Tissue Outline Chapter 4 The Tissue Level of Organization I. Definitions II. Cellular Connections III. Tissue Types IV. Membranes V. Tissue Repair 1 2 Tissue Cellular Connections Tissue Groups of cells that are similar in structure and perform a common or related function Special connections that hold cells together 1. Tight junctions 2. Desmosomes Hemidesmosomes 3. Gap junctions (nexus) 3 4 1
Tissue Tissue Groups of cells that are similar in structure and perform a common or related function Four main tissue types of the body 1. epithelial covering 2. connective support, transport, storage 3. muscular movement 4. nervous control 6 I. Function II. General features III. Specializations IV. Classification A. Simple/stratified squamous epithelum B. Simple/stratified cuboidal epithelium C. Simple/stratified columnar epithelium D. Pseudostratified columnar epithelium E. Transitional epithelium F. Glandular epithelium 1. Types 2. Modes of excretion Epithelia A sheet of cells that covers a surface or lines a body cavity Function Physical protection Control permeability Provide sensation Produce special secretions 7 8 2
General Features Cellularity: closely packed cells with little extracellular material Polarity: have apical and basal surfaces Attachment: basal surface attached to basal lamina (basement membrane) Basal lamina: thin extracellular layer of connective tissue Avascular: without blood vessels Regeneration: rapid cell division Specializations 9 10 Classification Arrangement of cells into layers Simple: one cell layer thick Stratified: many cell layers thick Pseudostratified: single layer of cells where all cells don t reach apical surface nuclei at found at different levels so it looks multilayered Shape of surface cells Squamous: flat Cuboidal: cube-shaped Columnar: tall column Transitional: shape varies with tissue stretching 11 Simple Squamous Epithelium Endothelium: lines heart and blood vessels Mesothelium: lines thoracic and abdominopelvic cavities and covers the organs within them 12 3
Stratified Squamous Epithelium Keratin: a waterproof protein that is resistant to friction and helps repel bacteria Keratinized: surface cells dead and filled with keratin Nonkeratinized: no keratin in moist living cells at surface Simple Cuboidal Epithelium Secretion: the production and release of a fluid that may contain a variety of substances 13 14 Stratified Cuboidal Epithelium Rare Simple Columnar 15 16 4
Stratified Columnar Epithelium Pseudostratified Epithelium 17 18 Transitional Epithelium Glandular Epithelium 19 Gland: a single cell or mass of epithelial cells adapted for secretion Exocrine glands: secrete their products into ducts Ducts: passageways that open onto an epithelial surface Endocrine glands: release their secretions into interstitial fluid ductless hormones 20 5
Modes of Secretion Merocrine -- most glands cells release their products by exocytosis mucus Apocrine upper part of cell pinches off & dies Holocrine whole cells die & rupture to release their products 21 Connective Tissue I. Basic elements A. Cells B. Extracellular matrix 1. Ground substance 2. Fibers II. Embryonic connective tissue III. Mature connective tissue A. See next slide for outline IV. Connective Tissue Framework A. Fascia 1. Superficial fascia 2. Deep fascia 3. Subserous fascia 23 Connective Tissue Framework Layers of connective tissue Provide strength and stability Maintain position of internal organs Provide routes for distribution of vessels and nerves Fascia: connective tissue layers that support and surround organs Superficial fascia (subcutaneous, hypodermis) Areolar tissue and adipose tissue Deep fascia Dense irregular tissue Subserous fascia Areolar tissue 24 6
Overview Connective Tissue Consists of three basic elements: 1. cells 2. ground substance 3. fibers extracellular matrix = ground substance and fibers 26 Connective Tissue Cell Types Immature cells: retain ability to divide & produce matrix fibroblast connective tissue proper chondroblast cartilage osteoblast bone hematopoietic stem cell blood Mature cells: cannot divide or produce matrix chondrocytes & osteocytes Macrophages: develop from monocytes and are phagocytic Plasma cells: develop into antibody producing B lymphocytes Mast cells: produce histamine, heparin, and proteases Adipocytes: store fat Ground Substance Connective Tissue Unstructured material that fills space between the cells and contains the fibers Substances found in the ground substance interstitial fluid cell adhesion proteins: connective tissue glue proteoglycans: hyaluronic acid, chondroitin sulfate, dermatan sulfate, and keratan sulfate Supports, binds, provides medium for the exchange of materials between the blood and cells, and is active in influencing cell functions White blood cells: neutrophils, eosinophils, lymphocytes 27 28 7
Connective Tissue Fibers Fibers in the matrix provide strength and support for tissues 3 types of fibers are are embedded in the matrix between cells and connective tissues collagen fibers elastic fibers reticular fibers Connective Tissue Fibers Collagen fibers composed of the protein collagen tough and resistant to stretching, yet allow some flexibility found in bone, cartilage, tendons, and ligaments Elastic fibers composed of the protein elastin provide strength and stretching capability found in skin, blood vessels, and lungs Reticular fibers consisting of collagen and glycoprotein thin, branched fibers that form framework of organs 29 30 Marfan Syndrome Connective Tissue Extracellular Matrix Ground substance and fibers Abundant with relatively few cells May be fluid, semifluid, gelatinous, fibrous, or calcified Usually secreted by the connective tissue cells and adjacent cells Determines the tissue s qualities 31 32 8
Connective Tissue Embyronic Connective Tissue Present primarily in the embryo or fetus Mesenchyme found almost exclusively in the embryo of fetus the tissue from which all other connective tissues may eventually arise Mucous connective tissue found in the umbilical cord of fetus gives support 34 Mature Connective Tissue I. Connective Tissue Proper A. Loose connective tissue 1. Areolar connective tissue 2. Adipose tissue 3. Reticular connective tissue B. Dense connective tissue 1. Dense regular connective tissue 2. Dense irregular connective tissue 3. Elastic connective tissue II. Fluid connective tissue A. Blood B. Lymph III. Supporting connective tissue A. Cartilage 1. Hyaline cartilage 2. Fibrocartilage 3. Elastic cartilage B. Bone 1. Compact bone 2. Spongy bone 35 Connective Tissue Mature Connective Tissue Exists in the newborn and adult Has cells differentiated from mesenchyme Does not change after birth Connective Tissue Proper Loose connective tissue Dense connective tissue Fluid connective tissue Blood Lymph Supporting connective tissue Cartilage Bone 36 9
Connective Tissue Proper Loose Connective Tissue The fibers are loosely woven and there are many cells Areolar tissue Adipose tissue Reticular tissue Connective Tissue Proper Loose Connective Tissue: Areolar Cell types = fibroblasts, plasma cells, macrophages, mast cells and a few white blood cells All 3 types of fibers present Gelatinous ground substance Functions: Diffusion for nutrients and wastes Support Padding Universal packing material 37 38 Areolar Connective Tissue Connective Tissue Proper Loose Connective Tissue: Adipose Peripheral nuclei due to large fat storage droplet Reduces heat loss, energy storage, protection Brown fat found in infants has more blood vessels and mitochondria and responsible for heat generation 40 10
Connective Tissue Proper Loose Connective Tissue: Reticular Network of fibers & cells that produce framework of organ Holds organ together liver, spleen, lymph nodes, bone marrow Connective Tissue Proper Dense Connective Tissue Contains more numerous and thicker fibers but considerably fewer cells than loose connective tissue Dense regular connective tissue Dense irregular connective tissue Elastic connective tissue 41 42 Connective Tissue Proper Dense CT: Dense Regular Consists of bundles of collagen fibers and fibroblasts Forms tendons, ligaments, and aponeuroses Provides strong attachments between various structures Connective Tissue Proper Dense CT: Dense Irregular Collagen fibers are irregularly arranged (interwoven) Tissue can resist tension from any direction Very tough tissue -- white of eyeball, dermis of skin 43 44 11
Connective Tissue Proper Dense CT: Elastic Consists of elastic fibers and fibroblasts Found in the lungs, walls of arteries, trachea, bronchial tubes, true vocal cords, and some ligaments Allows stretching of various organs Blood Fluid Connective Tissue Connective tissue with a liquid matrix = plasma Cell types red blood cells: erythrocytes white blood cells: leukocytes cell fragments: platelets or thrombocytes Clotting, immune functions, carry O 2 and CO 2 45 46 Fluid Connective Tissue Lymph Interstitial fluid being transported in lymphatic vessels Contains less protein than plasma Move cells and substances (lipids) from one part of the body to another White blood cells Participates in immune surveillance 47 Supporting Connective Tissue Cartilage Network of fibers in rubbery ground substance Resilient and can endure more stress than loose or dense connective tissue Chondrocytes: only cells in cartilage Lacunae: spaces or chambers in the matrix Surrounded by perichondrium Outer layer of dense irregular connective tissue Attachment, mechanical support, protection Inner layer of cellular Growth and maintenance 48 12
Supporting Connective Tissue Cartilage Types of cartilage hyaline cartilage fibrocartilage elastic cartilage Supporting Connective Tissue Hyaline Cartilage Bluish-shiny white rubbery substance Chondrocytes sit in spaces called lacunae No blood vessels or nerves repair is slow Articular cartilage: reduces friction at joints 49 50 Supporting Connective Tissue Fibrocartilage Many more collagen fibers causes rigidity & stiffness Strongest type of cartilage (intervertebral discs) Supporting Connective Tissue Elastic Cartilage Elastic fibers help maintain shape after deformations Ear, nose, vocal cartilages 51 52 13
Supporting Connective Tissue Cartilage: Growth and Repair Grows and repairs slowly because is avascular Interstitial growth chondrocytes divide and form new matrix occurs in childhood and adolescence Appositional growth chondroblasts secrete matrix onto surface produces increase in width 53 Ehlers-Danlos Syndrome Supporting Connective Tissue Bone (Osseous) Tissue Matrix contains mineral salts, collagenous fibers and osteocytes Surrounded by periosteum Calcium salts hardness Collagen fibers strength Osteocytes 55 Protects, provides for movement, stores minerals, site of blood cell formation 56 14
Muscle Tissue I. Function II. Types A. Skeletal muscle B. Cardiac muscle C. Smooth muscle 58 Muscle Tissue Highly cellular, well-vascularized Consists of cells that are modified for contraction thus provide motion, maintenance of posture, and heat production Three types skeletal muscle cardiac muscle smooth muscle 59 15
Neural Tissue Neural Tissue Only two principle kinds of cells neurons: nerve cells Neuroglia: supporting cells that protect, insulate and support neurons Neurons generate and conduct nerve impulses Dendrite: signal travels towards the cell body Axon: signal travels away from cell body 61 62 Membranes Membranes I. mucous membrane II. serous membrane III. synovial membrane IV. cutaneous membrane (skin) Epithelial layer sitting on a thin layer of connective tissue (lamina propria) Types of membranes mucous membrane serous membrane synovial membrane cutaneous membrane (skin) 63 64 16
Mucous Membranes Lines a body cavity that opens to the outside mouth, vagina, anus etc Epithelial cells form a barrier to microbes Tight junctions between cells Mucous is secreted from underlying glands to keep surface moist 65 Serous Membranes Simple squamous cells overlying loose CT layer Squamous cells secrete slippery fluid Lines a body cavity that does not open to the outside such as chest or abdominal cavity Examples pleura, peritoneum and pericardium membrane on walls of cavity = parietal layer membrane over organs in cavity = visceral layer 66 Membranes Synovial Line joint cavities of all freely movable joints No epithelial cells---just special cells that secrete slippery fluid Membranes Cutaneous skin Epidermis: keratinized stratified squamous epithelium Dermis: thick layer of dense irregular connective tissue 67 68 17
Tissue Repair Tissue Repair 69 Inflammation: isolation and clean up of damaged cells and tissue components Infection: presence of pathogens Necrosis: cell and tissue death due to damage or infection Pus: debris, fluid, dead and dying cells Abscess: accumulation of pus in an enclosed tissue space Regeneration: the replacement of damaged or destroyed cells by healthy ones Restoration: replacement of destroyed tissue with the same kind of tissue Fibrosis: involves proliferation of fibrous connective tissue (scar tissue) Adhesions: sometimes result from scar tissue formation, cause abnormal joining of adjacent tissues, 70 18