Chapter 5 Tissue Organization I PDF

Chapter 5: Tissue Organization 1 5.0 What are the Tissues of the Body? Tissues Groups of cells with similar structure, function and extracellular material Study of tissues, histology Four types of tissues Epithelial, connective, muscle, nerv...

Chapter 5: Tissue Organization 1 5.0 What are the Tissues of the Body? Tissues Groups of cells with similar structure, function and extracellular material Study of tissues, histology Four types of tissues Epithelial, connective, muscle, nervous Varied structure and function Table 5.1 2 5.1a What is Epithelial Tissue (Epithelium)? Composed of one or more layers of closely packed cells Contains little to no extracellular matrix Covers body surfaces Lines body cavities Forms majority of glands Table 5.1 3  5.1a What are Characteristics of Epithelial Tissue? Cellularity Composed almost entirely of tightly packed cells Polarity Apical surface o Exposed to external environment or internal body space Lateral surface with intercellular junctions Basal surface o Epithelium attached to connective tissue Fig 5.1 4 5.1a What are Characteristics of Epithelial Tissue? Attachment to basement membrane Barrier between epithelium and connective tissue Avascularity Nutrients obtained across apical surface or from basal surface High regeneration capacity Fig 5.1 5 5.1b What are the functions of Epithelial Tissue? Physical protection Selective permeability Secretions Sensations Fig 5.1 6  5.1c How is Epithelial Tissue Classified? Body has different types of epithelia Epithelia classification indicated by two-part name ̶Number of epithelial cell layers ̶Shape of cells at apical surface Fig 5.2 7  How is Epithelial Tissue classified by number of cells? Simple epithelium One cell layer thick All cells in direct contact with basement membrane In areas where stress is minimal Filtration, absorption, or secretion is primary function E.g., lining of air sacs of lungs, intestines, blood vessels Fig 5.2 8  How is Epithelial Tissue classified by number of cells? Stratified epithelium Two or more layers of epithelial cells Only basal layer in contact with basement membrane In areas subjected to mechanical stress o Better able to resist wear and tear o E.g., skin, lining of the esophagus, lining of urinary bladder Cells in basal layer o Continuously regenerate as apical layer cells lost Fig 5.2 9 How is Epithelial Tissue classified by number of cells? Pseudostratified epithelium – Appears layered o Due to cells’ nuclei distribution at different levels – All cells attached to basement membrane – Some do not reach the apical surface – Simple epithelium APR 10  How is Epithelial Tissue classified by Cell Shape? Cell Shape at Apical Surface Squamous cells Flat, wide, irregular in shape Cuboidal cells About as tall as they are wide Columnar cells Slender and taller than they are wide Fig 5.2 11  How is Epithelial Tissue classified by Cell Shape? Transitional cells Change shape, depending on stretch of epithelium Located where epithelium stretches and relaxes o E.g., lining of the bladder Polyhedral when epithelium relaxed More flat when epithelium stretched APR 12 5.1c What are the roles of Simple vs Stratified Epithelial Tissue? Review of relationship between type and function Simple epithelia – Better designed for diffusion, absorption, and secretion o Thinner than stratified epithelium Stratified epithelia – Better suited for protective functions Fig 5.2 13  5.1d What are Glands? Individual cells or multicellular organs Epithelial tissue Secrete substances used elsewhere or for elimination Examples: Mucin, Electrolytes, Hormones, Enzymes, Urea Goblet Cells Fig 5.5 APR 14  5.1d What are two major types of Glands? Endocrine glands ( Covered in more detail in Bio 145) Lack ducts Secrete hormones into blood Chemical messengers that influence cell activity elsewhere Exocrine glands Connected with epithelial surface by duct E.g., sweat glands, mammary glands, salivary glands Goblet Cells APR Fig 5.5 15  5.1d How are Exocrine Glands Classified? Exocrine glands are classified by anatomic form or method of secretion Three Methods of secretion: Merocrine, Apocrine, Holocrine Fig 5.7 16  Chapter 5: Tissue Organization pt I BlackBoard Lecture pt I 17 Organization and Relationship of Epithelia Types Figure 5.3 18 5.1c What is Simple squamous epithelium? Single layer of flat cells Thinnest barrier Allows rapid movement of molecules across surface Lines air sacs of lungs (alveoli) Lines blood and lymph vessel walls (endothelium) Serous membrane of cavities (mesothelium) Table 5.2 19  Simple Squamous Epithelium Simple Squamo squamous us cell epithelium Loose Nucleus connectiv of e tissue squamo us cell APR  5.1c What is Simple cuboidal epithelium? Single layer Cells about as tall as they are wide Designed for absorption and secretion Ideal for structural components of glands o Surface of ovary o Walls of kidney tubules o Secretory regions/ducts of most glands Table 5.2 21  Simple Cuboidal Epithelium Simple cuboidal Cuboidal cell epithelium Lumen of Nucleus of cuboidal tubule cell APR 5.1c What is Simple columnar epithelium? Single layer of cells Cells taller than they are wide Ideal for secretory and absorptive functions Two forms: Nonciliated or Ciliated Table 5.2 23 5.1c What is Simple columnar epithelium? Nonciliated Contains microvilli o Fuzzy structure—brush border Unicellular glands—goblet cells o Secrete glycoprotein—mucin o Forms mucus when mixed with water Lines most of digestive tract from stomach to anal canal Table 5.2 24  Simple Columnar Epithelium (nonciliated) Simple columnar Goblet cell epithelium APR Simple columnar Lumen of jejenum Microvilli (brush Lamina propria 5.1c What is Simple columnar epithelium? Ciliated – Cilia project from apical surface o Move mucus along – Goblet cells interspersed – Lines o Bronchioles o Uterine tubes ˗ Helps move oocyte from ovary to uterus Table 5.2 26  Simple Columnar Epithelium (Ciliated) Simple columnar Basement epithelium membrane (ciliated) APR Simple columnar Lamina propria cell (ciliated) Lumen of uterine Cilia 5.1cWhat is Pseudostratifed columnar epithelium? – Appears as multiple cell layers – Not really stratified o All cells in direct contact with basement membrane o Nuclei scattered at different distances o Not all cells reach apical surface – Most common form is Ciliated* – Protective functions – Goblet cells secrete mucin – Located in large passageways of respiratory system 28 Table 5.2  Pseudostratified Columnar Epithelium Lumen of trachea Pseudostratified Nucleus of basal cell columnar epithelium Cilia Columnar epithelial cell (ciliated) Lamina propria APR  5.1c What is Stratified squamous epithelium? Multiple cell layers o Only deepest in direct contact with basement membrane Apical cells with squamous shape Protects against abrasion and friction Stem cells in basal layer continuously divide o Replace lost cells at surface Exists in keratinized and nonkeratinized forms Table 5.3 30  5.1c What is Stratified squamous epithelium? Keratinized Cells in basal region migrate toward apical surface Fill with keratin and die Found in epidermis Table 5.3 31  Stratified Squamous Epithelium (Keratinized) Epidermi Dermi s s (Stratified squamous epithelium) Stratum Stratum Stratum Stratum spinosum granulosum corneum basale APR  5.1c What is Stratified squamous epithelium? Nonkeratinized All cells alive Kept moist with secretions (e.g., saliva, mucus) Protects from abrasion Lines o Oral cavity, part of pharynx, esophagus, vagina, anus Table 5.3 33  Stratified Squamous Epithelium (Nonkeratinized) Stratified squamous epithelium (nonkeratinized) Lamina propria Squamous cell APR 34  5.1c What is Stratified cuboidal epithelium? Two or more layers of cells Superficial cells cuboidal in shape Forms tubes and coverings Protection and secretion Forms walls of ducts in most exocrine glands o Sweat glands, parts of male urethra, periphery of ovarian follicles Table 5.3 35  Stratified Cuboidal Epithelium Stratified cuboidal Cuboidal cell Lumen of parotid Venule duct APR  5.1c What is Stratified columnar epithelium? – Rare – Two or more layers of cells – Columnar cells at apical surface – Protects and secretes – Found in o Large ducts of salivary glands o Some segments of male urethra Table 5.3 37  5.1c What is Transitional epithelium? Limited to urinary tract In relaxed state o Apical cells large and rounded In stretched state o Apical cells flattened Allows for stretching as bladder fills Table 5.3 38  Transitional Epithelium Lumen of bladder Transitional epithelium Lamina propria APR Luminal cells Blood capillary  Transitional Epithelium Cross-section LM: High Magnification of ureter Mucosa of ureter Transitional epithelium of ureter APR 40 Chapter 5: Tissue Organization 41  5.2 What is Connective Tissue? Cells in a Extracellular Matrix (fibers and ground substance) Most diverse, abundant, and widely distributed of tissues Supports, protects, and binds organs Examples: Tendons, Adipose tissue, Cartilage, Bone, Blood Fig 5.8 42  5.2a What cells are in Connective Tissue? Resident Cells: Fibroblasts Produce fibers and ground substance of extracellular matrix Adipocytes (fat cells) Mesenchymal cells Stem cell that divides to replace damaged cells Fixed macrophages Phagocytize (engulf) damaged cells or pathogens Release chemicals that attract wandering leukocytes Wandering Leukocytes: Mast cells, Plasma cells, Free macrophages, Neutrophils, T-lymphocytes Fig 5.8 43 5.2a What Protein Fibers are in Connective Tissue? Collagen fibers Strong, flexible, and resistant to stretching Numerous in tendons and ligaments Reticular fibers Form branching, interwoven framework Abundant in stroma (CT framework) lymph nodes, spleen, liver Elastic fibers Stretch and recoil easily Help structures return to normal shape Fig 5.8 after stretching Found in skin, arteries, lungs 44  5.2aWhat is the Ground Substance of Connective Tissue? Noncellular material produced by CT cells Ground substance + protein fibers = extracellular matrix Glycosaminoglycans (GAGs) o Carbohydrate building blocks o Negatively charged and hydrophilic o Charge attracts cations and water o Types: Chondroitin sulfate, Heparin sulfate, Hyaluronic acid Proteoglycans o Formed with GAG linked to a protein o Perform numerous important functions Adherent glycoproteins o Proteins with carbohydrates attached o Bond CT cells and fibers to ground substance o Includes: fibronectin, fibrillin, laminin 45 5.2b What are the Functions of Connective Tissue? Physical protection Bones of skull and thoracic cage protect delicate organs Adipose tissue protects kidneys and eyes Support and structural framework Bones, body framework Place for muscle attachment Cartilage keeps trachea and bronchi open Supportive capsules around kidney and spleen Binding of structures Ligaments bind bone to bone Tendons bind muscle to bone Dense irregular tissue anchors skin to muscle and bone Fig 7.2 46  5.2b What are the Functions of Connective Tissue? Storage Adipose CT is the major energy reserve Bone, primary reservoir for calcium and phosphorus Transport Blood carries nutrients, gases, wastes between regions of body Immune protection Leukocytes protects body against disease 47  Chapter 5: Tissue Organization BlackBoard Lecture pt II 48 5.2d How is Connective Tissue Classified? Fig 5.9 49  5.2d What is Areolar Connective Tissue? Loose organization of collagen and elastic fibers Highly vasularized Contains all fixed and wandering cells of CT proper Ground substance is abundant and viscous Found in the papillary layer of dermis Major component of subcutaneous layer Surrounds organs, nerve and muscle cells, and blood vessels Table 5.5 50  Areolar Connective Tissue Collagen fibers Ground substance Elastic fibers Capillary Endothelial cell of capillary APR Mast cell with Nucleus of granules fibroblasts  5.2d What is Adipose Connective Tissue? Composed mostly of adipocytes Stores energy, acts as insulator, cushions Adipocyte number remains stable Weight gain/loss due to adipocytes enlarging or shrinking Table 5.5 52  Adipose Connective Tissue Adipocytes Lipid inclusions of adipocytes Nuclei of adipocytes Capillaries APR  5.2d What is Reticular Connective Tissue? Meshwork of reticular fibers, fibroblasts, leukocytes Structural framework of many lymphatic organs ˗ Spleen, Thymus, Lymph nodes, Bone marrow Table 5.5 54  Reticular Connective Tissue Reticular Ground fibers substance Leukocytes Macrophages APR  5.2d What is Dense Regular Connective Tissue? Tightly packed, parallel collagen fibers In tendons and ligaments Stress typically applied in a single direction Few blood vessels Takes a long time to heal Table 5.6 56  Dense Regular Connective Tissue Collagen fibers Ground substance Nuclei of fibroblasts APR  5.2d What is Dense Irregular Connective Tissue? Clumps of collagen fibers extend in all directions Provides support and resistance to stress in multiple directions Extensive blood supply Found in: ˗ Most of the skin dermis ˗ Periosteum of bone ˗ Perichondrium of cartilage Forms capsules around some internal organs Table 5.6 58  Dense Irregular Connective Tissue Collagen fibers Ground substance Nuclei of fibroblasts APR  5.2d What is Elastic Connective Tissue? Branching, densely packed elastic fibers Able to stretch and recoil Found in ˗ Walls of large arteries ˗ Trachea ˗ Vocal cords Table 5.6 60  Elastic Connective Tissue Lumen of Elastic elastic artery lamellae Nuclei of Endothelium fibroblasts of elastic artery Nuclei of Tunica intima Tunica media Internal elastic APR smooth of elastic of elastic lamella muscle cells artery artery  5.2d What is Cartilage? Type of Supporting CT Firm, semisolid extracellular matrix Collage and elastic protein fibers Chondrocytes occupy small spaces called lacunae Surrounded by a dense irregular CT covering o Perichondrium In areas of body that need support and must withstand deformation (e.g., tip of nose) Avascular in mature state Table 5.7 62  5.2d What is Hyaline cartilage? Most common type Clear, glassy appearance under microscope Located in o Nose, trachea, and larynx o Costal cartilage o Articular ends of long bones o Most of fetal skeleton Table 5.7 63  Hyaline Cartilage Chondrocytes Lacunae Extracellular matrix Nuclei of Perichondrium chondrocytes APR  5.2d What is Fibrocartilage cartilage? Weight-bearing cartilage, resists compression Protein fibers in irregular bundles between chondrocytes Located in o Intervertebral discs o Pubic symphysis o Menisci of knee joint Table 5.7 65  Fibrocartilage Chondrocytes Lacunae Collagen fibers Nuclei of Ground substance chondrocytes APR  5.2d What is Elastic cartilage? Flexible, springy cartilage Numerous densely packed elastic fibers o Ensure tissue is resilient and flexible Located in external ear and epiglottis Table 5.7 67  Elastic Cartilage Chondrocytes Elastic fibers Ground substance Lacunae Nuclei of chondrocytes APR Perichondrium 68  5.2d What is Bone? – Organic components (collagen and glycoproteins) – Inorganic components (calcium salts) – Bone cells—osteocytes o Housed within spaces called lacunae – Compact bone o Cylindrical structures—osteons – Spongy bone (Cover in Chpt. 7) Table 5.8 69  Osteon Interstitial Compact lamellae Bone Cement line Central Canal Osteocytes in lacuna APR 70  5.2d What is Blood? Fluid connective tissue with formed elements o Erythrocytes transport respiratory gases o Leukocytes protect against infectious agents o Cellular fragments, called platelets, help clot blood Liquid ground substance is called plasma o Dissolved proteins o Transports nutrients, wastes, hormones Table 5.9 71  Fluid Connective Tissue Blood Erythrocytes Platelets Neutrophils APR 72 5.2d What is Lymph? Derived from blood plasma No cellular components or fragments Ultimately returned to bloodstream 73 Chapter 5: Tissue Organization 74 5.3 What is Muscle Tissue? Cells contract when stimulated Contraction causes movement o Voluntary motion of body parts o Contraction of heart o Propulsion of material through digestive and urinary tracts 75  5.3 What is Skeletal Muscle Tissue? Moves skeleton Long cylindrical cells: Skeletal muscle fibers Arranged in parallel bundles that run length of entire muscle Multinucleated Alternating light and dark bands, striations Does not contract unless stimulated o Voluntary Table 5.10 76  5.3 What is Cardiac Muscle Tissue? Responsible for heart contraction to pump blood Striated Cells short and often bifurcating Cells connected by intercalated discs Strengthen connection between cells Promote rapid conduction of electrical activity Involuntary Cannot be controlled by voluntary nervous system Pacemaker cells initiate contraction Table 5.10 77  5.3 What is Smooth Muscle Tissue? Visceral or involuntary muscle tissue Lacks striations; appears smooth Cells shaped like elongated footballs Found in walls of hollow organs Helps propel movement through these organs No voluntary control over the muscle Table 5.10 78  5.4 What is Nervous Tissue? Located in the brain, spinal cord, and nerves Cells called neurons o Receive, transmit, and process nerve impulses Larger number of glial cells o Do not transmit nerve impulses o Instead, are responsible for protection, nourishment, and support of neurons Table 5.11 79 5.4 What are the parts of a Neuron? Cell body o Houses nucleus and other organelles Nerve cell processes extend from cell body Shorter and more numerous processes are called dendrites o Receive incoming signals and transmit information Axon is the single long process extending from the cell body o Carries outgoing signals to other cells Neurons are longest cells in the body Table 80 5.11  Nervous Tissue Neuron Nucleus of neuron Nucleolus of neuron Dendrites Nissl substance APR Axon Nuclei of glial  5.5a What is an Organ? Two or more tissue types Work together to perform specific complex functions Different structures must work in concert E.g., stomach, contains all four tissue types Fig 5.11 82 5.5b What are the Body Membranes? Mucous membrane Lines compartments that open to external environment Serous membrane Lines body cavities that do not open to external environment Cutaneous membrane Skin Covers external surface of body Synovial membrane Lines some joints in body Fig 5.12 83 5.6a How do Mature Tissues Develop? In an embryo Three primary germ layers Ectoderm Forms outer layer of skin Mesoderm Forms all muscle tissue Endoderm Becomes innermost germ layer Forms Epithelial linings of digestive, respiratory, reproductive, and Fig 5.13 urinary tract 84