Connective Tissue - Karary University Biology Department PDF

Karary University College of Medicine Biology department Connective Tissue Dr. Hiba mohammed suiliman Connective Tissue Definition Connective tissue is a fibrous tissue, responsible for providing structural support for the organs of the body....

Karary University College of Medicine Biology department Connective Tissue Dr. Hiba mohammed suiliman Connective Tissue Definition Connective tissue is a fibrous tissue, responsible for providing structural support for the organs of the body. General characteristics of connective tissue: Connective tissue differs from other tissues in that it is a fibrous tissue , found throughout the body contains large amounts of extracellular matrix. - Extracellular matrix is nonliving material that surrounds living cells (embedded in the matrix). all connective tissue forms from (embryonic tissue derived from the mesoderm germ layer ). It is found everywhere and includes the most abundant and widely distributed tissue Responsible for providing structural support for the tissues and organs of the body. The tissue derives its name from its function in connecting or binding cells and tissues. Found in skin, membranes, muscles, bones, nerves and all internal organs The cells are not resting on a basement membrane. Connective tissue is highly vascular Supplied with nerves Exception is cartilage and tendon. Both have little or no blood supply and no nerves  Functions of Connective Tissue Protection of organs Enclose organs as a capsule and separate organs into layers. Areolar Connect tissues to one another. Tendons and ligaments. Support and movement. Bones. Storage of energy. Fat. Thermal Insulation. Fat. Transport. Blood. Protection. Bone, cells of the immune system. Metabolic functions Structural Elements of Connective Tissue ❖ 3 main components of connective tissue 1. Ground substance matrix 2. Fibers 3. Cells Matrix A non-living, extracellular matrix is material located between the cells and holds the cells of the connective tissue apart. Made up of three things: Ground substance: clear, semifluid gel Fibers: collagen, reticular, and/or elastic Tissue Fluid: clear and watery (not preserved in histological preparations) Cells of the matrix  Structural Elements of Connective Tissue 1. Ground substance (Extracellular Matrix) clear, semi-fluid gel that consists of polysaccharides and proteins. The thickness of the ground substance varies with the type of connective tissue. May be liquid, gel-like, or rock-hard  Structural Elements of Connective Tissue 2. Fibers (Extracellular Matrix) 3 different types of fibers that can be in the matrix: Collagen fibers (high strength): formed primarily of collagen type 1, add strength to the C.T. in tendons (join muscles to bone) and ligaments (join bones together). Elastic fibers (stretch and recoil): These are made up of randomly coiled proteins that can stretch without becoming deformed. (skin, walls of blood vessels, lungs) Reticular fibers (fine fibers, internal ‘skeleton’): formed of collagen type 111, very fine short collagen fibers that branch to form the supporting network for internal framework for soft organs like the spleen and liver. They are an important part of the basement membrane.  Structural Elements of Connective Tissue 3. Cells Primary cell types are: 1. Connective tissue proper fibroblast 2. Cartilage chondroblast 3. Bone osteoblast 4. Blood hemocytoblast (always actively mitotic). Each cell type exists in immature & mature forms These cells are actively mitotic when immature & less active when mature “—blast” = immature cell “—cyte” = mature cell  Chief function Cell type Embryonic source of all connective Mesenchyme tissue cells Structural support Fibroblasts Chondroblasts Osteoblasts Defense and immune Plasma cells Lymphocytes Neutrophils Eosinophils Basophils Mast cells Macrophages Metabolic Adipocytes Energy storage Thermal insulation  Types of connective tissues According to the component or structural characteristic of the tissue to: 1. Connective tissues proper 2. Connective tissues with special properties 3. Supporting Connective tissues 1. C.T. Proper: (gelatinous matrix). The two main categories of this connective tissue are: Loose Connective Tissue Dense Connective Tissue  I. Loose Connective Tissue (Areolar Tissue): ▪ Gel like ground with both Elastic & Collagen Fibers running though the ground in many directions ▪ Contains several types of cells and all three fibers ▪ This is the tissue that fills the spaces. ▪ is soft and flexible and serves as a kind of packing material between other tissues and organs Location: In the subcutaneous layer of the skin It is found between muscles, allowing one to move freely over the other Function: protection, bind the different muscles together… Connective Tissues Loose Connective Tissue Areolar Tissue  II. Dense connective tissue : ▪ Contains relatively few cells with much greater numbers of collagen fibers. ▪ Is divided into two sub-categories: a. dense regular connective tissue b. dense irregular connective tissue a. dense regular connective tissue: ▪ Bundles of collagen fibers are regularly arranged in parallel patterns for strength ▪ found where tension is exerted in a particular direction Location Tendons (muscle to bone) and ligaments (bone to bone) Function Provide attachment dense regular connective tissue Figure 4-9(c) dense regular connective tissue:  b. dense irregular connective tissue ▪ Collagen fibers are usually irregularly arranged. ▪ Forms “sheets” where tension is exerted in many directions Function Provides structural strength Location Dermis of skin dense irregular connective tissue  2. Connective tissues with special properties: I. Adipose Tissue: II. Elastic connective tissues III. Reticular connective tissues IV. Mucous connective tissue V. Vascular C.T  I. Adipose Tissue: ▪ Has very little collagen and elastic fibers ▪ Large cells filled with lipids adipose cells contain a (large vacuole which contains lipids). ▪ Cell nucleus and cytoplasm are pushed out to edge of cell membrane. ▪ highly vascular Location: ▪ Forms the subcutaneous tissues found below the skin , breast, around the kidney. Function: ▪ Energy store (accumulate or reserved the fat), Reduce heat loss, protect organs Connective Tissues Adipose Tissue Adipose Tissue  II. Elastic connective tissues ▪ Composed of mostly elastin fibers. ▪ Strong, yet elastic; allows for recoil of tissue after being stretched. Location: In walls of elastic arteries (aorta), lungs, vocal ligaments Function: Found where elasticity needed e.g. in blood vessel to accommodate any increasing in blood pressure… Elastic connective tissues III. Reticular connective tissues ▪ Branching reticular fibres. ▪ fibers forming a soft internal skeleton for other tissues. ▪ It is mostly found in lymphoid organs. ▪ Matrix of this tissue is like lymph. Location: lymph nodes, spleen, liver, bone marrow… Function: Provide support and strength and form the stroma (Frame work) of soft organs. – Spleen – Lymph nodes (Tonsils). – Cortex of ovary. Reticular connective tissues Reticular connective tissues IV. Mucous connective tissue ▪ Also called Embryonic Tissue because it is mainly found during embryonic life. ▪ Matrix is in abundance. Matrix is composed of jelly like material called Wharton's Jelly. ▪ Few collagen fibers & fibroblast cell may be present. Location In embryos: Umbilical cord (connect Placenta with fetus). Function: Supporting the blood vessels of the umbilical cord. Mucous connective tissue  V. Vascular C.T Distinctive collections of cells in a fluid matrix. This matrix is different from the other connective tissue matrix because it is not made by the cells suspended in it. Matrix = plasma consisting water, salts and dissolved proteins What would cause the plasma to change? Changes as gasses, nutrients, waste products, and hormones are added and removed. Plasma is produced by several organ systems consists of: Lymph: is formed as interstitial fluid is collected into lymphatic vessels to be brought back to the blood vessels. Blood: Blood cells float in a liquid matrix called plasma. Blood  VI. Vascular C.T Types of Blood cells which float in plasma. 1. erythrocytes = red blood cells 2. leucocytes = white blood cells ▪ granulocytes neutrophile: arrive at injury - phagocytotic Basophile: release histamine & heparin Eosinophile: destroy parasites - involved in allergies ▪ agranulocytes Monocytes: Destroy Bacteria & Viruses by phagocytosis that have left the circulation and release compliment proteins (inflame mediators) Lymphocytes : T cells & B cells - function in immunity 3. Platelets are not really cells but cell fragments that help blood clot  VI. Vascular C.T Location: blood system Function: Respiratory, nutritional, thermoregulation, excretory, defensive, transports of hormones and regulation of metabolism Blood 3. Supporting Connective tissues They are either cartilage or bone. Cartilage : 1-Hyaline cartilage. 2-Elastic cartilage. 3-fibro-cartilage. Bone: 1- Soft bones (Skull). 2- Compact bone (Femur).  1. Cartilage: ▪ Composed of cartilage cells or Chondrocytes ▪ Located in the matrix along with collagen, which the ground of matrix is gum like. ▪ Cells are found in Lacunae within the matrix. ▪ Fibers may be elastic or non-elastic, or reticular. It gives the matrix elasticity. ▪ cartilage has no blood vessels and the cells are entirely dependent on diffusion as the source of their nutrients and oxygen. Hyaline Cartilage - example on the ends of bones Fibro Cartilage - example nose cartilage. Elastic Cartilage - example ear cartilage I. Hyaline cartilage ▪ Most common/abundant cartilage ▪ It appear glassy ▪ Supports & Resists compressive stress Location: Nose , trachea, end of long bones, thoracic cage… Function: ▪ Protecting the bone against friction. ▪ keeping air pathway opened… ▪ Covers the ends of long bones as articular cartilage (helps to absorb compressive at joints). Connective Tissues Hyaline Cartilage Figure 4-10(a) Hyaline cartilage II. Fibrocartilage ▪ Highly compressible & resists tension. ▪ Has more fibrous tissue than does hyaline cartilage (Bundles of collagen) ▪ Found where hyaline cartilage meets a true ligament or tendon; where strong support & ability to tolerate heavy pressure are required Location: Found in Intervertebral disk (between vertebrae) and Figure 3.18c spongy cartilage of knees Function: support (strong and flexible), protect the bone against friction. lide 3.58b Fibro cartilage Fibro cartilage II. Fibrocartilage III. Elastic cartilage ▪ maintains shape of a structure while allowing great flexibility/elasticity ▪ Contains more elastin fibers than hyaline cartilage. ▪ Coiled fibers amongst bundles of collagen fibers. ▪ Can recoil to its original shape when bent ▪ Located primarily in areas were strength & exceptional stretch ability are needed Location: Ear pinna & epiglottis Example: supports the external ear & found in epiglottis Function: Maintains shape of structure and allows great flexibility Connective Tissues Elastic Cartilage Figure 4-10(b) Elastic Cartilage  3. Bone (osseous) ▪ Is hard connective tissue that consists of cells and a mineralized matrix. ▪ Osteoblasts secrete the matrix called lamellae. ▪ once osteoblasts are trapped in their secretion, they are called osteocytes ▪ Osteocytes are located in lacunae ▪ Used to protect and support & protect the body ▪ Provides cavities for fat storage & synthesis of blood cells ▪ unlike cartilage, bone is very well supplied by blood vessels ▪ compact bone consists of repeating unit called osteon or Haversian system. ▪ Unlike cartilage, bone contains small tubular canals through which the cells are nourished. ▪ Bone Composed of: a. Bone cells in lacunae (cavities) b/c of these 2, bone matrix is harder b. Hard matrix of calcium salts (bone salts) & more rigid than cartilage matrix c. Large numbers of collagen fibers ▪ Bone exists in two forms: ▪ compact and spongy. I. Compact bone: Location: Long bones (femur, shaft)… Function: Movement, protection, support, mineral storage… II. Soft bone (spongy bone): Location: Inside the compact bone… Function: Provides cavities for fat storage & synthesis of blood cells (Blood cell are produced). Supporting Connective Tissues: Bone Haversian System/Osteon Bone