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Connective tissues connects the epithelial tissues to the rest of the body other types if connecti

Functions
1. protection for delicate organs
2. fluid & dissolved minerals transportation
3. structure for body
4. support, surround, interconnect tissues
5. defence against invasion of microorganisms
6. store energy reserves (via triglycerides)
THREE components
1. fluid known as ground substance
  1. extracellular fibres and ground substance make up matrix (surrounds cells — makes up bulk of connective tissue) occur throughout body, but is never exposed to outside environment they are vascular (have many blood vessels) have sensory pain, temp, pressure receptors
  2. fills spaces between cells and surrounds connective tissue fibres in connective tissue proper — ground substance is clear, colourless, discuss due to proteoglycans and glycoproteins viscous bc bacteria have trouble moving about — makes them slower so phagocytes can catch them
2. extracellular protein fibers
3. specialized calls
Classification of connective tissues
1. Connective tissue proper — tissues with many type of cells and extracellular fibers in a syrupy ground substance
  1. loose connective (ADIPOSE/FAT) — more ground substance, less fibres
    1. Areolar tissue — least specialized connective tissue in adults contain all cells and fibers of any connective tissue proper in loosely organized fashion — can distort w/o damage open framework viscous ground substance provides most of volume and absorbs shocks return to original state after stretching separates skin from deeper structure capillaries in tissue deliver OXYGEN and NUTRIENTS and remove carbon dioxide and waste epithelium cover areola tissue and fibrocytes maintain the layer of basement membrane that separates the two kind of tissues epithelium tissue require oxygen from the underlying connective tissue
    2. Adipose (fat) tissue — adipocytes (fat cells) are most volume of adipose tissue — extract blood glucose after meals provides: padding, absorbs shocks, insulates (slows heat lost from skin) common under skin of flanks (b/w last rib and hips), butts and breasts fills eye sockets and surrounds kidneys common under mesothelial lining of pericardial and peritoneal cavities adipocytes cannot divide in adults, their #s first established in newborns expand to store fat — shrink as fats are released Loose connective tissue have mesenchymal cells that will divide and allow for regeneration of adipose tissue and when more storage is needed white fat — most of adipose tissue — white, yellowish colour brown fat (common in kids, dissipates overtime)— highly vascularized and adipocytes have mitochondria — deep, rich colour adipocytes are metabolically active cells — their lipids are being broken down and their fatty acids support metabolism — used as energy animals with brown fat can oxidize an
    3. 3. Reticular Tissue — reticular fibers form a complex 3D stroma spleen and liver made of this tissue stroma supports functional cells, or parenchyma, of these organs fibrous framework found in lymph nodes and bone marrow fixed macrophages, fibroblasts, fibrocytes are associated with reticular fibres
  2. dense connective (TENDONS) — more fibers, less ground substance
    1. Dense regular connective tissue collagen fibers parallel to one another, packed tightly, aline with the forces applied to tissue tendons — cords of dense regular connective tissue that attach skeletal muscles to bones —collagen fibers run longitudinally along the tendon and transfer the pull of the contacting muscle to the bone ligaments — resemble tendons, but connect one bone to another OR stabilize the position of internal organs aponeurosis — tendinous sheet that attaches a broad, flat muscle to another muscle OR to several bones of skeleton can stabilize the positions of tendons and ligaments associate with large muscles of skull, lower back, abs, and w/ the palms of the hands and soles of feet fibroblasts are scattered among collagen fibres of tendons, ligaments, aponeuroses
      1. Elastic tissue — dense regular connective tissue made up of mainly elastic fibres elastic ligaments dominated by elastic fibers — help stabilize positions of vertebrae of spinal column
    2. Dense irregular connective tisse form an interwoven meshwork in no pattern strengthen and support areas subjected to stresses from many directions layer of dense irregular connective tissue gives skin its strength at joint, it forms sheath around cartilages and bones also forms thick, fibrous layer called capsule — surrounds internal organs — liver, spleen, kidneys, enclosing cavities of joints dense regular and irregular have variable amounts of elastic fibers more elastic fibers compared to collagen fibers means that the tissue is more springy, resilient that allows it to withstand extension and recoil connective tissue with a lot of elastic fibers that supports transitional epithelia are present in — walls of large blood vessels like — aorta, around respiratory passageways
  3. have a lot of cell types, extracellular fibers and a viscous ground substance come cells function in local maintenance, repair and energy storage fibroblasts, fibrocytes, adipocytes, mesenchymal cells are permanent residents of connective tissue macrophages, mast cells, lymphocytes, plasma cells, microphages are mobile (migrate/ travel) cells that defend and repair damaged tissues
  4. Cell Populations
    1. Fibroblasts (most abundant, permanent) — always present in connective tissue proper secrete hyaluronan (help lock epithelial tissues together) contribute to the making of ground substance viscosity secrete proteins that seems extracellular fibers
    2. Fibrocytes — second most abundant, permanent spindle-shaped cells that maintain connective tissue proper
    3. Adipocytes — aka FAT cells that vary in number depending on tissue type has a single, big lipid droplet nucleus, organelles, cytoplasm squeezed to one side
    4. Melanocytes — synthesizes and stores melanin common in epithelium of skin where they determine skin colour abundant in connective tissue of eye and dermis of skin
    5. Lymphocytes — migrate t/o body via connective tissue & others increase when there is tissue damage can develop into plasma cells, producing antibodies that deadened against disease
    6. Mesenchymal cells — stem cells that are present in many tissues respond to injury/ infection by dividing to produce daughter cells that form into fibroblasts, macrophages, etc
    7. Macrophages — large phagocytic cells throughout matrix (not abundant) engulf damaged cells/ pathogens that enter tissue release chemicals that activate immune system large macrophages either — fixed macrophages (spend a long time in tissues) OR free macrophages (migrate fast)
    8. Mast cells — small, mobile, common near blood vessels have Histamine (released after injury, stimulates inflammatory effects) and Heparin (anticogulant that enhances blood flow during inflammation and reduces blood clots)
    9. Microphages — phagocytic blood cell that moves through connective tissue in small #s attracted to sites of infection or injury by chemicals
2. Supporting connective tissue has less diverse cell pop. matrix has denser packed fibres protect soft tissues and support weight of most of the body types — cartilage (has gel matrix) AND bone (matrix is calcified bc of mineral deposits)
3. Fluid connective tissue — distinct pop. of cells suspend in watery matrix that has dissolved proteins Types — blood AND lymph
Connective Tissue Fibers
1. Collagen fibers (extremely strong) — most common fibers in connective tissue long, straight, unbranched, flexible has a bundle of fibrous protein tendons (connect bone to muscles)— made of mostly collagen fibres ligaments (connect bone to bone) — made of collagen fibres
2. Elastic fibers have protein elastin branched, wavy, return to original form after stretching elastic ligaments (RARE)— dominated by elastic fibers, interconnect vertebrae
3. Reticular fibers have same protein subunits like collagen, but ARRANGED DIFFERENTLY thin, branching, interwoven flexible, tough framework, stroma stroma stabilizes positions of functional cells OR parenchyma of organs AND blood vessels, nerves resist any applied forces
Embryonic Connective Tissue
1. Mesenchyme — embryonic connective tissue — first to appear in developing embryo has star-shaped stem cells separate by matrix with fine proteins filaments gives rise to other connective tissues
2. Mucous connective tissue (Wharton’s jelly) — loose connective tissue found in many parts of embryo, including umbilical cord
fasciae
1. provides internal structure of body layers of connective tissue surround and support organs in trunk cavities and connect them to rest of body
2. Function
  1. provide strength and stability
  2. maintain the realties pistons of internal organs
  3. supply a route for distribution of blood vessels, lymphatic vessels, nerves
3. Tyoes
  1. deep fascia — interwoven dense irregular connective tissue — makes it strong each layer if fibres run in same direction, but orientation of fibres change in from layer to layer — arrangement helps tissue resist forces coming from many directions bound to capsules, tendons and ligaments, and perichondrium around cartilages, periosteum around bones, connective tissue of muscle
  2. superficial fasciae (aka hypodermis / subcutaneous) — layer of areolar tissue and fat separates the skin the underlying tissues and organs provides insulation and padding, and lets skin and underlying structures move independently
  3. subserous fascia layer of areola tissue that lies b/w deep fascia and serous membranes that line body cavities movements of muscles/ muscular organs do not severely distort the delicate body cavity linings

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Connective tissues connects the epithelial tissues to the rest of the body other types if connecti

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	Created by Jeannene Rumball about 9 years ago