163 ch 04_lecture_presentation

© 2013 Pearson Education, Inc.

PowerPoint® Lecture Slidesprepared byMeg FlemmingAustin Community College

C H A P T E R4

The Tissue Level of Organization


Chapter 4 Learning Outcomes

• 4-1

• Identify the body's four basic types of tissues and describe their roles.

• 4-2

• Describe the characteristics and functions of epithelial cells.

• 4-3

• Describe the relationship between form and function for each type of epithelium.

• 4-4

• Compare the structures and functions of the various types of connective tissues.


Chapter 4 Learning Outcomes

• 4-5

• Explain how epithelial and connective tissues combine to form four types of tissue membranes, and specify the functions of each.

• 4-6

• Describe the three types of muscle tissue and the special structural features of each.

• 4-7

• Discuss the basic structure and role of neural tissue.

• 4-8

• Explain how injuries affect the tissues of the body.

• 4-9

• Describe how aging affects the tissues of the body.


Tissues (4-1)

• Collections of cells and cell products that perform specific,

limited functions

• Histology

• The study of tissues

• Four types of tissues

1. Epithelial

2. Connective

3. Muscle

4. Neural


CELLSThat

secreteand

regulate

EXTRACELLULARMATERIAL

AND FLUIDS

EPITHELIAL TISSUE• Covers exposed

surfaces• Lines internal

passageways andchambers

• Produces glandularsecretions

CONNECTIVE TISSUE• Fills internal spaces• Provides structural

support• Stores energy

MUSCLE TISSUE• Contracts to produce

active movement

NEURAL TISSUE• Conducts electrical

Impulses• Carries information

Combine to form

TISSUESwith special functions

Combineto form

ORGANSwith multiple functions

Interactin

ORGAN SYSTEMSChapters 5–20

Figure 4-1 An Orientation to the Tissues of the Body.


Checkpoint (4-1)

1. Define histology.

2. List the four basic types of tissues in the body.


Epithelial Tissue (4-2)

• Covers body surfaces

• Lines cavities

• Lines tubular structures

• Serves essential functions


Characteristics of Epithelial Tissue (4-2)

• Cellularity (cell junctions)

• Polarity (apical and basal surfaces)

• Attachment

• Avascularity

• Regeneration


Functions of Epithelia (4-2)

• Provide physical protection

• Control permeability

• Provide sensation

• Produce specialized secretions (glandular

epithelium)

• Exocrine glands

• Endocrine glands


Intercellular Connections (4-2)

• Support and communication

• Cell adhesion molecules (CAMs)

• Transmembrane proteins

• Intercellular cement

• Proteoglycans


Three Common Cell Junctions (4-2)

1. Tight junctions

2. Gap junctions

3. Desmosomes

• Form bonds with other cells or extracellular material


Figure 4-2a Cell Junctions.

Tight junction

Adhesion belt

Spotdesmosome

Gapjunctions

This is aDiagrammaticview of anepithelial cell,showing themajor types ofIntercellularconnections.

Hemidesmosome


Figure 4-2b Cell Junctions.

Interlockingjunctional

proteinsTight junction

Adhesion belt

Spotdesmosome

Gapjunctions

Hemidesmosome

A tight junction is formed by the fusion of the outerlayers of two plasma membranes. Tight junctionsprevent the diffusion of fluids and solutes betweenthe cells. A continuous adhesion belt deep to thetight junction is tied to the microfilaments of thecytoskeleton.

Adhesion belt

Tight junction


Figure 4-2c Cell Junctions.

Tight junction

Adhesion belt

Spotdesmosome

Gapjunctions

Hemidesmosome

Embedded proteins(connexons)

Gap junctions permitthe free diffusion ofions and small mol-ecules between twocells.


Tight junction

Adhesion belt

Spotdesmosome

Gapjunctions

Hemidesmosome

Intermediatefilaments

Dense area

Proteoglycans

A spot desmosometies adjacent cellstogether.

Cell adhesionmolecules (CAMs) Hemidesmosomes attach a

cell to extracellularstructures, such as theprotein fibers in the basementmembrane.

Tight junction

Adhesion belt

Spotdesmosome

Gapjunctions

Hemidesmosome

Basementmembrane

Figure 4-2d-e Cell Junctions.


The Epithelial Surface (4-2)

• Apical surface is exposed

• Basal surface is connected to deeper connective

tissue with basement membrane


Figure 4-3 The Surfaces of Epithelial Cells.

Cilia

Microvilli

Apicalsurface

Golgiapparatus

Nucleus

Mitochondria

Basement membrane


Epithelial Renewal and Repair (4-2)

• Epithelia are replaced by mitosis

• Cell division of stem cells (germinative cells)

• Occurs near basement membrane


Checkpoint (4-2)

3. List five important characteristics of epithelial tissue.

4. Identify four essential functions of epithelial tissue.

5. Identify the three main types of epithelial cell

junctions.

6. What physiological functions are enhanced by the

presence of microvilli or cilia on epithelial cells?


Classification of Epithelia (4-3)

• Combines a cell shape with the number of layers

of cells

• Example:

• Simple (one layer) cuboidal (square shape)


Cell Layers and Cell Shapes (4-3)

• Classification is based on layers

• Simple epithelium: single layer of cells

• Stratified epithelium: several layers of cells

• Classification is based on shape

• Squamous epithelia: thin and flat

• Cuboidal epithelia: square shaped

• Columnar epithelia: tall, slender rectangles


Table 4-1 Classifying Epithelia


Figure 4-4a Simple Epithelia.

Cytoplasm

Nucleus

Connective tissueLining of peritoneal cavity

LM x 238

Simple Squamous Epithelium

LOCATIONS: Epithelia lining ventral body cavities; lining heartand blood vessels; portions ofkidney tubules (thin sections of nephron loops); inner lining ofcornea; alveoli (air sacs) of lungs

FUNCTIONS: Reduces friction;controls vessel permeability;performs absorption and secretion


Figure 4-4b Simple Epithelia.

Connectivetissue

Nucleus

Cuboidalcells

Kidney tubule LM x 650

Basementmembrane

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

FUNCTIONS: Limited protection,secretion, absorption

Simple Cuboidal Epithelium


Figure 4-4c Simple Epithelia.

LM x 350

Microvilli

Cytoplasm

Nucleus

BasementmembraneConnective

tissueIntestinal lining

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

FUNCTIONS: Protection,secretion, absorption

Simple Columnar Epithelium


Figure 4-5a Stratified Epithelia.

Stratified Squamous Epithelium

Squamoussuperficial cells

Stem cellsBasementmembraneConnective

tissue LM x 310Surface of tongue

LOCATIONS: Surface ofskin; lining of mouth, throat,esophagus, rectum, anus,and vaginaFUNCTIONS: Provides physicalprotection against abrasion,pathogens, and chemical attack


Figure 4-5b Stratified Epithelia.

CytoplasmCilia

Nuclei

BasementmembraneConnective

tissueLM x 350

Pseudostratified Ciliated Columnar Epithelium

Trachea

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

FUNCTIONS: Protection,secretion, move mucuswith cilia


Figure 4-5c Stratified Epithelia.

Transitional Epithelium

Epithelium(relaxed)

Basement membraneConnective tissue andsmooth muscle layers LM x 400

Epithelium(stretched)

Basement membraneConnective tissue andsmooth muscle layersFull bladder

Empty bladder

Urinary bladderLM x 400

LOCATIONS: Urinarybladder; renal pelvis;ureters

FUNCTIONS: Permitsexpansion and recoilafter stretching


Glandular Epithelia (4-3)

• Endocrine glands

• Release hormones:

• Into interstitial fluid and plasma

• No ducts

• Exocrine glands

• Produce secretions:

• Onto epithelial surfaces

• Through ducts


Glandular Secretion (4-3)

• Merocrine secretion

• Produced in Golgi apparatus

• Released by vesicles (exocytosis)

• Example: sweat glands

• Apocrine secretion

• Produced in Golgi apparatus

• Released by shedding cytoplasm

• Example: mammary glands


Glandular Secretion (4-3)

• Holocrine secretion

• Released by cells bursting, killing gland cells

• Gland cells replaced by stem cells

• Example: sebaceous glands


SecretoryvesicleGolgiapparatus

Nucleus

Merocrine. In merocrine secretion, the contents of secretoryvesicles are discharged at the apical surface of the gland cellby exocytosis.

Breaksdown

Golgi apparatus

Salivary gland

Mammarygland

Secretion Regrowth

Apocrine. Apocrine secretion involves the loss of apical cytoplasm.Inclusions, secretory vesicles, and other cytoplasmic componentsare shed in the process. The gland cell then undergoes growth andrepair before it releases additional secretions.

Cells burst, releasingcytoplasmic contents

Cells produce secretion,increasing in size

Cell division replaceslost cells

Holocrine. Holocrine secretion occurs as superficial gland cellsburst. Continued secretion involves the replacement of these cellsthrough the mitotic division of underlying stem cells.

Sebaceousgland

Hair

Hair follicle

TEM x 3039

Stem cell

Figure 4-6 Mechanisms of Glandular Secretion.


Figure 4-6a Mechanisms of Glandular Secretion.

SecretoryvesicleGolgiapparatus

Nucleus

Merocrine. In merocrine secretion, the contents of secretoryvesicles are discharged at the apical surface of the gland cellby exocytosis.

Salivary gland

Mammarygland

Sebaceousgland

Hair

Hair follicle

TEM x 3039


Figure 4-6b Mechanisms of Glandular Secretion.

Breaksdown

Golgi apparatus

Salivary gland

Mammarygland

Secretion Regrowth

Apocrine. Apocrine secretion involves the loss of apical cytoplasm.Inclusions, secretory vesicles, and other cytoplasmic componentsare shed in the process. The gland cell then undergoes growth andrepair before it releases additional secretions.

Sebaceousgland

Hair

Hair follicle


Salivary gland

Mammarygland

Cells burst, releasingcytoplasmic contents

Cells produce secretion,increasing in size

Cell division replaceslost cells

Holocrine. Holocrine secretion occurs as superficial gland cellsburst. Continued secretion involves the replacement of these cellsthrough the mitotic division of underlying stem cells.

Sebaceousgland

Hair

Hair follicle

Stem cell

Figure 4-6c Mechanisms of Glandular Secretion.


Types of Secretion (4-3)

• Serous glands

• Watery secretions

• Mucous glands

• Secrete mucins

• Mixed exocrine glands

• Both serous and mucous


Table 4-2 A Classification of Exocrine Glands


Checkpoint (4-3)

7. Identify the three cell shapes characteristic of

epithelial cells.

8. Using a light microscope, you examine a tissue and

see a simple squamous epithelium on the outer

surface. Can this be a sample of skin surface?

9. Name the two primary types of glandular epithelia.


Checkpoint (4-3)

10.The secretory cells of sebaceous glands fill with

secretions and then rupture, releasing their

contents. Which mechanism of secretion occurs

in sebaceous glands?

11.Which type of gland releases its secretions

directly into the extracellular fluid?


Connective Tissue (4-4)

• Provides a protective structural framework for

other tissue types

• Three basic components

1. Specialized cells

2. Solid extracellular protein fibers

3. Fluid extracellular ground substance


Characteristics of Connective Tissue (4-4)

• The extracellular components of connective

tissues (fibers and ground substance) make up the

matrix

• Majority of tissue volume

• Determines specialized function


Functions of Connective Tissue (4-4)

• Support and protection

• Transportation of materials

• Storage of energy reserves

• Defense of the body


Figure 4-7 Major Types of Connective Tissue.

CONNECTIVE TISSUES

CONNECTIVE TISSUE PROPER FLUID CONNECTIVE TISSUES SUPPORTING CONNECTIVE TISSUES

LOOSE DENSE BLOOD LYMPH CARTILAGE BONE

Solid, crystallinematrix

Solid, rubberymatrix

Flows withinlymphatic

system

Flows withincardiovascular

system

Fibers denselypacked

Fibers createloose, openframework


Three Major Types of Connective Tissue (4-4)

1. Connective tissue proper

2. Fluid connective tissues

3. Supporting connective tissues


Cells of Connective Tissue Proper (4-4)

• Fibroblasts

• Most abundant cells in connective tissue proper

• Produce connective tissue fibers and ground substance

• Macrophages

• Scattered throughout the matrix

• Phagocytize damaged cells or pathogens that enter the tissue

• Release chemicals that mobilize the immune system


Cells of Connective Tissue Proper (4-4)

• Fat cells (adipocytes)

• Permanent residents

• Number of fat cells vary

• Mast cells

• Small, mobile cells often found near blood vessels

• Cytoplasm is packed with vesicles

• Filled with chemicals that are released to begin body's

defensive activities after an injury or infection


Three Basic Types of Connective Tissue Fibers (4-4)

1. Collagen fibers

• Long, straight, unbranched

• Strong, but flexible

• Most common

2. Elastic fibers

• Branched and wavy

• After stretching, they will return to their original length

• Contain the protein elastin


Three Basic Types of Connective Tissue Fibers (4-4)

3. Reticular fibers

• Made of same protein subunits as collagen fibers, but

arranged differently

• Thinner than collagen fibers

• Form branching, interwoven framework in various

organs

• Least common


Ground Substance (4-4)

• Clear, colorless, and viscous

• Fills spaces between cells and slows pathogen

movement


Types of Connective Tissue Proper (4-4)

• Loose connective tissue

• "Packing materials" of the body

• More ground substance, fewer fibers

• Example: fat (adipose tissue)

• Dense connective tissue

• Tough, strong, and durable

• More fibers, less ground substance

• Example: tendons


Figure 4-8 Cells and Fibers of Connective Tissue Proper.

Reticularfibers

Fixedmacrophage

Antibodyproducing cell

Blood invessel

Adipocytes(fat cells)

Groundsubstance

Mast cell

Elasticfibers

Freemacrophage

Collagenfibers

Fibroblast

Stem cell

White bloodcell


Figure 4-9a Loose Connective Tissues.

Mast cell

Collagenfibers

Fat cell

Fibroblasts

Elastic fibers

Macrophage

LM x 400Areolar tissue

Areolar Tissue

LOCATIONS: Beneath dermis ofskin, digestive tract, respiratoryand urinary tracts; betweenmuscles; around blood vessels,nerves, and around joints

FUNCTIONS: Cushionsorgans; provides supportbut permits independentmovement; phagocyticcells provide defenseagainst pathogens


Figure 4-9b Loose Connective Tissues.

Adipocytes

LM x 300Adipose tissue

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

FUNCTIONS: Providespadding and cushionsshocks; insulates(reduces heat loss);stores energy

Adipose Tissue


Figure 4-9c Loose Connective Tissues.

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

FUNCTIONS: Provides supportingframework

Reticular Tissue

Reticularfibers

LM x 375Reticular tissuefrom liver Reticular tissue


Figure 4-10a Dense Connective Tissues.

LOCATIONS: Between skeletalmuscles and skeleton (tendonsand aponeuroses); betweenbones or stabilizing positionsof internal organs (ligaments);covering skeletal muscles;deep fasciae

FUNCTIONS: Providesfirm attachment; conductspull of muscles; reducesfriction between muscles;stabilizes relative positionsof bones

Collagenfibers

Fibroblastnuclei

Tendon LM x 440

Dense Regular Connective Tissue


Figure 4-10b Dense Connective Tissues.

Deep dermis

Collagenfiber

bundles

Dense Irregular Connective Tissue

LM x 111

LOCATIONS: Capsules ofvisceral organs; periosteaand perichondria; nerveand muscle sheaths; deepdermis of the skin

FUNCTIONS: Providesstrength to resist forcesapplied from manydirections; helpsprevent overexpansionof organs such asthe urinary bladder


Fluid Connective Tissues (4-4)

• Blood and lymph

• Watery matrix of dissolved proteins

• Carry specific cell types (formed elements)

• Formed elements of blood

• Red blood cells

• White blood cells

• Platelets


Supporting Connective Tissues (4-4)

• Cartilage

• Gel-type ground substance

• For shock absorption and protection

• Bone

• Calcified (made rigid by calcium salts, minerals)

• For weight support


Cartilage (4-4)

• Cartilage matrix

• Proteoglycans derived from chondroitin sulfates

• Ground substance proteins

• Chondrocytes (cartilage cells)

• Surrounded by lacunae (chambers)


Cartilage Structure (4-4)

• Avascular

• Chondrocytes found in pockets called lacunae

• Perichondrium

• Outer, fibrous layer (for strength)

• Inner, cellular layer (for growth and maintenance)


Three Major Types of Cartilage (4-4)

1. Hyaline cartilage

• Stiff, flexible support

• Reduces friction between bones

• Found in synovial joints, rib tips, sternum, and trachea

2. Elastic cartilage

• Supportive but bends easily

• Found in external ear and epiglottis

3. Fibrocartilage

• Limits movement

• Prevents bone-to-bone contact

• Pads knee joints

• Found between pubic bones and intervertebral discs


Figure 4-11a Types of Cartilage.

LOCATIONS: Between tips of ribsand bones of sternum; coveringbone surfaces at synovial joints;supporting larynx (voice box),trachea, and bronchi; forming partof nasal septum

FUNCTIONS: Provides stiff butsomewhat flexible support;reduces frictionbetween bonysurfaces

Chondrocytesin lacunae

Matrix

Hyaline cartilageLM x 500

Hyaline Cartilage


Elastic Cartilage

ChondrocyteIn lacuna

Elastic fibersin matrix

LM x 358Elastic cartilage

LOCATIONS: Auricle of external ear;epiglottis; auditory canal; cuneiformcartilages of larynx

FUNCTIONS: Provides support, buttolerates distortion withoutdamage and returnsto original shape

Figure 4-11b Types of Cartilage.


Figure 4-11c Types of Cartilage.

Fibrocartilage

Chondrocytesin lacunae

Fibrousmatrix

LM x 400

Fibrocartilage

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

FUNCTIONS: Resistscompression;prevents bone-to-bonecontact; limitsmovement


Bone (4-4)

• Or osseous tissue

• Strong (hard calcium compounds)

• Resists shattering (flexible collagen fibers)

• Bone cells or osteocytes

• Arranged around central canals within matrix

• Small channels through matrix (canaliculi) access blood

supply


Periosteum (4-4)

• Covers bone surfaces

• Fibrous layer

• Cellular layer


Figure 4-12 Bone.

Osteon

Canaliculi

Lacunae (contain osteocytes)

MatrixCentral canal

Blood vessels

FibrouslayerCellularlayer

Periosteum

Osteon LM x 375


Table 4-3 A Comparison of Cartilage and Bone


Checkpoint (4-4)

12. Identify several functions of connective tissues.

13.List the three types of connective tissues.

14.Which type of connective tissue contains primarily triglycerides?

15.Lack of vitamin C in the diet interferes with the ability of fibroblasts to produce collagen. What effect might this interference have on connective tissue?

16.Which two types of connective tissue have a fluid matrix?


Checkpoint (4-4)

17. Identify the two types of supporting connective

tissue.

18. Why does cartilage heal slower than bone?


Tissue Membranes (4-5)

• Membranes

• Are physical barriers

• Line or cover portions of the body

• Consist of:

• An epithelium

• Supported by connective tissues


Four Types of Tissue Membranes (4-5)

1. Mucous membranes

2. Serous membranes

3. Cutaneous membrane

4. Synovial membranes


Figure 4-13 Tissue Membranes.

Mucous membranes are coated with the secretions of mucous glands. These membranes line the digestive, respiratory, urinary, and reproductive tracts.

Serous membranes line the ventral body cavities (the perito-neal, pleural, and pericardial cavities).

The cutaneous membrane, or skin, covers the outer surface of the body.

Synovial membranes line joint cavities and produce the fluid within the joint.

Mucous secretion

Epithelium

Lamina propria(areolar tissue)

Serous fluid

Epithelium

Areolar tissue

Epithelium

Areolar tissue

Dense irregularconnective tissue

Articular (hyaline) cartilage

Synovial fluid

Capsule

Capillary

Adipocytes

Areolartissue

EpitheliumSynovialmembrane

Bone


Mucous Membranes (4-5)

• Also known as mucosae

• Line passageways that have external connections

• In digestive, respiratory, urinary, and reproductive tracts

• Epithelial surfaces must be moist

• To reduce friction

• To facilitate absorption and excretion

• Lamina propria

• Made of areolar tissue


Mucous membranes are coated with the secretions of mucous glands. These membranes line the digestive, respiratory, urinary, and reproductive tracts.

Mucous secretion

Epithelium

Lamina propria(areolar tissue)

Figure 4-13a Tissue Membranes.


Serous Membranes (4-5)

• Line cavities not open to the outside

• Are thin but strong

• Have fluid transudate to reduce friction

• Have a parietal portion covering the cavity

• Have a visceral portion (serosa) covering the

organs


Three Serous Membranes (4-5)

1. Pleura

• Lines pleural cavities

• Covers lungs

2. Peritoneum

• Lines peritoneal cavity

• Covers abdominal organs

3. Pericardium

• Lines pericardial cavity

• Covers heart


Serous membranes line the ventral body cavities (the perito-neal, pleural, and pericardial cavities).

Serous fluid

Epithelium

Areolar tissue

Figure 4-13b Tissue Membranes.


The Cutaneous Membrane (4-5)

• Is skin

• Covers the surface of the body

• Thick, waterproof, and dry


The cutaneous membrane, or skin, covers the outer surface of the body.

Epithelium

Areolar tissue

Dense irregularconnective tissue

Figure 4-13c Tissue Membranes.


Synovial Membranes (4-5)

• Line moving, articulating joint cavities

• Produce synovial fluid (lubricant)

• Protect the ends of bones

• Lack a true epithelium


Synovial membranes line joint cavities and produce the fluid within the joint.

Articular (hyaline) cartilageSynovial fluid

Capsule

Capillary

Adipocytes

Areolartissue

EpitheliumSynovialmembrane

Bone

Figure 4-13d Tissue Membranes.


Checkpoint (4-5)

19. Identify the four types of tissue membranes found in the body.

20. How does a plasma (cell) membrane differ from a tissue membrane?

21. What is the function of fluids produced by serous membranes?

22. The lining of the nasal cavity is normally moist, contains numerous mucous cells, and rests on a layer of areolar tissue. Which type of membrane is this?


Three Types of Muscle Tissue (4-6)

1. Skeletal muscle tissue

• Large body muscles responsible for movement

2. Cardiac muscle tissue

• Found only in the heart

3. Smooth muscle tissue

• Found in walls of blood vessels

• Found around hollow organs such as the urinary bladder

• Around the respiratory, digestive, and reproductive tracts


Functions of Muscle Tissue (4-6)

• Specialized for contraction

• Produces all body movement


Cells are long, cylindrical, striated, and multinucleate.

LOCATIONS: Combined withconnective tissues and neural tissue in skeletal muscles

FUNCTIONS: Moves or stabilizes the position of the skeleton; guardsentrances and exits to the digestive, respiratory, and urinary tracts;generates heat; protects internalorgans

Nuclei

Musclefiber

Striations

Skeletal Muscle Tissue

Skeletal muscleLM x 180

Figure 4-14a Muscle Tissue.


Figure 4-14b Muscle Tissue.

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

LOCATION: Heart

FUNCTIONS: Circulates blood; maintains blood (hydrostatic) pressure

Cardiac Muscle Tissue

Cardiac muscle

Nucleus

Cardiacmuscle

cells

Intercalateddiscs

Striations

LM x 450


Figure 4-14c 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 reproductiveorgans

FUNCTIONS: Moves food, urine, andreproductive tract secretions; controlsdiameter of respiratory passageways;regulates diameter of blood vessels

Smooth Muscle Tissue

Nucleus

Smoothmuscle

cell

Smooth muscle LM x 235


Checkpoint (4-6)

23. Identify the three types of muscle tissue in the

body.

24. Voluntary control is restricted to which type of

muscle tissue?

25. Which type of muscle tissue has small, tapering

cells with single nuclei and no obvious striations?


Neural Tissue (4-7)

• Also called nervous or nerve tissue

• Specialized for conducting electrical impulses

• Rapidly senses internal or external environment

• Processes information and controls responses


Neural Tissue (4-7)

• Concentrated in the central nervous system

• Brain

• Spinal cord


Two Kinds of Neural Cells (4-7)

1. Neurons

• Nerve cells

• Perform electrical communication

2. Neuroglia

• Supporting cells

• Repair and supply nutrients to neurons


Cell Parts of a Neuron (4-7)

• Cell body

• Contains the nucleus and nucleolus

• Dendrites

• Short branches extending from the cell body

• Receive incoming signals

• Axon (nerve fiber)

• Long, thin extension of the cell body

• Carries outgoing electrical signals to their destination


Axonterminals

Brain

Spinalcord

Cellbody

Axon

Neuron

Nuclei ofneuroglia

Nucleusof neuron

Axon

Dendrites

Cell body

LM x 600

Photomicrographof neuron cellbody

Figure 4-15 Neural Tissue.


Checkpoint (4-7)

26. A tissue contains irregularly shaped cells with

many projections, including some several

centimeters long. These are probably which type

of cell?

27. Why are both skeletal muscle cells and axons

also called fibers?


Tissue Injuries and Repair (4-8)

• Tissues respond to injuries to maintain

homeostasis

• Cells restore homeostasis with two processes

1. Inflammation

2. Regeneration


Inflammation (4-8)

• Inflammatory response

• The tissue's first response to injury

• Signs and symptoms include:

• Swelling

• Heat

• Redness

• Pain


Inflammatory Response (4-8)

• Can be triggered by:

• Trauma (physical injury)

• Infection (the presence of harmful pathogens)


Checkpoint (4-8)

28. Identify the two phases in the response to tissue

injury.

29. What signs and symptoms are associated with

inflammation?

30. What is fibrosis?


Aging Tissue (4-9)

• With age:

• Rate of tissue repair declines

• Cancer rates increase


Aging and Tissue Structure (4-9)

• Speed and efficiency of tissue repair decrease

with age due to:

• Slower rate of energy consumption (metabolism)

• Hormonal alterations

• Reduced physical activity


Aging and Cancer Incidence (4-9)

• Cancer rates increase with age

• 1 in 4 people in the United States develops cancer

• Cancer is the #2 cause of death in the United States

• Environmental chemicals and cigarette smoke cause cancer


Checkpoint (4-9)

31. Identify some age-related factors that affect

tissue repair and structure.

Technology

163 ch 04_lecture_presentation