Cells & Tissues
Introduction to Cells and TissuesIntroduction to Cells and Tissues
Slide 3.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Carry out all chemical activities needed to sustain life
Cells are the building blocks of all living things
Tissues are groups of cells that are similar in structure and function
Disorders can happen due to a problem with a cell organelle and its function
Anatomy of the CellAnatomy of the Cell
Slide 3.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cells are not all the same
All cells share general structures
Cells are organized into three main regions Nucleus
Cytoplasm
Plasma membrane
Figure 3.1a
Cell DiversityCell Diversity
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Figure 3.7; 1, 2
Cell DiversityCell Diversity
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Figure 3.7; 3
Cell DiversityCell Diversity
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Figure 3.7; 4, 5
Cell DiversityCell Diversity
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Figure 3.7; 6, 7
Plasma Membrane – Begin notesPlasma Membrane – Begin notes
Slide 3.7aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Maintains the boundaries of the cell - Barrier for cell contents
Phospholipid bilayer interspersed with proteins Impermeable to water soluble substances
Permeable to lipid soluble substances
Plasma MembraneHydrophilic vs. HydrophobicPolar head and non polar tails make phospholipids self orienting in body fluids
Very important for membrane construction and repair to happen correctly
Plasma MembraneCholesterol
Stabilizes bilayer by immobilizing phospholipids
Plasma MembraneEnzymes that act as catalysts for reactionsPeripheral proteins
Stuck on membrane surface or on other proteins and act as binding sites for hormones or chemical messengers (these act as enzymes mentioned earlier)ADD: Can also have mechanical functions
Changing cell shapeMuscle contraction
Integral ProteinsProteins that extend through the width of the membrane (transmembrane)Known as INTEGRAL proteins have transport functions
Can cluster to form pores/channels through which water, small water soluble molecules & ions can passAct as carriers that bind to a molecule & help it move through
GlycoproteinsGlycoproteins (sugar-proteins)
Branching sugar groups attached to a proteinExamples:
Determine blood typeAct in cell recognition (MHC)Receptors for toxins, viruses, bacteria
GlycocalyxCoating of cell surface by glycoproteins and sugar groups – gives fuzzy look
Plasma MembranePlasma Membrane
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Figure 3.2
Membrane Specializations
Plasma Membrane SpecializationsPlasma Membrane Specializations
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Microvilli Finger-like projections
that increase surface area for absorption
Imp: nutrient absorption/waste exchange
Found on surface of absorptive cells such as small intestine & kidney tubules
Figure 3.3
Plasma Membrane SpecializationsPlasma Membrane Specializations
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Tight Junctions
Form impermeable junctions to prevent passage of molecules
Imp: prevent free passage of molecules
Example: lining of digestive tract
Imp: digestive enzymes & bacteria kept away from cells
Figure 3.3
Plasma Membrane SpecializationsPlasma Membrane Specializations
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Desmosomes
Form mechanical junction or adhesion layers to prevent separation of tissues due to mechanical stress
Examples: skin, heart muscle, neck of uterus
Figure 3.3
Plasma Membrane SpecializationsPlasma Membrane Specializations
Slide 3.8bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Gap junctions
Provide for direct passage of chemical substances between adjacent cells
Figure 3.3
Plasma Membrane SpecializationsPlasma Membrane Specializations
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Gap junctions
Cells are connected by Connexons: hollow cylinders (transmembrane)
Important
Allowing direct passage of molecules,etc.
Figure 3.3
Plasma Membrane SpecializationsPlasma Membrane Specializations
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Gap junctions
Found in electrically excitable tissues (heart, smooth muscle, embryonic)
Importance: allowing smooth synchronization due to ion passage
Figure 3.3
FluidsFluids
Slide 3.9Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cytosol
Fluid portion that suspends stuff inside cell
Part of cytoplasm
Interstitial fluid
AKA: EC (extracellular matrix)
Fluid that surrounds a cell
Cytoplasmic OrganellesCytoplasmic Organelles
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Figure 3.4
Cytoplasmic OrganellesCytoplasmic Organelles
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Figure 3.5
Cell Transports
INTRODUCTIONINTRODUCTION
Slide 3.20Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Membrane Transport – movement of substance into and out of the cell
Transport is by two basic methods Passive transport
No energy is required
Active transport
The cell must provide metabolic energy
Passive TransportMovement of substances across the cell membrane WITHOUT using energy
No ATP required by the cellMoves from HIGH to LOW concentrationsCONCENTRATION GRADIENT is the difference between the high and low concentration
Passive TransportOnly a limited number of substances can go through the membrane
Which?N2, O2, water, carbon dioxide, glucose, fat soluble substances
Passive Transport ProcessesPassive Transport Processes
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Diffusion – No ATP required
Figure 3.8
INTRODUCTION TO DIFFUSIONINTRODUCTION TO DIFFUSION
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Simple diffusionMovement is from high concentration to low concentration, (down a concentration gradient)
Solutes are lipid-soluble materials or small enough to pass through membrane pores (such as water)
BBC Education - AS Guru - Biology - Cells - Pathways - Simple Diffusion (Passive)
Diffusion through membrane
Example of DiffusionOxygen must diffuse from the higher pressure in your lungs to the lower pressure in your blood so it can then get to your cellsCarbon dioxide must diffuse from the higher pressure in your blood to the lower pressure in your lungs so you can then exhale it
Passive Transport ProcessesPassive Transport Processes
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Osmosis – simple diffusion of water
Highly polar water (a small molecule) easily crosses the plasma membrane
Osmotic Pressure
Tendency of a solution to move water into and out of itself or The force exerted by the water motion against the membrane
TonicityTonicity compares the concentrations of the water molecules on the inside and outside of the cellThe terms can also be used to describe the concentrations of what is dissolved in the waterIMPORTANT INFO: Just remember: All Substances ALWAYSmove from high to low concentration in passive processes (No ATP)
ISOTONICConcentration of water molecules is EQUAL on both sides of membranePressure on membrane is equal from both sides so no net water motion
HYPERTONIC( have a higher solute and lower water concentration than the cells do) in other words, water concentration will be more concentrated inside of the cell than outside the cell SO:Pressure on the inside of the membrane causes water to move OUT of the cellProblem: the cell will CRENATE aka. shrivel up
CrenationCrenate: bloodcells are shrivelingbecause wateris leaving
They are dehydrating
HYPOTONIC( have a lower solute and higher water concentration than the cells do) in other words, water concentration will be less concentrated inside of the cell than outside the cell SO:Pressure on the outside of the membrane causes water to move INTO the cellProblem: the cell will LYSE aka. rupture
HYPOTONICConcentration of water molecules is greater on the outside of the cellPressure on the outside of the membrane causes water to enter the cellProblem:
Swell & lyse: animal cell may rupture
HypotonicNotice RBC isvery plumpNo dent incenter
osmosis#Osmosis#Osmosis#Osmosis
Facilitated DiffusionSome molecules need a little help to get through the membrane so they use a CARRIER PROTEINThe cell still does NOT need to use energy (ATP)BBC Education - AS Guru - Biology - Cells - Pathways - Facilitated Diffusion
Carrier ProteinsVery molecule specific
Structure determines function so the types of carrier proteins on a cell gives the cell job specificity
Speed up diffusionAffected by ion charges, concentration gradients, chemical substances in your blood (such as alcohol, medications, etc)
Carrier ProteinsHelp in glucose absorption
FYI (don’t memorize): In type II diabetes – the carrier proteins don’t listen to your insulin so your cells don’t let the glucose in – thus your blood sugar levels goes up which causes LOTS of problemsInjecting insulin into your body won’t help because your cells won’t listen to itPrevent type II diabetes by restricting the amount of sugary foods you eat
Diffusion through the Plasma Diffusion through the Plasma MembraneMembrane
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Figure 3.9
Plasma Membrane proteins
RecognitionReceptorsEnzymesTransport Channels
FEATURES OF ACTIVE TRANSPORT
Energy required to move substances AGAINST the concentration gradient
BBC Education - AS Guru - Biology - Cells - Pathways - Active TransportIn other words, from a low into a high concentrationOR some other reason that a molecule might not be able to cross the membrane on its own power
Needed in order to maintain homeostasis in certain conditions
FEATURES OF ACTIVE TRANSPORT
Maintaining homeostasis examples:Nutrients that are scarce in the cell’s environment
Cell needs to take in ALL the nutrients (not leaving half outside which is what happens at equilibrium!)
Kidney cells sorting waste material from needed material
Don’t want half the waste left in your blood!
MOLECULAR (ION) PUMPThis is also known as solute pumping & there are several types. We will focus on the general infoCarrier protein binds to the particleAnother location on the carrier protein binds to an ATP for energyEnergy in ATP is transferred to protein so it can move particle in desired direction
Ion pumpSome pumps are coupled – move one ion in while moving another ion out
Active Transport ProcessesActive Transport Processes
Slide 3.28bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.10
EXOCYTOSISBulk transport of substances OUT of the cell
Examples:Producing proteins to secrete to surroundings:
Digestive enzymes in stomach, saliva, insulin, sweat
Excreting waste from cell to blood
Golgi apparatus aids in secretion & storage then exocytosis excretes them from cell to where ever they are neededhttp://www.bbc.co.uk/education/asguru/biology/01cellbiology/05pathways/09endoexo/index.shtml
Active Transport - exocytosisActive Transport - exocytosis
Slide 3.29bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.11
ENDOCYTOSISBulk transport of material INTO cellMaterial is engulfed to form a vacuole – it does not ever go through the membraneVacuole can then join with a lysosome so it can digest the food
ENDOCYTOSISPHAGOCYTOSIS
Engulfing of LARGE particlesEx: a white blood cell engulfing a bacteria or virus
PINOCYTOSISEngulfing of SMALL particles of food or liquid
Active Transport -endocytosisActive Transport -endocytosis
Slide 3.30bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.12
Types of Tissues
Body TissuesBody Tissues
Slide 3.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cells are specialized for particular functions
Tissues Groups of cells with similar structure and
function
Extracellular Matrix
Aka: intercellular matrix, interstitial fluid
“cell glue” between cells
Histology = study of tissue
Body TissuesBody Tissues
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Four primary types (functional categories) Epithelium =
protection/secretion/absorption/filtration Connective tissue = support & structure Nervous tissue = communication & control Muscle = movement (internal & external
EPITHELIAL TISSUES
Epithelium CharacteristicsEpithelium Characteristics
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High cellularity = cells fit closely together – very little EC matrix
Contains specialized contacts = tight junctions & desmosomes
Tissue layer always has one free surface (apical) that may have modification such as microvilli
Epithelium CharacteristicsEpithelium Characteristics
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Avascular = no blood vessels within it – diffusion provides nutrients & carries waste away – lots of nerve fibers
Basement Membrane
Reinforcement & connection
Defines boundaries – cancer causes a breach in these boundaries
Regenerate easily if well nourished
Found in areas of high friction
Classification of EpitheliumClassification of Epithelium
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Shape of cells
Squamous – flattened
Cuboidal – cube-shaped
Columnar – column-like
Figure 3.16b
Classification of EpitheliumClassification of Epithelium
Slide 3.44aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Number of cell layers
Simple – one layer
Found in areas of transport
Stratified – more than one layer
High abrasion areas for protection
Secretory membranes
Named according to cell shape on apical surface Figure 3.16a
Covering & Lining Epithelium
Endothelium = friction reducing – lines all circulatory system organsReduces friction due to blood flow
Epithelial MembranesMucous membranes
Line body cavities OPEN to the exteriorExample: digestive, respiratory, urogenitalMucus protects by trapping microorganisms, substances in mucus will destroy them
Epithelial MembranesCutaneous Membranes
SkinHelps waterproof & protect body First line of defense in immune system
Epithelial MembranesSerous Membranes
Lines all CLOSED body cavitiesSerous fluid located between layers to reduce friction due to organ motion
Remember naming:Visceral vs. parietalPleura, pericardium, peritoneum
Glandular EpitheliumGlandular Epithelium
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Gland – one or more cells that secretes a particular product
Two major gland types Endocrine gland
Ductless – secretes product directly into blood or tissue
Produces hormones
Exocrine gland
Empty through ducts to the epithelial surface
Include sweat and oil glands
Google Image Result for http://www.willamette.edu/~stas/physiology/labs/lab1/epithelial2a.jpg
Identification of Epithelial tissue
See handoutGo to website:
Essentials of Human Anatomy & Physiology
Make flashcards & studyStudy microscope slides in class
Simple EpitheliumSimple Epithelium
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Simple squamous Single layer of flat
cells
Usually forms membranes
Lines body cavities
Lines lungs and capillaries
Figure 3.17a
Simple EpitheliumSimple Epithelium
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Simple cuboidal Single layer of
cube-like cells
Common in glands and their ducts
Forms walls of kidney tubules
Covers the ovaries Figure 3.17b
Simple EpitheliumSimple Epithelium
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Simple columnar
Single layer of tall cells
Often includes goblet cells, which produce mucus
Lines digestive tract
Figure 3.17c
Simple EpitheliumSimple Epithelium
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Pseudostratified Single layer, but
some cells are shorter than others
Often looks like a double cell layer
Sometimes ciliated, such as in the respiratory tract
May function in absorption or secretion
Figure 3.17d
Stratified EpitheliumStratified Epithelium
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Stratified squamous Cells at the free edge
are flattened
Found as a protective covering where friction is common
Locations Skin Mouth Esophagus Figure 3.17e
Stratified EpitheliumStratified Epithelium
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Stratified cuboidal Two layers of cuboidal cells
Stratified columnar Surface cells are columnar, cells
underneath vary in size and shape
Stratified cuboidal and columnar Rare in human body
Found mainly in ducts of large glands
Stratified EpitheliumStratified Epithelium
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Transitional epithelium
Shape of cells depends upon the amount of stretching
Lines organs of the urinary system
Figure 3.17f
Connective tissues
Support & strengthen & provide structure
Connective TissueConnective Tissue
Slide 3.53Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Found everywhere in the body
Includes the most abundant and widely distributed tissues
Functions Binds body tissues together
Supports the body
Provides protection
Insulates to maintain body temperature
Transportation of other molecules
Origin of Connective Tissue
Mesenchyme: embryonic tissue that differentiates into all forms of CT
Connective Tissue CharacteristicsConnective Tissue Characteristics
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Variations in blood supply
Some tissue types are well vascularized
Some have poor blood supply or are avascular
Blood supply is necessary for healing (it brings oxygen & “spare parts”)
Cartilage vs bone
Connective Tissue Characteristics
Composed largely of EC matrixImportant to remember: More matrix = less flexibility
Extracellular MatrixExtracellular Matrix
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Two main elements Ground substance - proteins and
polysaccharide molecules that function as a molecular sieve to diffuse nutrients & other substances
Fibers – know function Produced by the cells Three types
Collagen fibers – tensile strength Elastic fibers – stretch with recoil Reticular fibers - supportive
CellsPrefixes
FibroOsteoChondroHemo(cyto)
SuffixesBlast – build the tissueCyte – maintain the tissueClast – breakdown the cells
Websitehttp://www.udel.edu/Biology/Wags/histopage/colorpage/cct/cctm.GIF
Connective Tissue TypesConnective Tissue Types
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Bone (osseous tissue) Composed of:
Bone cells in lacunae (cavities)
Hard matrix of calcium salts
Large numbers of collagen fibers
Used to protect and support the body Figure 3.18a
Connective Tissue TypesConnective Tissue Types
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Hyaline cartilage Most common
cartilage
Composed of:
Abundant collagen fibers
Rubbery matrix
Entire fetal skeleton is hyaline cartilage Figure 3.18b
Connective Tissue TypesConnective Tissue Types
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Elastic cartilage
Provides elasticity
Example: supports the external ear
Connective Tissue TypesConnective Tissue Types
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Fibrocartilage
Highly compressible
Example: forms cushion-like discs between vertebrae
Figure 3.18c
Connective Tissue TypesConnective Tissue Types
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Dense connective tissue Main matrix element
is collagen fibers
Cells are fibroblasts
Examples Tendon – attach
muscle to bone
Ligaments – attach bone to bone Figure 3.18d
Connective Tissue TypesConnective Tissue Types
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Areolar connective tissue Most widely
distributed connective tissue
Soft, pliable tissue
Contains all fiber types
Can soak up excess fluid Figure 3.18e
Connective Tissue TypesConnective Tissue Types
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Adipose tissue Matrix is an areolar tissue in which fat
globules predominate
Many cells contain large lipid deposits
Functions Insulates the body
Protects some organs
Serves as a site of fuel storage
Figure 3.18f
Connective Tissue TypesConnective Tissue Types
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Reticular connective tissue Delicate network of
interwoven fibers
Forms stroma (internal supporting network) of lymphoid organs Lymph nodes Spleen Bone marrow
Figure 3.18g
Connective Tissue TypesConnective Tissue Types
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Blood
Blood cells surrounded by fluid matrix
Fibers are visible during clotting
Functions as the transport vehicle for materials
Figure 3.18h
Muscle TissueMuscle Tissue
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Function is to produce movement
Three types Skeletal muscle
Cardiac muscle
Smooth muscle
Muscle Tissue TypesMuscle Tissue Types
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Skeletal muscle Can be controlled
voluntarily
Cells attach to connective tissue
Cells are striated
Cells have more than one nucleus
Figure 3.19b
Muscle Tissue TypesMuscle Tissue Types
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Cardiac muscle Found only in the
heart
Function is to pump blood (involuntary)
Cells attached to other cardiac muscle cells at intercalated disks
Cells are striated
One nucleus per cell Figure 3.19c
Muscle Tissue TypesMuscle Tissue Types
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Smooth muscle Involuntary muscle
Surrounds hollow organs
Attached to other smooth muscle cells
No visible striations
One nucleus per cell Figure 3.19a
Nervous TissueNervous Tissue
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Neurons and nerve support cells
Function is to send impulses to other areas of the body
Irritability
Conductivity Figure 3.20
Tissue RepairTissue Repair
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Regeneration Replacement of destroyed tissue by the
same kind of cells
Fibrosis Repair by dense fibrous connective tissue
(scar tissue)
Determination of method Type of tissue damaged
Severity of the injury
Events in Tissue RepairEvents in Tissue Repair
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Capillaries become very permeable Introduce clotting proteins
Wall off injured area
Formation of granulation tissue
Regeneration of surface epithelium
Regeneration of TissuesRegeneration of Tissues
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Tissues that regenerate easily Epithelial tissue
Fibrous connective tissue and bone
Tissues that regenerate poorly Skeletal muscle
Tissues that are replaced largely with scar tissue Cardiac muscle
Nervous tissue within the brain and spinal cord
Developmental Aspects of TissueDevelopmental Aspects of Tissue
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Epithelial tissue arises from all three primary germ layers
Muscle and connective tissue arise from the mesoderm
Nervous tissue arises from the ectoderm
With old age there is a decrease in mass and viabililty in most tissues