N109 Objective 3 Part B (2023) PDF

PN 1109 ANATOMY & PHYSIOLOGY I OBJECTIVE 3 PART B CHAPTER 4 LEARNER OBJECTIVES • Discuss the development of tissues of the body. • Identify the main kinds of tissues of the body and the general location and functions of each. • Identify and differentiate between the two types of glands. • Identif...

PN 1109 ANATOMY & PHYSIOLOGY I OBJECTIVE 3 PART B CHAPTER 4 LEARNER OBJECTIVES • Discuss the development of tissues of the body. • Identify the main kinds of tissues of the body and the general location and functions of each. • Identify and differentiate between the two types of glands. • Identify and differentiate between the different types of membranes. • Discuss the steps in tissue repair. © 2016 Pearson Education, Inc. • Individual body cells are specialized • Each type performs specific functions that maintain homeostasis • Tissues • Groups of cells similar in structure that perform common or related function • Histology • Study of tissues • Four basic tissue types: epithelial, connective, muscle, and nervous tissue © 2016 Pearson Education, Inc. Nervous tissue: Internal communication • Brain • Spinal cord • Nerves Muscle tissue: Contracts to cause movement • Muscles attached to bones (skeletal) • Muscles of heart (cardiac) • Muscles of walls of hollow organs (smooth) Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters • Lining of digestive tract organs and other hollow organs • Skin surface (epidermis) Connective tissue: Supports, protects, binds other tissues together • Bones • Tendons • Fat and other soft padding tissue © 2016 Pearson Education, Inc. • Main component of nervous system (brain, spinal cord, nerves) • Regulates and controls body functions NERVOUS TISSUE • Made up of two specialized cells: • Neurons: specialized nerve cells that generate and conduct nerve impulses • Neuroglia: Supporting cells that support, insulate, and protect neurons • (will discuss more in later objectives) MUSCLE TISSUE • Highly vascularized • Responsible for most types of movement • Three types of muscle tissues: • Skeletal muscle • Cardiac muscle • Smooth muscle © 2016 Pearson Education, Inc. MUSCLE TISSUE Skeletal muscle tissue • Attached to and causes movement of bones • Also called voluntary muscle • Skeletal muscles can be consciously controlled • Cells are called muscle fibers • Contain multiple nuclei • Appear striated or banded © 2016 Pearson Education, Inc. MUSCLE TISSUE Cardiac muscle tissue • Found only in walls of heart • Involuntary muscle • Like skeletal muscle, contains striations; but cells have only one nucleus (uninucleate) • Cells can have many branches that join branches of other cardiac cells • Intercalated discs are special joints where cardiac cells are joined © 2016 Pearson Education, Inc. MUSCLE TISSUE Smooth muscle tissue • Found mainly in walls of hollow organs (other than heart) • Involuntary muscle • Has no visible striations • Spindle-shaped cells with one nucleus © 2016 Pearson Education, Inc. EPITHELIAL TISSUE • Epithelial tissue (epithelium) is a sheet of cells that covers body surfaces or cavities (forms boundaries) • Two main forms: • Covering and lining epithelia • On external and internal surfaces (example: skin) • Glandular epithelia • Secretory tissue in glands (example: salivary glands) • Main functions: protection, absorption, filtration, excretion, secretion, and sensory reception © 2016 Pearson Education, Inc. CHARACTERISTICS OF EPITHELIAL TISSUES • Epithelial tissue has five distinguishing characteristics: 1. Polarity 2. Specialized contacts 3. Supported by connective tissues 4. Avascular, but innervated 5. Regeneration © 2016 Pearson Education, Inc. • Polarity • Cells have polarity (top and bottom) • All epithelia have an upper free side that is exposed to surface of the body or an internal cavity • Most upper surfaces are smooth, but some have specialized fingerlike projections called microvilli(i.e. intestine) or cilia (i.e. trachea) • lower attached surface faces inwards toward body • Attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells • Both surfaces differ in structure and function © 2016 Pearson Education, Inc. • Specialized contacts • Epithelial tissues need to fit closely together • Many form continuous sheets except glandular epithelia • Specialized contact points bind adjacent epithelial cells together • Lateral contacts include: • Tight junctions • Desmosomes © 2016 Pearson Education, Inc. • Connective tissue support • All epithelial sheets are supported by connective tissue • Reticular lamina • Deep to basal lamina found in the basal surface • Consists of network of collagen fibers • Basement membrane • Made up of basal and reticular lamina • Reinforces epithelial sheet • Resists stretching and tearing • Defines epithelial boundary © 2016 Pearson Education, Inc. • 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 • Regeneration • Epithelial cells have high regenerative capacities • Stimulated by loss of apical-basal polarity and broken connections between the tight junctions & desmosomes • Some cells are exposed to friction, some to hostile substances, resulting in damage • Must be replaced • Requires adequate nutrients and cell division © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA • 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 © 2016 Pearson Education, Inc. FIGURE 4.2A CLASSIFICATION OF EPITHELIA. © 2016 Pearson Education, Inc. Apical surface Basal surface Simple Apical surface Basal surface Stratified Classification based on number of cell layers. FIGURE 4.2B CLASSIFICATION OF EPITHELIA. © 2016 Pearson Education, Inc. Squamous Cuboidal Columnar Classification based on cell shape. CLASSIFICATION OF EPITHELIA (CONT.) 1. Simple epithelia • Involved in absorption, secretion, or filtration processes A) Simple squamous epithelium • Cells are flattened laterally, and are thin and permeable • Function where rapid diffusion is priority • Example: kidney, lungs • Two special locations: • Endothelium: lining of lymphatic vessels, blood vessels, and heart • Mesothelium: serous membranes in the ventral body cavity © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA (CONT.) B) Simple cuboidal epithelium • Single layer of cells as tall as they are wide • Involved in secretion and absorption • Forms walls of smallest ducts of glands and many kidney tubules © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA (CONT.) C) 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 • Found in digestive tract, gallbladder, ducts of some glands, bronchi, and uterine tubes © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA (CONT.) D) Pseudostratified columnar epithelium • Cells vary in height and • appear to be multi-layered and stratified, but is not • “Pseudo” means false • Many cells are ciliated • Involved in secretion & absorption • Located mostly in upper respiratory tract, ducts of large glands, and tubules in testes © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA (CONT.) 2. Stratified epithelial tissues • two or more layers of cells • New cells regenerate from below • Basal cells divide and migrate toward surface • More durable than simple epithelia • protection is the major role A) Stratified squamous epithelium • Most widespread of stratified epithelia • Free surface is squamous, with deeper cuboidal or columnar layers • Located in areas of high wear and tear (example: skin) • Keratinized cells found in skin; non-keratinized cells are found in moist linings © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA (CONT.) B) Stratified cuboidal epithelium • Quite rare • Found in some sweat and mammary glands • Typically only two cell layers thick C) Stratified columnar epithelium • limited distribution in body • Small amounts found in pharynx, in male urethra, and lining some glandular ducts • Usually occurs at transition areas between two other types of epithelia • Only upper layer is columnar © 2016 Pearson Education, Inc. CLASSIFICATION OF EPITHELIA (CONT.) D) Transitional epithelium • Forms lining of hollow urinary organs • Found in bladder, ureters, and urethra • lower 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 © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA • 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) © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA (CONT.) • Endocrine glands • Aka: Ductless glands • Secretions are not released into a duct; but are released into surrounding interstitial fluid, which is picked up by circulatory system • Secrete hormones, which are messenger chemicals that travel through lymph or blood to their specific target organs • Target organs respond in some characteristic way © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA (CONT.) • Exocrine glands • Secretions are released onto body surfaces, such as skin, or into body cavities • More numerous than endocrine glands • Secrete products into ducts • Examples include mucous, sweat, oil, and salivary glands • Can be: • Unicellular • Multicellular © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA (CONT.) • 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 mucus, a slimy protective, lubricating coating © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA (CONT.) • 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 • Connective tissue can form capsule around gland, and also extend into gland, dividing it into lobes • Classified by: • Structure • Mode of secretion © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA (CONT.) • Multicellular exocrine glands (cont.) • Structure • Simple glands have unbranched ducts • compound glands have branched ducts • In a tubular gland, secretory cells form a duct, whereas in alveolar glands, secretory cells form sacs • Tubuloalveolar glands have both types of glands © 2016 Pearson Education, Inc. GLANDULAR EPITHELIA (CONT.) • Multicellular exocrine glands (cont.) • Mode of secretion • Merocrine: most secrete products by exocytosis as secretions are produced (sweat, pancreas, saliva) • Holocrine: accumulate products within, then the entire cell ruptures (sebaceous oil glands) • Apocrine: accumulate products within, but only a portion ruptures; whether this type exists in humans is controversial (maybe mammary cells?) © 2016 Pearson Education, Inc. CONNECTIVE TISSUE • Connective tissue is the most abundant and widely distributed of the tissues • Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood) • Four main classes (table 4.1, p. 126): • Connective tissue proper • Cartilage • Bone • Blood © 2016 Pearson Education, Inc. CHARACTERISTICS OF CONNECTIVE TISSUE • Three characteristics make connective tissues different from other 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-sugar mesh) • Matrix supports cells so they can bear weight, withstand tension, endure abuse, that no other tissue can tolerate © 2016 Pearson Education, Inc. STRUCTURAL ELEMENTS OF CONNECTIVE TISSUE • All connective tissues have three main elements • Ground substance • 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 © 2016 Pearson Education, Inc. STRUCTURAL ELEMENTS OF CONNECTIVE TISSUE (CONT.) • Ground substance • Unstructured gel-like material that fills space between cells • Medium through which solutes diffuse between blood capillaries and cells • Components • Interstitial fluid • Cell adhesion proteins (“glue” for attachment) • Water also is trapped in varying amounts, affecting viscosity of ground substance © 2016 Pearson Education, Inc. STRUCTURAL ELEMENTS OF CONNECTIVE TISSUE (CONT.) 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” © 2016 Pearson Education, Inc. STRUCTURAL ELEMENTS OF CONNECTIVE TISSUE (CONT.) • Cells • “Blast” cells • Immature form of cell • Mitotically active • 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 form, • maintain health of matrix • Chondrocytes in cartilage • Osteocytes in bone © 2016 Pearson Education, Inc. STRUCTURAL ELEMENTS OF CONNECTIVE TISSUE (CONT.) • 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 © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES: CONNECTIVE TISSUE PROPER • There are four main classes of connective tissue: • Connective tissue proper • Cartilage • Bone • Blood © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) 1. 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 (aka: fibrous) © 2016 Pearson Education, Inc. • Dense regular • Dense irregular • Elastic TYPES OF CONNECTIVE TISSUES (CONT.) Areolar connective tissue • Most widely distributed CT • Supports and binds other tissues • Universal packing material between other tissues • Provides reservoir of water and salts • Defend against infection • Contains fibroblasts that secrete loose arrangement of mostly collagen fibers • Loose fibers allow for increased ground substance, which can act as water reservoir by holding more interstitial fluid • Macrophages and fat cells are contained in spaces • When inflamed soaks up fluid = edema © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Adipose tissue • fat • Similar to areolar tissue but greater nutrient storage • Cells are called adipocytes; store nutrients • Scanty matrix • Richly vascularized • Functions in shock absorption, insulation, and energy storage • Brown fat • Use lipid fuels to heat bloodstream rather than to produce ATP, as does white fat (ex: back of babies) © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Reticular connective tissue • Resembles areolar tissue but fibers are reticular fibers • Fibroblast cells are called reticular cells • Secrete reticular fibers made up of thin collagen • support for blood cells in lymph nodes, spleen, and bone marrow © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Dense connective tissues • Three varieties of dense connective tissue • Dense regular • Dense irregular • Elastic © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Dense regular connective tissue • Very high tensile strength; can withstand high tension and stretching • Closely packed bundles of thick collagen fibers run parallel to direction of pull • Fibers appear as white structures • • • • • • Great resistance to pulling Fibers slightly wavy, so stretch a little Fibroblasts manufacture collagen fibers and ground substance Very few cells and ground substance, mostly fibers Poorly vascularized Example: tendons and ligaments © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Dense irregular connective tissue • Same elements as dense regular, but bundles of collagen are thicker and irregularly arranged • Forms sheets rather than bundles • Resists tension from many directions • Found in: • Dermis • Fibrous joint capsules • Fibrous coverings of some organs © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Elastic connective tissue • Some ligaments are very elastic • Example: ligaments connecting adjacent vertebrae • Also found in walls of many large arteries • Arteries need to stretch when blood enters and recoil to push blood out © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Cartilage • Matrix secreted from chondroblasts (during growth) and chondrocytes (adults) • Chondrocytes found in cavities called lacunae • 80% water, with packed collagen fibers and sugar proteins (chondroitin and hyaluronic acid) • Tough yet flexible material that lacks nerve fibers • Up to 80% water; can rebound after compression • Avascular: receives nutrients from membrane surrounding it (perichondrium) • Periochondrium gives rise to chondroblasts and chondrocytes © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) • Three types of cartilage: • Hyaline cartilage • Most abundant; “gristle” • Appears as shiny bluish glass • Provides firm support with some pliability • 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 where strength and stretchability are needed • Fibrocartilage • Properties between hyaline and dense regular tissue • Strong, so found in areas where strong support and ability to withstand heave pressure is needed, such as intervertebral discs and knee © 2016 Pearson Education, Inc. Hyaline Cartilage Elastic Cartilage Fibrocartilage TYPES OF CONNECTIVE TISSUES (CONT.) Bone • Also called osseous tissue • Supports and protects body structures • Stores fat and synthesizes blood cells in cavities • Has more collagen compared to cartilage • Has inorganic calcium salts • Osteoblasts produce matrix • Osteocytes maintain the matrix • Reside in cavities in matrix called lacunae • Osteons: individual structural units • Richly vascularized © 2016 Pearson Education, Inc. TYPES OF CONNECTIVE TISSUES (CONT.) Blood • Most atypical connective tissue because it is fluid • Consists of cells surrounded by matrix (plasma) • Red blood cells are most common cell type • Also contains white blood cells and platelets • Fibers are soluble proteins that precipitate during blood clotting • Functions in transport and in carrying nutrients, wastes, gases, and other substances © 2016 Pearson Education, Inc. COVERING AND LINING MEMBRANES • Composed of at least two main tissue types: • an epithelium bound to underlying connective tissue proper layer • Are simple organs • Three types • Cutaneous membranes • Mucous membranes • Serous membranes • One type of connective tissue membrane • Synovial membranes © 2016 Pearson Education, Inc. CUTANEOUS MEMBRANES • skin • Covers the body surface • Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis) • skin is a dry membrane © 2016 Pearson Education, Inc. MUCOUS MEMBRANES • Mucosa indicates location, not cell composition • Also called mucosae • Line body cavities that are open to the exterior (example: digestive, respiratory, urogenital tracts) • Moist membranes bathed by secretions (or urine) • Epithelial sheet lies over layer of loose connective tissue • May secrete mucus © 2016 Pearson Education, Inc. SEROUS MEMBRANES • Also called serosae • Found in closed ventral body cavities • Constructed from simple squamous epithelium resting on thin areolar connective tissue • Parietal layer line internal body cavity walls • Visceral layer cover internal organs • Cavity between layers is filled with slippery serous fluid, so these are moist membranes • Special names given to show location: pleurae (lungs), pericardium (heart), peritoneum (abdomen) © 2016 Pearson Education, Inc. SYNOVIAL MEMBRANES • Lines cavities of movable joints • Secrete thick, colorless lubricating fluid (synovial fluid) • No epithelial layer TISSUE REPAIR • When the body’s barriers are compromised, the inflammatory and immune responses are activated • Repair starts very quickly • Repair is the function of the inflammatory process • Repair can occur in two major ways: • Regeneration: same kind of tissue replaces destroyed tissue, so original function is restored • Fibrosis: connective tissue replaces destroyed tissue, and original function lost • Which of these occurs depends on the type of tissue damage and the severity © 2016 Pearson Education, Inc. STEPS IN TISSUE REPAIR • Step 1: Inflammation sets stage • Release of inflammatory chemicals causes: • Dilation of blood vessels • Increase in blood vessel permeability • Clotting of blood occurs • 4 cardinal signs of inflammation: • Redness • Heat • Swelling (edema) • pain © 2016 Pearson Education, Inc. STEPS IN TISSUE REPAIR • Step 2: Organization restores blood supply • blood clot is replaced with granulation tissue • Epithelium begins to regenerate • Fibroblasts produce collagen fibers to bridge the gap until regeneration is complete • debris is phagocytized © 2016 Pearson Education, Inc. STEPS IN TISSUE REPAIR (CONT.) • Step 3: Regeneration and fibrosis effect permanent repair • The scab detaches • Fibrous tissue matures • Epithelium thickens and begins to resemble adjacent tissue • Results in a fully regenerated epithelium with underlying scar tissue, which may or may not be visible © 2016 Pearson Education, Inc. REGENERATIVE CAPACITY OF DIFFERENT TISSUES • Regenerate extremely well include: • Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue • Moderate regenerating capacity: • Smooth muscle and dense regular connective tissue • Virtually no functional regenerative capacity: • Cardiac muscle and nervous tissue of brain and spinal cord • New research shows cell division does occur, and efforts are underway to coax them to regenerate better © 2016 Pearson Education, Inc.