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A&P I, Chap. 5
Tissue organizatoin
Question | Answer |
---|---|
Four types of tissues | Epithelial, muscle, connective, nervous |
Smooth muscle | a.k.a. visceral muscle, involuntary |
Epithelial tissue | Covers body surfaces, lines body cavities, forms majority of glands |
Epithelium | Composed of one or more layers of closely packed cells, contains little or no extracellular matrix, contains no blood vessels (avascular), remains mitotic |
Three surfaces of epithelial tissue | Apical (top), lateral (middle), basal (bottom) |
Epithelium contains | Apical and lateral surfaces |
Basement membrane contains | Basal surface |
Epithelial tissue functions | Physical protection, selective permeability, secretions, sensations |
Simple epithelium | One layer thick, areas of minimal stress, filtration, absorption or secretion primary function, lining of air sacs of lungs, intestines, blood vessels |
Stratified epithelium | Two or more layers, found in areas of mechanical stress such as skin, lining of the pharynx, esophagus, cells in basal layer constantly regenerate as apical layer cells are lost |
Pseudostratified epithelium | Type of simple epithelium, attached to basement membrane, appear layered |
Squamous cells | Flat, wide, irregular shape, arranged like flattened floor tiles, nucleus flattened |
Cuboidal cells | Slender and taller than they are wide, nucleus spherical and in center of cell |
Columnar cells | Slender and taller than they are wide, nucleus oval |
Transitional cells | Change shape depending on stretch of epithelium, occur where epithelium stretches and relaxes (bladder lining), polyhedral in shape when epithelium relaxed, more flattened when epithelium is stretched |
Simple squamous epithelium | Thinnest possible barrier, single layer of flattened cells, spherical or oval nucleus, allows rapid movement of molecules across surface |
Endothelium | Simple squamous epithelial tissue that lines blood and lymph vessels |
Mesothelium | Simple squamous epithelial tissue that forms the serous membrane of cavities |
Simple cuboidal epithelium | Contains uniformed shaped cells, ideal for small ducts and glands, absorbs fluids, secretion, walls of kidney tubules, forms secretory regions of glands, forms smaller ducts of exocrine glands, covers surface of ovaries, thyroid gland. |
Simple columnar epithelium | Single layer of columnar cells, ideal for secretion and absorption, can be either ciliated or nonciliated |
Non-ciliated simple columnar epithelium | Often contains microvilli, goblet cells (secretes mucin - forms mucus when mixed with water), lines majority of digestive tract from stomach to anus |
Ciliated simple columnar epithelium | Cilia projecting from apical surface, moves mucus, goblet cells interspersed, found in bronchioles, lines uterine tubes, helps move oocyte from ovary to uterus |
Pseudostratified columnar epithelium | Appears to consist of multiple cell layers, not really stratified (nuclei scattered at different distances, not all cells reach apical membrane), can be either ciliated or nonciliated |
Ciliated pseudostratified columnar epithelium | Houses goblet cells, mucus moved by cilia, found in large passageways of the respiratory system |
Nonciliated pseudostratified columnar epithelium | Lacks goblet cells and cilia, occurs mainly in male urethra and epididymis |
Stratified squamous epithelium | Protects against abrasion and friction, has multiple cell layers (direct contact with basement membrane), constantly replacing lost cells, nonkeratinized and keratinized forms |
Nonkeratinized stratified squamous epithelium | Kept moist with secretions (saliva, mucus), lack keratin and protective protein, found in oral cavity, pharynx, esophagus, vagina and anus |
Keratinized stratified squamous epithelium | Superficial layers of dead cells, lack nuclei, filled with keratin, found in epidermis, fill with keratin and die |
Stratified cuboidal epithelium | Two or more layers of cells, superficial cells cuboidal in shape, protective function, forms walls of ducts of most exocrine glands, ex: ducts of sweat glands, strengthens walls of gland ducts, strengthens some sections of male urethra |
Stratified columnar epithelium | Two or more layers of cells, protects and secretes, found in large ducts of salivary glands, membranous segment of male urethra, relatively rare |
Transitional epithelium | Limited to the urinary tract, in relaxed state (apical cells are large and rounded), in stretched state (apical cells are flat), contained binucleated cells, allows for stretching as bladder fills |
Simple epithelia | Better designed for diffusion, absorption and secretion functions (thinner than stratified epithelium) |
Stratified epithelia | Better suited for protective functions |
Glands | Individual cells or multicellular organs, made up of mostly epithelial tissue, secrete substances or for elimination, may secrete: mucin, electrolytes, hormones, enzymes, urea |
Endocrine glands | Lack ducts, secrete hormone products into interstitial fluid and blood |
Exocrine glands | Formed from invaginated epithelium in connective tissue, connected with epithelial surface by duct (epithelium-lined tube for gland secretion), includes sweat glands, mammary glands, salivary glands |
Unicellular exocrine glands | Typically do not contain a duct, located close to epithelium surface, most common type is the goblet cell |
Multicellular exocrine glands | Contain acini (cell clusters produce secretions), contain ducts transporting secretions to epithelial surface, surrounded by fibrous capsule, partitioned into lobes (extensions of the capsule) |
Simple gland | Single, unbranched duct |
Compound glands | With branched ducts |
Tubular glands | Secretory portion and duct of uniform diameter |
Acinar glands | Secretory portion forming an expanded sac |
Tubuloacinar gland | Has both tubules and acini |
Merocrine gland | Package secretions into vesicles, released by exocytosis, types of glands include: tear, salivary, some sweat, exocrine gland of pancreas, gastric gland of stomach |
Apocrine gland | Pinching off of apical membrane around portion of cytoplasm, contains secretory product, damage repaired by glandular cells, release secretions by exocytosis, types include: mammary and some types of sweat glands in axillary and pubic regions |
Holocrine gland | Accumulation of a product in a cell, followed by cell disintegration, viscous mixture of cell fragments and cell product, ruptured cell replaced, types include: oil producing glands in skin |
Connective tissue | Most diverse, abundant, widely distributed tissue |
Functions of connective tissue | Support, protect and bind organs |
Examples of connective tissue | Tendons, ligaments, body fat, cartilage, bone and blood |
Resident cells | Stationary cells permanently housed within connective tissue, ex: fibroblasts, adipocytes, mesenchymal, fixed macrophases |
Fibroblasts | Most abundant resident cells in connective tissue, produce fibers and ground substance of extracellular matrix, flat cells with tapered ends |
Adipocytes | a.k.a. fat cells, appear in small clusters with some types of connective tissue, if found in a large area - referred to as adipose connective tissue |
Mesenchymal | Type of embryonic stem cell, divide to replace damaged cells, divided cell becomes committed connective tissue cell |
Fixed macrophage | Relatively large, irregular shaped cells, derived from monocytes, type of blood cell, dispersed throughout the matrix, phagocytose damaged cells or pathogens |
Wandering cells | Continuously move through connective tissue, component of immune system, helps repair damaged extracellular matrix, primary type of leukocyte (wbc) |
Types of wandering cells | Mast cells, plasma cells, free macrophages, leukocytes |
Mast cells | Small, mobile cells close to blood vessels, secrete heparin to inhibit blood clotting, secrete histamine to dilate blood vessels |
Plasma cells | Formed when B-lymphocytes activated by foreign material, produce antibodies, proteins that immobilize foreign material |
Free macrophages | Mobile phagocytic cells, function like fixed macrophages |
Leukocytes | Include neutrophils (phagocytize bacteria), include lymphocytes (attack and kill foreign materials) |
Protein fibers | Strengthen and support tissue |
Types of protein fibers | Collagen, reticular and elastic |
Collagen fibers | Unbranched, cable like fibers, strong, flexible and resistant to stretching, appear white in fresh tissue, numerous in tendons and ligaments |
Reticular fibers | Similar to collage fibers but thinner, form branching/interwoven framework, tough but flexible, abundant in connective tissue framework) of: lymph nodes, spleen, liver |
Elastic fibers | Contain protein elastin, branching wavy fibers, stretch and recoil easily, yellow in color when fresh, help structures return to normal shape after stretching, found in skin, lungs and arteries |
Extracellular matrix | Ground substance + protein fibers = |
Scurvy | Collagen is an important protein, Vit. C is needed for healthy collagen fibers, caused by Vit. C deficiency |
Symptoms of scurvy | Weakness, gum ulceration, hemorrhages, abnormal bone growth |
Treatment of scurvy | Consuming foods high in Vit. C or taking supplements |
Functions of connective tissue | Protection, support and structural framework, binding structures, storage, transport, immune protection |
Protection | Bones of skull and thoracic cage protecting delicate organs, adipose tissue protecting kidneys and posterior eyes |
Support/structural framework | Bones as framework, cartilage keeping trachea and bronchi open, supportive tissues around kidney and spleen |
Binding of structures | Ligaments binding bone to bone, tendons bind muscle to bone, dense irregular tissue anchoring skin to muscle and bone |
Storage | of adipose tissue, the major energy reserve, bone is primary reserve for calcium and phosphorus |
Transport | Blood carries nutrients, gases and wastes |
Immune protection | Leukocytes protecting body against disease, extracellular matrix restricting movement of infectious organisms |
Mesenchyme | First type of connective tissue in developing embryo, star shaped, dispersed in ground substance with immature protein fibers, source of all other connective tissue, adult connective tissue with mesenchymal stem cells (provide support and repair) |
Mucous connective tissue | Second type of embryonic connective tissue, more numerous immature protein fibers than in mesenchyme, found in umbilical cord only |
Marfan Syndrome | Genetic disease of connective tissue, causes skeletal, cardiovascular and visual abnormalities, usually death before age of 50 due to cardiovascular problems |
Signs of Marfan Syndrome | Abnormally long limbs, fingers and toes. Malformation of the thoracic cage and vertebral column. Easily dislocated joints, resulting from weak ligaments, tendons and joint capsules. Weakness in the aorta and abnormal heart valves. Slipped lens in eyes |
Mesenchyme separates into..... | connective tissue, supporting connective and fluid connective tissue |
Connective tissue (two categories) | Loose connective, dense connective tissue |
Loose connective tissue | Contains relatively fewer cells and protein fibers, abundant ground substance, acts as body's "packing material" by supporting structures |
Loose connective tissue (three types) | Areolar, adipose, reticular |
Areolar connective tissue (pt. 1) | Loose organization of collagen and elastic fibers, abundant distribution of blood vessels, contains all fixed and wandering cells of connective tissue proper... |
Areolar connective tissue (pt. 2) | Found in the papillary layer of the dermis, major component of subcutaneous layer, surrounds organs, nerve and muscle cells and blood vessels |
Adipose connective tissue | a.k.a. fat, composed primarily of adipocytes, stores energy, acts as an insulator, serves as packing and cushion around structures, located in subcutaneous layer, surrounds various organs |
Reticular connective tissue | Contains meshwork of reticular fibers, fibroblasts and leukocytes. Forms the structural framework of many lymphatic organs, ex: spleen, thymus, lymph nodes, bone marrow |
Dense connective tissue | Composed of primarily protein fibers. Has proportionately less ground substance than loose connective tissue. Collagen fibers usually the dominant fiber type. |
Dense connective tissue (three categories) | Dense regular connective tissue, dense irregular connective and elastic connective |
Dense regular connective tissue | Contains tightly packed parallel collagen fibers. Resemble stacked lasagna noodles. Found in tendons and ligaments - stress typically applied in one direction. Few blood cells, long time to heal. |
Dense irregular connective tissue | Contains clumps of collagen fibers in all directions. Provides support and resistance to stress in multiple directions. Has extensive blood supply. |
Dense irregular connective tissue (found in) | Most of the skin dermis, periosteum of bone, perichondrium of cartilage, capsules around some internal organs - ex: liver |
Elastic connective tissue | Branching, densely packed elastic fibers. Has more fibroblasts than loose connective tissue. Able to stretch and recoil. |
Elastic connective tissue (found in) | Walls of large arteries, trachea, vocal cords, suspensory ligament of the penis |
Supportive connective tissue (cartilage pt. 1) | Has a firm, semisolid extracellular matrix. Contains collagen and elastic protein fibers. Mature cells termed chondrocytes (occupy small spaces termed lacunae) |
Supportive connective tissue (cartilage pt. 2) | Surrounded by a dense irregular connective covering - perichondrium, has an outer fibrous layer and inner cellular layer. Stronger and more resilient than previously discussed types. Provides more flexibility than bone. |
Supportive connective tissue (cartilage pt. 3) | Occurs in areas of body that need support and must withstand deformation. Avascular in mature state. |
Supportive connective tissue (types) | Hyaline cartilage, fibrocartilage, elastic cartilage |
Hyaline cartilage characteristics | Most common type of cartilage. Clear, glassy appearance under microscope. Chondrocytes irregularly scattered. Surrounded by perichondrium. |
Fibrocartilage characteristics | Weight-bearing cartilage which resists compression. Protein fibers in irregular bundles between chondrocytes (contribute to durability). Sparse amount of ground substance. No perichondrium. |
Fibrocartilage - found in | Intervertebral discs, pubic symphysis, menisci of knee joint. |
Hyaline cartilage - found in | Found in: nose, trachea, larynx, costal cartilage, articular ends of long bones, most of fetal skeleton. |
Elastic cartilage characteristics | Flexible, springy cartilage. Numerous densely packed elastic fibers (ensure tissue is resilient and flexible). Resists deformational pressure. Chondrocytes closely packed. Surrounded by a perichondrium. |
Elastic cartilage - found in | External and epiglottis |
Bone characteristics | More solid than cartilage. Provides greater support, but less flexible. Contains organic components (collagen and glycoproteins). Contains inorganic components (calcium salts). Called osteocytes. Covered by periosteum. |
Bone - found in | Housed within spaces in the extracellular matrix, lacunae. |
Compact bone characeristics | Perforated by neurovascular canals. Formed from cylindrical structures (osteons). Display concentric rings or bone connective tissue, lamellae. Encircle central canal housing blood vessels and nerves. |
Spongy bone characteristics | Located in terior of bone. Latticework structure, strong and lightweight. |
Bone functions | Provides levers for movements. Supports tissues and protect vital organs. Stores minerals (calcium, phosphorus). Houses hemopoietic cells which make blood cells. |
Fluid connective tissue | Blood and lymph |
Blood characteristics | Composed of cells and cellular fragments, platelets (for clotting). Cells include erythrocytes (transport O2). Include leukocytes (immune response). |
Blood functions | Ground substance termed plasma, containing dissolved proteins (transports nutrients, wastes, hormones) |
Lymph characteristics | Other type of fluid connective tissue. Derived from blood plasma. Ultimately returned to bloodstream. |
Muscle tissue | Cells that can contract with nervous system stimulation. |
Muscle tissue functions | Voluntary motion of body parts. Contraction of the heart. Propulsion of material through digestive and urinary tracts. |
Muscle tissue - three types | Skeletal, cardiac, smooth |
Skeletal muscle tissue characteristics (pt. 1) | Also known as striated or voluntary muscle. Primarily responsible for movement of the skeleton. Composed of long cylindrical cells (skeletal muscle fibers). |
Skeletal muscle tissue characteristics (pt. 2) | Multinucleated. Alternative light and dark bands (striations). Does not contract unless stimulated by somatic nervous system (considered voluntary). |
Cardiac muscle tissue (pt. 1) | Confined to middle layer of heart wall, myocardium. Responsible for heart contraction. Contains visible striations. Cells short and often bifurcating. Contains one or two nuclei. |
Cardiac muscle tissue (pt. 2) | Cells connected by intercalated discs - strengthen attachments between cells - promote rapid conduction of electrical activity. Does not require nervous system to initiate a contraction. |
Smooth muscle tissue (pt. 1) | Lacks striations seen in other tissues. Appears smooth. Cells thick in the middle and tapered at the ends. Cells short with one central oval nucleus. |
Smooth muscle tissue (pt. 2) | Also called visceral muscle tissue - found in walls of intestines, stomach, airways, bladder, uterus, blood vessels. Helps propel movement through these organs. Involuntary. |
Nervous tissue characteristics | Consists of cells called neurons - receive, transmit and process nerve impulses. Contains larger number of glial cells - do not transmit nerve impulses - protection, nourishment, support. |
Parts of neuron - cell body | Houses the nucleus and organelles |
Parts of neuron - nerve cell process | Extending from cell body |
Parts of neuron - Dendrites | Shorter and more numerous process - receive incoming signals and transmit information. |
Parts of neuron - axon | Single long process extending from cell body - carries outgoing signals to other cells. |
Organs characteristics | Structures composed of two or more tissue types. Work together to perform specific complex functions. Ex: The stomach contains all four tissue types. |
Stomach tissues - epithelium | Lining of stomach. Secretes substances for chemical digestion of nutrients. |
Stomach tissues - areolar | Also dense connective tissue in walls. Houses blood vessels and nerves and provides shape and support. |
Stomach tissues - smooth | Three layers in wall. Contract and relax to mix materials. |
Stomach tissues - nervous | In abundance. Responsible for regulating muscle contraction and gland secretion. |
Body membranes characteristics | Formed from epithelial tissue bound to underlying connective tissue. Lines body cavities. Covers viscera and body's external surface. |
Body membranes - four types | Mucous, serous, cutaneous, synovial |
Mucous membrane characteristics | Formed from epithelium and underlying connective tissue - connective tissue component termed lamina propria, often covered with a layer of mucus. |
Mucous membrane functions | Perform absorptive, protective and secretory functions. |
Mucous membrane location | Lines compartments that open to the external environment. Also found in digestive, respiratory, urinary and reproductive tracts. |
Serous membrane characteristics | Membrane composed of a simple squamous epithelium - termed mesothelium |
Serous membrane location | Lines body cavities that do not open to external environment. |
Serous membrane functions | Produce thin, watery serous fluid - derived from blood plasma, reduces friction between opposing surfaces. |
Cutaneous membrane characteristics | Composed of keratinized stratified squamous epithelium, underlying connective tissue. |
Cutaneous membrane location | a.k.a. skin, covers the external surface of the body |
Cutaneous membrane function | Protects internal organs and prevents water loss |
Synovial membrane characteristics | Composed of areolar connective tissue. Covered by squamous epithelial cells lacking basement membrane. Found in some joints. |
Synovial fluid | Secreted by epithelial cells. Reduces friction among moving bone parts. Distributes nutrients to cartilage. |
Hypertrophy | Increase in size of existing cells of a tissue |
Hyperplasia | Increase in number of cells of a tissue. |
Neoplasia | Tissue growth proceeding out of control. Development of tumor of abnormal tissue. |
Atrophy (pt. 1) | Shrinkage of tissue by decrease in cell number or size. May result from normal aging. May result from failure to use organ or tissue. |
Atrophy (pt. 2) | Bedridden individual - affected muscles with disuse atrophy, skeletal muscle fibers becoming smaller, can usually be reversed by physical therapy |
Necrosis | Tissue death. Due to irreversible tissue damage. Inflammatory response to tissue damage. ex: gangrene |