Basic Cellular Concepts Basic Cellular Concepts

John P. McDonough,John P. McDonough, CRNA, Ed.D., ARNPCRNA, Ed.D., ARNP

Cellular FunctionsCellular Functions

Cells become specialized through Cells become specialized through differentiationdifferentiation. . The 7 chief functions are: The 7 chief functions are:– movementmovement– conductivityconductivity– metabolic absorptionmetabolic absorption– secretionsecretion– excretionexcretion– respirationrespiration– reproductionreproduction

Structure & Function of Typical Structure & Function of Typical “eukaryotic” Cell“eukaryotic” Cell

The 3 components:The 3 components: Plasma membrane (plasmalemma)Plasma membrane (plasmalemma) CytoplasmCytoplasm OrganellesOrganelles

OrganellesOrganelles

NucleousNucleous– surrounded by cytoplasm (not a cytoplasmic surrounded by cytoplasm (not a cytoplasmic

organelle)organelle)– largest membrane bound organellelargest membrane bound organelle– 2 membrane “nuclear envelope”2 membrane “nuclear envelope”– nucleolus (houses DNA, histones, etc)nucleolus (houses DNA, histones, etc)– controls cell division and genetic informationcontrols cell division and genetic information

Organelles (con’t)Organelles (con’t)

RibosomesRibosomes Endoplasmic reticulum Endoplasmic reticulum Golgi complexGolgi complex LysosomesLysosomes PerioxomesPerioxomes Mitochondria Mitochondria Cytoskeleton Cytoskeleton Microtubules & Actin filamentsMicrotubules & Actin filaments

Cellular ReceptorsCellular Receptors

Protein molecules capable of:Protein molecules capable of:– recognizing ligandsrecognizing ligands– binding with ligandsbinding with ligands

Classified on basis of location and functionClassified on basis of location and function Receptors for drugs are found on the Receptors for drugs are found on the

membrane, cytoplasm & nucleusmembrane, cytoplasm & nucleus Membrane receptors are known for:Membrane receptors are known for:

– anesthetics, opiates, endorphins, enkephalins, etc.anesthetics, opiates, endorphins, enkephalins, etc.

Cell-To-Cell CommunicationCell-To-Cell Communication

EndocrineEndocrine ParacrineParacrine AutocrineAutocrine SynapticSynaptic

Cellular Intake & OutputCellular Intake & Output

Cells continually have “in & out” trafficCells continually have “in & out” traffic Passive transport (no Passive transport (no lifelife required) required)

– diffusiondiffusion– hydrostatic pressurehydrostatic pressure– osmosis osmosis

Active transportActive transport– requires energyrequires energy– requires receptors requires receptors

Active Transport of NaActive Transport of Na++ & K & K++

Found in virtually all mammalian cellsFound in virtually all mammalian cells Na Na ++ moves in, K moves in, K++ moves out moves out Uses energy of ATP (60-70% total used)Uses energy of ATP (60-70% total used) Transporter is an enzymeTransporter is an enzyme

– ATPaseATPase Skeletal & cardiac muscle pumps CaSkeletal & cardiac muscle pumps Ca++ ++ alsoalso

Types of TissuesTypes of Tissues

Epithelial (simple & stratified) Epithelial (simple & stratified) – covers most internal & external surfacescovers most internal & external surfaces– attached to a basement membraneattached to a basement membrane– surfaces differ according to locationsurfaces differ according to location

» smooth smooth

» microvillimicrovilli

» ciliacilia

Types of Tissues (Con’t)Types of Tissues (Con’t)

ConnectiveConnective– varies in structure & functionvaries in structure & function– framework on which epithelial cells clusterframework on which epithelial cells cluster– abundant extracellular matrixabundant extracellular matrix

Types of Tissues (Con’t)Types of Tissues (Con’t)

MuscleMuscle– made up of myocytesmade up of myocytes– highly contractilehighly contractile– 3 major types3 major types

» skeletal (striated) skeletal (striated)

» cardiaccardiac

» smoothsmooth

Types of Tissues (Con’t)Types of Tissues (Con’t)

NeuralNeural– receive & transmit electrical impulsesreceive & transmit electrical impulses– transmitted across synapses transmitted across synapses

» nerve to nervenerve to nerve» nerve to musclenerve to muscle» transmission achieved with neurotransmitters transmission achieved with neurotransmitters » total number fixed at birthtotal number fixed at birth

– all neurons have:all neurons have:» 1 cell body, 1 axon, 1 or more dendrites 1 cell body, 1 axon, 1 or more dendrites

Cellular AdaptationCellular Adaptation

AtrophyAtrophy– decrease in cell sizedecrease in cell size– if enough cells if enough cells in size, so will organ in size, so will organ– disuse atrophydisuse atrophy– nutrition deprivationnutrition deprivation– atrophy due to atrophy due to physiological stimulation physiological stimulation

Cellular AdaptationCellular Adaptation

HypertrophyHypertrophy– increase in cell sizeincrease in cell size– heart & kidneys particularly responsiveheart & kidneys particularly responsive– associated with associated with in cell protein, not in cell protein, not in water in water– hypertrophy may be normalhypertrophy may be normal

» muscle in exercise muscle in exercise

» uterus and mammary glands in pregnancyuterus and mammary glands in pregnancy

Cellular AdaptationCellular Adaptation

HyperplasiaHyperplasia cell numbers from cell numbers from cell division cell division – normal (physiologic)normal (physiologic)

» compensatorycompensatory» hormonal hormonal

– pathologicalpathological» abnormal proliferation of normal cellsabnormal proliferation of normal cells» endometrium most common siteendometrium most common site» failure of growth controlfailure of growth control malignant transformation malignant transformation

Cellular AdaptationCellular Adaptation

DysplasiaDysplasia– ““atypical hyperplasia”atypical hyperplasia”– abnormal changes in size, shape & organizationabnormal changes in size, shape & organization– seen in epithelial cells of the cervix & resp tractseen in epithelial cells of the cervix & resp tract– graded low graded low high high– when inciting stimuli removed when inciting stimuli removed reversible reversible

Cellular AdaptationCellular Adaptation

MetaplasiaMetaplasia– reversible replacement reversible replacement

» one mature cell type by anotherone mature cell type by another

– reversed if inducing stimuli removedreversed if inducing stimuli removed– prolonged exposure prolonged exposure malignant malignant

transformationtransformation

Common Areas in Cellular InjuryCommon Areas in Cellular Injury

ATP depletionATP depletion Oxygen derived free radicalsOxygen derived free radicals cytosolic Cacytosolic Ca++++ Defects in membrane permeability Defects in membrane permeability

Cellular InjuryCellular Injury

Adaptation Adaptation ReversibleReversible IrreversibleIrreversible NecrosisNecrosis ApoptosisApoptosis

Cellular InjuryCellular Injury

HypoxicHypoxic– ischemia Vs hypoxiaischemia Vs hypoxia

Chemical injuryChemical injury– lead, CO, ethanol, recreational drugslead, CO, ethanol, recreational drugs

Infectious Infectious Immunologic & inflammatoryImmunologic & inflammatory Injurious genetic factors Injurious genetic factors

Cellular InjuryCellular Injury

Nutritional imbalancesNutritional imbalances Injurious physical agentsInjurious physical agents

– thermal injury thermal injury – Ionizing radiationIonizing radiation– IlluminationIllumination– Mechanical stressMechanical stress– NoiseNoise

AgingAging

AtrophyAtrophy Decreased functionDecreased function Loss of cells (? Apoptosis)Loss of cells (? Apoptosis) Compensatory changesCompensatory changes

– hypertrophy, hyperplasia, hypertrophy, hyperplasia, metaplasia metaplasia dysplasia dysplasia neoplasia neoplasia