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Body Tissues (Connective Tissue (major function (• Support and binding of…

- - - - ground substance
      - fibers
        
        Collagen (tensile support)
        
        characteristics
        
        tough
        
        thick
        
        fibrous
        
        do not branch
        
        proteins
        
        most abundant fibers
        
        types:
        
        Type I: dermis of skin, tendons, bone
        
        Type II: hyaline cartilage, and elastic cartilage,
        
        Type III: these are the reticular fibers,
        
        Type IV: the basal lamina of the basement membranes.
        
        Elastic (stretchable fiber)
        
        characteristics
        
        thin small branching
        
        contain protein elastin
        
        Stretchable
        
        responsible for elastic recoil
        
        location
        
        lung
        
        bladder
        
        skin
        
        big blood vessels
        
        Reticular (forms stroma of solid organs & lymphoid tissue)
        
        characteristics
        
        type III collagen
        
        Detected if the tissue is stained with silver stain
        
        location
        
        bone marrow
        
        liver
        
        lung
        
        lymph nodes
        
        spleen
      - is mainly composed of ground substance - (glycosaminoglycans: fibrillar proteins secreted by fibroblasts; spongy & viscous part) and interstitial fluid (tissue fluid derived from blood).
  - - - Specialized supportive C.T. in which the extracellular matrix is calcified (hardest CT)
      - It forms the adult skeleton which protects vital organs and is important for body movement
      - Bone matrix consists of organic and inorganic components:
        
        Organic: type I collagen.
        
        Inorganic: calcium phosphate, bicarbonate, etc. (Main body’s reserve of calcium)
      - types of bone:
        
        Compact (cortical) bone
        
        80% 0f body bone
        
        Made of large number tube-shaped units called osteons (Haversian systems)
        
        Spongy (cancellous) bone
        
        Made of trabeculae (small beams of compact bone), space in between contains bone marrow
        
        Cancellous Bone
    - - Specialized form of supportive C.T. in which the extracellular matrix is firm and contains collagen
      - Firmest CT
        
        location
        
        ends of long bones
        
        larynx
        
        trachea
        
        bronchi
      - Cartilage cells are called chondrocytes
      - 3 types of cartilage identified by the types of fibers in the extracellular matrix:
        
        Hyaline (type II
        collagen); commonest (found in articular, costal surfaces, trachea)
        
        Elastic (elastic fibers, type II collagen), found
        in ear lobule, epiglottis.
        
        Fibrocartilage (type
        I collagen) – tough and slightly flexible. Found in intervertebral discs.
    - - a special type of C.T. in which the extracellular matrix is fluid (plasma)
      - The blood cells suspended in the plasma are:
        
        leukocytes (W.B.Cs) – defenses against infection
        
        containing granules (Granulocytes); are the neutrophils, eosinophils and basophils.
        
        leukocytes which do not have granules (Agranulocytes) are the lymphocytes and monocytes.
        
        platelets – promote coagulation (clotting)
        
        (thrombocytes) are non nucleated, disk like cell fragments of the (Megakaryocytes of the bone marrow).
        
        erythrocytes (R.B.Cs) – transport O2
        
        non nucleated biconcave disks
    - - Forms ligaments (binds bones together)
      - Outer protective covering of bones
      - Outer protective covering of organs (e.g. skin, brain, kidneys)
- - - - the structural and functional unit nerve cells responsible for reception, transmission and processing of stimuli and responses
      - Each neuron consists of a cell body containing :
        
        the nucleus (perikaryon)
        
        dendrites (cytoplasmic processes receiving stimuli)
        
        an axon (the cytoplasmic process which conduct impulses from the cell body)
      - Neurons can be:
        
        sensory (afferents) or motor (efferents)
        
        voluntary (somatic) or involuntary (autonomic)
      - Axons can be:
        
        myelinated (somatic) or unmyelinated (autonomic) for fast or slow rates of conduction, respectively.
    - - Neuroglia are classified into five types:
        
        1) Astrocytes: Blood Brain Barrier
        
        2) Oligodendrocytes: MYELIN in the CNS
        
        3) Microglia: Phagocytic cells (for Defense)
        
        4) Ependyma: Secrete cerebrospinal fluid (CSF)
        
        5) Schwan cells: MYELIN in PNS
- - - - location
        
        muscles attached to bones(skeleton)
      - characteristics
        
        voluntary (consciously)(بوعي)
        
        quick
        
        forceful (strong)
        
        have striations (stripes)
        
        so that it can elongate to provide long axis for contraction
        
        long, cylindrical, multinucleated cells
        
        the nuclei are peripheral
    - - location
        
        muscles of heart walls
      - characteristics
        
        striated and branched
        
        involuntary
        
        rhythmic contraction (بشكل متواصل)
        
        intercalated disks (junctional complexes)
        
        Contain 1–2 central large pale nuclei
    - - location
        
        muscles of walls of hollow organs (stomach, small intestine, uterus, blood vessels)
      - characteristics
        
        unstriated (no stripes)
        
        involuntary (not consciously)(من غير وعي يصير )
        
        slow
        
        Elongated
        
        usiform cells with single central nucleus (folded and tapers)