accounts of the 25% of dermis height loose aeroler CT basement membrane 80% reticular layer dense irregular CT cleave lines collage ﬁbers arranged in bundles from cleave (tension) line incisions made parallel to cleavage lines help more readily incisions are slower to heal and they can become permanent skin appendages are derivations of epidermis with a role in maintaining homeostatis sweat glands (sudoriferous glands)(merocrine) found everywhere except nipples and external genitali eccrine most abundant high density on palms, sole of foot and forehead secrete sweat hypotonic blood ﬁltrate 99% h2o, some NaCl other material acidic (pH 4-6) apocrine conﬁned to axillary and anogenital area, little role in thermoregulation larger, ducts emory into hair follicles similarity to sexual scent gland- sexual foreplay increases activity bacteria break down the secretions Audio File sebaceous (oil) glands puke to keep your skin soft and smooth alveolar glands everywhere except palms and soles of feet secrete sebum (holocrine) lipid and cell fragments function lubrication skin: slowing water loss hair: prevents brittleness bactericidal function stimulated by androgens acne develops when: hair follicles become plugged sebum dead skin cells bacteria then trigger: inﬂammation infection pus- dead white blood cells localized inﬂammation Hair why do we have hair? protects from environment hair on scalp protects it from the sun nasal hairs protects the respiratory system eyelashes hair is distributed over the entire skin surface except palms, soles, and lips nipples and portions of the external genitalia hair is ﬁlamentous strands of keratinized cells hair: shaft projecting from the skin root embedded in the dermis root could be in the reticular layer or in the thinner layers in the hypodermis cells called hard keratin epidermis is made up of soft keratin consists of 3 layers of cell: medulla- dense, hollow tube in the middle of the shaft; not allows present cortex cuticle- split ends?? exposure to the cortex cuticle can begin to fray or wear oﬀ straight, curly depends on how round the hair shaft is curly- ﬂat side of the shaft wavy- not really round not really ﬂat straight- round hair follicle follicle wall connective tissue root sheath glassy membrane- equivalent of basement membrane external epithelial root sheath- epidermis internal epithelial root sheath- epidermis hair root cuticle cortec medulla hair matrix hair papilla melanocyte number are uniform in everyone amount produced is diﬀerent thea crome- gives tissues a reddish color dark hair- lost of black combination is what giver our hair color subcutaneous adipose tissue hair care- a multibillion dollar business types of hair terminal hair on your scalp, leg, eyebrow, chin thick, can grow long active growth phase vellus forehead thin, short peach fuzz does not always grow long enough to break through the surface not always visible alopecia- hair thinning not active growth phase hair follicles going dormant as you age, more enter the dormant stage then the active true or frank, baldness genetically determined and sex-inﬂuenced condition male pattern baldness- cause by follicular response to DHT mutation to the receptor receptor is speciﬁc to a testosterone DHT when this hormone binds to receptor, cause hair to become dormant women don’t get as aﬀected 2 x chromosomes not much testosterone in females growth- 2.5mm/week growth cycles- active/dormant lose` ~ 90 hears per day Audio File eyebrow hairs go through growth phases and then become dormant has to do with short active growth phases hair on scalp has long growth phases Audio File when hair stands up, it traps more air for insulation erector pili muscle goosebumps hair stands up when cold Audio File Not all skin cancers are created equal basal cell carcinoma least malignant stratum basal cells proliferate and invade dermis sun exposed areas more common cancer of the keratinocytes in the basal layer rarely metastasizes 99 survival more common kinds squamous cell carcinoma keratinocytes of the stratum spinosum grows rapidly, metastasizes, good outcome if caught early melanoma most dangerous; highly metastatic, chemotherapy resistant spreads early cancer of melanocytes 1/3 from pre-existing moles can take up residence anywhere in the body and they can survive and thrive originates in the basal layers mitosis and cytokinesis over and over radial growth phase- spreads outwards; not towards the surface by the time you see it, it already has metastasized vertical growth phase- spreads downwards how to identify ABCD rule A-symmetry- two sides don’t match B-order irregularity- indentations in border C-olor- pigmented spot contains several black colors D-iameter- larger than 6mm diameter (pencil eraser) even if you see one of these four, get it checked out don’t need to have all four or three of four Burns Classiﬁcation of tissue injury by burns skin creates a water tight seal between body and environment signiﬁcant burn- ﬁrst 24 hours biggest problem is dehydration burns are loss of tissue ﬁrst degree- only the epidermis is damaged symptoms include localized redness, swelling and pain injury to the epidermis skin is still intact enough injury to get immune respone second degree- epidermis and upper regions of dermis are damaged symptoms mimic ﬁrst degree burns but blister also appear blister is result of the ﬂuid separating the epidermis and the dermis all of the cells in the basal layer of the epidermis are dead third degree- entire thickness of the skin is damaged burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed) no blistering skin is missing; skin in not intact nerve endings can regenerate in the endings diﬃcult to re-heal properly will see charring around the edges of the burn scars will be associated with this burn very diﬃcult injury to come back from associated with tissue grafts rule of thumb to quantify area burned auto graft- re-grow your own skin and place it on skin major problem with dehydration and infection considered critical if: over 25% of the body has second-degree burns over 10% of the body has third-degree burns there are third-degree burns on face, hands, or feet rules of nine tool to estimate body ﬂuid lost divide body into 11 regions (9%) starts with legs anterior is 9% each posterior 9% each al together account for 1/3 of entire body surface trunk and chest- chest 9% stomach 9%' upper back 9% lower back 9% arms 4.55 each head and neck 9% total ( ant and post) Audio File
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