BIOL 252 1st EditionExam # 2 Study Guide Lectures: 8 - 15The Integumentary SystemStructure and Function- Biological harm: keeps microbes and pathogens out- Chemical harm: waterproofing (helps us retain water or absorbing too much)- Physical harm: abrasions - Vitamin D synthesis - Sensory reception (pain, heat, movement, pressure, light touch)- Thermoregulation (involves 3 layers of skin)- Communication (facial muscles, skin color changes)Epidermis- Keratinocytes and stem cells (make keratin)- Melanocytes-protect against UV light (causes DNA mutations)- Tactile cells-sensory receptor for touch- Dendritic cellso Fight off microbes and bacteria for immune systemo First line of defense for body after the skin (so 2nd line of defense)o Signals to rest of immune system- Epidermis = keratinized stratified squamous epitheliumo Stratum basale: bottom-most Stem cells, melanocytes, tactile cellso Stratum spinosum = cells adhere (desmosomes-strong mechanical linkages) Deepest can divide Produce keratin Dendritic cells present o Stratum granulosum = keratohyaline granules Keratin binding proteins Lamellar granules Waterproof skin Start to lose organelles, cells begin to die o Stratum corneum = cells are dead and continually exfoliate o Which cells least likely to become skin cancer? Melanocytes, stratum basale, spinosum = naturally dividing cells Stratum granulosum – LEAST likely Skin Disorders (cancers of epidermis)- Basal cell carcinomao Most commono Least dangerouso Stratum basaleo Carcinoma = epithelial cancer- Squamous cell carcinomao Arises within stratum spinosumo Metastasizes (spreads) Leaves tissue of origin and can travel to other places – to lymph nodes Can be lethalo Malignant melanoma Rare but deadly – fatal Metastasizes readilyDermis- Superficial: papillary layero Areolar connective tissueo Forms papillae, dense w/ nerve endings and capillaries- Deep: reticular layero Dense irregular connective tissueo Contains larger blood vesselso Adipocyteso Comprises most of dermiso Leather- Why do we have fingerprints? To gripHypodermis- Last layer of skin- Fat layer at the bottom- Structureo Primarily adiposeo Rich in blood vessels and nerves- Functiono Fat (energy storage)o Thermal insulationo Communication- Health reflected by amount of fat you have Skin Coloration- Which molecule does not contribute to normal color of skin?o Hemoglobin Ranges from red to purple/blue Oxygenated = red; deoxygenated = blue Abnormal colors in skin- Cyanosis: poorly oxygenated hemoglobin- Pallor: yellow/green/pale skin resulting from poor blood supply- Erythema: abnormal reddening of skin (overheating, stress, burns,rashes)- Jaundice: yellowing due to buildup of bilirubin- Hematoma: bruise; a mass of clotted bloodo Melanin Produced by melanocytes Distributes on external face of keratinocytes Breaks down more rapidly in lighter skin tones Abnormal colors in skin- Albinism: lack of melanin; genetic Lots of melanin where strong UV light is (equator)o Keratin Does not contribute to skin color Waterproofs skin, gives abrasion resistanceo Carotene Normal pigment found in plants Carotenemia: carotene is normal in small amount but may accumulate in stratum corneum Bone TissueFunctions of the Skeleton- Protection- Support- Movement- Electrolyte balance- Blood formationHistology of Osseous Tissue- Osteogenic cello Multipotential stem cell- Osteoblasto Secretes bone matrixo Blast = in developmental stageo Complete process of differentiation to become an osteocyte- Osteocyteo Lives completely surrounded by the matrix it produceso Lacunae: packet w/in bone matrix where osteocytes liveo Interconnect themselves w/ dendrites in canaliculi (channels)o Gap junctions allow diffusion and passing along of nutrients- Osteoclasto Break down bone matrixo Lives on bone surfaces (external or internal) o Develop from macrophage-like cells Bone Matrix- Made of fibers and ground substance- Fibers are proteins- Ground substance is the fluid component of extracellular matrixo Interstitial- In boneo Fibers are collagen (touch, resists stretching)o Ground substance (fluid is essentially gone) Minerals precipitated out of solution Most is calcium (hydroxyapatite – calcium phosphate salt = 85% of inorganic matrix)- Bone in vinegaro Vinegar = acetic acido Acetic acid + calcium phosphate solubilizes the salto Illustrates that if you extract mineral component of bone, properties of the bone remain the same Flexibility comes from collagen Stiffness comes from hydroxyapatite Just removing the stiffness - Case: 5 year old girl is brought to clinic and legs bend under weighto What could explain this condition at tissue level and what might be the cause of tissue abnormality? Caused by: - Dietary deficiency of calcium- Vitamin D deficiency- Pathologieso Osteogenesis imperfecta: excessively brittle bones resulting from improperly formed collagen Long Bone Structure-- Epiphysis, diaphysis (shaft), epiphysis- Epiphyseal line: once were epiphyseal plates (site of bone growth)- Spongy bone: has pockets, made of bone matrixo Spaces not lacunaeo At the ends of bone- Compact bone: dense, heavier than spongy boneo All around edges- Nutrient forameno Provide vascular and nervous supply- Bone marrowo Ad adults, most is classified as yellowo Yellow bone marrow Made primarily of adipose tissue (most of bone marrow throughout body)o Red bone marrow Found in more select region of bones- Axial skeleton- More proximal parts of long bones- Can replace yellow bone marrowo Periosteum Connective tissue wraps around outside of bone If need to tear down bone matrix – use osteoclast If need to build bone matrix – use osteoblasto Endosteum Periosteum on inside Wherever you have bone marrow coming in contact w/ bone surface, have endosteum Bone is never in contact w/ marrow Osteoclast/blasts presento Articular cartilage Where bone articulates w/ another boneStructure of Flat Bone- No cartilaginous joints, have sutures- Thickness of bone is like a sandwich- On outside and inside = outer/inner compact bone- Middle/filling = spongy boneo In space of spongy bone = bone marrowo Trabeculae: connecting roads that make up solid part of boneo Why do we need spongy bone? Lighter FlexibilityHistology of Compact Bone-
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