INTEGUMENTARY & SKELETAL

INTEGUMENTARY & SKELETAL


Integumentary System (CH 6)

  • Layers of the skin

    • Epidermis - surface of skinĀ 

      • Stratum corneum - consists of up to 30 layers of dead, scaly,, keratinized cells, forms durable surfaceĀ 

      • Stratum lucidum (THICK SKIN ONLY) - densely packed keratinocytesĀ 

      • Stratum granulosum - three to five layers of keratinocytes - more in thick skin than thin

      • Stratum spinosum - several layers of keratinocytes, thickest stratum

      • Stratum basale - single layer of cuboidal to low columnar stem cells and keratinocytes resting on the basement membrane - stem cells

    • Dermis - connective tissue layerĀ 

      • Papillary layer - areolar tissue in and near the dermal papillae, allows for mobility of leukocytes and other defenses against organisms introduced through breaks in the epidermisĀ 

        • Blood vesselsĀ 

        • Upward waves - dermal papillae - cause fingerprints, handprintsĀ 

      • Reticular layer - deeper and tickerĀ 

        • Dense irregular tissueĀ 

        • Stretch marksĀ 

    • Hypodermis - more areolar and adipose tissue (not considered real layer of skin)

  • Pigments of skin and hairĀ 

    • Melanin - produced by melanocytes and accumulates in the keratinocytes of the stratum basale and stratum spinosumĀ 

      • Eumelanin - brownish blackĀ 

      • Pheomelanin - reddish, yellow

      • Hemoglobin - redĀ 

      • Carotene - yellowĀ 

  • Structure of hair and follicleĀ 

    • Hair divisible into 3 parts:Ā 

      • Bulb - where hair growth originatesĀ 

        • Grows around bud of vascular connective tissue called the dermal papilla, sole source of nutritionĀ 

        • Immediately above is the hair matrix, hair’s growth centerĀ 

      • Root - remainder of hair within follicleĀ 

      • Shaft - portion above skin surfaceĀ 

    • Hair into 3 parts:

      • Medulla - core of loosely arranged cells and air spaces - most prominent in thick hairĀ 

      • Cortex - most of bulk of hair, consists of several layers of keratinized cellsĀ 

      • Cuticle - multiple layers of very thin, scaly cells that overlap each other like roof shinglesĀ 

  • Types of skin cancerĀ 

    • Basal cell carcinoma - most common type and least deadly

      • Seldom metastasis, rises from cells of stratum basale and eventually invades the dermisĀ 

      • First appears as small, shiny bump

    • Squamous cell carcinoma

      • Arises from keratinocytes of stratum spinosum

      • Lesions commonly appearĀ 

    • Melanoma - least common, most deadly

      • Arises from melanocytes

  • Burns

    • First degree - epidermis

      • marked by redness, slight edema, and pain

      • heal in a few daysĀ 

    • Second degree - epidermis and part of the dermis

      • Partial thickness burnsĀ 

      • Tan, white

      • Blistered and very painfulĀ 

      • May take weeks to months to heal and may leave scarsĀ 

    • Third degree - epidermis, all of dermis, and deeper tissueĀ 

      • No dermis remains,so skin can only regenerate from edges of the wound

      • Often require skin graftsĀ 

  • Nails

    • Nail plate - hard part of nailĀ 

    • Free edge - part hanging off of nailĀ 

    • Nail root - extends proximally under the overlying skinĀ 

    • Nail fold - surrounding skin rises a bit above the nail

    • Nail groove - separates from margin of nail plate and nail foldĀ 

    • hyponychium - epidermis under nail bed

    • Nail matrix - stratum basale thickens into growth zoneĀ 

    • Lunule - white crescentĀ 

    • Cuticle - narrow zone of dead skinĀ 

Skeletal System

  • Structure

    • Outer shell consists of compact boneĀ 

    • Outer shell encases marrow cavity, contains bone marrow (also called medullary cavity)

    • Spongy bone found at the ends of the bone of its central spaceĀ 

    • Long bone

      • Diaphysis - shaft, provides leverageĀ 

      • Epiphysis - expanded head at each end, strengthen the joint, adds surface area for attachment of tendons and ligamentsĀ 

    • Periosteum - sheath that covers the boneĀ 

    • Endosteum - thin layer of reticular connective tissue that lines the internal marrow cavityĀ 

    • Children and adolescents have an epiphyseal plate of Ā hyaline cartilage separates the marrow spaces of epiphysis and diaphysis

      • Appears as narrow line at end of long boneĀ 

      • Zone where bones grow in length

    • Adults don’t have an epiphyseal plate bc their bones don’t grow any more, however they do have an epiphyseal line to mark where the plate used to beĀ 

  • TypesĀ 

    • Short - kind of looks like a square (ie patella)

    • Long - length longer than width (ie femur)

    • Irregular - random shape (ie vertebrae and ear bones)

    • Spongy bone - calcified and hard, has many spaces filled with marrowĀ 

    • Bone marrow - soft tissue that occupies marrow cavity of a long boneĀ 

      • Child - red bone marrow - produces RBC

      • Adults - yellow bone marrow - no longer produces blood, although in the event of tsever or chronic anemia, it can transform back into red marrow and resume its hematopoietic functionĀ 

  • Cell typesĀ 

    • Osteogenic - stem cells

    • Osteoblast -bone forming cellsĀ 

    • Osteocytes - former osteoblasts become trapped in the matrix they deposited, reside in tiny cavities called lacunaeĀ 

      • reabsorbs Ā bone matrix and others depositi it, contribute to homeostatic maintenance of both bone density and blood concentrations of calcium and phosphate ionsĀ 

    • Osteoclasts - bone dissolving cells on the bone surfaces, deveo from the same bone marrow stem cells that give rise to the blood cellsĀ 

  • Bone developmentĀ 

    • Intramembranous ossificationĀ 

      • Mesenchymal cells line up along blood vessels, become osteoblasts, and secrete soft collagenous osteoid tissueĀ 

      • Calcium phosphate and other minerals crystallize on the collagen fibers of the osteoid tissue and harden the matrixĀ 

      • Forging process continues, becomes perisoterijmĀ 

      • Blood vessels crowd the area, creating red bone marrow

    • Endochondral ossification

      • Mesenchymal cells differentiate into chondrocytes

      • Cartilage model of future bony skeleton and the perichondrium form

      • Capillaries prevent cartilageĀ Perichondrium transforms into periosteum. Periosteal collar develops. Primary ossification center develops

      • Cartilage and chondrocytes continue to grow at ends of the bone

      • Secondary ossification centers develop

      • Cartilage remains at epiphyseal (growth) plate and at joint surface as articular cartilage