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Chapter 5 Tissues

5.1 Introduction

A. Tissues

Cells are arranged in tissues that provide specific functions for the body. The types of tissues are nervous, epethilial,connective & muscle Epethilial tissues form protective coverings and function in secretion and absorbtion. Connective Tissues support soft body parts and bind structures together. Muscle tissues produce body movements. Nervous tissues conduct impulses that help control and coordinate body activities.

B.Extracellular Matrix non-living portion in cells. Transmits signals from outside cells into cells, and these signals influence how cells function.

Types of Tissues Type Function Location Distinguishing Characteristics

Epithelial Protection, secretion, absorbtion,excretion Cover body sufaces,cover and line internal organs, compose glands . Lack blood vessels, readily divide; cells are tightly packed

Connective Bind, support,protect,fill spaces,store fat, produce blood cells Widely distributed throughout the body. Mostly have good blood supply; cells are farther apart than epithelial cells with extracellular matrix in between.

Muscle Movement Attached to bones, in the walls of hollow internal organs, heart Able to contract in response to specific stimuli

Nervous Transmit impulses for coordination, regulation,integration, and sensory reception Brain, spinal cord, nerves Cells connect to each other and to other body parts.

5.2 Epithelial Tissues A. General Characteristics Epithelial tissues is widespread throughout the body (inside/Out) Anchored to a basement membrane, made of tightly packed cells containing little intercellular material. a). Epithelial Tissues Lacks blood vessels Nutrients diffuse to epithelium from underlyin connective tissue. Readily divide, injuries heal rapidly. Tightly packed,with little cellular matrix in between. Form effective protective barriers in such structures as the outer layer of the skin and the lining of the mouth. b). Basement Membrane Thin non-living layer Part of the extracellular matrix

  c). Classifications

Epethilial tissues are classified according to shape and number of layers. 1Shape Epithelial tissues composed of thin, flattened cells are called squamous. Cube-shaped cells are called cuboidal Elongated cells are called columnar. 12. Layers Single layer of cells are simple. Consisting of two or more layers of cells are stratified. B. Simple Squamous Epithelium (thin) ---- Made up of a single layer of thin flattened cells Suited for diffusion, exchange of gases in the lungs and line blood and lymph vessels as well as body cavities. C. Simple Cuboidal Single layer of cube-shaped cells with centrally located nuclei Secretion and absorbtion in kidneys and in secretion in glands D.Simple Columnar Row of elongated cells whose nuclei are located near the basement of cells. Sometimes cilitated Uterus,stomach & intestines protect digestive fluids and absorbs nutrients E.Pseudostratisfied Columnar Appears to be stratified or layered but they are not. A layered effect occurs because the cell nuclei are at two or more levels in the row of aligned cells. Commonly have cilia passages the respiratory system F.Stratifified Squamous Relatively thick Cells divide in the deeper layers, and newer cells push older ones farther outward, wehre they become flattened. Forms the outer layer of the skin (epidermis) Lines the oral cavity, esophagus,vagina, and anal canal. G.Stratified Cuboidal Epithelium Two or three layers of cuboidal cells theat form the lining of a lumen. The layering of the cells provides more protection than the single layer affords. Lines the larger ducts of the mammary glands, sweat glands, salivary glands, pancreas, developing ovarian follicles and seminiferous tubules. H. Stratified Columnar The superficial cells are columnar basal layers consist of cuboidal cells Found in male urethra, vas deferens, and the pharynx. I.Transitional Epithelium Specialized to change in response to increased tension. Inner lining of the urinary bladder and lines the ureters and part of the urethra. When walls contract the tissue consists of several layers of cuboidal cells When the organ distends the tissue stretches and the physical relationships among the cells change. Forms a barrier that helps prevent the contents of the urinary tract from diffusing into the internal environment. J.Glandular Epithelium Composed of cells that are specialized to produce and secrete substances into ducts or into body fluids. Found within columnar and cuboidal epithelia. One or more of these cells constitute a gland. 1.Exocrine Glands that secrete their products into ducts that open onto sufaces, such as the skin or the

           lining of the digestive tract.

1.Endocrine Glands that secrete their products into tissue fluid or blood. 1.Merocrine Glands that release watery, protein-rich fluids by exocytosis. 1.Apocrine Glands that lose small portions of their glandular cell bodies during secretion. 1.Holocrine Those which the entire cell lyses during secretion. 5.3 Connective Tissues A.General Characteristics 1). Connective Tissues Bind structures, prvide support and protection, serve as fameworks, fill spaces, store fat, produce blood cells. Protect against infections, and help repair tissue damaging. Connective tissues are farther apart than epithelial cells Cells usually divide varying degrees of vascularity 2).Extracellular Matrix Connective tissue have abundance of extracellular matrix between them. This matrix consists of fibers and a ground substance whose consistency varies from fluid to semisolid to solid. B.Major Cell types a).Fixed cells Reside in the tissue for an extended period of time. Include fobroblasts and mast cells b). Wandering cells Move through and appear in tissues temporatily Respond to injury or infection Include macrophages 1).Fibroblasts Most common type of fixed cell in connective tissue Large, star-shaped cells Produce fibers by secreting proteins into the extracellular matrix of connective tissue. 2).Macrophanges Histiocytes Originate as white blood cells Specialized to carry on phagocytosis move and function as cavenger and defensive cells that clear foreign particles from tissues. 3).Mast Cells Large and widely distributed in connective tissues located near blood vessels Release heparin,which prevents blood clotting Histamine promotes some of the reactions associated with inflammation and allergies. C.Connective Tissue Fiber Fibroblasts produce three types of connective tissue fibers 1).Collagenous Fibers Thick threads of the protein collagen. Grouped in long, parallel bundles, and they are flexible but only slightly elastic. Holds structures together a).Ligaments connect bones to bones b).Tendons Connect muscles to bones c.)Dense connective tissue contains abundant collagenous fibers Tissue appears white,can be called white fibers. 2).Elastic Fibers a).Elastin-Thin fibers that branch, forming complex networks. Weaker than collagenous Stretch easier Common in body parts that are frequently stretched, such as vocal cords Sometimes calle Yellow fibers because they appear yellowish. 3).Reticular Fibers Thin collagenous fibers Highly branched and form delicate supporting networks in a varitety of tissues like the spleen. D.Categories of Connective Tissue Broken down into two categories Connective tissue proper and specialized connective tissues. a).Connective tissue Proper loose connective tissue,adipose tissue, and dense connective tissue. b).Specialized connective tissues Cartilage,bone, and blood. 1).Loose Connective Tissue Areolar tissue forms delicate,thin membranes throughout the body. Mainly fribroblast located some distance apart separated by a gel-like extracellular matrix containin many collagenous and elastic fibers. 2).Adipose Tissue Fat specialized form of loose connective tissue that develops when certain cells (Adipocytes) store fat in droplets within their cytoplasm and enlarge Lies beneath the skin,between muscles,around the kidneys, behind the eyeballs,certain abdominal membranes,surface of heart,and around certain joints. 3).Dense Connective Tissue Consists of many closely packed,thick,collagenous fibers and a fine network of elastic fibers. Poor blood sypply, slow tissue repair parts of tendons and ligaments binds muscle to bone and bone to bone. In the protective white layer of the eyeball and in the deeper skin layers. 4).Cartilage Rigid connective tissue provides support, frameworks, and attachments protects underlyin tissues forms structural models for developing bones Cartilage extracellular matrix is abundant and is largely composed of collagenous fibers embedded in a gel-like substance. a).Chondrocytes cartilage cells occupy small chambers called lacunae Lies completely in the extracellular matrix b). Perichondrium Carilaginous structure enclosed in covering of connective tissue Contains blood vessels that provide cartilage cells with nutrients by diffusion. 1).Hyaline Cartilage The most common type Has very fine collagenous fibers in its extracellular matrix, looks like white glass Found in the ends of bones in many joints,soft part of the nose, and supporting rings of the respiratory passages. 2).Elastic Cartilage Contains dense network of elastic fibers more flexible than hyaline Provides the framework for the external ears and parts of the larynx

                 3).Fibrocartilage

Very tough tissue Contains many collagenous fibers Shock absorber for structures that are subjected to pressure Form pads between bones of the spinal colum, knees and pelvic girdle. 5).Bone Most rigid connective tissue hardness due to mineral salts, such as calcium phosphate and calcium carbonate Contains abundant collagenous fibers, which are flexible and reinforce the mineral components of bone. Heals rapidly than injured cartilage a). Lamallae Bone matrix is deposited in thin layers Form concentric patterns around tiny longitudinal tubes called central canals. b).Central Canals Haversian canals c).Osteocytes Bone cells located in lacunae, evenly spaced between the lamellae d).Osteon Haversian system Made of clusters osteocytes and layers of extracellular matrix Cylinder-shaped unit e). Canaliculi Small tubes 6).Blood Transports a variety of materials between interior body cells and those that exchange substances with the external environment. Helps maintain stable internal environmental conditions. Composed of formed elements suspended in a fluid extracellular matrix called blood plasma. Formed elements include red blood cells, white blood cells, and cell fragmens called patelets.

5.4 Muscle Tissue A. General Characteristics 1).Muscle Tissues Able to contract in response to specific stimuli As they contract, muscle fibers pull at their attached ends, and this action moves body parts. B.Skeletal Muscle Tissue Found in muscles that attach to bones controlled by conscious effort Called voluntary muscle tissue Striations- Long, threadlike cells of skeletal muscle that have alternating light and dark cross-markings. Move the head, trunk, and limbs. Enable us to make facial expressions, write, talk, sing chew...etc. C.Smooth Muscle Tissue Its cells do not have striations. Shorter than skeletal muscle cells Spindle shaped, each with a single, centrally located nucleus. Compromises the walls of hollow internal organs (Stomach, intestine, urinary bladder) Cannot be stimulated to contract by conscious efforts. Called involuntary muscle tissue. D.Cardiac Muscle Tissue Only in the heart. Striated cells are branched and joined end to end resulting in complex networks. Single nucleus Controlled involuntarily Makes up the bulk of the heart and pumps blood through the heart chambers and blood vessels. 1).Intercalated disc Touches another cells, specialized intercellular junction.

5.5 Nervous Tissue a). Nervous Tissue Found in the brain, spinal cord, and peripheral nerves. b). Neurons Nerve cells Sense certain types of changes in their surroundings. Respond by transmittin impulses along cytoplasmic exxtentions. Coordinate, regulate and integrate many body functions. c).Neurological Cells Support and bind the components of nervous tissue, carry on phagocytosis, and help supply nutrients to neurons by connectino them to blood vessels.

5.6 Types of Membranes 1).Organ Two or more kinds of tissues grouped together and performing specialized functions. 2).Epithelial membranes Thin, sheetlike membranes composed of epithelium and connective tissue cover body surfaces and line body cavites A. Major types of membranes 1).Serous Membranes Line body cavities that lack openings to the outside. Form the inner linings of the thorax and abdomen cover the organs within these cavities. Consists of a layer of simple squamous epithelium and a thin layer of loose connective tissue. Secrete watery serous fluid, which lubricates membrane surfaces. 2).Mucous Membranes Line cavities and tubes that open to the outside of the body include the oral and nasal cavities Consists of epithelium overlying a layer of loose connective tissue Goblet cells secret mucus 3).Cutraneous Membrane Skin 4).Synovial Membrane Lines joints Composed entirely of connective tissues.