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					     Unit 4:

     Ch. 6
               Types of Membranes
   Serous – secretes serous fluid
       Lines body cavities that do not open to outside
       Simple squamous epithelium – mesothelium
       Watery fluid, high with electrolytes and enzymes,
        lubricates surfaces
   Mucous – secretes mucus
       Lines cavities and tubes that open to the outside
            Oral, nasal, digestive, respiratory, urinary, reproductive
       Mucus rich with glycoprotein (Mucin)
   Synovial – lines joint cavities with freely movable
    bones (synovial joints)
       Synovial fluid is a thick, colorless fluid  lubrication
   Cutaneous – skin  see rest of notes
                      Layers of the Skin
   EPIDERMIS – outermost layer of skin
       Simple squamous epithelium
       Avascular – must obtain nutrients from dermis
       Layers from deepest to most superficial:
            Stratum Basale (germantivum) – bottom layer
                 Cells divide here – push cells toward surface as new cells form
                 Find melanocytes – specialized cells that secrete melanin for
                  skin color
                     About the same number of melanocytes for each individual
                        the amount of melanin differs
                     Amt of melanin depends on Genetics and Environment
                     UV rays stimulate production of melanin  sun tan;
                       protects underlying tissues from damaging rays
                     Cytocrine Secretion – passing of melanin to nearby cells
                  Layers of the Skin
   Layers of Epidermis (continued)
        Stratum Basale – see previous slide
        Stratum Spinosum
        Stratum Granulosum – cytoplasm turns granular
        Stratum Lucidum – clear
             Only found in palms, soles and lips
        Statum Corneum – dead layer (outermost)
             Constantly rubbed off
             Thickness depends on location and how much wear  more
              cell loss triggers higher cell division and a thicker stratum
                 Calluses and corns

   Keritinization – hardening and waterproofing of outer
    epidermal cells
        Accumulate the protein “Keratin”
        Develops as cells grow older and get pushed toward surface
        Kerotinocytes – older cells, stuck tight together
                       Layers of the Skin
   DERMIS – 2nd layer; beneath epidermis
       Thicker region
       Composed of irregular dense fibrous connective tissue
            Gives toughness (collagenous fibers) + elasticity (elastic fibers)
       Dermal Papillae – finger like projections of the dermis that extend into
        the epidermis to help bind the two together
       Fingerprints – cutaneous ridges at tips of fingers
            Genetically determined but changes during fetal development; no two are
             exactly alike, including identical twins
       Contains many accessory organs – hair follicles, sebaceous glands,
        sweat glands, nerves, blood vessels, muscle fibers
       Nerves:
            Pacinian Corpuscles – deep, stimulated by heavy pressure
            Meisner’s Corpuscles – closer to surface; stimulated by light touch
            Heat and Cold receptors – free nerve endings
            Pain receptors – free nerve endings
       Muscle tissue
            Arrector Pili Muscle – attaches to base of hair  goose bumps
            Dartos Muscle – found in skin of scrotum; regulates temp of testes
            Skeletal Muscle attached to dermis
                   Layers of the Skin
   SUBCUTANEOUS LAYER – hypodermis
       Beneath dermis; binds skin to underlying
          Fat is used for: 1) energy storage; 2) inslulation;
           3) cushioning
          No distinct boundary between layers

       Composed of loose fibrous connective tissue
        and adipose tissue
       Major blood vessels that supply skin found
            Rete Cutaneum – network of blood vessels found
             where dermis and subcutaneous layer meet
                     Accessory Organs
   Hair Follicles – actually extensions of epidermal cells into
       Found on all skin except: palms, soles, lips, external
        reproductive organs and nipples
       Hair is layers of dead, scalelike epidermal cells stacked on top of
        one another
            Hair cells originate near base and push already made hair above
       Hair Papillae – indentation at base of follicle that supplies hair
        with blood and nerves
       Arrector Pili muscle – attached at base of follicle
            Contracts when body temp lowers  stands hair up  helps trap
             warm air
       Baldness – see clinical application 6.2
       Hair color
            Amount of melanin
            Red  Trichosiderin; iron containing pigment
                     Accessory Organs
   Sebaceous Gland
       Gland associated with hair follicles; few open directly to surface
        of skin
       Produce Sebum – oily substance that helps keep skin and hair
        soft and pliable
       Holocrine gland – cell + fatty material excreted
       Often overactive during puberty
            Produces acne – sebum clogs pores and causes pimples (pustules)
             or blackheads (comedones)
   Nails – protective coverings on ends of fingers and toes
       Nail plate – the nail itself; specialized, highly keratinized
        epithelial cells; continuous with epidermis
       Nail Bed – area that nail plate lies on
       Lunula – half moon shaped region of nail near base (cuticle)
            Most active growing region
            Nail appearance can be indicator of health – see box P. 171
                        Accessory Organs
   Sweat Glands – sudoriferous glands
       Ball shaped, highly coiled glands deep in dermis or in top part of
       Duct leads to opening (pore) on skin surface
       Eccrine Glands – produce sweat
            Most numerous; especially in palms
            Respond to elevated body temp or emotional distress
            Replaced with fibrous connective tissue as a person ages
            Sweat consists of mainly water + salts and wastes (urea and uric acid)
       Apocrine Glands – scent glands
            Most numerous in armpits and groin
            Become functional at puberty; causes body odor
            Activated by fright, upset, pain, sexual arousal
            Contains pheromones  chemical attractants to opposite sex
            Ceruminous (ear wax) and Mammary glands specialized apocrine glands
                  Ear wax is water resistant and an insect repellent
                  Mammary glands only found in female breast region  stimulated by prolactin to
                   produce breast milk
   Normal Body Heat – 98o F; 37o C
   Controlled by hypothalamus
   Ways skin helps to control body temp
       Superficial blood vessels near skin can help blood leave body
        (superficial vasodilation)
       Ways body loses heat
            Radiation, conduction, convection, evaporation
       Sweat glands promote evaporation
       Arrector Pili muscles and goose bumps
   Humid days  hard to evaporate, hard to cool
   High air temperatures  body gains heat from surroundings
   Hypothermia – too much heat loss
       Uncontrolled shivering
       Mental confusion, loss of reflexes, unconscious
       Shut down major organs  respiratory failure, heart arrythmias
                   Skin and Hair Color
   See notes on melanin and melanocytes
        Genetics and environment
   Albinism – genetic defect where a person does not produce any
        White skin and white hair
        Higher risk of skin burn and skin cancer
   Blood
        Red skin – superficial blood vessels dilated (open)
        Blue skin – cyanosis
             Cold – superficial blood vesses constricted (closed) or low oxygen in blood
   Certain Foods
        Carotene (pigment in yellow vegetables) can accumulate in skin and
         give yellowish appearance (you are what you eat)
   Jaundice – liver malfunction
        Bilirubin (digestion pigment) accumulates in skin
        Sun helps break down  discovered by nurse 1958 when she took out
         a jaundice baby and jaundice cleared up except where diaper was
                        Damages to Skin
   Cuts/ Abrasions
       Shallow cuts heal easily; fill in damage with epithelial tissue
       Deep cuts into dermis
            Require clot to stop bleeding
            Fibroblasts blasts produce collagenous fibers to repair skin damage  scar
            C. T. release growth factors for cell division
            Phagocytic cells remove dead cells
   Burns
       1st degree (superficial partial thickness)
            only damages epidermis
       2nd degree (deep partial thickness)
            Epidermis + part of dermis
            Blisters, dark red to waxy white; most painful
       3rd degree (full thickness)
            Destroys epidermis, dermis and accessory organs
            Skin will not regenerate on its own with out accessory organs – skin grafts
            Not as painful – nerve endings destroyed
       Rule of Nine – a way a doctor can assess burn damage based on
        regions of the body that are approximately 9% portions
                  Skin Disorders
   Know Skin Cancer Types (Clin. App. 6.1)
       P 168
       Cutaneous Carcinomas
       Cutaneous Melanomas
       Xeroderma Pigmentosum
       How to reduce risks
   Psoriasis
   Dermititis
   Bed Sores – Pressure Ulcers
   Rashes
   Folliculitis

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