Chapter 4 Anaphy

8/12/2019 Chapter 4 Anaphy

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Epithelial Tissue – found throughout the body,covering internal and external surfaces- forms most glands

- has very little extracellular material- mostly has a free surface

Functions of Epithelia:1.) Protects underlying structures2.) Acts as barriers3.) Permits passage of substances4.) Secretes substances5.) Absorbs substances

Classification of Epithelia:According to cell layers

1.) Simple Epithelium – single layer of cells2.) Stratified Epithelium – more than one layer

of cells, with some cells sitting on top ofother cells

According to cell shape1.) Squamous – relating to scales2.) Cuboidal – cube-like3.) Columnar – tall and thin

Simple Squamous Epithelium – single layer of thin,flat cells. Often found where diffusion or filtration

take place- also functions to prevent abrasion between organsin the pericardial, pleural, and peritoneal cavities*Alveoli – small sacs that allows oxygen from the airto diffuse into the body and carbon dioxide todiffuse out of the body into the airSimple Cuboidal Epithelium – single layer of cube-like cells that carry out active transport, facilitateddiffusion or secretionSimple Columnar Epithelium – single layer of tall,thin cells that enable them to perform complexfunctionsPseudostratified Columnar Epithelium (pseudomeaning false) – special type of simple epithelium,appears to be stratified, but not. Consists of onelayer of cells, with all the cells attached to thebasement membraneStratified Squamous Epithelium – forms a thickepithelium because it consists of several layers ofcells*The deepest cells are cuboidal and columnar andare capable of dividing and producing new cellsStratified Cuboidal Epithelium – consists of more

than one layer of cuboidal epithelial cells- Relatively rare and is found in sweat gland ducts,ovarian follicular cells, and salivary glands- Functions in absorption, secretion & protection

Stratified Cuboidal Epithelium – consists of morethan one layer of cuboidal epithelial cells- Relatively rare and is found in sweat gland ducts,

ovarian follicular cells, and salivary glands- Functions in absorption, secretion & protectionStratified Columnar Epithelium – consists of morethan one layer of epithelial cells, but only the surfacecells are columnar in shape- Also relatively rare, found in locations such as themammary gland, ducts, larynx and male urethra*The deeper cells are irregular in shape or cuboidalTransitional Epithelium – special type of stratifiedepithelium that can be greatly stretched*In the unstretched state, it consists of 5 or morelayers of cuboidal or columnar cells that often aredome-shaped at the free surface

Structural and Functional RelationshipsCell LayersThe number of cell layers and the shape of the cell ina specific type of epithelium reflect the function theepithelium performsTwo Important Functions:1.) Controlling the passage of materials through theepithelium2.) Protecting the underlying tissues

Mucus – a clear, viscous material usually found insecretory vesicles- Protects the stomach lining against digestiveenzymes and acid produced in the stomach

Free Cell SurfacesThe free surface can be smooth, or it can havemicrovilli or ciliaSmooth Surfaces – reduce frictionMicrovilli – cylindrical extensions of the cellmembrane that function to increase the cell surfaceareaCilia – propel materials along the surface of cells*Goblet – specialized mucus-producing cellsintermixed with the ciliated cellsDust and other materials are trapped in the mucusthat covers epithelium. The constant movement ofmucus helps to keep respiratory passages clean

Cell ConnectionsTight junctions – bind adjacent cells together andform permeability barriers. Prevent the passage ofmaterials between cells

-found in lining of intestines and most other simpleepitheliaDesmosomes – mechanical links that function tobind cells together

Chapter 4Tissues, Glands, Membranes



Hemidesmosomes – modified desmosomes thatanchor cells to the basement membraneGap Junctions – small channels that allow smallmolecules and ions to pass from one epithelial cell toan adjacent one

GlandsGland – multicellular structure that secretes

substances onto a surface, into a cavity or into theblood- composed primarily of epithelium cellsEndocrine – no ductsExocrine – with ductsSimple – ducts that have no branchesCompound – ducts that have many branchesThe end of a duct can be tubular Acinus/Alveolus – sac-like structure ends*The endocrine glands empty their secretions intothe blood. These secretions called hormones arecarried by blood to other parts of the body

Connective TissueConnective Tissues – usually characterized by largeamounts of extracellular materials that separatecells from one another

3 Major Components of Extracellular Matrix:1. Proteins2. Ground Substance (Non-fibrous protein)3. Fluid

3 Types of Protein Fibers:1. Collagen Fibers – resemble microscopic ropes, areflexible but resist stretching2. Reticular Fibers – very fine, short collagen fibersthat branch to form a supporting network3. Elastic Fibers – have a structure similar to coiledmetal bedsprings. After stretching, they have theability to recoil to their original shape

Ground Substance – shapeless background againstwhich cells and collagen fibers are seen in the lightmicroscopeProteoglycan – resemble the limbs of pine trees,with proteins forming the branches andpolysaccharides forming the pine needles

*Connective tissue cells are named according totheir functionsBlast Cells – produce the matrixCyte Cells – maintain matrixClast Cells – break down matrix for remodelingFibroblasts – cells that form fibers and groundsubstance in the extracellular matrix

Fibrocytes – cells that maintain fibersOsteoblasts – form bonesOsteocytes – maintain bonesOsteoclast – break down bones

Macrophages – large cells that are capable of movingabout and ingesting foreign substancesMast Cells – non-motile cells that release chemicals,such as histamine, that promote inflammation

Functions of Connective Tissue:1.) Enclosing and Separating2.) Connecting tissues to one another

3.) Supporting and Moving4.) Storing5.) Cushioning and Insulating6.) Transporting7.) Protecting

Mesenchyme – gives rise to 6 major categories ofconnective tissueClassification of Connective Tissues:

1.) Loose/Areolar – has extracellular matrixconsisting mostly of collagen and a fewelastic fibers. Most common cells found inloose connective tissue are the fibroblastsresponsible for the production of the matrix

2.) Adipose (subcutaneous layer) – extracellularmatrix with collagen and elastic fibers but isnot a typical connective tissue because it hasvery little extracellular matrix

3.) Dense Connective Tissue – has extracellularmatrix that consists of densely packed fibersproduced by fibroblastsa. Dense Collagenous Connective Tissue –

consists mostly of collagen fibers. Ex:tendons, ligaments, bones, much ofdermis

b. Dense Elastic Connective Tissue – hasabundant elastic fibers among collagenfibers. Ex: vocal chords, walls of elasticlarge arteries & ligaments

4.) Cartilage – composed of cartilage cells or‘chondrocyte s’, located in spaces called‘lacunae ’. Resilient because proteoglycans ofthe matrix trap watera. Hyaline Cartilage – most abundant type

of cartilage. Covers the ends of boneswhere bones come together to formjoints. Also forms costal cartilages

b. Fibrocartilage – has more collagen thanhyaline cartilage, and bundles of collagencan be seen in the matrix. Able to resistpulling or tearing forces. Found in disksbetween vertebrae and joints in the kneeand jaw

c. Elastic Cartilage – contains elastic fibersin addition to collagen and

proteoglycans. Able to recoil to itsoriginal shape. Found in external ear,epiglottis and auditory tube



5.) Bone – hard connective tissue that consistsof living cells and a mineralized matrix. 2 Types of Bones: Compact and Cancellous*Bone cells or ‘osteocytes’ are located withinspaces in the matrix called lacunae

6.) Blood – unique because the matrix is liquid,enabling blood cells to move through bloodvessels

Muscle TissueThe main characteristic of muscle tissue is its abilityto contract, or shorten, making movement possible.The length of muscle cells is greater than thediameter.Muscle cells are sometimes called muscle fibers because they often resemble tiny threads.3 Types of Muscle Tissue:

1. Skeletal – what normally is thought of asmuscle. Meat of animals and constitutesabout 40% of a persons body weight

2. Cardiac – muscle of the heart, responsible forpumping blood. Under involuntary orunconscious control, and are cylindrical inshape. Often are branched and connected toone another by ‘intercalated disks’

3. Smooth – forms the walls of hollow organs.Responsible for movement of food andemptying of the urinary bladder

Nerve TissueNerve tissue – forms the brain, spinal chord and

nerves. Responsible for coordinating and controllingmany bodily activities such as awareness of selves,emotions, skills and memoryAction Potentials – electrical signals of nerve tissuesNeurons (nerve cells) – responsible for theconduction of action potentials

a.) Dendrites – nerve cell processes. Usuallyreceive stimuli

b.) Cell Body – site of general cell functionsc.) Neuroglia – support cells of the nervous

system. Function to nourish, protect andinsulate the neurons

MembranesMembrane – thin sheet or layer of tissue that coversa structure or lines of cavity2 Major Categories:

1. Mucous Membranes – consist of variouskinds of epithelium resting on thick layer ofloose connective tissue

2. Serous Membranes – consists of simplesquamous epithelium resting on a delicatelayer of loose connective tissue. Line the

trunk cavities and cover the organs locatedwithin cavitiesNamed according to their location:Pleural – associated with lungsPericardial – associated with heart

Peritoneal – located in abdominopelvic cavity

Rhinitis – inflammation of the mucous membrane ofthe nasal passagesPericarditis or Peritonitis – inflammation ofpericardial and peritoneal membranesPleurisy – inflammation of pleural membranes

Other MembranesSkin (cutaneous membrane) – stratified squamousepithelium and dense connective tissueSynovial Membranes – line the inside of jointcavitiesPeriosteum – surrounds bone

InflammationInflammatory Response or Inflammation – occurswhen tissues are damagedMediators of Inflammation – activated or released ininjured tissues and adjacent blood vessels. Theyincrease permeability of blood vesselsEx: kinins, prostaglandins, leuokotrienesEdema – swelling of tissues, results when water,proteins, and other substances from the blood moveinto the tissuesNeutrophil – phagocytic white blood cell that fightsinfections against bacteriaMacrophages – ingest tissue debris, clearing area oftissue repair. Removes dead neutrophilsChronic or Prolonged Inflammation – results whenthe agent responsible for an injury is not removed or

something else interferes with the process of healing

Tissue RepairTissue Repair – substitution of viable cells for deadcells. Can occur by regeneration or replacementRegeneration – new cells are the same type as thosethat were destroyedReplacement – new type of tissue develops thateventually causes scar production and loss of sometissue function3 Groups of Cells:

1. Labile – continue to divide throughout life2. Stable – do not actively divide after growth

ceases3. Permanent – have little or no ability to

divide

Stem Cells – precursor cells that are not fullydifferentiated into mature cellsClot – contains thread-like protein, fibrin, whichbinds the edges of the wound together and stops thebleedingScab – dried surface of the clot which seals the

wound and helps to prevent infectionGranulation Tissue – consists of fibroblasts, collagenand capillariesWound Contracture – result of the contraction offibroblasts in the granulation tissue

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Chapter 4 Anaphy