Cells Cells are the structural units of all living things The human body has 50 to 100 trillion cells 2015 Pearson Education Inc Four Concepts of the Cell Theory A cell is the basic structural and functional unit of living organisms ID: 625220
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Slide1
© 2015 Pearson Education, Inc.Slide2
Cells
Cells are the structural units of all living things
The human body has 50 to 100 trillion cells
© 2015 Pearson Education, Inc.Slide3
Four Concepts of the Cell Theory
A cell is the basic structural and functional unit of living organisms.
The activity of an organism depends on the collective activities of its cells.
According to the
principle of complementarity
, the biochemical activities of cells are dictated by the relative number of their specific subcellular structures.Continuity of life has a cellular basis.
© 2015 Pearson Education, Inc.Slide4
Chemical Components of Cells
Most cells are composed of four elements:
Carbon
Hydrogen
Oxygen
NitrogenCells are about 60% water© 2015 Pearson Education, Inc.Slide5
Anatomy of a Generalized Cell
In general, a cell has three main regions or parts:
Nucleus
Cytoplasm
Plasma membrane
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Figure 3.1a Anatomy of the generalized animal cell nucleus.
Nucleus
Cytoplasm
Plasma
membrane
(a)Slide7
The Nucleus
Control center of the cell
Contains genetic material known as deoxyribonucleic acid, or DNA
DNA is needed for building proteins
DNA is necessary for cell reproduction
Three regions:Nuclear envelope (membrane)NucleolusChromatin
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Figure 3.1b Anatomy of the generalized animal cell nucleus.
Nucleus
Rough ER
Nuclear envelope
Chromatin
Nucleolus
Nuclear
pores
(b)Slide9
The Nucleus
Nuclear envelope (membrane)
Consists of a double membrane that bounds the nucleus
Contains nuclear pores that allow for exchange of material with the rest of the cell
Encloses the jellylike fluid called the
nucleoplasm© 2015 Pearson Education, Inc.Slide10
The Nucleus
Nucleoli
Nucleus contains one or more nucleoliSites of ribosome assembly
Ribosomes migrate into the cytoplasm through nuclear pores to serve as the site of protein synthesis
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The Nucleus
Chromatin
Composed of DNA and protein
Present when the cell is not dividing
Scattered throughout the nucleus
Condenses to form dense, rod-like bodies called chromosomes when the cell divides© 2015 Pearson Education, Inc.Slide12
Plasma Membrane
Transparent barrier for cell contents
Contains cell contents Separates cell contents from surrounding environment
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Plasma Membrane
Fluid mosaic model is constructed of:
Phospholipids
Cholesterol
Proteins
Sugars© 2015 Pearson Education, Inc.Slide14
Figure 3.2 Structure of the plasma membrane.
Glycoprotein
Glycolipid
Cholesterol
Channel
Cytoplasm
(watery environment)
Filaments of
cytoskeleton
Proteins
Extracellular fluid
(watery environment)
Sugar
group
Polar heads
of phospholipid
molecules
Bimolecular
lipid layer
containing
proteins
Nonpolar tails
of phospholipid
moleculesSlide15
Concept Link
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Plasma Membrane
Fluid mosaic model
Phospholipid arrangement
Hydrophilic (“water-loving”) polar “heads” are oriented on the inner and outer surfaces of the membrane
Hydrophobic (“water-hating”) nonpolar “tails” form the center (interior) of the membraneSlide17
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Plasma Membrane
Fluid mosaic model
Phospholipid arrangement
The hydrophobic interior makes the plasma membrane impermeable to most water-soluble moleculesSlide18
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Plasma Membrane
Fluid mosaic model
Proteins
Responsible for specialized functions
Roles of proteins EnzymesReceptorsTransport as channels or carriersSlide19
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Plasma Membrane
Fluid mosaic model
Sugars
Glycoproteins are branched sugars attached to proteins that abut the extracellular space
Glycocalyx is the fuzzy, sticky, sugar-rich area on the cell’s surfaceSlide20
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Plasma Membrane Junctions
Membrane junctions
Cells are bound together in three ways:
Glycoproteins in the
glycocalyx act as an adhesive or cellular glueWavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion
Special membrane junctions are formed, which vary structurally depending on their rolesSlide21
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Plasma Membrane Junctions
Membrane junctions
Tight junctions
Impermeable junctions
Bind cells together into leakproof sheetsPrevent substances from passing through extracellular space between cellsSlide22
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Plasma Membrane Junctions
Membrane junctions
Desmosomes
Anchoring junctions that prevent cells from being pulled as a result of mechanical stress
Created by buttonlike thickenings of adjacent plasma membranesSlide23
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Plasma Membrane Junctions
Membrane junctions
Gap junctions
Allow communication between cells
Hollow cylinders of proteins (connexons) span the width of the abutting membranesMolecules can travel directly from one cell to the next through these channelsSlide24
Figure 3.3
Cell junctions.
Microvilli
Connexon
Underlying
basement
membrane
Extracellular
space between
cells
Gap
(communicating)
junction
Plasma
membranes of
adjacent cells
Desmosome
(anchoring
junction)
Tight
(impermeable)
junctionSlide25
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Cytoplasm
The material outside the nucleus and inside the plasma membrane
Site of most cellular activitiesSlide26
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Cytoplasm
Contains three major elements
Cytosol
Fluid that suspends other elements
OrganellesMetabolic machinery of the cell “Little organs” that perform functions for the cell
Inclusions
Chemical substances, such as stored nutrients or cell productsSlide27
Figure 3.4 Structure of the generalized cell
.
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Rough
endoplasmic
reticulum
Ribosomes
Golgi
apparatus
Secretion being
released from cell
by exocytosis
Peroxisome
Intermediate
filaments
Microtubule
Centrioles
Mitochondrion
Lysosome
Cytosol
Smooth
endoplasmic
reticulumSlide28
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Cytoplasmic Organelles
Organelles
Specialized cellular compartments
Many are membrane-bound
Compartmentalization is critical for organelle’s ability to perform specialized functionsSlide29
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Cytoplasmic Organelles
Mitochondria
“Powerhouses” of the cell
Change shape continuously
Mitochondrial wall consists of a double membrane with cristae on the inner membraneCarry out reactions where oxygen is used to break down foodProvides ATP for cellular energySlide30
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Cytoplasmic Organelles
Ribosomes
Bilobed
dark bodies
Made of protein and ribosomal RNASites of protein synthesisFound at two locations:Free in the cytoplasmAs part of the rough endoplasmic reticulumSlide31
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Cytoplasmic Organelles
Endoplasmic reticulum (ER)
Fluid-filled cisterns (tubules or canals) for carrying substances within the cell
Two types:
Rough ERSmooth ERSlide32
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Cytoplasmic Organelles
Endoplasmic reticulum (ER)
Rough endoplasmic reticulum
Studded with ribosomes
Synthesizes proteins Transport vesicles move proteins within cellAbundant in cells that make and export proteinsSlide33
Figure 3.5 Synthesis and export
of a protein by the rough ER.
Ribosome
1
2
3
4
2
3
4
1
mRNA
Rough ER
Protein
Transport
vesicle buds off
Protein inside
transport vesicle
As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
The protein is packaged in a tiny
membranous sac called a transport vesicle.
The transport vesicle buds from the
rough ER and travels to the Golgi apparatus
for further processing.
Slide 1Slide34
Figure 3.5 Synthesis and export
of a protein by the rough ER.
Ribosome
1
1
mRNA
Rough ER
Protein
As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
Slide 2Slide35
Figure 3.5 Synthesis and export
of a protein by the rough ER.
Ribosome
1
2
2
1
mRNA
Rough ER
Protein
As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
Slide 3Slide36
The protein is packaged in a tiny
membranous sac called a transport vesicle.
Figure 3.5 Synthesis and export
of a protein by the rough ER.
Ribosome
1
2
3
2
3
1
mRNA
Rough ER
Protein
Transport
vesicle buds off
As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
Slide 4Slide37
The transport vesicle buds from the
rough ER and travels to the Golgi apparatus
for further processing.
The protein is packaged in a tiny
membranous sac called a transport vesicle.
Figure 3.5 Synthesis and export
of a protein by the rough ER.
Ribosome
1
2
3
4
2
3
4
1
mRNA
Rough ER
Protein
Transport
vesicle buds off
Protein inside
transport vesicle
As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
Slide 5Slide38
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Cytoplasmic Organelles
Endoplasmic reticulum (ER)
Smooth endoplasmic reticulum
Functions in lipid metabolism
Detoxification of drugs and pesticidesSlide39
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Cytoplasmic Organelles
Golgi apparatus
Appears as a stack of flattened membranes associated with tiny vesicles
Modifies and packages proteins arriving from the rough ER via transport vesicles
Produces different types of packagesSecretory vesicles (pathway 1)In-house proteins and lipids (pathway 2)Lysosomes (pathway 3)Slide40
Figure 3.6 Role of the Golgi apparatus in packaging the products
of the rough ER.
Rough ER
Cisterns
Proteins in cisterns
Membrane
Transport
vesicle
Lysosome fuses
with ingested
substances.
Golgi vesicle containing
digestive enzymes
becomes a lysosome.
Golgi
apparatus
Pathway 1
Secretory vesicles
Proteins
Secretion by
exocytosis
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle.
Golgi vesicle containing
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid
Pathway 2
Pathway 3Slide41
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Cytoplasmic Organelles
Lysosomes
Membranous “bags” packaged by the Golgi apparatus
Contain enzymes produced by ribosomes
Enzymes can digest worn-out or nonusable cell structuresHouse phagocytes that dispose of bacteria and cell debrisSlide42
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Cytoplasmic Organelles
Peroxisomes
Membranous sacs of oxidase enzymes
Detoxify harmful substances such as alcohol and formaldehyde
Break down free radicals (highly reactive chemicals)Free radicals are converted to hydrogen peroxide and then to waterReplicate by pinching in half or budding from the ER Slide43
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Cytoplasmic Organelles
Cytoskeleton
Network of protein structures that extend throughout the cytoplasm
Provides the cell with an internal framework
Three different types of elements:Microfilaments (largest)Intermediate filaments
Microtubules (smallest)Slide44
Figure 3.7 Cytoskeletal
elements support the cell and help to generate movement.
Actin subunit
7 nm
Fibrous subunits
Tubulin subunits
10 nm
25 nm
Microfilaments form the blue
batlike
network.
(a) Microfilaments
(b) Intermediate filaments
(c) Microtubules
Intermediate filaments form
the purple network
surrounding the pink nucleus.
Microtubules appear as gold
networks surrounding the
cells’ pink nuclei.Slide45
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Cytoplasmic Organelles
Centrioles
Rod-shaped bodies made of microtubules
Generate microtubules
Direct the formation of mitotic spindle during cell divisionSlide46
Table 3.1 Parts of the Cell: Structure and Function (1 of 5).Slide47
Table 3.1 Parts of the Cell: Structure and Function (2 of 5).Slide48
Table 3.1 Parts of the Cell: Structure and Function (3 of 5).Slide49
Table 3.1 Parts of the Cell: Structure and Function (4 of 5).Slide50
Table 3.1 Parts of the Cell: Structure and Function (5 of 5).Slide51
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Cell Extensions
Surface extensions found in some cells
Cilia move materials across the cell surface
Located in the respiratory system to move mucus
Flagella propel the cell The only flagellated cell in the human body is spermMicrovilli are tiny, fingerlike extensions of the plasma membraneIncrease surface area for absorptionSlide52
Figure 3.8g Cell diversity.
Nucleus
Flagellum
Sperm
(g) Cell of reproductionSlide53
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Cell Diversity
The human body houses over 200 different cell types
Cells vary in length from 1/12,000 of an inch to over 1 yard (nerve cells)
Cell shape reflects its specialized functionSlide54
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Cell Diversity
Cells that connect body parts
Fibroblast
Secretes cable-like fibers
Erythrocyte (red blood cell)Carries oxygen in the bloodstreamSlide55
Figure 3.8a Cell diversity.
Rough ER and Golgi
apparatus
No organelles
Nucleus
Fibroblasts
Erythrocytes
(a) Cells that connect body partsSlide56
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Cell Diversity
Cells that cover and line body organs
Epithelial cell
Packs together in sheets
Intermediate fibers resist tearing during rubbing or pullingSlide57
Figure 3.8b Cell diversity.
Nucleus
Intermediate
filaments
Epithelial
cells
(b) Cells that cover and line body organsSlide58
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Cell Diversity
Cells that move organs and body parts
Skeletal muscle and smooth muscle cells
Contractile filaments allow cells to shorten forcefully Slide59
Figure 3.8c Cell diversity.
Nuclei
Contractile
filaments
Skeletal
muscle cell
Smooth
muscle cells
(c) Cells that move organs and body partsSlide60
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Cell Diversity
Cell that stores nutrients
Fat cells
Lipid droplets stored in cytoplasmSlide61
Figure 3.8d
Cell diversity.
Lipid droplet
Nucleus
Fat cell
(d) Cell that stores
nutrientsSlide62
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Cell Diversity
Cell that fights disease
Macrophage (a phagocytic cell)
Digests infectious microorganismsSlide63
Figure 3.8e Cell diversity.
Lysosomes
Macrophage
(e) Cell that fights
disease
Pseudo-
podsSlide64
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Cell Diversity
Cell that gathers information and controls body functions
Nerve cell (neuron)
Receives and transmits messages to other body structuresSlide65
Figure 3.8f Cell diversity.
Processes
Rough ER
Nucleus
(f) Cell that gathers information and
controls body functions
Nerve cellSlide66
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Cell Diversity
Cells of reproduction
Oocyte (female)
Largest cell in the body
Divides to become an embryo upon fertilizationSperm (male)Built for swimming to the egg for fertilizationFlagellum acts as a motile whip Slide67
Figure 3.8g Cell diversity.
Nucleus
Flagellum
Sperm
(g) Cell of reproductionSlide68
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Cell Physiology
Cells have the ability to:
Metabolize
Digest food
Dispose of wastesReproduceGrowMoveRespond to a stimulus Slide69
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Membrane Transport
Solution—homogeneous mixture of two or more components
Solvent—dissolving medium; typically water in the body
Solutes—components in smaller quantities within a solutionSlide70
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Membrane Transport
Intracellular fluid
Nucleoplasm and cytosol
Solution containing gases, nutrients, and salts dissolved in water
Interstitial fluidFluid on the exterior of the cellContains thousands of ingredients, such as nutrients, hormones, neurotransmitters, salts, waste productsSlide71
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Membrane Transport
The plasma membrane is a selectively permeable barrier
Some materials can pass through while others are excluded
For example:
Nutrients can enter the cellUndesirable substances are kept outSlide72
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Membrane Transport
Two basic methods of transport
Passive processes
No energy (ATP) is required
Active processesCell must provide metabolic energy (ATP)Slide73
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Passive Processes
Diffusion
Particles tend to distribute themselves evenly within a solution
Driving force is the kinetic energy (energy of motion) that causes the molecules to move about randomlySlide74
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Passive Processes
Diffusion
Molecule movement is from high concentration to low concentration, or down a concentration gradient
Size of molecule and temperature affects the speed of diffusion
The smaller the molecule, the faster the rate of diffusionThe warmer the molecule, the faster the rate of diffusionSlide75
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Passive Processes
Example of diffusion:
Pour a cup of coffee and drop in a cube of sugar
Do not stir the sugar into the coffee; leave the cup of coffee sitting all day, and it will taste sweet at the end of the day.
Molecules move by diffusion and sweeten the entire cupSlide76
Figure 3.9 Diffusion.Slide77
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Passive Processes
Molecules will move by diffusion if any of the following applies:
The molecules are small enough to pass through the membrane’s pores (channels formed by membrane proteins)
The molecules are lipid-soluble
The molecules are assisted by a membrane carrierSlide78
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Passive Processes
Types of diffusion
Simple diffusion
An unassisted process
Solutes are lipid-soluble or small enough to pass through membrane poresSlide79
Figure 3.10a Diffusion through the plasma membrane.
Lipid-
soluble
solutes
Extracellular
fluid
(a) Simple
diffusion
of fat-soluble
molecules
directly
through the
phospholipid
bilayer
CytoplasmSlide80
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Passive Processes
Types of diffusion (continued)
Osmosis—simple diffusion of water
Highly polar water molecules easily cross the plasma membrane through aquaporins
Water moves down its concentration gradientSlide81
Figure 3.10d Diffusion through the plasma membrane.
Water
molecules
Lipid
bilayer
(d) Osmosis
,
diffusion
of water through a
specific channel
protein (aquaporin)
or through the lipid
bilayerSlide82
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Passive Processes
Osmosis—A Closer Look
Isotonic solutions have the same solute and water concentrations as cells and cause no visible changes in the cell
Hypertonic solutions contain more solutes than the cells do; the cells will begin to shrink
Hypotonic solutions contain fewer solutes (more water) than the cells do; cells will plumpSlide83
A Closer Look 3.1 IV Therapy and Cellular “Tonics.”
(a) RBC in isotonic
solution
(b) RBC in hypertonic
solution
(c) RBC in hypotonic
solutionSlide84
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Passive Processes
Types of diffusion (continued)
Facilitated diffusion
Transports lipid-insoluble and large substances
Glucose is transported via facilitated diffusionProtein membrane channels or protein molecules that act as carriers are usedSlide85
Figure 3.10b-c Diffusion through the plasma membrane.
Lipid-
insoluble
solutes
Small lipid-
insoluble
solutes
(b) Carrier-mediated
facilitated diffusion
via
protein carrier specific for
one chemical; binding of
substrate causes shape
change in transport protein
(c) Channel-
mediated
facilitated
diffusion
through a
channel protein;
mostly ions,
selected on
basis of
size and chargeSlide86
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Passive Processes
Filtration
Water and solutes are forced through a membrane by fluid, or hydrostatic pressure
A pressure gradient must exist
Solute-containing fluid (filtrate) is pushed from a high-pressure area to a lower-pressure areaFiltration is critical for the kidneys to work properlySlide87
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Active Processes
Sometimes called
solute pumping
Requires protein carriers to transport substances that:
May be too large to travel through membrane channelsMay not be lipid-solubleMay have to move against a concentration gradientATP is used for transportSlide88
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Active Processes
Active transport
Amino acids, some sugars, and ions are transported by protein carriers known as
solute pumps
ATP energizes solute pumpsIn most cases, substances are moved against concentration (or electrical) gradientsSlide89
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Active Processes
Example of active transport is the sodium-potassium pump
Sodium is transported out of the cell
Potassium is transported into the cellSlide90
Figure 3.11 Operation of the sodium-potassium
pump, a solute pump.
Na
+
-K
+
pump
2
3
1
3
2
1
Na
+
Extracellular fluid
K
+
Na
+
Na
+
Na
+
Na
+
Na
+
K
+
K
+
K
+
P
P
ATP
ADP
Binding of cytoplasmic Na
+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
The shape change expels
Na
+
to the outside. Extracellular
K
+
binds, causing release of the
phosphate group.
Loss of phosphate
restores the original
conformation of the pump
protein. K
+
is released to the
cytoplasm, and Na
+
sites are
ready to bind
Na
+
again; the
cycle repeats.
Cytoplasm
Slide 1Slide91
Binding of cytoplasmic Na
+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
Figure 3.11 Operation of the sodium-potassium
pump, a solute pump.
Na
+
-K
+
pump
1
1
Extracellular fluid
Na
+
Na
+
Na
+
P
ATP
ADP
Cytoplasm
Slide 2Slide92
Binding of cytoplasmic Na
+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
The shape change expels
Na
+
to the outside. Extracellular
K
+
binds, causing release of the
phosphate group.
Figure 3.11 Operation of the sodium-potassium
pump, a solute pump.
Na
+
-K
+
pump
2
1
2
1
Na
+
Extracellular fluid
K
+
Na
+
Na
+
Na
+
Na
+
Na
+
K
+
P
P
ATP
ADP
Cytoplasm
Slide 3Slide93
Binding of cytoplasmic Na
+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
The shape change expels
Na
+
to the outside. Extracellular
K
+
binds, causing release of the
phosphate group.
Loss of phosphate
restores the original
conformation of the pump
protein. K
+
is released to the
cytoplasm, and Na
+
sites are
ready to bind
Na
+
again; the
cycle repeats.
Figure 3.11 Operation of the sodium-potassium
pump, a solute pump.
Na
+
-K
+
pump
2
3
1
3
2
1
Na
+
Extracellular fluid
K
+
Na
+
Na
+
Na
+
Na
+
Na
+
K
+
K
+
K
+
P
P
ATP
ADP
Cytoplasm
Slide 4Slide94
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Active Processes
Vesicular transport: substances are moved without actually crossing the plasma membrane
Exocytosis
Endocytosis
PhagocytosisPinocytosisSlide95
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Active Processes
Vesicular transport (continued)
Exocytosis
Moves materials out of the cell
Material is carried in a membranous sac called a vesicleVesicle migrates to plasma membraneVesicle combines with plasma membraneMaterial is emptied to the outside
Refer to Pathway 1 in Figure 3.6Slide96
Figure 3.6 Role of the Golgi apparatus in packaging the products
of the rough ER.
Rough ER
Cisterns
Proteins in cisterns
Membrane
Transport
vesicle
Lysosome fuses
with ingested
substances.
Golgi vesicle containing
digestive enzymes
becomes a lysosome.
Golgi
apparatus
Pathway 1
Secretory vesicles
Proteins
Secretion by
exocytosis
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle.
Golgi vesicle containing
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid
Pathway 2
Pathway 3Slide97
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Active Processes
Vesicular transport (continued)
Exocytosis docking process
Transmembrane proteins on the vesicles are called
v-SNAREs (v for vesicle)
Plasma membrane proteins are called t-SNAREs
(
t
for
target
)
v-SNAREs recognize and bind t-SNAREs
Membranes corkscrew and fuse togetherSlide98
Figure 3.12a
Exocytosis.
Extracellular
fluid
2
3
1
Plasma
membrane
SNARE
(t-SNARE)
Vesicle
SNARE
(v-SNARE)
Molecule
to be
secreted
Secretory
vesicle
Fusion pore formed
Fused
SNAREs
The membrane-
bound vesicle
migrates to the
plasma membrane.
There, v-SNAREs
bind with t-SNAREs,
the vesicle and
plasma membrane
fuse, and a pore
opens up.
Vesicle contents
are released to the
cell exterior.
Cytoplasm
(a) The process of exocytosisSlide99
Figure 3.12b
Exocytosis.
(b) Electron micrograph of a
secretory vesicle in
exocytosis (190,000
×
)Slide100
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Active Processes
Vesicular transport (continued)
Endocytosis
Extracellular substances are engulfed by being enclosed in a membranous vescicle
Vesicle typically fuses with a lysosomeContents are digested by lysosomal enzymesIn some cases, the vesicle is released by exocytosis on the opposite side of the cellSlide101
Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Lysosome
Pit
Ingested
substance
Detached vesicle
Vesicle
Extracellular
fluid
Cytosol
Release of
contents to
cytosol
Vesicle fusing
with lysosome
for digestion
Transport to plasma
membrane and exocytosis
of vesicle contents
Membranes and receptors
(if present) recycled to plasma
membrane
1
(a)
2
3
Slide 1Slide102
Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Extracellular
fluid
Vesicle fusing
with lysosome
for digestion
1
(a)
Slide 2Slide103
Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Lysosome
Detached vesicle
Vesicle
Extracellular
fluid
Cytosol
Release of
contents to
cytosol
Vesicle fusing
with lysosome
for digestion
Transport to plasma
membrane and exocytosis
of vesicle contents
1
(a)
2
Slide 3Slide104
Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Lysosome
Pit
Ingested
substance
Detached vesicle
Vesicle
Extracellular
fluid
Cytosol
Release of
contents to
cytosol
Vesicle fusing
with lysosome
for digestion
Transport to plasma
membrane and exocytosis
of vesicle contents
Membranes and receptors
(if present) recycled to plasma
membrane
1
(a)
2
3
Slide 4Slide105
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Active Processes
Vesicular transport (continued)
Types of endocytosis
Phagocytosis—“cell eating”
Cell engulfs large particles such as bacteria or dead body cellsPseudopods are cytoplasmic extensions that separate substances (such as bacteria or dead body cells) from external environmentPhagocytosis is a protective mechanism, not a means of getting nutrientsSlide106
Figure 3.13b Events and types of endocytosis.
Pseudopod
Bacterium
or other
particle
Extracellular
fluid
Cytoplasm
(b)Slide107
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Active Processes
Vesicular transport (continued)
Types of endocytosis
Pinocytosis—“cell drinking”
Cell “gulps” droplets of extracellular fluid containing dissolved proteins or fatsPlasma membrane forms a pit, and edges fuse around droplet of fluidRoutine activity for most cells, such as those involved in absorption (small intestine)Slide108
Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Lysosome
Pit
Ingested
substance
Detached vesicle
Vesicle
Extracellular
fluid
Cytosol
Release of
contents to
cytosol
Vesicle fusing
with lysosome
for digestion
Transport to plasma
membrane and exocytosis
of vesicle contents
Membranes and receptors
(if present) recycled to plasma
membrane
1
(a)
2
3Slide109
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Active Processes
Vesicular transport (continued)
Types of endocytosis
Receptor-mediated endocytosis
Method for taking up specific target moleculesReceptor proteins on the membrane surface bind only certain substancesHighly selective process of taking in substances such as enzymes, some hormones, cholesterol, and ironSlide110
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Active Processes
Vesicular transport (continued)
Types of endocytosis
Receptor-mediated endocytosis
Both the receptors and target molecules are in a vesicleContents of the vesicles are dealt with in one of the ways shown in the next figureSlide111
Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Lysosome
Pit
Ingested
substance
Detached vesicle
Vesicle
Extracellular
fluid
Cytosol
Release of
contents to
cytosol
Vesicle fusing
with lysosome
for digestion
Transport to plasma
membrane and exocytosis
of vesicle contents
Membranes and receptors
(if present) recycled to plasma
membrane
1
(a)
2
3Slide112
Figure 3.13c Events and types of endocytosis.
Membrane
receptor
(c)Slide113
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Cell Life Cycle
Cell life cycle is a series of changes the cell experiences from the time it is formed until it dividesSlide114
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Cell Life Cycle
Cycle has two major periods
Interphase
Cell grows
Cell carries on metabolic processesLonger phase of the cell cycleCell division Cell replicates itself
Function is to produce more cells for growth and repair processesSlide115
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DNA Replication
Genetic material is duplicated and readies a cell for division into two cells
Occurs toward the end of interphaseSlide116
Concept Link
© 2015 Pearson Education, Inc.Slide117
© 2015 Pearson Education, Inc.
DNA Replication
DNA uncoils into two nucleotide chains, and each side serves as a template
Nucleotides are complementary
Adenine (A) always bonds with thymine (T)
Guanine (G) always bonds with cytosine (C)For example, TACTGC bonds with new nucleotides in the order ATGACGSlide118
Figure 3.14 Replication of the DNA molecule during interphase.
KEY:
Adenine
Thymine
Cytosine
Guanine
Old
(template)
strand
Newly
synthesized
strand
New
strand
forming
Old (template)
strand
DNA of one chromatidSlide119
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Events of Cell Division
Mitosis—division of the nucleus
Results in the formation of two daughter nuclei
Cytokinesis—division of the cytoplasm
Begins when mitosis is near completionResults in the formation of two daughter cellsSlide120
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Stages of Mitosis
Prophase
First part of cell division
Chromatin coils into chromosomes
Chromosomes are held together by a centromereA chromosome has two strandsEach strand is called a chromatidSlide121
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Stages of Mitosis
Prophase (continued)
Centrioles migrate to the poles to direct assembly of mitotic spindle fibers
Mitotic spindles are made of microtubules
Spindle provides scaffolding for the attachment and movement of the chromosomes during the later mitotic stagesNuclear envelope breaks down and disappearsSlide122
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Stages of Mitosis
Metaphase
Chromosomes are aligned in the center of the cell on the metaphase plate
Metaphase plate is the center of the spindle midway between the centrioles
Straight line of chromosomes is now seenSlide123
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Stages of Mitosis
Anaphase
Centromere splits
Chromatids move slowly apart and toward the opposite ends of the cell
Anaphase is over when the chromosomes stop movingSlide124
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Stages of Mitosis
Telophase
Reverse of prophase
Chromosomes uncoil to become chromatin
Spindles break down and disappearNuclear envelope reforms around chromatinNucleoli appear in each of the daughter nuclei Slide125
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Stages of Mitosis
Cytokinesis
Division of the cytoplasm
Begins during late anaphase and completes during telophase
A cleavage furrow forms to pinch the cells into two partsCleavage furrow is a contractile ring made of microfilamentsSlide126
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Stages of Mitosis
Two daughter cells exist at the end of cell division
In most cases, mitosis and cytokinesis occur together
In some cases, the cytoplasm is not divided
Binucleate or multinucleate cells resultCommon in the liverMitosis gone wild is the basis for tumors and cancersSlide127
Spindle
microtubules
Chromosome,
consisting of two
sister chromatids
Fragments of
nuclear envelope
Daughter
chromosomes
Figure 3.15
Stages of mitosis.
Centrioles
Chromatin
Centrioles
Forming
mitotic
spindle
Centromere
Centromere
Plasma
membrane
Nuclear
envelope
Nucleolus
Spindle
pole
Metaphase
plate
Nucleolus
forming
Cleavage
furrow
Spindle
Sister
chromatids
Nuclear
envelope
forming
Interphase
Early prophase
Late prophase
Metaphase
Anaphase
Telophase
and cytokinesis
Slide 1Slide128
Figure 3.15
Stages of mitosis (1
of 6)
.
Centrioles
Chromatin
Plasma
membrane
Nuclear
envelope
Nucleolus
Interphase
Slide 2Slide129
Figure 3.15 Stages of mitosis
(2
of 6).
Chromosome,
consisting of two
sister chromatids
Centrioles
Forming
mitotic
spindle
Centromere
Early prophase
Slide 3Slide130
Figure 3.15 Stages of mitosis
(3
of 6).
Spindle
microtubules
Fragments of
nuclear envelope
Centromere
Spindle
pole
Late prophase
Slide 4Slide131
Figure 3.15 Stages of mitosis
(4
of 6).
Metaphase
plate
Spindle
Sister
chromatids
Metaphase
Slide 5Slide132
Figure 3.15 Stages of mitosis
(5
of 6).
Daughter
chromosomes
Anaphase
Slide 6Slide133
Figure 3.15 Stages of mitosis
(6
of 6).
Nucleolus
forming
Cleavage
furrow
Nuclear
envelope
forming
Telophase
and cytokinesis
Slide 7Slide134
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Protein Synthesis
DNA serves as a blueprint for making proteins
Gene: DNA segment that carries a blueprint for building one protein or polypeptide chain
Proteins have many functions
Fibrous (structural) proteins are the building materials for cellsGlobular (functional) proteins act as enzymes (biological catalysts)Slide135
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Protein Synthesis
DNA information is coded into triplets
Triplets
Contain three bases
Call for a particular amino acidFor example, a DNA sequence of AAA specifies the amino acid phenylalanineSlide136
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Protein Synthesis
Most ribosomes, the manufacturing sites of proteins, are located in the cytoplasm
DNA never leaves the nucleus in interphase cells
DNA requires a decoder and a messenger to build proteins, both are functions carried out by RNA (ribonucleic acid)Slide137
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Protein Synthesis
How does RNA differ from DNA? RNA:
Is single-stranded
Contains ribose sugar instead of
deoxyriboseContains uracil (U) base instead of thymine (T)Slide138
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Role of RNA
Transfer RNA (tRNA)
Transfers appropriate amino acids to the ribosome for building the protein
Ribosomal RNA (rRNA)
Helps form the ribosomes where proteins are builtMessenger RNA (mRNA)Carries the instructions for building a protein from the nucleus to the ribosomeSlide139
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Role of RNA
Protein synthesis involves two major phases:
Transcription
Translation
We will detail these two phases nextSlide140
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Protein Synthesis
Transcription
Transfer of information from DNA’s base sequence to the complementary base sequence of mRNA
Only DNA and mRNA are involved
Triplets are the three-base sequence specifying a particular amino acid on the DNA geneCodons
are the corresponding three-base sequences on mRNASlide141
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Protein Synthesis
Example of transcription:
DNA triplets AAT-CGT-TCG
mRNA codons UUA-GCA-AGCSlide142
As the ribosome
moves along the mRNA,
a new amino acid is
added to the growing
protein chain.
Released
tRNA
reenters the
cytoplasmic pool,
ready to be recharged
with a new amino
acid.
mRNA specifying one
polypeptide is made on
DNA template.
mRNA leaves
nucleus and attaches
to ribosome, and
translation begins.
Incoming
tRNA
recognizes a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
mRNA
Figure 3.16
Protein synthesis.
Nuclear membrane
2
1
3
4
5
Nuclear pore
Nucleus
(site of transcription)
DNA
Amino
acids
Cytoplasm
(site of translation)
Synthetase
enzyme
Correct amino
acid attached to
each species of
tRNA
by an
enzyme
Growing
polypeptide
chain
Peptide bond
tRNA
“head”
bearing anticodon
Large ribosomal subunit
Codon
Portion of
mRNA already
translated
Small ribosomal subunit
Direction of
ribosome
advance;
ribosome moves the
mRNA strand along
sequentially as each
codon is read.
Met
Gly
Ser
Phe
Ala
Slide 1Slide143
mRNA specifying one
polypeptide is made on
DNA template.
Figure 3.16
Protein synthesis (1 of
2)
.
mRNA
Nuclear membrane
1
Nuclear pore
Nucleus
(site of transcription)
DNA
Amino
acids
Cytoplasm
(site of translation)
Synthetase
enzyme
Correct amino
acid attached to
each species of
tRNA
by an
enzyme
Slide 2Slide144
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Protein Synthesis
Translation
Base sequence of nucleic acid is translated to an amino acid sequence
Amino acids are the building blocks of proteinsSlide145
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Protein Synthesis
Translation (continued)
Steps correspond to Figure 3.16 (
step 1 covers transcription
)mRNA leaves nucleus and attaches to ribosome, and translation beginsIncoming tRNA
recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon.Slide146
mRNA leaves
nucleus and attaches
to ribosome, and
translation begins.
mRNA specifying one
polypeptide is made on
DNA template.
Figure 3.16
Protein synthesis (1 of
2)
.
mRNA
Nuclear membrane
1
Nuclear pore
Nucleus
(site of transcription)
DNA
Amino
acids
Cytoplasm
(site of translation)
Synthetase
enzyme
Correct amino
acid attached to
each species of
tRNA
by an
enzyme
2
Slide 3Slide147
Incoming
tRNA
recognizes
a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
Figure 3.16
Protein synthesis (2 of 2).
tRNA
“head”
bearing anticodon
Large ribosomal subunit
Codon
Portion of
mRNA already
translated
Small ribosomal subunit
Direction of
ribosome
advance;
ribosome moves the
mRNA strand along
sequentially as each
codon is read.
3
Slide 4Slide148
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Protein Synthesis
Translation (continued)
Steps correspond to Figure 3.16
As the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain.
Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid.Slide149
Incoming
tRNA
recognizes
a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
As the ribosome
moves along the mRNA,
a new amino acid is
added to the growing
protein chain.
Figure 3.16
Protein synthesis (2 of 2).
Growing
polypeptide
chain
Peptide bond
tRNA
“head”
bearing anticodon
Large ribosomal subunit
Codon
Portion of
mRNA already
translated
Small ribosomal subunit
Direction of
ribosome
advance;
ribosome moves the
mRNA strand along
sequentially as each
codon is read.
3
4
Met
Gly
Ser
Phe
Ala
Slide 5Slide150
Released
tRNA
reenters the
cytoplasmic pool,
ready to be recharged
with a new amino
acid.
Incoming
tRNA
recognizes
a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
As the ribosome
moves along the mRNA,
a new amino acid is
added to the growing
protein chain.
Figure 3.16
Protein synthesis (2 of 2).
Growing
polypeptide
chain
Peptide bond
tRNA
“head”
bearing anticodon
Large ribosomal subunit
Codon
Portion of
mRNA already
translated
Small ribosomal subunit
Direction of
ribosome
advance;
ribosome moves the
mRNA strand along
sequentially as each
codon is read.
3
4
5
Met
Gly
Ser
Phe
Ala
Slide 6Slide151
Concept Link
© 2015 Pearson Education, Inc.Slide152
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Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types:
Epithelial tissue (epithelium)Connective tissueMuscle tissue
Nervous tissueSlide153
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Epithelial Tissues
Locations:
Body coverings
Body linings
Glandular tissueFunctions:ProtectionAbsorptionFiltrationSecretionSlide154
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Epithelium Characteristics
Cells fit closely together and often form sheets
The apical surface is the free surface of the tissue
The lower surface of the epithelium rests on a basement membrane
Avascular (no blood supply)Regenerate easily if well nourishedSlide155
Figure 3.17a
Classification and functions of epithelia.
Basal
surface
Apical surface
Basal
surface
Apical surface
Simple
Stratified
(a) Classification based on number of cell layersSlide156
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Classification of Epithelia
Number of cell layers
Simple—one layer
Stratified—more than one layerSlide157
Figure 3.17a
Classification and functions of epithelia.
Basal
surface
Apical surface
Basal
surface
Apical surface
Simple
Stratified
(a) Classification based on number of cell layersSlide158
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Classification of Epithelia
Shape of cells
Squamous
Flattened, like fish scales
CuboidalCube-shaped, like diceColumnarColumn-like Slide159
Figure 3.17b
Classification and functions of epithelia.
Squamous
Cuboidal
Columnar
(b) Classification based on cell shapeSlide160
Figure 3.17c
Classification and functions of epithelia.
Diffusion and filtration
Secretion in serous membranes
Protection
Secretion and absorption; ciliated
types propel mucus or
reproductive cells
Secretion and absorption; ciliated
types propel mucus or
reproductive cells
Protection; these tissue types are rare
in humans
Protection; stretching to accommodate
distension of urinary structures
(c) Function of epithelial tissue related to tissue type
Number of layers
Cell shape
One layer: simple epithelial
tissues
More than one layer: stratified
epithelial tissues
Squamous
Cuboidal
Columnar
TransitionalSlide161
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Simple Epithelia
Simple squamous
Single layer of flat cells
Location—usually forms membranes
Lines air sacs of the lungs Forms walls of capillariesForms serous membranes (serosae) that line and cover organs in ventral cavityFunctions in diffusion, filtration, or secretion in membranesSlide162
Figure 3.18a Types of epithelia and their common locations in the body.
Nucleus of
squamous
epithelial cell
Basement
membrane
Air sacs of
lungs
Nuclei of
squamous
epithelial
cells
(a) Diagram:
Simple squamous
Photomicrograph:
Simple
squamous epithelium forming part
of the alveolar (air sac) walls (275
×
).Slide163
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Simple Epithelia
Simple cuboidal
Single layer of cube-like cells
Locations:
Common in glands and their ductsForms walls of kidney tubulesCovers the surface of ovariesFunctions in secretion and absorption; ciliated types propel mucus or reproductive cellsSlide164
Figure 3.18b Types of epithelia and their common locations in the body.
Nucleus of
simple
cuboidal
epithelial
cell
Basement
membrane
Simple
cuboidal
epithelial
cells
Basement
membrane
Connective
tissue
(b) Diagram:
Simple cuboidal
Photomicrograph:
Simple cuboidal
epithelium in kidney tubules (250
×
).Slide165
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Simple Epithelia
Simple columnar
Single layer of tall cells
Goblet cells secrete mucus
Location: Lines digestive tract from stomach to anus Mucous membranes (mucosae) line body cavities opening to the exteriorFunctions in secretion and absorption; ciliated types propel mucus or reproductive cellsSlide166
Figure 3.18c Types of epithelia and their common locations in the body.
Basement
membrane
Basement
membrane
Mucus of a
goblet cell
Nucleus of
simple
columnar
epithelial cell
Simple
columnar
epithelial cells
(c) Diagram:
Simple columnar
Photomicrograph:
Simple columnar
epithelium of the small intestine (575
×
).Slide167
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Simple Epithelia
Pseudostratified columnar
All cells rest on a basement membrane
Single layer, but some cells are shorter than others giving a false (pseudo) impression of stratification
Location:Respiratory tract, where it is ciliated and known as pseudostratified ciliated columnar epitheliumFunctions in absorption or secretionSlide168
Figure 3.18d Types of epithelia and their common locations in the body.
(d) Diagram:
Pseudostratified
(ciliated) columnar
Photomicrograph:
Pseudostratified
ciliated columnar epithelium lining the
human trachea (560
×
).
Basement
membrane
Basement
membrane
Pseudo-
stratified
epithelial
layer
Pseudo-
stratified
epithelial layer
Cilia
Connective
tissueSlide169
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Stratified Epithelia
Stratified squamous
Named for cells present at the free (apical) surface, which are flattened
Functions as a protective covering where friction is common
Locations—lining of the:Skin (outer portion)MouthEsophagusSlide170
Figure 3.18e Types of epithelia and their common locations in the body.
Basement
membrane
Basement
membrane
Connective
tissue
Stratified
squamous
epithelium
Stratified
squamous
epithelium
(e) Diagram:
Stratified squamous
Photomicrograph:
Stratified squamous
epithelium lining of the esophagus (140
×
).
NucleiSlide171
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Stratified Epithelia
Stratified cuboidal—two layers of cuboidal cells; functions in protection
Stratified columnar—surface cells are columnar, and cells underneath vary in size and shape; functions in protection
Stratified cuboidal and columnar
Rare in human bodyFound mainly in ducts of large glandsSlide172
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Stratified Epithelia
Transitional epithelium
Composed of modified stratified squamous epithelium
Shape of cells depends upon the amount of stretching
Functions in stretching and the ability to return to normal shapeLocations: urinary system organsSlide173
Figure 3.18f Types of epithelia and their common locations in the body.
Basement
membrane
Basement
membrane
Connective
tissue
Transi
-
tional
epithelium
Transitional
epithelium
(f) Diagram:
Transitional
Photomicrograph:
Transitional epithelium lining of
the bladder, relaxed state (270
×
); surface rounded cells
flatten and elongate when the bladder fills with urine.Slide174
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Glandular Epithelium
Gland
One or more cells responsible for secreting a particular product
Secretions contain protein molecules in an aqueous (water-based) fluid
Secretion is an active processSlide175
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Glandular Epithelium
Two major gland types
Endocrine gland
Ductless; secretions diffuse into blood vessels
All secretions are hormonesExamples include thyroid, adrenals, and pituitarySlide176
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Glandular Epithelium
Two major gland types
Exocrine gland
Secretions empty through ducts to the epithelial surface
Include sweat and oil glands, liver, and pancreasIncludes both internal and external glandsSlide177
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Connective Tissue
Found everywhere in the body
Includes the most abundant and widely distributed tissues
Functions:
Provides protectionBinds body tissues togetherSupports the bodySlide178
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Connective Tissue Characteristics
Variations in blood supply
Some tissue types are well vascularized
Some have a poor blood supply or are avascular
Extracellular matrixNonliving material that surrounds living cellsSlide179
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Extracellular Matrix
Two main elements
Ground substance—mostly water along with adhesion proteins and polysaccharide molecules
Fibers
Produced by the cellsThree types:Collagen (white) fibers
Elastic (yellow) fibers
Reticular fibers (a type of collagen)Slide180
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Connective Tissue Types
From most rigid to softest, or most fluid:
Bone
Cartilage
Dense connective tissueLoose connective tissueBloodSlide181
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Connective Tissue Types
Bone (osseous tissue)
Composed of:
Osteocytes (bone cells) sitting in lacunae (cavities)
Hard matrix of calcium saltsLarge numbers of collagen fibersFunctions to protect and support the bodySlide182
Figure 3.19a Connective tissues
and their common body locations.
Bone cells
in lacunae
Central
canal
Lacunae
Lamella
(a) Diagram:
Bone
Photomicrograph:
Cross-sectional
view of ground bone (165
×
)Slide183
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Connective Tissue Types
Cartilage
Less hard and more flexible than bone
Found in only a few places in the body
Chondrocyte (cartilage cell) is the major cell typeSlide184
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Connective Tissue Types
Hyaline cartilage
Hyaline cartilage is the most widespread type of cartilage
Composed of abundant collagen fibers and a rubbery matrix
Locations:LarynxEntire fetal skeleton prior to birthEpiphyseal platesFunctions as a more flexible skeletal element than boneSlide185
Figure 3.19b Connective tissues
and their common body locations.
Chondrocyte
(cartilage cell)
Chondrocyte
in lacuna
Matrix
Lacunae
Photomicrograph:
Hyaline cartilage
from the trachea (400
×
)
(b) Diagram:
Hyaline
cartilageSlide186
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Connective Tissue Types
Elastic cartilage (not pictured)
Provides elasticity
Location:
Supports the external earFibrocartilageHighly compressibleLocation:Forms cushionlike
discs between vertebrae of the spinal columnSlide187
Figure 3.19c Connective tissues
and their common body locations.
Chondro
-
cytes
in
lacunae
Collagen
fibers
Chondrocytes
in lacunae
Collagen fiber
Photomicrograph:
Fibrocartilage of an
intervertebral disc (150
×
)
(c) Diagram:
FibrocartilageSlide188
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Connective Tissue Types
Dense connective tissue (dense fibrous tissue)
Main matrix element is collagen fiber
Fibroblasts are cells that make fibers
Locations:Tendons—attach skeletal muscle to boneLigaments—attach bone to bone at joints and are more elastic than tendonsDermis—lower layers of the skinSlide189
Figure 3.19d Connective tissues
and their common body locations.
Ligament
(d) Diagram:
Dense
fibrous
Photomicrograph:
Dense fibrous
connective tissue from a tendon (475
×
)
Collagen
fibers
Nuclei of
fibroblasts
Nuclei of
fibroblasts
Collagen
fibers
TendonSlide190
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Connective Tissue Types
Loose connective tissue types
Areolar tissue
Most widely distributed connective tissue
Soft, pliable tissue like “cobwebs”Functions as a universal packing tissue and “glue” to hold organs in placeLayer of areolar tissue called lamina propria
underlies all membranes
All fiber types form a loose network
Can soak up excess fluid (causes edema)Slide191
Figure 3.19e Connective tissues
and their common body locations.
Mucosa
epithelium
Lamina
propria
Fibers of
matrix
Nuclei of
fibroblasts
Elastic
fibers
Collagen
fibers
Fibroblast
nuclei
(e) Diagram:
Areolar
Photomicrograph:
Areolar connective tissue,
a soft packaging tissue of the body (270
×
)Slide192
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Connective Tissue Types
Loose connective tissue types
Adipose tissue
Matrix is an areolar tissue in which fat globules predominate
Many cells contain large lipid deposits with nucleus to one side (signet ring cells)FunctionsInsulates the bodyProtects some organsServes as a site of fuel storageSlide193
Figure 3.19f Connective tissues
and their common body locations.
Nuclei of
fat cells
Vacuole
containing
fat droplet
Vacuole
containing
fat droplet
Nuclei of
fat cells
(f) Diagram:
Adipose
Photomicrograph:
Adipose tissue from the
subcutaneous layer beneath the skin (570
×
)Slide194
© 2015 Pearson Education, Inc.
Connective Tissue Types
Loose connective tissue types
Reticular connective tissue
Delicate network of interwoven fibers with reticular cells (like fibroblasts)
Locations:Forms stroma (internal framework) of organs, such as these lymphoid organs:Lymph nodes
Spleen
Bone marrowSlide195
Figure 3.19g Connective tissues
and their common body locations.
Spleen
(g) Diagram:
Reticular
Photomicrograph:
Dark-staining network
of reticular connective tissue (400
×
)
Reticular
cell
Blood
cell
Reticular
fibers
White blood cell
(lymphocyte)
Reticular fibersSlide196
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Connective Tissue Types
Blood (vascular tissue)
Blood cells surrounded by fluid matrix known as
blood plasma
Soluble fibers are visible only during clottingFunctions as the transport vehicle for the cardiovascular system, carrying:NutrientsWastesRespiratory gasesSlide197
Figure 3.19h Connective tissues
and their common body locations.
Photomicrograph:
Smear of human
blood (1290
×
)
(h) Diagram:
Blood
Blood cells
in capillary
White
blood cell
Red
blood cells
Neutrophil
(white blood
cell)
Red blood
cells
Monocyte
(white blood
cell)Slide198
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Muscle Tissue
Function is to contract, or shorten, to produce movement
Three types:
Skeletal muscle
Cardiac muscleSmooth muscleSlide199
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Muscle Tissue Types
Skeletal muscle
Voluntarily (consciously) controlled
Attached to the skeleton and pull on bones or skin
Produces gross body movements or facial expressionsCharacteristics of skeletal muscle cellsStriations (stripes)Multinucleate (more than one nucleus)
Long,
cylindrical shapeSlide200
Figure 3.20a Type
of muscle tissue and their common locations in the body.
Nuclei
Part of muscle
fiber
Photomicrograph:
Skeletal muscle (195
×
)
(a) Diagram:
Skeletal muscleSlide201
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Muscle Tissue Types
Cardiac muscle
Involuntarily controlled
Found only in the heart
Pumps blood through blood vesselsCharacteristics of cardiac muscle cellsStriationsUninucleate, short, branching cellsIntercalated discs contain gap junctions to connect cells togetherSlide202
Figure 3.20b Type
of muscle tissue and their common locations in the body.
Intercalated
discs
Nucleus
Photomicrograph:
Cardiac muscle (475
×
)
(b) Diagram:
Cardiac muscleSlide203
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Muscle Tissue Types
Smooth (visceral) muscle
Involuntarily controlled
Found in walls of hollow organs such as stomach, uterus, and blood vessels
Peristalsis, a wavelike activity, is a typical activityCharacteristics of smooth muscle cellsNo visible striationsUninucleateSpindle-shaped cellsSlide204
Figure 3.20c Type
of muscle tissue and their common locations in the body.
Smooth
muscle cell
Nuclei
Photomicrograph:
Sheet of smooth muscle (285
×
)
(c) Diagram:
Smooth muscleSlide205
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Nervous Tissue
Composed of neurons and nerve support cells
Function is to receive and conduct electrochemical impulses to and from body parts
Irritability
ConductivitySupport cells called neuroglia insulate, protect, and support neuronsSlide206
Figure 3.21
Nervous tissue.
Brain
Spinal
cord
Nuclei of
supporting
cells
Cell body
of neuron
Neuron
processes
Nuclei of
supporting
cells
Neuron
processes
Cell body
of neuron
Diagram:
Nervous
tissue
Photomicrograph:
Neurons (320
×
)Slide207
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Summary of Tissues
Figure 3.22 summarizes the tissue types and functions in the bodySlide208
Figure 3.22
Summary of the major functions and body locations of the four tissue types: epithelial, connective, muscle, and nervous tissues.
Nervous tissue:
Internal communication
• Brain, spinal cord, and nerves
Muscle tissue:
Contracts to cause movement
Epithelial tissue:
Forms boundaries between
different environments, protects, secretes, absorbs,
filters
Connective tissue:
Supports, protects, binds
other tissues together
• Muscles attached to bones (skeletal)
• Muscles of heart (cardiac)
• Muscles of walls of hollow organs (smooth)
• Lining of GI tract organs and other hollow organs
• Skin surface (epidermis)
• Bones
• Tendons
• Fat and other soft padding tissueSlide209
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Tissue Repair (Wound Healing)
Tissue repair (wound healing) occurs in two ways:
Regeneration
Replacement of destroyed tissue by the same kind of cells
FibrosisRepair by dense (fibrous) connective tissue (scar tissue)Slide210
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Tissue Repair (Wound Healing)
Whether regeneration or fibrosis occurs depends on:
Type of tissue damaged
Severity of the injury
Clean cuts (incisions) heal more successfully than ragged tears of the tissueSlide211
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Events in Tissue Repair
Inflammation
Capillaries become very permeable
Clotting proteins migrate into the area from the bloodstream
A clot walls off the injured areaGranulation tissue formsGrowth of new capillariesPhagocytes dispose of blood clot and fibroblastsRebuild collagen fibersSlide212
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Events in Tissue Repair
Regeneration of surface epithelium
Scab detaches
Whether scar is visible or invisible depends on severity of woundSlide213
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Regeneration of Tissues
Tissues that regenerate easily
Epithelial tissue (skin and mucous membranes)
Fibrous connective tissues and bone
Tissues that regenerate poorlySkeletal muscleTissues that are replaced largely with scar tissueCardiac muscleNervous tissue within the brain and spinal cordSlide214
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Development Aspects of Cells and Tissues
Growth through cell division continues through puberty
Cell populations exposed to friction (such as epithelium) replace lost cells throughout life
Connective tissue remains mitotic and forms repair (scar) tissue
With some exceptions, muscle tissue becomes amitotic by the end of pubertyNervous tissue becomes amitotic shortly after birth. Slide215
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Developmental Aspects of Cells and Tissues
Injury can severely handicap amitotic tissues
The cause of aging is unknown, but chemical and physical insults, as well as genetic programming, have been proposed as possible causesSlide216
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Developmental Aspects of Cells and Tissues
Neoplasms, both benign and cancerous, represent abnormal cell masses in which normal controls on cell division are not working
Hyperplasia (increase in size) of a tissue or organ may occur when tissue is strongly stimulated or irritated
Atrophy (decrease in size) of a tissue or organ occurs when the organ is no longer stimulated normally