BIOL 252 1st Edition Exam 2 Study Guide Lectures 8 15 The Integumentary System Structure 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 cells o Fight off microbes and bacteria for immune system o 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 epithelium o Stratum basale bottom most Stem cells melanocytes tactile cells o 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 carcinoma o Most common o Least dangerous o Stratum basale o Carcinoma epithelial cancer Squamous cell carcinoma o Arises within stratum spinosum o Metastasizes spreads Leaves tissue of origin and can travel to other places to lymph nodes Can be lethal o Malignant melanoma Rare but deadly fatal Metastasizes readily Dermis Superficial papillary layer o Areolar connective tissue o Forms papillae dense w nerve endings and capillaries Deep reticular layer o Dense irregular connective tissue o Contains larger blood vessels o Adipocytes o Comprises most of dermis o Leather Why do we have fingerprints To grip Hypodermis Last layer of skin Fat layer at the bottom Structure o Primarily adipose o Rich in blood vessels and nerves Function o Fat energy storage o Thermal insulation o 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 blood o 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 resistance o Carotene Normal pigment found in plants Carotenemia carotene is normal in small amount but may accumulate in stratum corneum Bone Tissue Functions of the Skeleton Protection Support Movement Electrolyte balance Blood formation Histology of Osseous Tissue Osteogenic cell o Multipotential stem cell Osteoblast o Secretes bone matrix o Blast in developmental stage o Complete process of differentiation to become an osteocyte Osteocyte o Lives completely surrounded by the matrix it produces o Lacunae packet w in bone matrix where osteocytes live o Interconnect themselves w dendrites in canaliculi channels o Gap junctions allow diffusion and passing along of nutrients Osteoclast o Break down bone matrix o 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 matrix o Interstitial In bone o 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 vinegar o Vinegar acetic acid o Acetic acid calcium phosphate solubilizes the salt o 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 weight o 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 Pathologies o 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 matrix o Spaces not lacunae o At the ends of bone Compact bone dense heavier than spongy bone o All around edges Nutrient foramen o Provide vascular and nervous supply Bone marrow o Ad adults most is classified as yellow o 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 marrow o Periosteum Connective tissue wraps around outside of bone If need to tear down bone matrix use osteoclast If need to build bone matrix use osteoblast o 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 present o Articular cartilage Where bone articulates w another bone Structure 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 bone o In space of spongy bone bone marrow o Trabeculae connecting roads that make up solid part of bone o Why do we need spongy bone Lighter Flexibility Histology of Compact Bone Osteon o Circular arrangement around blood vessel o Unit of bone o Also called the Haversion system o Collagen oriented in different directions Layers lamella Histology of Spongy Bone Bone matrix are arranged in two trabeculae beams Spongy bone contains slivers spicules and beams trabeculae of bone providing strength w minimal weight Trabeculae align along lines of stress through the process of remodeling o