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, hairās 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 donāt have an epiphyseal plate bc their bones donāt 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