BSCI 201 Review Sheet for Exam 2 A Tissues 1 List describe and give the function of the different types of Connective tissues Common characteristics of connective tissue All derived from the embryonic tissue Mesenchyme Exhibit a degree of vascularity avascular poor vascularity highly vascular Composed of 2 parts The nonliving portion the extracellular matrix composed of The ground substance o Intertitial fluid Tissue fluid extracellular fluid that surrounds cells o Cell adhesion proteins act as molecular glue to attach cells to the matrix o The nonliving portion o The living portion within tissues Fibronectin Laminan o Proteoglycans composed of protein core with glycosamino glycons GAGs attached Increase in these materials result in an increase of the ground substance s viscosity ex low viscosity would be runny potatoes high viscosity would be harder potatoes The GAGs are Keratin sulfate Chondroitin sulfate Hyaluronic acid o Ground substances can be fluid solid semi solid and gel like The living portion is made of cells derived directly from Mesenchyme There are 4 types of cells that secrete the 4 classes of connective tissue o 1 Fibroblasts secrete the connective tissue class connective tissue proper o 2 Chondroblast secrete the class cartilage o 3 Osteoblasts secrete the connective tissue class bone or osseous tissue o 4 Hematopoietic stem cells secrete the class of connective tissue blood There are 3 types of extracellular matrix connective tissues o 1 Collagen Fibers composed of the fibrous protein COLLAGEN The collagen fibers are arranged in rope like fashion providing tensile strength ability to withstand stress pressure to the connective tissue A collagen fiber is stronger than steel fiber In freshly prepared connection tissue the collagen fibers appear glistening white collagen fibers are known as white fibers o 2 Elastic Fiber Yellow fibers are composed of the fibrous protein ELASTIN The elastin fibers exhibit the stretch recoil property under pressure the elastic fibers stretch to accommodate the pressure but when the pressure is removed the elastic fibers recoil to assume regular shape and length o 3 Reticular Fibers composed of fine collagenous fibers that branch extensively to form networks These fibers are abundant in areas where connective tissue abuts is next to other types of primary tissues Ex reticular lamina of the basement membrane 1 Class Connective tissue proper a Cells secreted fibroblasts b Consistency of the ground substance gel like c 2 types of connective tissue proper i Loose CT 1 3 subtypes a Areolar CT small open spaces i Referred to as Packing Material because it surrounds cells in tissues of the body interstitial fluid ii Gel like consistency iii Contains all 3 types of fibers collagen elastic and reticular iv Location most widely distributed type of CT in the body and supports epithelial tissues v Basal Lamina of the basement membrane 1 Ex papillary layer of the dermis is areolar vi Lamina Propria surrounds tissues in the mucus CT membranes vii Functions 1 Cushioning of structures 2 Holds the interstitial fluid 3 Plays role in inflammation by holding more interstitial fluid when edema swelling occurs at a sight of injury Chicken wire appearance b Adipose CT i ii Cells called adipose fat cells store triglycerides neutral fat which are able to expand to store more fat used for protection and insulation iii As cells expand the nuclei are pushed to the periphery of cell iv Location 1 Surrounds organs in the body 2 In the subcutaneous layer below the dermis v Function 1 Cushioning of organs 2 Protects against trauma 3 Holds organs in anatomical position a Ex holds kidney against abdominal wall Without the adipose capsule like during anorexia the body will catabolize the fat in the adipose capsule for energy Gravity will cause the kidneys to drop causing the urethra to twist and drain This will result in kidney failure In the subcutaneous layer the adipose CT acts as insulation to prevent heat loss 4 c Reticular Connective Tissue i Contains reticular fibers ONLY ii The reticular fibers form networks within organs The networks act as internal frameworks within the organs referred to as the STROMA iii The stroma accommodate immune cells which proliferate in the stroma of organs called the lymphoid organs spleen lymph nodes thymus ii Dense CT 1 Dense because composed of many fibers also referred to as FIBROUS CT 2 3 types a Dense regular CT i Made up of bundles of collagen arranged in a regular orderly fashion parallel to the pull stress ii Can withstand stress applied in one direction iii Dense regular CT has elastic fibers because of its stretch recoil properties however the stretch is limited by the opposition of the collagen fibers not as flexible as elastic CT iv Location 1 Ligaments bind bones at the joint site 2 Tendons bind bone to skeletal muscle 3 Flat like or sheet like tendons are referred b Dense Irregular CT to as apnevrosis i Made up of thick bundles or collagen fibers facing in ALL DIRECTIONS arranged in an irregular haphazard manner ii Can withstand stress applied from different directions c Elastic CT i iii Located in the reticular layer of the dermis Increased elastic fibers stretch recoil properties ii Location ligaments connecting the intervertebral discs iii Function elastic CT is for stretching when under pressure and to rebound to its original size shape when pressure is removed 1 Ex Ligaments flava allow for the bending of the spinal cord vertebral column The vertebral column bounces back to its original length in an upright position 2 Cartilage second class of connective tissue Secreted by chondroblasts a b Has a semi solid ground substance c Avascular d There are 3 types of cartilage i Hyaline Cartilage 1 Most abundant type of cartilage in the human body 2 Many bones start off as hyaline cartilage a Forms the embryonic skeleton which is ossified into bone tissue right before birth 3 Location post natal in the epiphyseal plates between the diaphysis of the epiphyses of long bones a The epiphyseal plates allow for longitudinal linear growth of long bones b The articular cartilage which caps the end of an epiphysis The articular cartilage acts as resilient cushions to protect the ends of bones at the site of a joint prevents rubbing The absence of these cushions causes osteoarthritis immune disease c Costal cartilage joins the rib to the sternum s anterior It acts as a resilient cushion d Forms some structures of the respiratory
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