Dr. B Ch 03_lecture_presentation

© 2012 Pearson Education, Inc.

3Foundations:Tissues and Early Embryology

PowerPoint® Lecture Presentations prepared bySteven BassettSoutheast Community College Lincoln, Nebraska


Introduction

• This chapter concentrates on cells and tissues• There are over 75 trillion cells in the body• All cells can be placed into one of the four

tissue categories• Epithelial tissue• Connective tissue• Muscular tissue• Neural tissue


Figure 3.1 An Orientation to the Tissues of the Body

MOLECULESATOMS

CELLSEXTRACELLULAR

MATERIALAND FLUIDS

TISSUESwith special functions

ORGANSwith multiple functions

Organic / Inorganic

Combineto form

Interactto form

Thatsecrete

andregulate

Combine to form

Combineto form

ORGAN SYSTEMSChapters 4–27

Interactin

EPITHELIA

CONNECTIVETISSUES

MUSCLE TISSUE

NEURAL TISSUE

• Cover exposed surfaces• Line internal passageways and chambers• Produce glandular secretions See Figures 3.2 to 3.10

• Store energy See Figures 3.11 to 3.19, 3.21

• Contracts to produce active movement See Figure 3.22

• Conducts electrical impulses• Carries information See Figure 3.23

• Fill internal spaces• Provide structural support


Epithelial Tissue

• Epithelial Tissue Characteristics• Cellularity

• Cells are bound close together• No intercellular space

• Polarity • Have an exposed apical surface• Have an attached basal surface


Epithelial Tissue

• Epithelial Tissue Characteristics (continued)• Attachment

• Basal layer is attached to the basal lamina

• Avascularity• Do not consist of blood vessels


Epithelial Tissue

• Epithelial Tissue Characteristics (continued)• Arranged in sheets

• Composed of one or more layers of cells

• Regeneration• Cells are continuously replaced via cell

reproduction


Figure 3.2a Polarity of Epithelial CellsCilia

Microvilli

Apicalsurface

Golgiapparatus

Nucleus

Mitochondria

Basal lamina

Basolateralsurfaces

Many epithelial cells differ in internal organization along anaxis between the apical surface and the basal lamina. Theapical surface frequently bears microvilli; less often, it mayhave cilia or (very rarely) stereocilia. A single cell typicallyhas only one type of process; cilia and microvilli are showntogether to highlight their relative proportions. Tightjunctions prevent movement of pathogens or diffusion ofdissolved materials between the cells. Folds of plasmalemmanear the base of the cell increase the surface area exposed tothe basal lamina. Mitochondria are typically concentrated atthe basolateral region, probably to provide energy for thecell’s transport activities.


Epithelial Tissue

• Functions of Epithelial Tissue• Provides physical protection• Controls permeability• Provides sensation• Produces secretions


Epithelial Tissue

• Specialization of Epithelial Cells• Microvilli

• For absorption and secretion

• Stereocilia• Long microvilli, commonly found in the inner ear

• Ciliated epithelium• Moves substances over the apical surfaces of the

cells


Figure 3.2a Polarity of Epithelial CellsCilia

Microvilli

Apicalsurface

Golgiapparatus

Nucleus

Mitochondria

Basal lamina

Basolateralsurfaces

Many epithelial cells differ in internal organization along anaxis between the apical surface and the basal lamina. Theapical surface frequently bears microvilli; less often, it mayhave cilia or (very rarely) stereocilia. A single cell typicallyhas only one type of process; cilia and microvilli are showntogether to highlight their relative proportions. Tightjunctions prevent movement of pathogens or diffusion ofdissolved materials between the cells. Folds of plasmalemmanear the base of the cell increase the surface area exposed tothe basal lamina. Mitochondria are typically concentrated atthe basolateral region, probably to provide energy for thecell’s transport activities.


Figure 3.2b Polarity of Epithelial Cells

Cilia

Microvilli

An SEM showing the surface of the epithelium thatlines most of the respiratory tract. The small, bristlyareas are microvilli found on the exposed surfaces ofmucus-producing cells that are scattered among theciliated epithelial cells.


Epithelial Tissue

• Maintaining the Integrity of the Epithelium• Three factors involved in maintenance

• Intercellular connections• Attachment to the basal lamina

Lamina lucida: a clear layer of proteins that provides a barrier that restricts the movement of proteins and other large molecules.

Lamina densa: provided by underlying connective tissue and gives strength to basal lamina.

• Epithelial maintenance and renewal is self-perpetuated


Figure 3.3b Epithelia and Basal Laminae

Basallamina

Clear layerDense layer

CAMsProteoglycans(intercellular cement)Plasmalemma

Connective tissue

At their basal surfaces, epithelia are attached to abasal lamina that forms the boundary between theepithelial cells and the underlying connective tissue.


Epithelial Tissue

• Classification of Epithelia• Simple

• Epithelium has only one layer of cells

• Stratified • Epithelium has two or more layers of cells


Epithelial Tissue

• Epithelial Tissue Cells• Squamous cells

• Thin, flat cells / “squished” nuclei

• Cuboidal cells• Cube-shaped cells / centered, round nucleus

• Columnar cells• Longer than they are wide / nucleus near the base

• Transitional cells• Mixture of cells / nuclei appear to be scattered


Figure 3.4a Histology of Squamous Epithelia

Simple Squamous Epithelium

Connective tissue

Locations: Mesothelialining ventral body cavi-ties; endothelia liningheart and blood vessels;portions of kidney tubules(thin sections of nephronloops); inner lining ofcornea; alveoli of lungs

Functions: Reducesfriction; controls vesselpermeability; performsabsorption and secretion

A superficial view of the simple squamous epithelium (mesothelium) that lines the peritoneal cavity

Lining of peritoneal cavity

Cytoplasm

Nucleus

LM 238


Figure 3.4b Histology of Squamous Epithelia

Stratified Squamous Epithelium

Locations: Surface ofskin; lining of mouth, throat,esophagus, rectum, anus,and vagina

Functions: Provides physicalprotection against abrasion,pathogens, and chemical attack

Sectional views of the stratified squamous epithelium that covers the tongue

Surface of tongue

Stem cells

Basal lamina

Squamoussuperficial cells

Connectivetissue

LM 310


Figure 3.5a Histology of Cuboidal Epithelia

Simple Cuboidal Epithelium

LOCATIONS: Glands; ducts;portions of kidney tubules; thyroidgland

FUNCTIONS: Limited protection,secretion, absorption

A section through the simple cuboidal epithelium lining a kidney tubule. The diagrammatic view emphasizes structural details that permit the classification of an epithelium as cuboidal.

Connectivetissue

Cuboidalcells

Basallamina

Nucleus

LM 1400

Kidney tubule


Figure 3.5b Histology of Cuboidal Epithelia

Stratified Cuboidal Epithelium

LM 1413

Lumen of duct

Basal lamina

Nucleus

Connective tissue

Stratifiedcuboidal cells

Sweat gland duct

A sectional view of the stratified cuboidal epithelium lining a sweat gland duct in the skin

FUNCTIONS: Protection, secretion, absorption

LOCATIONS: Lining of some ducts(rare)


Figure 3.6a Histology of Columnar Epithelia

Simple Columnar Epithelium

Intestinal lining

A light micrograph showing the characteristics of simple columnar epithelium. In thediagrammatic sketch, note the relationships between the height and width of each cell; the relative size, shape, and location of nuclei; and the distance between adjacent nuclei. Contrast these observations with the corresponding characteristics of simple cuboidal epithelia.

LM 350

Loose connectivetissue

Basal lamina

Nucleus

Cytoplasm

Microvilli

LOCATIONS: Lining ofstomach, intestine, gallbladder,uterine tubes, and collectingducts of kidneys

FUNCTIONS: Protection,secretion, absorption


Figure 3.6b Histology of Columnar Epithelia

Stratified Columnar Epithelium

Salivary gland duct

FUNCTION: Protection

LOCATIONS: Small areas ofthe pharynx, epiglottis, anus,mammary gland, salivarygland ducts, and urethra

Lumen

A stratified columnar epithelium is sometimes found along large ducts, such as this salivary gland duct. Note the overall height of the epithelium and the location and orientation of the nuclei.


Deeper basalcells

Superficialcolumnar cells

Cytoplasm

Nuclei

Basal lamina

Lumen

LM 175


Figure 3.7a Histology of Pseudostratified Ciliated Columnar and Transitional Epithelia

Pseudostratified ciliated columnar epithelium

Pseudostratified ciliated columnar epithelium. The pseudostratified, ciliated, columnar epithelium of the respiratory tract. Note the uneven layering of the nuclei.

LOCATIONS: Lining ofnasal cavity, trachea, andbronchi; portions of malereproductive tract

FUNCTIONS: Protection,secretion

Trachea

Cilia

Cytoplasm

Nuclei

Basal lamina


LM 350


Figure 3.7b Histology of Pseudostratified Ciliated Columnar and Transitional Epithelia

Transitional epithelium

Transitional epithelium. A sectional view of the transitional epithelium lining the urinary bladder. The cells from an empty bladder are in the relaxed state, while those lining a full urinary bladder show the effects of stretching on the arrangement of cells in the epithelium.

LM 450

LM 450

Epithelium(relaxed)

Basal lamina

Connective tissue andsmooth muscle layers

Relaxed bladder

LOCATIONS: Urinarybladder; renal pelvis;ureters

FUNCTIONS: Permitsexpansion and recoilafter stretching

Basal lamina

Epithelium(stretched)

Stretched bladderConnective tissue andsmooth muscle layers


Epithelial Tissue

• Glandular Epithelia• Many epithelia are mixed with gland cells• Types of glands

• Serous glands: secrete watery fluids rich in enzymes

• Mucous glands: secrete glycoproteins (mucins) that absorb water to produce mucus

• Mixed exocrine glands: contain both serous and mucous secretions


Epithelial Tissue

• Glandular Epithelia (continued)• Endocrine glands

• Secretions enter into the blood or lymph

• Exocrine glands• Secretions travel through ducts to the epithelial

surface


Figure 3.9 A Structural Classification of Simple and Compound Exocrine Glands (Part 1 of 2)

Simple Glands

SIMPLETUBULAR

SIMPLE COILEDTUBULAR

SIMPLE BRANCHEDTUBULAR

SIMPLE ALVEOLAR(ACINAR)

SIMPLE BRANCHEDALVEOLAR

Examples: Examples: Examples: Examples: Examples:

Glandcells

Duct

• Intestinal glands • Merocrine sweat glands

• Gastric glands• Mucous glands of esophagus, tongue, duodenum

• Not found in adult; a stage in development of simple branched glands

• Sebaceous (oil) glands

Those that form blind pockets are alveolar oracinar.

Glands whose glandular cells form tubes aretubular; the tubes may be straight or coiled.


Epithelial Tissue

• Glandular Epithelia• Modes of Secretion

• Merocrine secretion• Apocrine secretion• Holocrine secretion


Epithelial Tissue

• Modes of Secretion• Merocrine Secretion

• Secretions released through exocytosis• Examples:

• Goblet cells of the trachea• Cells in the axilla region regarding sweat

production


Figure 3.10a Mechanisms of Glandular Secretion

Salivary gland

Secretory vesicle

Golgi apparatus

Nucleus

TEM 2300

In merocrine secretion, secretoryvesicles are discharged at the surfaceof the gland cell through exocytosis.


Epithelial Tissue

• Modes of Secretion• Apocrine Secretion

• Secretions released via the loss of cytoplasm

• Example: • Cells of the mammary glands for milk secretion


Figure 3.10b Mechanisms of Glandular Secretion

Mammarygland

Breaksdown

Secretion Regrowth

Apocrine secretion involves the loss of cytoplasm. Inclusions, secretory vesicles, and other cytoplasmiccomponents are shed at the apical surface of the cell. The gland cell then undergoes a period of growth and repair before releasing additional secretions.

Golgi apparatus


Epithelial Tissue

• Modes of Secretion• Holocrine Secretion

• Secretions released upon bursting of the glandular cells

• Example: • Cells of the sebaceous glands


Figure 3.10c Mechanisms of Glandular Secretion

Hair

Sebaceousgland

Hair follicle

Cells burst, releasingcytoplasmic contents

Cells produce secretion,increasing in size

Cell division replaceslost cells

Stem cell

Holocrine secretion occurs as superficial gland cells break apart. Continued secretion involves the replacement of these cells through the mitotic division of underlying stem cells.


Connective Tissues

• All connective tissues have three main components:• Specialized cells• Matrix

• The matrix is the collective term for the extracellular component of any connective tissue that is made of protein fibers and the ground substance

Collagen fibers are very long, cylindrical fibers made up of three subunits coiled around one another.

Collagen is the most common and strongest fiber. Reticular fibers are a single unit of collagen proteins. Elastic fibers contain the protein elastin.


Connective Tissues

• Functions of Connective Tissue• Establishing the structural framework of the

body• Transporting fluid and dissolved materials• Protecting organs• Supporting, surrounding, and connecting

other tissues• Storing energy• Defending the body from microorganisms


Connective Tissues

• Classification of Connective Tissue• Connective tissue proper

• Has a matrix of fibers (loose fibers and dense fibers)

• Fluid connective tissue• Has a matrix of liquid (blood and lymph)

• Supporting connective tissue• Has a matrix consisting of a gel or a solid (cartilage

and bone)


Figure 3.11 A Classification of Connective Tissues

Connective Tissues

Connective Tissue Proper Supporting Connective TissueBlood and Lymph

Loose Dense Blood Lymph Cartilage Bone

Solid,crystallinematrix

Solid, rubberymatrix

• hyaline cartilage

• elastic cartilage

• fibrous cartilage

Containedin lymphoidsystem

Contained in cardiovascularsystem

Fibers denselypacked

Fibers createloose, openframework

• areolar tissue

• adipose tissue• reticular tissue

• dense regular

• dense irregular

• elastic

can be divided into three types


Connective Tissue Proper

• Connective Tissue Proper• Loose fibers

• Areolar tissue• Adipose tissue• Reticular tissue

• Dense fibers• Dense regular• Dense irregular• Elastic



• Areolar Tissue (details)• Location

• Deep dermis• Between muscles

• Function• Connects skin to muscle

• Matrix• Fibers


Figure 3.14a Histology of Loose Connective Tissues

Areolar Tissue

Areolar tissue. Note the open framework; all the cells of connective tissue proper are found in areolar tissue.

LOCATIONS: Within and deep to the dermis of skin, and covered by the epithelial lining of the digestive,respiratory, and urinary tracts;between muscles; around bloodvessels, nerves, and around joints

FUNCTIONS: Cushions organs;provides support but permitsindependent movement; phagocytic cells provide defense against pathogens

Areolartissue frompleura

Collagenfibers

Mast cell

Elastic fibers

Adipocyte

Fibrocytes

Macrophage

LM 380



• Adipose Tissue (details)• Location

• Hypodermis• Buttocks, surrounds organs

• Function• Cushion• Insulation



Figure 3.14b Histology of Loose Connective Tissues

Adipose Tissue

Adipose tissue. Adipose tissue is a loose connective tissue dominated by adipocytes. In standard histological views, the cells look empty because their lipid inclusions dissolve during slide preparation.

LM 300

Adipocytes(white adipose cells)

LOCATIONS: Deep to the skin,especially at sides, buttocks,breasts; padding around eyesand kidneys

FUNCTIONS: Provides padding and cushions shocks; insulates(reduces heat loss); stores energy



• Reticular Tissue (details)• Location

• Liver, spleen, kidney, lymph nodes, tonsils, appendix, bone marrow

• Function• Supporting framework



Figure 3.14c Histology of Loose Connective Tissues

Reticular Tissue

Reticular tissue. Reticular tissue consists of an open framework of reticular fibers. These fibers are usually very difficult to see because of the large numbers of cells organized around them.

LOCATIONS: Liver, kidney, spleen,lymph nodes, and bone marrow

FUNCTIONS: Provides supporting framework

Reticular tissuefrom liver

Reticularfibers

LM 375



• Dense Regular Connective Tissue (details)• Location

• Tendons, aponeuroses, ligaments• Elastic tissue

• Function• Tendons: connect muscle to bone• Aponeuroses: connect muscle to muscle or covers entire

muscle• Ligaments: connect bone to bone• Elastic: stabilizes the vertebrae• Deep fasciae: which surrounds the muscles.



Figure 3.15a Histology of Dense Connective Tissues

Dense Regular Connective Tissue

Tendon. The dense regular connective tissue in a tendon consists of densely packed, parallel bundles of collagen fibers. The fibrocyte nuclei can be seen flattened between the bundles. Most ligaments resemble tendons in their histological organization.

LM 440

Collagenfibers

Fibrocytenuclei

LOCATIONS: Between skeletalmuscles and skeleton (tendonsand aponeuroses); betweenbones or stabilizingpositions of internalorgans (ligaments);covering skeletalmuscles; deep fasciae

FUNCTIONS: Provides firm attachment;conducts pull of muscles; reducesfriction between muscles; stabilizes relative positions of bones


Figure 3.15b Histology of Dense Connective Tissues

Elastic Tissue

Elastic Ligament. Elastic ligaments extend between the vertebrae of the spinalcolumn. The bundles of elastic fibers are fatter than the collagen fiber bundles of a tendon or typical ligament.

LM 887

Fibrocytenuclei

Elasticfibers

LOCATIONS: Between vertebrae of the spinal column (ligamentumflavum and ligamentum nuchae); ligaments supporting penis;ligaments supporting transitional epithelia; in blood vessel walls

FUNCTIONS: Stabilizes positions of vertebrae and penis; cushionsshocks; permits expansion and contraction of organs



• Dense Irregular Connective Tissue (details)• Location

• Nerve and muscle sheaths

• Function• Provides strength



Figure 3.15c Histology of Dense Connective Tissues

Dense Irregular Connective Tissue

Deep Dermis. The deep portion of the dermis of the skin consists of a thick layer of interwoven collagen fibers oriented in various directions.

LM 111

Collagenfiber

bundles

FUNCTIONS: Provides strength to resist force appliedfrom many directions; helps prevent overexpansionof organs such as the urinary bladder

LOCATIONS: Capsules of visceral organs; periosteaand perichondria; nerve and muscle sheaths; dermis


Fluid Connective Tissue

• Blood (details)• Location: circulatory system• Erythrocytes

• Transport oxygen and carbon dioxide

• Leukocytes• Fight infections

• Platelets• Blood clotting

• Matrix• Liquid (plasma)


Figure 3.16 Formed Elements of the Blood

Red blood cells White blood cells Platelets

Red blood cells areresponsible for thetransport of oxygen(and, to a lesser degree,of carbon dioxide) inthe blood.

Red blood cellsaccount for roughly halfthe volume of wholeblood, and give bloodits color.

White blood cells, or leukocytes(LOO-ko-sıts; leuko-, white), help defend thebody from infection and disease.

Monocytes arerelated to the freemacrophages inother tissues.

Lymphocytes arerelatively rare in theblood, but they arethe dominant celltype in lymph.

Eosinophils and neutrophilsare phagocytes. Basophilspromote inflammation muchlike mast cells in otherconnective tissues.

Eosinophil

Neutrophil

Basophil

The third type of formedelement consists ofmembrane-enclosedpackets of cytoplasmcalled platelets.

These cell fragmentsfunction in the clottingresponse that sealsleaks in diamaged orbroken blood vessels.


Fluid Connective Tissue

• Lymph (details)• Location

• Lymphoid system

• Lymphocytes• Develop into T cells and B cells (for example)

• Function• Involved with the immune system


Supporting Connective Tissue

• Supporting Connective Tissue• Cartilage and Bone

• Provide a strong framework that supports rest of body



• Cartilage• Types of Cartilage:

• Hyaline cartilage: the most common type of cartilage.

• Elastic cartilage• Fibrous cartilage


Figure 3.18a Histology of the Three Types of Cartilage

Hyaline Cartilage

Hyaline cartilage. Note the translucent matrix and the absence of prominent fibers.

LOCATIONS: Between tips of ribs and bones of sternum; covering bone surfaces at synovial joints; supporting larynx (voice box), trachea, and bronchi; forming part of nasal septum

FUNCTIONS: Provides stiff but somewhat flexible support; reducesfriction between bony surfaces

Chondrocytesin lacunae

Matrix

LM 500


Figure 3.18b Histology of the Three Types of Cartilage

Elastic Cartilage

Elastic cartilage. The closely packed elastic fibers are visible between the chondrocytes.

LM 358

Chondrocytein lacuna

Elastic fibersin matrix

LOCATIONS: Auricle of external ear; epiglottis; auditory canal; cuneiform cartilages of larynx

FUNCTIONS: Provides support, but tolerates distortion without damage and returns to original shape


Figure 3.18c Histology of the Three Types of Cartilage

Fibrous Cartilage

Fibrous cartilage. The collagen fibers are extremely dense, and the chondrocytes are relatively far apart.

LM 400

Chondrocytes

Fibrousmatrix

LOCATIONS: Pads within knee joint; between pubic bones ofpelvis; intervertebral discs

FUNCTIONS: Resists compression; prevents bone-to-bonecontact; limits relative movement



• Bone• Location

• Skeletal system

• Function• Support and strength

• Matrix• Solid (lamellae)


Figure 3.19 Anatomy and Histological Organization of Bone

Osteon

Osteon LM 375

Canaliculi

Osteocytesin lacunae

Matrix

Central canal

Blood vessels

Fibrouslayer

Cellularlayer

Periosteum

Periosteum

Compact bone

Compactbone

Spongybone

Small vein(contained incentral canal)

CapillaryConcentric

lamellae


Membranes

• Membranes• Epithelia and connective tissue combine to

form membranes• Each membrane consists of:

• Sheet of epithelial cells• An underlying connective tissue


Membranes

• Mucous membrane: • Covers the cavities that open to exterior.• Lines digestive, respiratory, urinary and reproductive system.

• Serous membrane:• Lines thoracic and abdominopelvic cavity.• Made of two leyers:

• Parietal layer: lines inside surface of thoracic andabdominopelvic cavity.

• Visceral layer: lines the outer surface of organs in the thoracic and abdominopelvic cavity.

• Synovial membrane:• Lines the joints.

• Cutaneous membrane:• Makes skin.


Figure 3.20a Membranes

Mucous secretion

Epithelium

Lamina propria(areolar tissue)

Mucous membranesare coated with the secretions of mucousglands. Mucousmembranes line mostof the digestive andrespiratory tracts andportions of the urinaryand reproductive tracts.


Figure 3.20b Membranes

Transudate

Mesothelium

Areolar tissue

Serous membranes linethe ventral bodycavities (the peritoneal,pleural, and pericardialcavities).


Figure 3.20c Membranes

Epithelium

Areolar tissue

Dense irregularconnective tissue

The cutaneousmembrane, the skin,covers the outersurface of the body.


Figure 3.20d Membranes

Articular (hyaline) tissue

Synovial fluid

Capsule

Capillary

Adipocytes

Areolar tissue

Epithelium

Bone

Synovialmembrane

Synovial membranesline joint cavities andproduce the fluid withinthe joint.


The Connective Tissue Framework of the Body

• Connective tissue creates the internal framework of the body

• Layers of connective tissue connect organs with the rest of the body

• Layers of connective tissue are called fascia• Superficial fascia• Deep fascia• Subserous fascia


Figure 3.21 The Fasciae

Connective Tissue Framework of Body

Superficial Fascia

Deep Fascia

Subserous Fascia

• Between skin and underlying organs

• Areolar tissue and adipose tissue

• Also known as subcutaneous layer or hypodermis

• Forms a strong, fibrous internal framework

• Dense connective tissue

• Bound to capsules, tendons, ligaments, etc.

• Between serous membranes and deep fascia

• Areolar tissue

Body cavity

Rib

Serousmembrane

Cutaneousmembrane

Skin

Body wall


Muscle Tissue

• Three types of muscle tissue• Skeletal muscle

• Has striations

• Smooth muscle• Ends of the cells are pointy

• Cardiac muscle• Has intercalated discs


Muscle Tissue

• Skeletal muscle• Muscles that move the skeleton• Voluntary control

• Smooth muscle• Muscles that line the digestive tract, respiratory

tract, and blood vessels• Involuntary control

• Cardiac muscle• Found in the myometrium of the heart• Muscles cells that contract rhythmically


Figure 3.22a Histology of Muscle Tissue

Skeletal Muscle Tissue

Cells are long, cylindrical,striated, and multinucleate.

LOCATIONS: Combined with connective tissues and neuraltissue in skeletal muscles

FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, andurinary tracts; generates heat; protects internal organs

Skeletal Muscle Fibers. Note the large fiber size, prominent banding pattern,multiple nuclei, and unbranched arrangement.

Nuclei

Musclefiber

Striations

LM 180


Figure 3.22c Histology of Muscle Tissue

Smooth Muscle Tissue

Cells are short, spindle-shaped, andnonstriated, with a single, centralnucleus

LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs

FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratorypassageways; regulates diameter of blood vessels

Smooth Muscle Cells. Smooth muscle cells are small and spindle shaped, with a central nucleus. They do not branch, and there are no striations.

LM 235

Nucleus

Smoothmuscle

cell


Figure 3.22b Histology of Muscle Tissue

Cardiac Muscle Tissue

Nuclei

Striations

Cardiacmuscle

cells

Intercalateddiscs

Cells are short, branched, and striated,usually with a single nucleus; cells areinterconnected by intercalated discs.

LOCATION: Heart

FUNCTIONS: Circulates blood;maintains blood (hydrostatic) pressure

LM 450

Cardiac Muscle Cells. Cardiac muscle cells differ from skeletal muscle fibers in three major ways: size (cardiac muscle cells are smaller), organization (cardiac muscle cells branch), and number of nuclei (a typical cardiac muscle cell has one centrally placed nucleus). Both contain actin and myosin filaments in an organized array that produces the striations seen in both types of muscle cell.


Neural Tissue

• Neural Tissue• Specialized to conduct electrical signals

through the body• Two types of neural cells

• Neurons are the cells that actually transmit the impulse (electrical signals)

• Neuroglia are the supporting cells of the neural tissue; these cells protect the neurons


Figure 3.23a Histology of Neural Tissue

Brain

Spinal cord

Cell body

Axon

Nucleus ofneuronNucleolus

Dendrites

Diagrammatic view of a representative neuron


Figure 3.23b Histology of Neural Tissue

Nuclei ofneuroglia

Cell body

Nucleus ofneuron

Nucleolus

Axon

Dendrites

Neuron cell body LM 600

Histological view of arepresentative neuron


Tissues, Nutrition, and Aging

• Repair and maintenance become less efficient as one ages

• Hormonal changes and lifestyle changes also affect the functioning of tissues

• Epithelia become thinner and connective tissues become fragile

• Cardiac muscle cells and neural tissue cannot regenerate; therefore, relatively minor damage adds up over time, sometimes causing severe health issues

Dr. B Ch 03_lecture_presentation

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