chapter 3 & 4 cells and tissues. anatomy of a cell plasma membrane “cell” –fluid mosaic...

Chapter 3 & 4 Cells and Tissues

Anatomy of a Cell• Plasma Membrane “cell”

– Fluid Mosaic Model• Phospholipids – cushioning insulation• Proteins – growth maintenance and

repair• Both are double layered• semipermeable

• Specializations– Microvilli – tiny projections that

absorb nutrients– Membrane Junctions

Cellular Organization• Cytoplasm – jelly like material in cells

– 70% H20, 30% proteins lipids minerals• Organelles

– Mitochondria• “powerhouse” • “cellular respiration” • makes energy ATP

– Ribosomes• Makes “protein synthesis”

– Endoplasmic Reticulum• “canal systems”• Rough E.R. – transport proteins• Smooth E.R. – make lipids & transport them

More Cellular Organization

• Golgi Apparatus– Package and store proteins, lipids,

carbohydrates• Lysosomes

– Digestive organelles• Vacuoles

– Storage organelles• Cytoskeletal

– Support cell, protein filaments• Centrioles

– Cell division, cylinders

Nucleus – control center• Nuclear Membrane

• Nucleoli (nucleolus)– makes ribosomes & RNA

• Chromatin– Thread like– All chromosomes in a strand– DNA – heredity (code of life)

5-6

The Primary Tissue Classes

• tissue – a group of similar cells and cell products that arise from the same region of the embryo and work together to perform a specific structural or physiological role in an organ.

• four primary tissues differ from one another in the:– types and functions of their cells– the characteristics of the matrix (extracellular material)– the relative amount of space occupied by cells versus matrix

• matrix – (extracellular material) is composed of :– fibrous proteins– a clear gel known as ground substance , tissue fluid,

extracellular fluid (ECF), interstitial fluid, or tissue gel

5-7

The Study of Tissues• 50 trillion cells of 200 different cell types

• four broad categories of tissues– epithelial tissue– connective tissue– nervous tissue– muscular tissue

• organ - structure with discrete boundaries that is composed of two or more tissue types

• histology (microscopic anatomy) – the study of tissues and how they are arranged into organs

5-8

Types of Tissue Sections

• longitudinal section (l.s.)– tissue cut along long direction of

organ

• cross section (c.s. or x.s.) or transverse section (t.s.)– tissue cut perpendicular to

length of organ

• oblique section– tissue cut at angle between

cross and longitudinal section

Figure 5.2

Longitudinal sections

Cross sections

Oblique sections

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Epithelial Tissues– Primary Functions

• Protection• Absorption• Filtration• Secretion

• Features of Epithelial Cells– Cell Junctions – close– One cell surface is free

• Apical – exposed to surface or cavity

Epithelial Cont..– Basement membrane – lowest

surface– Avascular – no blood supply,

diffusion– Regeneration – easy fast, mitosis

• Cell Shapes– Squamous

• Scale, flattened– Cuboidal

• Cube shaped– Columnar

• Taller than wide

Types of Epithelial Tissues• Simple

– Single layer• Stratified

– Many layers• Pseudostratified

– Looks like many layers- is really only one

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Simple vs. Stratified Epithelia• Simple epithelium

– contains one layer of cells– named by shape of cells– all cells touch the basement

membrane

• Stratified epithelium– contains more than one layer– named by shape of apical cells– some cells rest on top of others

and do not touch basement

membrane

Figure 5.3

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Squamous Cuboidal Columnar

Simple

(a) Classes of epithelium

Pseudostratifiedcolumnar

Stratified

(b) Cell shapes

Epithelial • Simple Squamous

–One layer–Filtration–Diffusion–Locations: Pericardium,Pleura, Alveoli, Capillary walls

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• single row of thin cells• permits rapid diffusion or transport of substances• secretes serous fluid• alveoli, glomeruli, endothelium, and serosa

Figure 5.4b,iFigure 5.4a

Squamous epithelial cells

Basement membrane

Nuclei of smooth muscle

(b)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

(a)

Simple Squamous Epithelium

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Simple CuboidalOne layerCube shapedLocations: thyroid glandSalivary glands, kidney tubules

Stratified CuboidalMore than one layerCube shapedLocations: lines sweat glands

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Simple Cuboidal Epithelium

• single layer of square or round cells• absorption and secretion, mucus production and movement• liver, thyroid, mammary and salivary glands, bronchioles,

and kidney tubules

Figure 5.5b,iFigure 5.5a

(a)

Lumen of kidney tubule Cuboidal epithelial cells Basement membrane

(b)

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a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

5-17

Simple ColumnarTaller than wideLine digestive tractGoblet cells

Secrete mucus

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• single row tall, narrow cells– oval nuclei in basal half of cell– brush border of microvilli, ciliated in some organs, may possess

goblet cells• absorption and secretion; mucus secretion • lining of GI tract, uterus, kidney and uterine tubes

Figure 5.6a

(a)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Connectivetissue

Basementmembrane Nuclei

Gobletcell

(b)

Columnarcells

Brush border(microvilli)

Figure 5.6b,i

Simple Columnar Epithelium

a: © Lester V. Bergman

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Pseudostratified ColumnarOne cell layer(looks like more)Ciliated w/Goblet cellsLine respiratory tract

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Pseudostratified Epithelium

• looks multilayered; some not reaching free surface; all touch basement membrane– nuclei at several layers– with cilia and goblet cells

• secretes and propels mucus • respiratory tract and portions of male urethra

Figure 5.7b,iFigure 5.7a

(a)

Cilia Basal cells Goblet cell

(b)

Basement membrane

a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-21

Stratified SquamousSeveral layersLocated: Rectum, SkinLining of mouth, top third of esophagus Keratinized(callus) and Non Keratinized

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Keratinized Stratified Squamous

• multiple cell layers with cells becoming flat and scaly toward surface

• epidermis; palms and soles heavily keratinized• resists abrasion; retards water loss through skin; resists

penetration by pathogenic organisms

Figure 5.8b,iFigure 5.8a

(a)

Dead squamous cells Living epithelial cellsDense irregularconnective tissue

(b)

Areolar tissue

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a: © The McGraw-Hill Companies, Inc./Joe DeGrandis, photographer

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Nonkeratinized Stratified Squamous

• same as keratinized epithelium without the surface layer of dead cells

• tongue, oral mucosa, esophagus and vagina• resists abrasion and penetration of pathogens

Figure 5.9b,iFigure 5.9a

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a: © Ed Reschke

(a)

Living epithelial cells Connective tissue

(b)

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TransitionalLocated: bladder, uterusStretched – one layerRelaxed – many layers

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Transitional Epithelium

• multilayered epithelium surface cells that change from round to flat when stretched

• allows for filling of urinary tract• ureter and bladder

Figure 5.11b,iFigure 5.11a

(a)

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Connectivetissue

(b)

Basementmembrane

Binucleateepithelial cell

a: Johnny R. Howze

• Glandular Epithelial- secretes– Endocrine “in”

• Ductless• Hormones -- blood

– Exocrine “out”• Ducts

– Lined with stratified cuboidal or stratified columnar

– Sweat, salivary, oil glands, bile duct, pancreatic duct

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Types of Secretions• serous glands

– produce thin, watery secretions• perspiration, milk, tears and digestive juices

• mucous glands– produce glycoprotein, mucin, that absorbs water to form a

sticky secretion called mucus– goblet cells – unicellular mucous glands

• mixed glands – contain both cell types and produce a mixture of the two

types of secretions

• cytogenic glands – release whole cells, sperm and egg cells

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Functions of Connective Tissue• binding of organs – tendons and ligaments

• support – bones and cartilage

• physical protection – cranium, ribs, sternum

• immune protection – white blood cells attack foreign invaders

• movement – bones provide lever system

• storage – fat, calcium, phosphorus

• heat production – metabolism of brown fat in infants

• transport - blood

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VascularizedGood blood supplyExcept for …

TendonsLigamentsCartilage have none

Extracellular matrixNon living

LiquidGel solidSemi solidsolid

Connective Tissues– Fibers

• Collagen - protein– White- strength

• Elastin– Yellow- stretch

• Reticular fibers• thin collagen fibers coated with glycoprotein• form framework of such organs as spleen and lymph

nodes

(b)

ReticularfibersLeukocytes

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Reticular Tissue

• mesh of reticular fibers and fibroblasts• forms supportive stroma (framework) for

lymphatic organs• found in lymph nodes, spleen, thymus and bone

marrow

Figure 5.15aa: The McGraw-Hill Companies, Inc./Al Telser, photographer

(a)

Figure 5.15b,i

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5-32

Types of Fibrous Connective Tissue

• loose connective tissue– much gel-like ground

substance between cells– types

• areolar• reticular

• dense connective tissue– fibers fill spaces between cells– types vary in fiber orientation

• dense regular connective tissue• dense irregular connective tissue

Figure 5.13

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Tendons

© The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/Don Kincaid, dissections

5-33

Specialized CellsFibroblasts- make fibersOsteocytes- bone cellsChondrocytes- cartilage cellsMacrophages- engulf bacteria

Types of Connective Tissues

–Loose – areolar (most common)• Matrix : liquid• Fibers: collagen & elastin• Cells: fibroblasts, macrophages, fat cells, plasma cells

5-35

Areolar Tissue

• loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space

• underlies all epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels

Figure 5.14a

(a)

Elasticfibers

Collagenousfibers

(b)

FibroblastsGroundsubstance

Figure 5.14b,i

a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-36

Dense – “fibrous” poor blood supplyCollagen fibers few fibroblastsTendons – bone to muscleLigaments- bone to bone

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Dense Regular Connective Tissue

• densely, packed, parallel collagen fibers– compressed fibroblast nuclei

• tendons attach muscles to bones and ligaments hold bones together

Figure 5.16b,iFigure 5.16a

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(a) (b)

Fibroblast nucleiGround substanceCollagen fibers

a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

• Adipose – “fat”–Large vacuole w/ droplet of oil–Subcutaneous layer around

organs– Insulation–Cushion–Store energy

• on average, women have more fat than men• too little fat can reduce female fertility• most adult fat is called white fat• brown fat – in fetuses, infants, children – a heat

generating tissue

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Adipose Tissue

• empty-looking cells with thin margins; nucleus pressed against cell membrane

• energy storage, insulation, cushioning– subcutaneous fat and organ packing– brown fat (hibernating animals) produces heat

Figure 5.18b,iFigure 5.18a

(a) (b)

Lipid inadipocyte

Adipocytenucleus

Bloodvessel

a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

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Osseous Tissue• Bone Bone cells- osteocytes

– Collagen fibers– Solid matrix – Ca & P

5-41

Bone Tissue (compact bone)

• most compact bone is arranged in cylinders that surround central (haversian or osteonic) canals that run longitudinally through shafts of long bones– blood vessels and nerves travel through central canal

• bone matrix deposited in concentric lamella– onionlike layers around each central canal

• osteon – central canal and its surrounding lamellae• osteocytes – mature bone cells that occupy the lacunae• canaliculi – delicate canals that radiate from each lacuna to its neighbors, and

allows osteocytes to contact each other• periosteum – tough fibrous connective tissue covering of the bone as a whole

Figure 5.22a Figure 5.22b,i

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(a)

a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

(b)

Concentriclamellaeof osteon

CentralcanalLacunae Canaliculi Osteon

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Blood – “liquid”Blood cells

RedWhiteplatelets

Fluid matrixPlasmaFibers

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Blood• fluid connective tissue

• transports cells and dissolved matter from place to place

• plasma – blood’s liquid ground substance

• formed elements – cells and cell fragments– erythrocytes – red blood

cells – transport O2 and CO2

– leukocytes – white blood cells – defense against infection and other diseases

– platelets – cell fragments involved in clotting and other mechanisms

Figure 5.23b,i

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(b)

MonocyteErythrocytesLymphocyteNeutrophilsPlatelets

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Cartilage – no blood supplyCartilage cells in gel matrixCollagen & elastin fibersTypes

Hyaline – glassy “blue”Outer noseLarynxRibfetus

Elastin –mostly elastin fibersOuter earepiglottis

Fibrocartilage – collagen & found in vertebral discs & knees

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Hyaline Cartilage

• clear, glassy microscopic appearance because of unusualfineness of the collagen fibers

• usually covered by perichondrium• articular cartilage, costal cartilage, trachea, larynx, fetal skeleton• eases joint movement, holds airway open, moves vocal cords during

speech

Figure 5.19a

(a)

a: © Ed Reschke

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

(b)

ChondrocytesPerichondriumMatrix LacunaeCellnest

Figure 5.19b,i

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Elastic Cartilage

• cartilage containing elastic fibers • covered with perichondrium• provides flexible, elastic support

– external ear and epiglottis

Figure 5.20a

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(a) (b)

Perichondrium

Elasticfibers ChondrocytesLacunae

a: © Ed Reschke

Figure 5.20b,i

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• cartilage containing large, coarse bundles of collagen fibers • never has perichondrium• resists compression and absorbs shock

– pubic symphysis, menisci, and intervertebral discs

Figure 5.21a Figure 5.21b,i

Fibrocartilage

(a)

a: Dr. Alvin Telser

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(b)

Collagenfibers Chondrocytes

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Muscular Tissue• muscular tissue – elongated cells that are

specialized to contract in response to stimulation

• primary job is to exert physical force on other tissues and organs

• creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation

• important source of body heat

• three types of muscle: skeletal, cardiac, and smooth

Striated Muscle Tissue– Skeletal

• Striations• Voluntary• Attached to bone• Gross movements

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Skeletal Muscle• long, threadlike cells – muscle fibers• most attach to bone• exceptions – in tongue, upper esophagus, facial muscles, some

sphincter muscles – (ringlike or cufflike muscles that open and close body passages)

• contains multiple nuclei adjacent to plasma membrane• striations – alternating dark and light bands• voluntary – conscious control over skeletal muscles

Figure 5.25a Figure 5.25b,i

(a)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Striations Muscle fiber

(b)

Nuclei

a: © Ed Reschke

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CardiacStriationsBranchingInvoluntaryHeart

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Cardiac Muscle• limited to the heart• myocytes or cardiocytes are much shorter, branched, and notched at

ends• contain one centrally located nucleus surrounded by light staining

glycogen• intercalated discs join cardiocytes end to end

– provide electrical and mechanical connection• striated, and involuntary (not under conscious control)

Figure 5.26a Figure 5.26b,i

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(a) (b)

GlycogenStriationsIntercalated discs

© Ed Reschke

5-53

Smooth MuscleNo striationsInvoluntaryBlood vesselsOrgans of digestionperistalsis

5-54

Smooth Muscle

Figure 5.27a

(a)

Muscle cellsNuclei

(b)

Figure 5.27b,ia: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• lacks striations and is involuntary• relatively short, fusiform cells (thick in middle, tapered at ends)• one centrally located nucleus• visceral muscle – forms layers of digestive, respiratory, and urinary tract:

blood vessels, uterus and other viscera• propels contents through an organ, regulates diameter of blood vessels

Nervous Tissues• Nervous Tissue

–Functions• Irritability “react to stimuli”• Conductivity – flow of ions Na+ & K+

– Neuron Types• Sensory• Motor• associative

5-56

Nervous Tissue• nervous tissue – specialized for

communication by electrical and chemical signals

• consists of neurons (nerve cells) – – detect stimuli– respond quickly– transmit coded information rapidly to

other cells

• and neuroglia (glial)– protect and assist neurons– ‘housekeepers’ of nervous system

• neuron parts– neurosoma (cell body)

• houses nucleus and other organelles• cell’s center of genetic control and protein

synthesis– dendrites

• multiple short, branched processes• receive signals from other cells• transmit messages to neurosoma

– axon (nerve fiber)• sends outgoing signals to other cells• can be more than a meter long

Figure 5.24b,i

(b)

DendritesNeurosomaAxonNuclei of glial cells

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Tissue Repair–Regeneration

•Mitosis•Replacement w/ same type of cell

–Fibrosis•Scar tissue•Repair w/ fibrous connective tissue

5-58

Wound Healing• severed blood vessels bleed

into cut

• mast cells and damaged cells release histamine– dilates blood vessels– increases blood flow to area– makes capillaries more

permeable

• blood plasma seeps into the wound carrying:– antibodies– clotting proteins– blood cellsFigure 5.33 (1)

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1 Bleeding into the wound

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Wound Healing

• blood clot forms in the tissue

• forms scab that temporarily seals wound and blocks infection

• macrophages phagocytize and digest tissue debris

Figure 5.33 (2)

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Scab

Blood clot

Macrophages

Fibroblasts

Leukocytes

Scab formation andmacrophage activity

2

5-60

Wound Healing

• new capillaries sprout from nearby vessels and grow into wound

• deeper portions become infiltrated by capillaries and fibroblastsbegins 3-4 days after injury and lasts up to 2 weeks

Scab

Macrophages

Fibroblasts

Formation of granulation tissue (fibroblastic phase of repair)

Blood capillary

Granulation tissue

3

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Figure 5.33 (3)

5-61

Wound Healing• surface epithelial cells

around wound multiply and migrate into wound area beneath scab

• epithelium regenerates

• connective tissue undergoes fibrosis

• scar tissue may or may not show through epithelium

• remodeling (maturation) phase begins several weeks after injury and may last up to two years

Epidermal regrowth

Scar tissue (fibrosis)

Epithelial regeneration and connective tissue fibrosis (remodeling phase of repair)

4

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Figure 5.33 (4)

Tissues

• Developmental Aspects– Growth

• mitosis– Aging

• Collagen fibers loss• Muscle-loss• Bone-loss• Thinning of epithelial

Tissues• Neoplasms

– Cancerous• Abnormal growth rapidly dividing cells

– Benign – stopped– Malignant – still undergoing rapid mitosis

– Hyperplasia• Enlargement of body tissue

– Atrophy• Decrease in size (muscle)

– Hypertrophy-increase

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Tissue Shrinkage and Death• necrosis – premature, pathological death of tissue due to

trauma, toxins, or infections– infarction – sudden death of tissue when blood supply is cut off– gangrene – tissue necrosis due to insufficient blood supply– decubitus ulcer – bed sore or pressure sore

• pressure reduces blood flow to an area• a form of dry gangrene

– gas gangrene - anaerobic bacterial infection

• apoptosis - programmed cell death– normal death of cells that have completed their function and best

serve the body by dying and getting out of the way

5-65

Changes in Tissue Types

• Tissues can change types

• Differentiation– unspecialized tissues of embryo become specialized

mature types• mesenchyme to muscle

• Metaplasia– changing from one type of mature tissue to another

• simple cuboidal tissue of vagina before puberty changes to stratified squamous after puberty

• pseudostratified columnar epithelium of bronchi of smokers to stratified squamous epithelium

5-66

Stem Cells• stem cells - undifferentiated cells that are not yet performing any

specialized function– have potential to differentiate into one or more types of mature

functional cells

• embryonic stem cells– have potential to develop into any type of fully differentiated human

cell

– can develop into any type of cell in the embryo• source - cells of inner cell mass of embryo

• adult stem cells - undifferentiated cells in tissues of adults– bone marrow producing several blood cell types– – most limited plasticity - only epidermal cells produced

5-67

Tissue Engineering• tissue engineering – artificial production of

tissues and organs in the lab for implantation in the human body– framework of collagen or biodegradable polyester fibers– seeded with human cells– grown in “bioreactor” (inside of mouse)

• supplies nutrients and oxygen to growing tissue

• skin grafts already available– research in progress on heart valves, coronary arteries,

bone, liver, tendons– human outer ear grown on back of mouse and recent

replacement of urinary bladder wall sections

5-68

Tissue Engineering

Figure 5.34

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5-69

Stem Cell Controversy• possible treatment for diseases caused by

loss of functional cell types by embryonic stem cells– cardiac muscle cells, injured spinal cord, insulin-

secreting cells

• skin and bone marrow stem cells have been used in therapy for years

• adult stem cells have limited developmental potential– difficult to harvest and culture