Chapter 4- Tissue - The Living Fabric PDF

Chapter 4 Tissue- The Living Fabric © 2015 Pearson Education, Inc.  Histology Branch of anatomy dealing with the microscopic structure of tissues. All cells in the human body can be classified in four different tissues:...

Chapter 4 Tissue- The Living Fabric © 2015 Pearson Education, Inc.  Histology Branch of anatomy dealing with the microscopic structure of tissues. All cells in the human body can be classified in four different tissues: Epithelial Connective Muscle Nervous © 2015 Pearson Education, Inc.  Epithelial Tissue Epithelial tissue, or an epithelium, is a sheet of cells that either Covers a body surface, or Lines a body cavity Two forms of epithelial tissue can be found in the body: Covering and lining epithelium, which forms the outer layer of skin; lines open cavities of the body, such as urogenital, digestive, etc.; and covers the walls and organs of the closed ventral body cavity, such as the pericardial mesothelium. Glandular epithelium, which fashions the glands of the body. © 2015 Pearson Education, Inc.  4-2 Epithelial Tissue Characteristics of Epithelia Cellularity. High density of cells joined together via cell junctions. Normally arranged in sheets (lining and covering epithelia) with very little extracellular space in between the epithelial cells). Polarity (apical and basal surfaces) Attachment to basement membrane Avascularity. They do not have own blood supply. They depend on diffusion from the capillaries in the underlying connective tissue for food and oxygen. Innervated Regeneration via mitosis 4-2 Epithelial Tissue Functions of Epithelial Tissue 1. Provide Physical Protection 2. Control Permeability 3. Provide Sensation 4. Absorption and secretion 5. Produce Specialized Secretions (glandular epithelium) 4-2 Epithelial Tissue 4-2 Epithelial Tissue Maintaining the Integrity of Epithelia 1. Intercellular connections 2. Attachment to the basement membrane 3. Epithelial maintenance and repair  4-2 Epithelial Tissue Intercellular Connections Cell junctions Form bonds with other cells or extracellular material 1. Tight junctions 2. Gap junctions 3. Desmosomes 4. Adherens junctions 5. Hemidesmosomes  4-2 Epithelial Tissue Tight Junctions Fused plasma membrane of adjacent cells Seal off passageways between adjacent cells Prevents passage of water and solutes Common in epithelial tissues of the stomach, intestines, and urinary bladder 4-2 Adherens Junctions Dense layer of proteins called plaque Hold epithelial cells together Located inside of the plasma membrane. Transmembrane proteins act as a “velcro”. Anchors cells to each other In epithelial cells, adhesion belts encircle the cell 4-2 Desmosomes (anchoring junctions) Button-like complex that contains plaque and cadherins that extends into the intercellular space to attach adjacent cells together Prevent epidermal cells from separating under tension and cardiac muscles cells from pulling apart during contraction Gap Junctions Channel proteins (connexons) that Allow rapid communication between cells by allowing ions and small molecules to pass from one epithelial cell to the other Coordinate contractions in heart muscle Hemidesmosomes Resemble half of a desmosome Do not link adjacent cells but anchor cells to the basement membrane Contains transmembrane glycoprotein integrin Copyright 2009, John Wiley & Sons, Inc.  Basement membrane Acellular tissue found between the basal layer of cells of an epithelium and the underlying connective tissue. Two layers: Basal lamina More superficial and in direct contact with the basal layer of cells of the epithelium It is synthesized and secreted by the epithelial cells It consists mostly of collagen fibers and ground substance Reticular lamina More deep and in direct contact with the connective tissue It consists mostly of reticular fibers and ground substance Functions: attachment of the epithelium to the underlying connective tissue; filtration and regulation of passage of substances between both tissues © 2015 Pearson Education, Inc. 4-2 Epithelial Tissue Two main classes Lining or Covering Epithelia Layers of cells covering internal or external surfaces Glands Structures that produce secretions 4-3 Classification of Lining and Covering Epithelia  COVERING OR LINING EPITHELIUM Simple Epithelia: single layer of cells. All cells contact the basement membrane Name of Epithelium Description Location Function Simple Squamous Single layer of flat cells; Lines heart and blood Filtration, diffusion, Epithelium flat, centrally located vessels (endothelium); osmosis, and secretion nucleus. forms epithelial layers of in serous membranes. serum membranes such as peritoneum, pleural, and pericardial (mesothelium). Simple Cuboidal Single layer of cube-like Covers surface of ovary; Secretion and Epithelium cells; round, centrally lines kidney tubules; absorption. located nucleus. makes up secreting portion of some glands (e.g., thyroid gland). Non-Ciliated Simple Single layer of non- Lines gastrointestinal Secretion and Columnar Epithelium ciliated cells with oval tract (from stomach to absorption. nucleus near the base of anus). cells. It contains: 1) microvilli(a) in apical surface of cells and 2) goblet cells(b). (a) Fingerlike cytoplasmic projections. Increases surface area of plasma membrane. (b) Modified columnar epithelial cells that secrete mucus, a slightly sticky fluid, at the apical surfaces. © 2015 Pearson Education, Inc.  COVERING OR LINING EPITHELIUM Simple Epithelia: single layer of cells. All cells contact the basement membrane Name of Epithelium Description Location Function Ciliated Simple Columnar Single layer of ciliated cells Lines some bronchioles; Cilia beat in unison, moving Epithelium with oval nucleus near the lines uterine (fallopian) mucus and foreign particles base of cells. It contains tubes; lines central canal towards throat, where they some goblet cells. spinal cord and ventricles of can be coughed up and brain. swallowed or spit out. Cilia help move oocytes expelled from ovaries through uterine tubes into uterus. Pseudostratified ciliated Appears to have different Lines airways of most upper Cilia beat in unison, moving Columnar Epithelium layers because cell nuclei respiratory tract. mucus and foreign particles are at various levels. All towards throat, where they cells are attached to can be coughed up and basement membrane in a swallowed or spit out. single layer. This epithelium has cilia and goblet cells. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc.  COVERING OR LINING EPITHELIUM Stratified Epithelia: Two or more layers of cells. Only cells in the basal layer contact the basement membrane. Name of Epithelium Description Location Function Non-keratinized Cells in apical layer are Wet surfaces: lining of Protection against Stratified Squamous squamous; cells in deeper mouth, esophagus, part of abrasion, water loss, UV Epithelium layers vary from cuboidal epiglottis, parts of pharynx, radiation, and first line of to columnar. and vagina) and covers defense against microbes. It does not contain large tongue. amounts of keratin. It is constantly moistened by mucous from saliva and mucous glands. keratinized Stratified Cells in apical layer are Epidermis of the skin. Protection against Squamous Epithelium squamous; cells in deeper abrasion, water loss, UV layers vary from cuboidal radiation, and first line of to columnar. This defense against microbes. epithelium develops tough layers of keratin(*) in apical layer of cells and several layers deep to it. Apical layers of cells are dead. (*) Keratin is a tough, fibrous, and insoluble in water intracellular protein that helps protect skin and underlying tissues from heat, chemicals, radiation, and dehydration. © 2015 Pearson Education, Inc.  COVERING OR LINING EPITHELIUM Stratified Epithelia: Two or more layers of cells. Only cells in the basal layer contact the basement membrane. Name of Epithelium Description Location Function Stratified Cuboidal Cells in apical layer are Ducts of sweat glands; part Protection; limited secretion Epithelium cube-shaped. of male urethra. and absorption. Stratified Columnar Apical layer has columnar Lines part of urethra. Protection and secretion. Epithelium shaped cells. Transitional epithelium Variable appearance Lines urinary bladder. Allows urinary organs to depending whether the organ stretch and maintain is relaxed (unstretched) or protective lining while holding stretched (full). variable amounts of urine without rupturing. Note: stratified cuboidal epithelium and stratified columnar epithelium will not be included in the exam © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc.  Form fits function! What is the probable function of an epithelial surface whose cells have microvilli? Cilla? Your skin is lined with a stratified squamous epithelium. Why do you think it is stratified? Why not simple? Your capillaries (the blood vessels responsible for exchange of gases and nutrients) are made of a simple squamous epithelium. Why do you think they are simple? Why not stratified? Glandular Epithelium GLANDULAR EPITHELIUM Name of Epithelium Description Location Function Endocrine Glands Secretions called hormones Pituitary gland, pineal gland, Hormones regulate many are released and enter thyroid and parathyroid gland, metabolic and physiological interstitial fluid and diffuse pancreas, adrenal glands, etc. activities to maintain directly into bloodstream homeostasis, E.g., insulin and without flowing through a glucose. duct. Exocrine Glands Secretory products are Sweat, oil, and earwax glands Produce substances such as released into ducts that empty of skin; digestive glands such sweat to help lower body onto the surface of a lining or as salivary glands (secrete temperature, oil, earwax, or covering epithelium, such as into mouth cavity) and digestive enzymes. skin surface or lumen of pancreas (secrete into small hollow organs (E.g., small intestine). intestine). Note: Goblet cells are the only unicellular exocrine glands in the human body  Glandular Epithelium © 2015 Pearson Education, Inc. Functional Classification of Exocrine Glands Product released by exocytosis. The most watery secretion. E.g., sudoriferous (sweat) glands, lacrimal glands, exocrine pancreas. Thicker secretion (it has more lipids). E.g., mammary glands ceruminous glands. Thickest and most viscous secretion. E.g., sebaceous glands.  Exocrine Glands © 2015 Pearson Education, Inc. Connective Tissue Connective Tissue connects Functions of Connective Tissue Establishing a structural framework for the body Transporting fluids and dissolved materials Protecting delicate organs Supporting, surrounding, and interconnecting other types of tissue Storing energy reserves, especially in the form of triglycerides Defending the body from invading microorganisms Connective Tissue Classification of Connective Tissues 1. Connective tissue proper Connect and protect 2. Fluid connective tissues Transport 3. Supporting connective tissues Structural strength  Connective Tissue Characteristics of Connective Tissue (CT) 1. Specialized cells. Differently from the CT epithelial cells, cell of the CT are not - Cells and connected by cell junctions - Matrix(fibers 2. Cells are embedded in an extracellular and ground matrix (which make up the majority of the substance) volume of the tissue). The matrix is produced and secreted by cells of the CT. 3. The matrix is composed by fibers (proteins) and ground substance 4. Highly vascular (except cartilage and tendons) 5. Innervated 6. Different degree of renovation (tissue dependent)  Connective Tissue © 2015 Pearson Education, Inc.  Cells of Connective Tissue Proper Fibroblasts The most abundant cell type. Found in all connective tissue proper. Produces and secretes the matrix of the ECM (extracellular matrix). Adipocytes Fat cells Each cell stores a single, large fat droplet. Nucleus and other organelles are usually squashed to the perimeter of the cell. Mast cells Largest cell found in CTs. Cells of the immune system that has granules in the cytoplasm, which contain inflammatory mediators (E.g., histamine, heparin). When stimulated after injury or infection, they release the content of the granules via exocytosis and inflammation starts.  Cells of Connective Tissue Proper Macrophages Large, amoeba-like cells of the immune system. Ingest and destroy pathogens and damaged cells Fixed or resident macrophages stay in tissue Free or migrant macrophages migrate Other immune cells Lymphocytes, neutrophils, eosinophils, etc. They migrate in and out of different CTs depending on the needs of the body.  4-4 Connective Tissue: The Matrix The matrix of the CT is composed by protein In the CT, the word fibers and ground substance! The matrix can fiber refers to any of be fluid (e.g. blood), gelatinous (e.g. cartilage), fibrous (e.g. tendons), solid (e.g. the three types of bone) proteins present in the Connective Tissue Fibers matrix! 1. Collagen fibers Also called white fibers Most common fibers in connective tissue proper Thick, long, straight, and unbranched Strong and flexible Great tensile strength. Resist force in one direction For example, tendons and ligaments 2. Reticular fibers Network of interwoven fibers Strong and flexible Resist force in many directions Stabilize functional cells and structures For example, sheaths around organs 3. Elastic fibers Also called yellow fibers Contain elastin Branched and wavy Return to original length after stretching For example, elastic ligaments of vertebrae  4-4 Connective Tissue: The Matrix Ground Substance An amorphous, clear, colorless, and viscous substance of the ECM containing water, very large proteins and polysaccharides Fibers embedded make it less pliable Functions: Fills spaces between cells Holds large amounts of fluids and function as a molecular sieve through which nutrients and other substances can diffuse between the blood capillaries and the cells slows pathogen movement  Classification Three Main Types of Connective Tissue Connective Tissue Proper: Loose CT Dense CT Supporting CT: Bone Cartilage Fluid CT: Blood Lymph © 2015 Pearson Education, Inc.  Connective Tissue- Classification: CT Proper 1. Connective Tissue Proper  Widely distributed in the body  Connects tissues and organs to one another and forms part of the internal architecture of some organs Types of CT Proper Loose connective tissue More ground substance, fewer fibers Relatively higher proportion of cells to matrix For example, fat (adipose tissue) Dense connective tissue More fibers, less ground substance Relatively less proportion of cells to matrix For example, tendons  Connective Tissue Proper: Loose CT Loose Connective Tissues The “packing materials” of the body Three types in adults 1. Areolar 2. Adipose 3. Reticular  Connective Tissue Proper: Loose CT Areolar Tissue Least specialized Elastic fibers Open framework Fibroblasts, adipocytes, cells of immune system Collagen Large amount of viscous fibers ground substance Fibroblast All three types of protein fibers Free Holds blood vessels and macrophage capillary beds For example, under skin (subcutaneous layer) Wall of hollow organs and Connective tissue proper LM  502 blood vessels  Connective Tissue Proper: Loose CT Adipose Tissue White fat Most common Fat-storing adipocytes with one large lipid inclusion in their cytosol, Adipocytes fibroblasts, and ECM (white adipose containing collagen fibers cells) Functions: energy storage, insulation, shock absorption, and protection LM  300 Found deep to skin (subcutaneous fat). It Adipose tissue also surrounds visceral organs Brown fat More vascularized Adipose Tissue Adipocytes (with multiple lipid inclusions in the cytosol) LOCATIONS: Deep to the skin, have many mitochondria especially at sides, buttocks, breasts; padding around eyes Functions: same as white fat plus when and kidneys stimulated by nervous system, fat breakdown accelerates, releasing energy FUNCTIONS: Provides padding and cushions to generate heat in cold temperatures shocks; insulates (reduces heat loss); Prevalent in infants and young children stores energy (neck and back) Absorbs energy from surrounding tissues  Connective Tissue Proper: Loose CT Reticular Tissue Provides support and framework Complex, three-dimensional network formed mainly by reticular fibers produced and secreted by fibroblasts (often called reticular cells) It supports small structures such as blood and lymphatic vessels Reticular fibers Provides a supporting framework for Reticular organs, which hold a huge LM  375 number of cells Reticular Tissue Spleen, liver, lymph nodes, and bone marrow Connective Tissue Proper: Dense CT Dense Connective Tissues Connective tissues proper, tightly packed with high numbers of collagen or elastic fibers. Three types: Dense regular connective tissue Dense irregular connective tissue Elastic tissue  Connective Tissue Proper: Dense CT Dense Regular (collagenous) Connective Tissue Tightly packed, thick parallel collagen fibers (forming bundles) Very strong, but they resist tension is only one plane. Thus, found in structures subjected to tension in one direction only Functions: provides firm attachment, conducts pull of muscles, stabilizes relative positions of bones Tendons attach muscles to bones Ligaments connect bone to bone and stabilize organs Collagen fibers Fibroblast nuclei Tendon LM  440  Connective Tissue: Dense CT Dense Irregular Connective Tissue Interwoven thick bundles of collagen fibers (predominant fiber). This organization makes the tissue quite strong and allows it to resist tension in all three palnes Deep dermis (deep to epidermis in skin) Around cartilages (perichondrium) Around bones (periosteum) Form capsules around some organs (e.g., liver, kidneys) Dense Irregular Connective Tissue LOCATIONS: Capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis FUNCTIONS: Provides strength to resist forces Collagen applied from many fiber directions; helps bundles prevent overexpansion of organs such as the urinary bladder  Connective Tissue Proper: Dense CT Elastic Tissue Made of parallel elastic fibers (predominant fiber). Fibroblasts in the tissue are responsible for producing and secreting the fibers Function: allows recoil of tissues after stretching (E.g., lungs); maintains pulsatile flow of blood through arteries; stabilizes position of vertebra For example, elastic ligaments of spinal vertebrae; wall of elastic arteries (aorta, pulmonary trunk); tissue of the lungs Elastic tissue in the wall of the aorta)  Connective Tissue: Fluid CT 2. Fluid Connective Tissues Blood The ECM is fluid and it is called plasma. RBC Gases, enzymes, nutrients, hormones, sugars, proteins, etc. are dissolved in plasma. It does not contain protein fibers as other CTs do. Formed elements: Erythrocytes (RBCs) bind and transport oxygen through the body Leukocytes (WBCs), which function in immunity Thrombocytes (platelets), which play a role in the blood clotting WBC Platelet process Note: Lymph is another type of fluid CT 4-5 Supporting Connective Tissues 3. Supporting Connective Tissue Support Soft Tissues and Body Weight Cartilage Gel-type ground substance For shock absorption and protection Bone Calcified (made rigid by calcium salts, minerals) For weight support, protection, mineral storage  Supporting Connective Tissues: Cartilage Cartilage is avascular! Cartilage Structure Cartilage Matrix Firm gel that contains polysaccharides derivatives called chondroitin sulfates Ground substance has collagen, elastic, and reticular fibers. Chondrocytes (cartilage cells) surrounded by lacunae (chambers) Only cells in the cartilage matrix. Chondrocytes produce antiangiogenesis factor Perichondrium It surrounds the cartilage and sets it apart from surrounding tissues Outer, fibrous layer (for strength) made out of dense irregular connective tissue. Inner, cellular layer (for growth and maintenance). Cells: chondroblasts. sets it apart from surrounding tissues  Supporting Connective Tissues: Cartilage © 2015 Pearson Education, Inc.  Hyaline Cartilage Elastic Cartilage Fibrocartilage Characteristics It is the most common type of Extremely flexible and Strongest of the three. Durable cartilage in the body. resilient because its and tough because its matrix Surrounded by perichondrium matrix contains contains densely interwoven (except inside joint cavities). numerous elastic fibers. thick collagen fibers. Tough but somewhat flexible. Matrix composed mainly of closely packed thin bundles of collagen fibers. Location In adults: connections Auricle of external ear; Pads between knee joints between the ribs and epiglottis. (meniscus); between pubic sternum; the nasal cartilages bones of pelvis; intervertebral and the supporting discs. passageways of the respiratory tract (e.g., in trachea); and the articular cartilages of synovial (movable joints) such as knee and elbow. In fetus: blueprint of future bones is made of this cartilage. In growing humans: epiphyseal plate of long bones. Functions -Provides stiff but somewhat Provides support, but Resists compression and flexible support. tolerates distortion pressure; prevents bone to -Reduces friction between without damage and bone contact; limits bony surfaces. returns to original movement. © 2015 Pearson Education, Inc. shape.  Hyaline Cartilage © 2015 Pearson Education, Inc.  Elastic Cartilage © 2015 Pearson Education, Inc.  Fibrocartilage © 2015 Pearson Education, Inc. Supporting Connective Tissues: Bone Osseous Tissue (bone tissue) Not covered in chapter 4…we have a whole chapter later on Bone! Muscle Tissue Property Skeletal Cardiac Smooth Morphology Cells are long, Called cardiocytes. Fusiform (spindle shape) cylindrical. Usually Shorter than skeletal and small. called muscle fibers. muscle cells. Cells are usually branched. Cardiac myocytes are joined end to end by junctions called intercalated discs (desmosomes and gap junctions). Number of nuclei Multinucleated. One nucleus; One nucleus; centrally Nuclei are peripheral centrally located. It is located. (near PM). not unusual to find cells with two nuclei. Striations Yes Yes No (sarcomeres) Actin and Myosin Yes Yes Yes Level of Control Voluntary Involuntary- Involuntary Regulated by pacemaker cells. Neural Input Somatic Autonomic Autonomic 4-8 Muscle Tissue Property Skeletal Cardiac Smooth Source of Calcium Sarcoplasmic Sarcoplasmic Sarcoplasmic reticulum and reticulum (Smooth reticulum and Extra- Extra-cellular Fluid Endoplasmic cellular Fluid (ECF) Reticulum) Gap Junctions No Yes Division through No No Yes Mitosis Location Associated with bones. Heart. Usually found as sheets of tissue in walls of blood vessels and viscera such as the digestive, respiratory, and urinary tract. Also in uterus; associated with hair follicles (arrector pili muscle); involuntary sphincter of urethra and anus; in the iris of the eye. Functions -Move or stabilizes the Pumping of blood. Swallowing, contraction of position of the stomach and intestines; skeleton. expulsion of feces and urine; -Guards entrances and labor contractions; control of exits from the blood pressure and flow; digestive, respiratory, control of respiratory airflow; and urinary systems. control of pupillary diameter; -Generates heat erection of hairs. (thermogenesis). -Protects internal organs.  Muscle Tissue © 2015 Pearson Education, Inc. Neural Tissue Neural Tissue Also called nervous or nerve tissue Specialized for conducting electrical impulses Rapidly senses internal or external environment Processes information and controls responses Neural tissue is concentrated in the central nervous system Brain Spinal cord Neural Tissue Two Types of Neural Cells 1. Neurons Nerve cells Perform electrical communication (action potential) 2. Neuroglia Supporting cells Repair and supply nutrients to neurons Neural Tissue Cell Parts of a Neuron Cell body Contains the nucleus and nucleolus Dendrites Short branches extending from the cell body Receive incoming signals Axon (nerve fiber) Long, thin extension of the cell body Carries outgoing electrical signals to their destination Dendrites (contacted by Axon (conducts other neurons) information to other cells) Microfibrils and microtubules Mitochondrion Nucleolus Nucleus Contact with other cells Cell body (contains nucleus and major organelles) A representative neuron (sizes and shapes vary widely)  Tissue Injuries and Repair © 2015 Pearson Education, Inc. Inflammation- non-specific defense response; protective response to injury; mediated by the CT and involves the circulatory system Function- to contain and destroy harmful invader/ injured tissue and promote healing. Produces specific signs & symptoms Heat- reaction to increased blood flow Redness (erythema)- reaction to increased blood flow Swelling (edema)- reaction to increased permeability PAIN is a prime symptom- injury to neurons or toxic chemical released by microbes (infection)  Not all tissues have the same healing capacity! © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Body Membranes Membranes Physical barriers Line or cover portions of the body Consist of epithelial and connective tissue Four Types of Membranes 1.Mucous membranes 2.Serous membranes 3.Cutaneous membrane 4.Synovial membranes Body Membranes 1. Mucous Membranes (Mucosae) Line passageways that have external connections In digestive, respiratory, Mucous secretion urinary, and reproductive Epithelium tracts Epithelial surfaces must be Lamina propria moist (areolar tissue) Mucous membranes are coated with the To reduce friction secretions of mucous glands. These membranes line the digestive, respiratory, To facilitate absorption urinary, and reproductive tracts. and excretion Lamina propria Is areolar tissue Body Membranes 2. Serous Membranes Line cavities not open to the outside Are thin but strong Have fluid transudate to reduce friction Have a parietal portion covering the cavity Have a visceral portion (serosa) covering the organs  Body Membranes Three Serous Membranes (called mesothelium) Transudate I. Pleura Mesothelium Lines pleural cavities Areolar tissue Covers lungs Serous membranes line the ventral body cavities (the peritoneal, pleural, and II. Peritoneum pericardial cavities). Lines peritoneal cavity Covers abdominal organs III. Pericardium Lines pericardial cavity Covers heart  Body Membranes Epithelium 3. Cutaneous Membrane Is skin, surface of the body Areolar tissue Dense irregular Simple squamous connective tissue keratinized epithelium The cutaneous membrane, or skin, covers the outer surface of the body. (epidermis)+dermis Thick, waterproof, and dry 4. Synovial Membranes Articular (hyaline) tissue Line moving, articulating Synovial fluid Capsule joint cavities Capillary Adipocytes Produce synovial fluid Areolar (lubricant) tissue Epithelium Synovial membrane Protect the ends of bones Bone Lack a true epithelium Synovial membranes line joint cavities and produce the fluid within the joint.