Human Anatomy and Physiology Eleventh Edition Chapter 4 PDF

Human Anatomy and Physiology Eleventh Edition Chapter 4 Tissue: The Living Fabric Slides have been modified and edited by C. Youngson PowerPoint® Lectures Slides pr...

Human Anatomy and Physiology Eleventh Edition Chapter 4 Tissue: The Living Fabric Slides have been modified and edited by C. Youngson PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community College Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved das Next Mon Zoom from how on classes A do morning to course still Raheem in map * check 1 Pre-lecture questions: 1. What are the four primary tissues? Give an example of each. 2. Compare and contrast cardiac, skeletal and smooth muscle. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Tissue: The Living Fabric Tissues – Groups of cells similar in structure that perform common or related function Histology – Study of tissues ↳ every hospital thar fist. dept Tissu -17 Four basic tissue types: epithelial, connective, muscle, and nervous tissue + desmosome light juntim to tre HE stain see · Tissue Architecture Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 3  after learning chapter Overview of Four Basic Stook Tissue Types: Epithelial, Connective, Muscle, and Nervous Tissues Figure 4.1 Overview of four basic tissue types: epithelial, connective, muscle, and nervous tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4 Microscopy of Human Tissue To be viewed under a microscope, tissue must be: – Fixed: tissue is preserved with solvent – Sectioned: cut into slices thin enough to transmit light or electrons – Stained: to enhance contrast ▪ Light microscopy uses colored dyes ▪ Electron microscopy uses heavy metal coatings Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 5 Comparison of Transmission and Electron Micrographs ↳ detail cellular Tracheil epithe Figure 4.2 Comparison of transmission and scanning electron micrographs. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 6  & linius.. covering - Epithelial Tissue epithelia glandulan - Epithelial tissue (epithelium) is a sheet of cells that covers body surfaces or cavities Two main forms: – Covering and lining epithelia ▪ On external and internal surfaces (example: skin) – Glandular epithelia Thet e ▪ Secretory tissue in glands (example: salivary glands) Chtypegland enlocime excrimt substance whard the darts : , are Main functions: protection, absorption, filtration, excretion, secretion, and sensory reception Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 7 Special Characteristics of Epithelial Tissues (1 of 7) Zeweir Epithelial tissue has five distinguishing characteristics: 1. Polarity 2. Specialized contacts 3. Supported by connective tissues 4. Avascular, but innervated 5. Regeneration Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 8 Special Characteristics of Epithelial Tissues Polarity – Cells have polarity (top and bottom) – Apical surface, upper free side, is exposed to surface or cavity ▪ Most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli – Basal surface, lower attached side, faces inwards toward body ▪ Attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 9 Special Characteristics of Epithelial Tissues Specialized contacts – Epithelial tissues need to fit closely together ▪ Many form continuous sheets – Specialized contact points bind adjacent epithelial cells together ▪ Tight junctions ▪ Desmosomes Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 10 Special Characteristics of Epithelial Tissues spithelium. Supported by connective tissues - feeds – All epithelial sheets are supported by connective tissue – Basement membrane ▪ Made up of basal and reticular lamina (consists of a network of collagen fibers) ▪ Reinforces epithelial sheet ▪ Resists stretching and tearing ▪ Defines epithelial boundary Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 11 #Clinical – Homeostatic Imbalance 4.1 Cancerous epithelial cells are not contained by the basement membrane boundary like other cells They penetrate the boundary and invade underlying tissues, resulting in spread of cancer Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 12 Special Characteristics of Epithelial Tissues Avascular, but innervated – No blood vessels are found in epithelial tissue ▪ Must be nourished by diffusion from underlying connective tissues – Epithelia are supplied by nerve fibers Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 13 Special Characteristics of Epithelial Tissues Regeneration – Epithelial cells have high regenerative capacities – Stimulated by loss of apical-basal polarity and broken lateral contacts – Some cells are exposed to friction, some to hostile substances, resulting in damage so must be replaced Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 14 Classification of Epithelia (1 of 10) All epithelial tissues have two names – First name indicates number of cell layers ▪ Simple epithelia are a single layer thick ▪ Stratified epithelia are two or more layers thick and involved in protection (example: skin) – Second name indicates shape of cells ▪ Squamous: flattened and scale-like ▪ Cuboidal: box-like, cube ▪ Columnar: tall, column-like – In stratified epithelia, shape can vary in each layer, so cell is named according to the shape in apical layer Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 15 Classification of Epithelia (2 of 10) Figure 4.3a Classification of epithelia. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 16 Classification of Epithelia (3 of 10) Figure 4.3b Classification of epithelia. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 17 Classification of Epithelia (4 of 10) Simple epithelia – Involved in absorption, secretion, or filtration processes – Simple squamous epithelium - for good gas exchange ▪ Cells are flattened laterally, and cytoplasm is sparse ▪ Function where rapid diffusion is priority ▪ Two special simple squamous epithelia are based on locations & – Endothelium: lining of lymphatic vessels, blood vessels, and heart – Mesothelium: serous membranes in the ventral body cavity the blook slippe , smoth , an't dimpt fe of damage Endothelium heart dis ↳ begging of Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 18 Epithelium: Simple Squamous * al Figure 4.4a Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 19 Classification of Epithelia (5 of 10) Simple cuboidal epithelium – Single layer of cells – Involved in secretion and absorption Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 20 Epithelium: Simple Cuboidal Figure 4.4b Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 21 Classification of Epithelia (6 of 10) Simple columnar epithelium – Single layer of tall, closely packed cells ▪ Some cells have microvilli, and some have cilia ▪ Some layers contain mucus-secreting goblet cells – Involved in absorption and secretion of mucus, enzymes, and other substances ▪ Ciliated cells move mucus Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 22 Epithelium: Simple Columnar * wit all Figure 4.4c Epithelial tissues. goblet Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 23 Classification of Epithelia (7 of 10) Pseudostratified columnar epithelium – Cells vary in height and appear to be multi-layered and stratified, but tissue is in fact single-layered simple epithelium ▪ “Pseudo” means false ▪ Many cells are ciliated – Involved in secretion and movement of mucus via cilia Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 24 Epithelium: Pseudostratified Columnar Figure 4.4d Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 25 Classification of Epithelia (8 of 10) Stratified epithelial tissues – Involve two or more layers of cells – New cells regenerate from below ▪ Basal cells divide and migrate toward surface – More durable than simple epithelia because protection is the major role – Stratified squamous epithelium ▪ Most widespread of stratified epithelia ▪ Free surface is squamous, with deeper cuboidal or columnar layers Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 26 Epithelium: Stratified Squamous Figure 4.4e Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 27 Classification of Epithelia (9 of 10) Stratified epithelial tissues (cont.) – Stratified cuboidal and columnar epithelium is rare. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 28 Classification of Epithelia (10 of 10) Stratified epithelial tissues (cont.) – Transitional epithelium ▪ Forms lining of hollow urinary organs – Found in bladder, ureters, and urethra ▪ Basal layer cells are cuboidal or columnar ▪ Ability of cells to change shape when stretched allows for increased flow of urine and, in the case of bladder, more storage space - Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 29 Epithelium: Transitional Figure 4.4f Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 30 Glandular Epithelia (1 of 7) Gland – One or more cells that makes and secretes an aqueous fluid called a secretion Classified by: – Site of product release: ▪ Endocrine: internally secreting (example: hormones) ▪ Exocrine: externally secreting (example: sweat) – Relative number of cells forming the gland ▪ Unicellular (example: goblet cells) or multicellular (example: salivary) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 31 Formation of Multicellular Exocrine and Endocrine Glands Figure 4.5 Formation of multicellular exocrine and endocrine glands. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 32 Glandular Epithelia (2 of 7) Endocrine glands – Ductless glands ▪ Secretions are released into surrounding interstitial fluid, which is picked up by circulatory system – Secrete (by exocytosis) hormones, messenger chemicals that travel through blood to their specific target organs Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 33 Glandular Epithelia (3 of 7) Exocrine glands – Secretions are released onto body surfaces, such as skin, or into body cavities – Secrete products into ducts – Examples include mucous, sweat, sebaceous oil, and salivary glands – Can be: ▪ Unicellular ▪ Multicellular Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 34 Glandular Epithelia (4 of 7) Unicellular exocrine glands – The only important unicellular glands are mucous cells and goblet cells – Found in epithelial linings of intestinal and respiratory tracts – All produce mucin, a sugar-protein that can dissolve in water to form mucous, a protective, lubricating coating Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 35 Goblet Cell (Unicellular Exocrine Gland) Figure 4.6 Goblet cell (unicellular exocrine gland). Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 36 Glandular Epithelia (5 of 7) Multicellular exocrine glands – Multicellular exocrine glands are composed of a duct and a secretory unit – Usually surrounded by supportive connective tissue that supplies blood and nerve fibers to gland – Classified by: ▪ Structure ▪ Mode of secretion Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 37 Glandular Epithelia (6 of 7) Multicellular exocrine glands (cont.) – Structure ▪ Simple exocrine glands have unbranched ducts, but compound glands have branched ducts ▪ In a tubular gland, secretory cells form a duct, whereas in alveolar glands, secretory cells form sacs Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 38 Types of Multicellular Exocrine Glands * # Lmayle Figure 4.7 Types of multicellular exocrine glands. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved kind of exoccive glands are * what ?In't into specifics there go 39 Glandular Epithelia (7 of 7) Multicellular exocrine glands (cont.) – Mode of secretion ▪ Merocrine: most secrete products by exocytosis as secretions are produced (sweat, pancreas) ▪ Holocrine: accumulate products within, then rupture (sebaceous oil glands) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 40 Chief Modes of Secretion in Human Exocrine Glands * Secti at 1997lock of Sebacious.... Figure 4.8 Chief modes of secretion in human exocrine glands. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 41 Connective Tissue Connective tissue is the most abundant and widely distributed of primary tissues Connective tissue is defined as “cells within an extracellular matrix” Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood) Four main classes – Connective tissue proper – Cartilage – Bone – Blood Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 42 Table 4.1-1 Comparison of Classes of Connective Tissues * Portfora & - & Table 4.1-1 Comparison of Classes of Connective Tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved map help wrupt 43 Table 4.1-2 Comparison of Classes of Connective Tissues Table 4.1-2 Comparison of Classes of Connective Tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 44 Common Characteristics of Connective Tissue Three characteristics make connective tissues different from other primary tissues: – All have common embryonic origin: all arise from mesenchyme tissue as their tissue of origin – Have varying degrees of vascularity (cartilage is avascular, bone is highly vascularized) – Cells are suspended/embedded in extracellular matrix (ECM) (protein-carbohydrate mesh) ↳ cello within matrixa ▪ Matrix supports cells so they can bear weight and withstand tension Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 45 Structural Elements of Connective Tissue (1 of 5) All connective tissues have three main elements thin smothe fill it in – Ground substance + cart filler to make protin , - – Fibers – Cells ▪ The first two elements (ground substance and fibers) together make up the extracellular matrix – Composition and arrangement of these three elements vary considerably in different types of connective tissues Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 46 Structural Elements of Connective Tissue (2 of 5) Ground substance – Unstructured gel-like material that fills space between cells – Components ▪ Interstitial fluid ▪ Cell adhesion proteins (“glue” for attachment) ▪ Proteoglycans made up of protein core + large polysaccharides – Example: chrondroitin sulfate and hyaluronic acid ▪ Water also is trapped in varying amounts, affecting viscosity of ground substance Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 47 Structural Elements of Connective Tissue (3 of 5) Connective tissue fibers Three types of fibers provide support – Collagen ▪ Strongest and most abundant type ▪ Tough; provides high tensile strength – Elastic fibers ▪ Networks of long, thin, elastin fibers that allow for stretch and recoil – Reticular ▪ Short, fine, highly branched collagenous fibers (different chemistry and form from collagen fibers) ▪ Branching forms networks that offer more “give” Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 48 Structural Elements of Connective Tissue (4 of 5) Cells – “Blast” cells ▪ Immature form of cell that actively secretes ground substance and ECM fibers ▪ Fibroblasts found in connective tissue proper ▪ Chondroblasts found in cartilage ▪ Osteoblasts found in bone ▪ Hematopoietic stem cells in bone marrow – “Cyte” cells ▪ Mature, less active form of “blast” cell that now becomes part of and helps maintain health of matrix Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 49 Structural Elements of Connective Tissue (5 of 5) Other cell types in connective tissues – Fat cells ▪ Store nutrients – White blood cells ▪ Neutrophils, eosinophils, lymphocytes ▪ Tissue response to injury – Mast cells ▪ Initiate local inflammatory response against foreign microorganisms they detect – Macrophages ▪ Phagocytic cells that “eat” dead cells, microorganisms; function in immune system Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 50 Areolar Connective Tissue: A Prototype (Model) Connective Tissue - hyal and Figure 4.9 Areolar connective tissue: A prototype (model) connective tissue. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 51 Types of Connective Tissues There are four main classes of connective tissue: – Connective tissue proper – Cartilage – Bone – Blood Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 52 Types of Connective Tissues Connective tissue proper – Consists of all connective tissues except bone, cartilage, and blood – Two subclasses ▪ CT proper: loose connective tissues – Areolar – Adipose – Reticular ▪ CT proper: dense connective tissues – Dense regular – Dense irregular – Elastic Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 53 Connective Tissues-Proper-Loose-Areolar Figure 4.11a Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 54 Connective Tissues-Proper-Loose-Adipose T store fat Figure 4.11b Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 55 Connective Tissues-Proper-Loose-Reticular Figure 4.11c Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 56 Connective Tissues-Proper-Dense-Regular Figure 4.11d Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 57 Connective Tissues-Proper-Dense-Irregular Figure 4.11e Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 58 Connective Tissues-Proper-Dense-Elastic # Figure 4.11f Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 59 Types of Connective Tissues Three types of cartilage: – Hyaline cartilage ▪ Most abundant; “gristle” ▪ Appears as shiny bluish glass -Ajant ▪ Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs – Elastic cartilage ▪ Similar to hyaline but with more elastic fibers ▪ Found in ears and epiglottis – Fibrocartilage ▪ Properties between hyaline and dense regular tissue ▪ Strong, so found in areas such as intervertebral discs and knee Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 60 Connective Tissues-Proper-Cartilage-Hyaline Figure 4.11g Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 61 Connective Tissues-Proper-Cartilage-Elastic Figure 4.11h Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 62 Connective Tissues-Proper-Cartilage-Fibrocartilage Figure 4.11i Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 63 * Clinical – Homeostatic Imbalance 4.2 Avascular cartilage loses ability to divide as we age, so injuries heal slowly – Common in people with sports injuries Later in life, cartilage can calcify or ossify (become bony), causing chondrocytes to die Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 64 Connective Tissues-Proper-Cartilage-Bone Figure 4.11j Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 65 Connective Tissues-Proper-Cartilage-Blood Figure 4.11k Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 66 Muscle Tissue Highly vascularized Responsible for most types of movement – Muscle cells possess myofilaments made up of actin and myosin proteins that bring about contraction Three types of muscle tissues: – Skeletal muscle - – Cardiac muscle – Smooth muscle Danswer pule Gl. Cardial Stricted - - : muide which of h are ↳ Skeletal voluntary : "are - 1) controlled by or Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 67 Skeletal Muscle Figure 4.12a Muscle tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 68 Cardiac Muscle *gap junction Figure 4.12b Muscle tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 69 Smooth Muscle Figure 4.12c Muscle tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 70 Nervous Tissue Main component of nervous system (brain, spinal cord, nerves) – Regulates and controls body functions Made up of two specialized cells: – Neurons: specialized nerve cells that generate and conduct nerve impulses – Supporting cells that support, insulate, and protect neurons Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 71 Nervous Tissue Figure 4.13 Nervous tissue. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 72 Covering and Lining Membranes Composed of at least two primary tissue types: an epithelium bound to underlying connective tissue proper layer Three types – Cutaneous membranes – Mucous membranes – Serous membranes Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 73 Classes of Covering and Lining Membranes (1 of 3) Figure 4.14a Classes of covering and lining membranes. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 74 Classes of Covering and Lining Membranes (2 of 3) da Figure 4.14b Classes of covering and lining membranes. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 75 Classes of Covering and Lining Membranes (3 of 3) laman ae · Figure 4.14c Classes of covering and lining membranes. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 76 Tissue Repair of a Skin Wound: Regeneration and Fibrosis (1 of 3) Figure 4.15 Tissue repair of a skin wound: regeneration and fibrosis. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 77 Tissue Repair of a Skin Wound: Regeneration and Fibrosis (2 of 3) Figure 4.15 Tissue repair of a skin wound: regeneration and fibrosis. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 78 Tissue Repair of a Skin Wound: Regeneration and Fibrosis (3 of 3) Figure 4.15 Tissue repair of a skin wound: regeneration and fibrosis. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 79 Regenerative Capacity of Different Tissues Tissues that regenerate extremely well include: – Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue Tissue with moderate regenerating capacity: – Smooth muscle and dense regular connective tissue Tissues with virtually no functional regenerative capacity: – Cardiac muscle and nervous tissue of brain and spinal cord – Current research shows cell division can occur, and efforts are underway to stimulate them to regenerate better Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 80 Clinical – Homeostatic Imbalance Scar tissue that forms in organs, particularly the heart, can severely impair the function of that organ – May cause the organ to lose volume capacity – May block substances from moving through organ – May interfere with ability of muscles to contract or may impair nerve transmissions Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 81 Developmental Aspects of Tissues (1 of 2) Primary germ layers – Superficial to deep: ectoderm, mesoderm, and endoderm – Formed early in embryonic development – Specialize to form the four primary tissues ▪ Nerve tissue arises from ectoderm ▪ Muscle and connective tissues arise from mesoderm ▪ Epithelial tissues arise from all three germ layers Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 82 Developmental Aspects of Tissues (2 of 2) Tissues function well through youth and middle age if given adequate diet and circulation and if wounds and infections are minimal As the body ages, epithelia thin, so they are more easily breached Tissue repair is less efficient Bone, muscle tissues, and nervous tissues begin to atrophy DNA mutations increase cancer risk Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 83 Embryonic Germ Layers and the Primary Tissue Types they Produce peridia malignancies Figure 4.16 Embryonic germ layers and the primary tissue types they produce. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 84 Independent Reading Cancer-The Intimate Enemy pg 144-145 mesatia enc gene Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved