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Chapter 3
Cells and Tissues
Lecture Presentation by
Patty Bostwick-Taylor
Florence-Darlington Technical College
© 2015 Pearson Education, Inc.
Cells
 Cells are the structural units of all living things
 The human body has 50 to 100 trillion cells
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Four Concepts of the Cell Theory
1. A cell is the basic structural and functional unit of
living organisms.
2. The activity of an organism depends on the
collective activities of its cells.
3. According to the principle of complementarity, the
biochemical activities of cells are dictated by the
relative number of their specific subcellular
structures.
4. Continuity of life has a cellular basis.
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Chemical Components of Cells
 Most cells are composed of four elements:
1.
2.
3.
4.
Carbon
Hydrogen
Oxygen
Nitrogen
 Cells are about 60% water
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Anatomy of a Generalized Cell
 In general, a cell has three main regions or parts:
1. Nucleus
2. Cytoplasm
3. Plasma membrane
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Figure 3.1a Anatomy of the generalized animal cell nucleus.
Nucleus
Cytoplasm
(a)
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Plasma
membrane
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:
1. Nuclear envelope (membrane)
2. Nucleolus
3. Chromatin
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Figure 3.1b Anatomy of the generalized animal cell nucleus.
Nuclear envelope
Chromatin
Nucleolus
Nuclear
pores
Rough ER
(b)
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Nucleus
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
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The Nucleus
 Nucleoli
 Nucleus contains one or more nucleoli
 Sites 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
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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
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Figure 3.2 Structure of the plasma membrane.
Extracellular fluid
(watery environment)
Glycoprotein Glycolipid
Cholesterol
Sugar
group
Polar heads
of phospholipid
molecules
Bimolecular
lipid layer
containing
proteins
Nonpolar tails
of phospholipid
molecules
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Channel
Proteins Filaments of
cytoskeleton
Cytoplasm
(watery environment)
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 membrane
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Plasma Membrane
 Fluid mosaic model
 Phospholipid arrangement
 The hydrophobic interior makes the plasma
membrane impermeable to most water-soluble
molecules
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Plasma Membrane
 Fluid mosaic model
 Proteins
 Responsible for specialized functions
 Roles of proteins
 Enzymes
 Receptors
 Transport as channels or carriers
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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 surface
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Plasma Membrane Junctions
 Membrane junctions
 Cells are bound together in three ways:
1. Glycoproteins in the glycocalyx act as an adhesive
or cellular glue
2. Wavy contours of the membranes of adjacent cells
fit together in a tongue-and-groove fashion
3. Special membrane junctions are formed, which vary
structurally depending on their roles
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Plasma Membrane Junctions
 Membrane junctions
 Tight junctions
 Impermeable junctions
 Bind cells together into leakproof sheets
 Prevent substances from passing through
extracellular space between cells
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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
membranes
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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 membranes
 Molecules can travel directly from one cell to the next
through these channels
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Figure 3.3 Cell junctions.
Tight
(impermeable)
junction
Microvilli
Desmosome
(anchoring
junction)
Plasma
membranes of
adjacent cells
Connexon
Gap
Underlying Extracellular
basement space between (communicating)
junction
membrane cells
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Cytoplasm
 The material outside the nucleus and inside the
plasma membrane
 Site of most cellular activities
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Cytoplasm
 Contains three major elements
1. Cytosol
 Fluid that suspends other elements
2. Organelles
 Metabolic machinery of the cell
 “Little organs” that perform functions for the cell
3. Inclusions
 Chemical substances, such as stored nutrients or cell
products
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Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
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Secretion being
released from cell
by exocytosis
Cytoplasmic Organelles
 Organelles
 Specialized cellular compartments
 Many are membrane-bound
 Compartmentalization is critical for organelle’s ability
to perform specialized functions
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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 membrane
 Carry out reactions where oxygen is used to break
down food
 Provides ATP for cellular energy
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Cytoplasmic Organelles
 Ribosomes
 Bilobed dark bodies
 Made of protein and ribosomal RNA
 Sites of protein synthesis
 Found at two locations:
 Free in the cytoplasm
 As part of the rough endoplasmic reticulum
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Cytoplasmic Organelles
 Endoplasmic reticulum (ER)
 Fluid-filled cisterns (tubules or canals) for carrying
substances within the cell
 Two types:
 Rough ER
 Smooth ER
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Cytoplasmic Organelles
 Endoplasmic reticulum (ER)
 Rough endoplasmic reticulum
 Studded with ribosomes
 Synthesizes proteins
 Transport vesicles move proteins within cell
 Abundant in cells that make and export proteins
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Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
Slide 1
mRNA
Rough ER
2
1
3
Protein
Transport
vesicle buds off
4
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
3 The protein is packaged in a tiny
membranous sac called a transport vesicle.
4 The transport vesicle buds from the
rough ER and travels to the Golgi apparatus
for further processing.
Protein inside
transport vesicle
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Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
Slide 2
mRNA
Rough ER
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
1
Protein
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Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
mRNA
Rough ER
2
1
Protein
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Slide 3
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
mRNA
Rough ER
2
1
3
Protein
Transport
vesicle buds off
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Slide 4
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
3 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
Slide 5
mRNA
Rough ER
2
1
3
Protein
Transport
vesicle buds off
4
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
3 The protein is packaged in a tiny
membranous sac called a transport vesicle.
4 The transport vesicle buds from the
rough ER and travels to the Golgi apparatus
for further processing.
Protein inside
transport vesicle
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Cytoplasmic Organelles
 Endoplasmic reticulum (ER)
 Smooth endoplasmic reticulum
 Functions in lipid metabolism
 Detoxification of drugs and pesticides
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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 packages
 Secretory vesicles (pathway 1)
 In-house proteins and lipids (pathway 2)
 Lysosomes (pathway 3)
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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.
Pathway 3
Golgi
apparatus
Pathway 2
Pathway 1
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle.
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Secretory vesicles
Proteins
Secretion by
exocytosis
Golgi vesicle containing
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid
Cytoplasmic Organelles
 Lysosomes
 Membranous “bags” packaged by the Golgi
apparatus
 Contain enzymes produced by ribosomes
 Enzymes can digest worn-out or nonusable cell
structures
 House phagocytes that dispose of bacteria and cell
debris
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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 water
 Replicate by pinching in half or budding from the ER
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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:
1. Microfilaments (largest)
2. Intermediate filaments
3. Microtubules (smallest)
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Figure 3.7 Cytoskeletal elements support the cell and help to generate movement.
(a) Microfilaments
(b) Intermediate filaments
(c) Microtubules
Tubulin subunits
Fibrous subunits
Actin subunit
7 nm
Microfilaments form the blue
batlike network.
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10 nm
Intermediate filaments form
the purple network
surrounding the pink nucleus.
25 nm
Microtubules appear as gold
networks surrounding the
cells’ pink nuclei.
Cytoplasmic Organelles
 Centrioles
 Rod-shaped bodies made of microtubules
 Generate microtubules
 Direct the formation of mitotic spindle during cell
division
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Table 3.1 Parts of the Cell: Structure and Function (1 of 5).
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Table 3.1 Parts of the Cell: Structure and Function (2 of 5).
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Table 3.1 Parts of the Cell: Structure and Function (3 of 5).
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Table 3.1 Parts of the Cell: Structure and Function (4 of 5).
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Table 3.1 Parts of the Cell: Structure and Function (5 of 5).
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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 sperm
 Microvilli are tiny, fingerlike extensions of the plasma
membrane
 Increase surface area for absorption
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Figure 3.8g Cell diversity.
Flagellum
Nucleus
Sperm
(g) Cell of reproduction
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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 function
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Cell Diversity
 Cells that connect body parts
 Fibroblast
 Secretes cable-like fibers
 Erythrocyte (red blood cell)
 Carries oxygen in the bloodstream
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Figure 3.8a Cell diversity.
Fibroblasts
Rough ER and Golgi
apparatus
No organelles
Nucleus
Erythrocytes
(a) Cells that connect body parts
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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
pulling
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Figure 3.8b Cell diversity.
Epithelial
cells
Nucleus
Intermediate
filaments
(b) Cells that cover and line body organs
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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
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Figure 3.8c Cell diversity.
Skeletal
muscle cell
Contractile
filaments
Nuclei
Smooth
muscle cells
(c) Cells that move organs and body parts
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Cell Diversity
 Cell that stores nutrients
 Fat cells
 Lipid droplets stored in cytoplasm
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Figure 3.8d Cell diversity.
Fat cell
Lipid droplet
Nucleus
(d) Cell that stores
nutrients
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Cell Diversity
 Cell that fights disease
 Macrophage (a phagocytic cell)
 Digests infectious microorganisms
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Figure 3.8e Cell diversity.
Lysosomes
Macrophage
Pseudopods
(e) Cell that fights
disease
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Cell Diversity
 Cell that gathers information and controls body
functions
 Nerve cell (neuron)
 Receives and transmits messages to other body
structures
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Figure 3.8f Cell diversity.
Processes
Rough ER
Nerve cell
Nucleus
(f) Cell that gathers information and
controls body functions
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Cell Diversity
 Cells of reproduction
 Oocyte (female)
 Largest cell in the body
 Divides to become an embryo upon fertilization
 Sperm (male)
 Built for swimming to the egg for fertilization
 Flagellum acts as a motile whip
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Figure 3.8g Cell diversity.
Flagellum
Nucleus
Sperm
(g) Cell of reproduction
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Cell Physiology
 Cells have the ability to:
 Metabolize
 Digest food
 Dispose of wastes
 Reproduce
 Grow
 Move
 Respond to a stimulus
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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
solution
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Membrane Transport
 Intracellular fluid
 Nucleoplasm and cytosol
 Solution containing gases, nutrients, and salts
dissolved in water
 Interstitial fluid
 Fluid on the exterior of the cell
 Contains thousands of ingredients, such as nutrients,
hormones, neurotransmitters, salts, waste products
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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 cell
 Undesirable substances are kept out
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Membrane Transport
 Two basic methods of transport
 Passive processes
 No energy (ATP) is required
 Active processes
 Cell must provide metabolic energy (ATP)
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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 randomly
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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
diffusion
 The warmer the molecule, the faster the rate of
diffusion
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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
cup
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Figure 3.9 Diffusion.
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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 carrier
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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 pores
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Figure 3.10a Diffusion through the plasma membrane.
Extracellular
fluid
Lipidsoluble
solutes
Cytoplasm
(a) Simple
diffusion
of fat-soluble
molecules
directly
through the
phospholipid
bilayer
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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 gradient
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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
bilayer
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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 plump
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A Closer Look 3.1 IV Therapy and Cellular “Tonics.”
(a) RBC in isotonic
solution
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(b) RBC in hypertonic
solution
(c) RBC in hypotonic
solution
Passive Processes
 Types of diffusion (continued)
 Facilitated diffusion
 Transports lipid-insoluble and large substances
 Glucose is transported via facilitated diffusion
 Protein membrane channels or protein molecules that
act as carriers are used
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Figure 3.10b-c Diffusion through the plasma membrane.
Lipidinsoluble
solutes
(b) Carrier-mediated
(c)
facilitated diffusion via
protein carrier specific for
one chemical; binding of
substrate causes shape
change in transport protein
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Small lipidinsoluble
solutes
Channelmediated
facilitated
diffusion
through a
channel protein;
mostly ions,
selected on
basis of
size and charge
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 highpressure area to a lower-pressure area
 Filtration is critical for the kidneys to work properly
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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
channels
 May not be lipid-soluble
 May have to move against a concentration gradient
 ATP is used for transport
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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 pumps
 In most cases, substances are moved against
concentration (or electrical) gradients
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Active Processes
 Example of active transport is the sodiumpotassium pump
 Sodium is transported out of the cell
 Potassium is transported into the cell
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Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Slide 1
Extracellular fluid
Na+
Na+
Na+-K+ pump
K+
Na+
Na+
Na+
K+
P
K+
P
ATP
Na+
1
2
3
K+
ADP
1 Binding of cytoplasmic Na+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
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2 The shape change expels
Na+
to the outside. Extracellular
binds, causing release of the
phosphate group.
K+
3 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
Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Slide 2
Extracellular fluid
Na+-K+ pump
Na+
Na+
P
ATP
Na+
1
ADP
1 Binding of cytoplasmic Na+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
Cytoplasm
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Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Slide 3
Extracellular fluid
Na+
Na+
Na+-K+ pump
K+
Na+
Na+
Na+
K+
P
P
ATP
Na+
1
2
ADP
1 Binding of cytoplasmic Na+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
2 The shape change expels
Na+ to the outside. Extracellular
K+ binds, causing release of the
phosphate group.
Cytoplasm
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Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Slide 4
Extracellular fluid
Na+
Na+
Na+-K+ pump
K+
Na+
Na+
Na+
K+
P
K+
P
ATP
Na+
2
1
3
K+
ADP
1 Binding of cytoplasmic Na+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
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2 The shape change expels
Na+
to the outside. Extracellular
binds, causing release of the
phosphate group.
K+
3 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
Active Processes
 Vesicular transport: substances are moved without
actually crossing the plasma membrane
 Exocytosis
 Endocytosis
 Phagocytosis
 Pinocytosis
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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
vesicle
 Vesicle migrates to plasma membrane
 Vesicle combines with plasma membrane
 Material is emptied to the outside
 Refer to Pathway 1 in Figure 3.6
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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.
Pathway 3
Golgi
apparatus
Pathway 2
Pathway 1
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle.
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Secretory vesicles
Proteins
Secretion by
exocytosis
Golgi vesicle containing
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid
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 together
© 2015 Pearson Education, Inc.
Figure 3.12a Exocytosis.
Extracellular Plasma
membrane
fluid
SNARE
(t-SNARE)
Secretory
vesicle
1 The membranebound vesicle
Vesicle
migrates to the
SNARE
(v-SNARE) plasma membrane.
Molecule
to be
secreted
Cytoplasm
Fusion pore formed
Fused
SNAREs
2 There, v-SNAREs
bind with t-SNAREs,
the vesicle and
plasma membrane
fuse, and a pore
opens up.
3 Vesicle contents
are released to the
cell exterior.
(a) The process of exocytosis
© 2015 Pearson Education, Inc.
Figure 3.12b Exocytosis.
(b) Electron micrograph of a
secretory vesicle in
exocytosis (190,000×)
© 2015 Pearson Education, Inc.
Active Processes
 Vesicular transport (continued)
 Endocytosis
 Extracellular substances are engulfed by being
enclosed in a membranous vescicle
 Vesicle typically fuses with a lysosome
 Contents are digested by lysosomal enzymes
 In some cases, the vesicle is released by exocytosis
on the opposite side of the cell
© 2015 Pearson Education, Inc.
Figure 3.13a Events and types of endocytosis.
Slide 1
Extracellular
fluid
Cytosol
Vesicle
1 Vesicle fusing
with lysosome
for digestion
Plasma
membrane
Lysosome
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
Ingested
substance
Pit
(a)
© 2015 Pearson Education, Inc.
3 Membranes and receptors
(if present) recycled to plasma
membrane
Figure 3.13a Events and types of endocytosis.
Extracellular
fluid
Plasma
membrane
1 Vesicle fusing
with lysosome
for digestion
(a)
© 2015 Pearson Education, Inc.
Slide 2
Figure 3.13a Events and types of endocytosis.
Extracellular
fluid
Slide 3
Cytosol
Vesicle
1 Vesicle fusing
with lysosome
for digestion
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
(a)
© 2015 Pearson Education, Inc.
Plasma
membrane
Lysosome
Figure 3.13a Events and types of endocytosis.
Slide 4
Extracellular
fluid
Cytosol
Vesicle
1 Vesicle fusing
with lysosome
for digestion
Plasma
membrane
Lysosome
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
Ingested
substance
Pit
(a)
© 2015 Pearson Education, Inc.
3 Membranes and receptors
(if present) recycled to plasma
membrane
Active Processes
 Vesicular transport (continued)
 Types of endocytosis
1. Phagocytosis—“cell eating”
 Cell engulfs large particles such as bacteria or dead
body cells
 Pseudopods are cytoplasmic extensions that separate
substances (such as bacteria or dead body cells) from
external environment
 Phagocytosis is a protective mechanism, not a means
of getting nutrients
© 2015 Pearson Education, Inc.
Figure 3.13b Events and types of endocytosis.
Extracellular
fluid
Pseudopod
(b)
© 2015 Pearson Education, Inc.
Cytoplasm
Bacterium
or other
particle
Active Processes
 Vesicular transport (continued)
 Types of endocytosis
2. Pinocytosis—“cell drinking”
 Cell “gulps” droplets of extracellular fluid containing
dissolved proteins or fats
 Plasma membrane forms a pit, and edges fuse around
droplet of fluid
 Routine activity for most cells, such as those involved
in absorption (small intestine)
© 2015 Pearson Education, Inc.
Figure 3.13a Events and types of endocytosis.
Extracellular
fluid
Cytosol
Vesicle
1 Vesicle fusing
with lysosome
for digestion
Plasma
membrane
Lysosome
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
Ingested
substance
Pit
(a)
© 2015 Pearson Education, Inc.
3 Membranes and receptors
(if present) recycled to plasma
membrane
Active Processes
 Vesicular transport (continued)
 Types of endocytosis
3. Receptor-mediated endocytosis
 Method for taking up specific target molecules
 Receptor proteins on the membrane surface bind only
certain substances
 Highly selective process of taking in substances such
as enzymes, some hormones, cholesterol, and iron
© 2015 Pearson Education, Inc.
Active Processes
 Vesicular transport (continued)
 Types of endocytosis
3. Receptor-mediated endocytosis
 Both the receptors and target molecules are in a
vesicle
 Contents of the vesicles are dealt with in one of the
ways shown in the next figure
© 2015 Pearson Education, Inc.
Figure 3.13a Events and types of endocytosis.
Extracellular
fluid
Cytosol
Vesicle
1 Vesicle fusing
with lysosome
for digestion
Plasma
membrane
Lysosome
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
Ingested
substance
Pit
(a)
© 2015 Pearson Education, Inc.
3 Membranes and receptors
(if present) recycled to plasma
membrane
Figure 3.13c Events and types of endocytosis.
Membrane
receptor
(c)
© 2015 Pearson Education, Inc.
Cell Life Cycle
 Cell life cycle is a series of changes the cell
experiences from the time it is formed until it divides
© 2015 Pearson Education, Inc.
Cell Life Cycle
 Cycle has two major periods
1. Interphase
 Cell grows
 Cell carries on metabolic processes
 Longer phase of the cell cycle
2. Cell division
 Cell replicates itself
 Function is to produce more cells for growth and
repair processes
© 2015 Pearson Education, Inc.
DNA Replication
 Genetic material is duplicated and readies a cell for
division into two cells
 Occurs toward the end of interphase
© 2015 Pearson Education, Inc.
Concept Link
© 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 ATGACG
© 2015 Pearson Education, Inc.
Figure 3.14 Replication of the DNA molecule during interphase.
KEY:
Adenine
Thymine
Cytosine
Guanine
Old
Newly
(template) synthesized
strand
strand
New
Old (template)
strand
forming strand
DNA of one chromatid
© 2015 Pearson Education, Inc.
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 completion
 Results in the formation of two daughter cells
© 2015 Pearson Education, Inc.
Stages of Mitosis
 Prophase
 First part of cell division
 Chromatin coils into chromosomes
 Chromosomes are held together by a centromere
 A chromosome has two strands
 Each strand is called a chromatid
© 2015 Pearson Education, Inc.
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 stages
 Nuclear envelope breaks down and disappears
© 2015 Pearson Education, Inc.
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 seen
© 2015 Pearson Education, Inc.
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
moving
© 2015 Pearson Education, Inc.
Stages of Mitosis
 Telophase
 Reverse of prophase
 Chromosomes uncoil to become chromatin
 Spindles break down and disappear
 Nuclear envelope reforms around chromatin
 Nucleoli appear in each of the daughter nuclei
© 2015 Pearson Education, Inc.
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
parts
 Cleavage furrow is a contractile ring made of
microfilaments
© 2015 Pearson Education, Inc.
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 result
 Common in the liver
 Mitosis gone wild is the basis for tumors and
cancers
© 2015 Pearson Education, Inc.
Figure 3.15 Stages of mitosis.
Slide 1
Centrioles
Chromatin
Centrioles
Forming
mitotic
spindle
Plasma
membrane
Interphase
Nuclear
Chromosome,
envelope consisting of two
Nucleolus sister chromatids
Early prophase
Metaphase
plate
Spindle
microtubules
Centromere
Centromere
Fragments of
nuclear envelope
Spindle
pole
Late prophase
Nucleolus
forming
Cleavage
furrow
Spindle
Metaphase
© 2015 Pearson Education, Inc.
Sister
chromatids
Daughter
chromosomes
Anaphase
Nuclear
envelope
forming
Telophase and cytokinesis
Figure 3.15 Stages of mitosis (1 of 6).
Slide 2
Centrioles
Plasma
membrane
Interphase
© 2015 Pearson Education, Inc.
Chromatin
Nuclear
envelope
Nucleolus
Figure 3.15 Stages of mitosis (2 of 6).
Slide 3
Centrioles
Forming
mitotic
spindle
Chromosome,
consisting of two
sister chromatids
Early prophase
© 2015 Pearson Education, Inc.
Centromere
Figure 3.15 Stages of mitosis (3 of 6).
Slide 4
Spindle
microtubules
Centromere
Fragments of
nuclear envelope
Late prophase
© 2015 Pearson Education, Inc.
Spindle
pole
Figure 3.15 Stages of mitosis (4 of 6).
Slide 5
Metaphase
plate
Spindle
Metaphase
© 2015 Pearson Education, Inc.
Sister
chromatids
Figure 3.15 Stages of mitosis (5 of 6).
Slide 6
Daughter
chromosomes
Anaphase
© 2015 Pearson Education, Inc.
Figure 3.15 Stages of mitosis (6 of 6).
Slide 7
Nucleolus
forming
Cleavage
furrow
Nuclear
envelope
forming
Telophase and cytokinesis
© 2015 Pearson Education, Inc.
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 cells
 Globular (functional) proteins act as enzymes
(biological catalysts)
© 2015 Pearson Education, Inc.
Protein Synthesis
 DNA information is coded into triplets
 Triplets
 Contain three bases
 Call for a particular amino acid
 For example, a DNA sequence of AAA specifies the
amino acid phenylalanine
© 2015 Pearson Education, Inc.
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)
© 2015 Pearson Education, Inc.
Protein Synthesis
 How does RNA differ from DNA? RNA:
 Is single-stranded
 Contains ribose sugar instead of deoxyribose
 Contains uracil (U) base instead of thymine (T)
© 2015 Pearson Education, Inc.
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 built
 Messenger RNA (mRNA)
 Carries the instructions for building a protein from the
nucleus to the ribosome
© 2015 Pearson Education, Inc.
Role of RNA
 Protein synthesis involves two major phases:
 Transcription
 Translation
 We will detail these two phases next
© 2015 Pearson Education, Inc.
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 gene
 Codons are the corresponding three-base
sequences on mRNA
© 2015 Pearson Education, Inc.
Protein Synthesis
 Example of transcription:
 DNA triplets
 mRNA codons
© 2015 Pearson Education, Inc.
AAT-CGT-TCG
UUA-GCA-AGC
Figure 3.16 Protein synthesis.
Slide 1
Nucleus
(site of transcription)
Cytoplasm
(site of translation)
DNA
1 mRNA specifying one
polypeptide is made on
DNA template.
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
Correct amino
acid attached to
each species of
tRNA by an
enzyme
4 As the ribosome
moves along the mRNA,
Met
a new amino acid is
Gly
added to the growing
protein chain.
Ser
Growing
polypeptide
chain
Phe
Ala
5 Released tRNA
reenters the
cytoplasmic pool,
ready to be recharged
with a new amino
acid.
Peptide bond
2 mRNA leaves
nucleus and attaches
to ribosome, and
translation begins.
Synthetase
enzyme
3 Incoming tRNA
recognizes a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
tRNA “head”
bearing anticodon
Large ribosomal subunit
Direction of
ribosome advance;
ribosome moves the
Portion of
mRNA strand along
mRNA already
sequentially as each
translated
codon is read.
Small ribosomal subunit
Codon
© 2015 Pearson Education, Inc.
Figure 3.16 Protein synthesis (1 of 2).
Nucleus
(site of transcription)
Slide 2
Cytoplasm
(site of translation)
DNA
1 mRNA specifying one
polypeptide is made on
DNA template.
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
© 2015 Pearson Education, Inc.
Correct amino
acid attached to
each species of
tRNA by an
enzyme
Synthetase
enzyme
Protein Synthesis
 Translation
 Base sequence of nucleic acid is translated to an
amino acid sequence
 Amino acids are the building blocks of proteins
© 2015 Pearson Education, Inc.
Protein Synthesis
 Translation (continued)
 Steps correspond to Figure 3.16 (step 1 covers
transcription)
2. mRNA leaves nucleus and attaches to ribosome,
and translation begins
3. Incoming tRNA recognizes a complementary mRNA
codon calling for its amino acid by binding via its
anticodon to the codon.
© 2015 Pearson Education, Inc.
Figure 3.16 Protein synthesis (1 of 2).
Nucleus
(site of transcription)
Slide 3
Cytoplasm
(site of translation)
DNA
1 mRNA specifying one
polypeptide is made on
DNA template.
2 mRNA leaves
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
© 2015 Pearson Education, Inc.
Correct amino
acid attached to
each species of
tRNA by an
enzyme
nucleus and attaches
to ribosome, and
translation begins.
Synthetase
enzyme
Figure 3.16 Protein synthesis (2 of 2).
Slide 4
3 Incoming tRNA
recognizes a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
tRNA “head”
bearing anticodon
Large ribosomal subunit
Direction of
ribosome advance;
ribosome moves the
Portion of
mRNA strand along
mRNA already
sequentially as each
translated
codon is read.
Small ribosomal subunit
Codon
© 2015 Pearson Education, Inc.
Protein Synthesis
 Translation (continued)
 Steps correspond to Figure 3.16
4. As the ribosome moves along the mRNA, a new
amino acid is added to the growing protein chain.
5. Released tRNA reenters the cytoplasmic pool,
ready to be recharged with a new amino acid.
© 2015 Pearson Education, Inc.
Figure 3.16 Protein synthesis (2 of 2).
Slide 5
4 As the ribosome
moves along the mRNA,
a new amino acid is
added to the growing
protein chain.
Met
Gly
Growing
polypeptide
chain
Ser
Phe
Ala
Peptide bond
3 Incoming tRNA
recognizes a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
tRNA “head”
bearing anticodon
Large ribosomal subunit
Direction of
ribosome advance;
ribosome moves the
Portion of
mRNA strand along
mRNA already
sequentially as each
translated
codon is read.
Small ribosomal subunit
Codon
© 2015 Pearson Education, Inc.
Figure 3.16 Protein synthesis (2 of 2).
Slide 6
4 As the ribosome
moves along the mRNA,
a new amino acid is
added to the growing
protein chain.
Met
Gly
Growing
polypeptide
chain
Ser
Phe
Ala
5 Released tRNA
reenters the
cytoplasmic pool,
ready to be recharged
with a new amino
acid.
Peptide bond
3 Incoming tRNA
recognizes a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
tRNA “head”
bearing anticodon
Large ribosomal subunit
Direction of
ribosome advance;
ribosome moves the
Portion of
mRNA strand along
mRNA already
sequentially as each
translated
codon is read.
Small ribosomal subunit
Codon
© 2015 Pearson Education, Inc.
Concept Link
© 2015 Pearson Education, Inc.
Body Tissues
 Tissues
 Groups of cells with similar structure and function
 Four primary types:
1.
2.
3.
4.
Epithelial tissue (epithelium)
Connective tissue
Muscle tissue
Nervous tissue
© 2015 Pearson Education, Inc.
Epithelial Tissues
 Locations:
 Body coverings
 Body linings
 Glandular tissue
 Functions:
 Protection
 Absorption
 Filtration
 Secretion
© 2015 Pearson Education, Inc.
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 nourished
© 2015 Pearson Education, Inc.
Figure 3.17a Classification and functions of epithelia.
Apical surface
Basal
surface
Simple
Apical surface
Basal
surface Stratified
(a) Classification based on number of cell layers
© 2015 Pearson Education, Inc.
Classification of Epithelia
 Number of cell layers
 Simple—one layer
 Stratified—more than one layer
© 2015 Pearson Education, Inc.
Figure 3.17a Classification and functions of epithelia.
Apical surface
Basal
surface
Simple
Apical surface
Basal
surface Stratified
(a) Classification based on number of cell layers
© 2015 Pearson Education, Inc.
Classification of Epithelia
 Shape of cells
 Squamous
 Flattened, like fish scales
 Cuboidal
 Cube-shaped, like dice
 Columnar
 Column-like
© 2015 Pearson Education, Inc.
Figure 3.17b Classification and functions of epithelia.
Squamous
Cuboidal
Columnar
(b) Classification based on cell shape
© 2015 Pearson Education, Inc.
Figure 3.17c Classification and functions of epithelia.
Number of layers
One layer: simple epithelial
tissues
More than one layer: stratified
epithelial tissues
Squamous
Diffusion and filtration
Secretion in serous membranes
Protection
Cuboidal
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
Cell shape
Columnar
Transitional
Protection; stretching to accommodate
distension of urinary structures
(c) Function of epithelial tissue related to tissue type
© 2015 Pearson Education, Inc.
Simple Epithelia
 Simple squamous
 Single layer of flat cells
 Location—usually forms membranes
 Lines air sacs of the lungs
 Forms walls of capillaries
 Forms serous membranes (serosae) that line and
cover organs in ventral cavity
 Functions in diffusion, filtration, or secretion in
membranes
© 2015 Pearson Education, Inc.
Figure 3.18a Types of epithelia and their common locations in the body.
Air sacs of
lungs
Nucleus of
squamous
epithelial cell
Basement
membrane
(a) Diagram: Simple squamous
© 2015 Pearson Education, Inc.
Nuclei of
squamous
epithelial
cells
Photomicrograph: Simple
squamous epithelium forming part
of the alveolar (air sac) walls (275×).
Simple Epithelia
 Simple cuboidal
 Single layer of cube-like cells
 Locations:
 Common in glands and their ducts
 Forms walls of kidney tubules
 Covers the surface of ovaries
 Functions in secretion and absorption; ciliated types
propel mucus or reproductive cells
© 2015 Pearson Education, Inc.
Figure 3.18b Types of epithelia and their common locations in the body.
Nucleus of
simple
cuboidal
epithelial
cell
Basement
membrane
(b) Diagram: Simple cuboidal
© 2015 Pearson Education, Inc.
Simple
cuboidal
epithelial
cells
Basement
membrane
Connective
tissue
Photomicrograph: Simple cuboidal
epithelium in kidney tubules (250×).
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 exterior
 Functions in secretion and absorption; ciliated types
propel mucus or reproductive cells
© 2015 Pearson Education, Inc.
Figure 3.18c Types of epithelia and their common locations in the body.
Nucleus of
simple columnar
epithelial cell
Basement
membrane
(c) Diagram: Simple columnar
© 2015 Pearson Education, Inc.
Mucus of a
goblet cell
Simple
columnar
epithelial cells
Basement
membrane
Photomicrograph: Simple columnar
epithelium of the small intestine (575×).
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 epithelium
 Functions in absorption or secretion
© 2015 Pearson Education, Inc.
Figure 3.18d Types of epithelia and their common locations in the body.
Cilia
Pseudostratified
epithelial
layer
Pseudostratified
epithelial layer
Basement
membrane
Basement
membrane
Connective
tissue
(d) Diagram: Pseudostratified
(ciliated) columnar
© 2015 Pearson Education, Inc.
Photomicrograph: Pseudostratified
ciliated columnar epithelium lining the
human trachea (560×).
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)
 Mouth
 Esophagus
© 2015 Pearson Education, Inc.
Figure 3.18e Types of epithelia and their common locations in the body.
Nuclei
Stratified
squamous
epithelium
Basement
membrane
(e) Diagram: Stratified squamous
© 2015 Pearson Education, Inc.
Stratified
squamous
epithelium
Basement
membrane
Connective
Photomicrograph:
tissue
Stratified squamous
epithelium lining of the esophagus (140×).
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 body
 Found mainly in ducts of large glands
© 2015 Pearson Education, Inc.
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 shape
 Locations: urinary system organs
© 2015 Pearson Education, Inc.
Figure 3.18f Types of epithelia and their common locations in the body.
Basement
membrane
Transitional
epithelium
Basement
membrane
Transitional
epithelium
Connective
tissue
(f) Diagram: Transitional
© 2015 Pearson Education, Inc.
Photomicrograph: Transitional epithelium lining of
the bladder, relaxed state (270×); surface rounded cells
flatten and elongate when the bladder fills with urine.
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 process
© 2015 Pearson Education, Inc.
Glandular Epithelium
 Two major gland types
 Endocrine gland
 Ductless; secretions diffuse into blood vessels
 All secretions are hormones
 Examples include thyroid, adrenals, and pituitary
© 2015 Pearson Education, Inc.
Glandular Epithelium
 Two major gland types
 Exocrine gland
 Secretions empty through ducts to the epithelial
surface
 Include sweat and oil glands, liver, and pancreas
 Includes both internal and external glands
© 2015 Pearson Education, Inc.
Connective Tissue
 Found everywhere in the body
 Includes the most abundant and widely distributed
tissues
 Functions:
 Provides protection
 Binds body tissues together
 Supports the body
© 2015 Pearson Education, Inc.
Connective Tissue Characteristics
 Variations in blood supply
 Some tissue types are well vascularized
 Some have a poor blood supply or are avascular
 Extracellular matrix
 Nonliving material that surrounds living cells
© 2015 Pearson Education, Inc.
Extracellular Matrix
 Two main elements
1. Ground substance—mostly water along with
adhesion proteins and polysaccharide molecules
2. Fibers
 Produced by the cells
 Three types:
1. Collagen (white) fibers
2. Elastic (yellow) fibers
3. Reticular fibers (a type of collagen)
© 2015 Pearson Education, Inc.
Connective Tissue Types
 From most rigid to softest, or most fluid:
 Bone
 Cartilage
 Dense connective tissue
 Loose connective tissue
 Blood
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Connective Tissue Types
 Bone (osseous tissue)
 Composed of:
 Osteocytes (bone cells) sitting in lacunae (cavities)
 Hard matrix of calcium salts
 Large numbers of collagen fibers
 Functions to protect and support the body
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Figure 3.19a Connective tissues and their common body locations.
Bone cells
in lacunae
Central
canal
Lacunae
Lamella
(a) Diagram: Bone
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Photomicrograph: Cross-sectional
view of ground bone (165×)
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 type
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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:
 Larynx
 Entire fetal skeleton prior to birth
 Epiphyseal plates
 Functions as a more flexible skeletal element than
bone
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Figure 3.19b Connective tissues and their common body locations.
Chondrocyte
(cartilage cell)
Chondrocyte
in lacuna
Lacunae
Matrix
(b) Diagram: Hyaline
cartilage
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Photomicrograph: Hyaline cartilage
from the trachea (400×)
Connective Tissue Types
 Elastic cartilage (not pictured)
 Provides elasticity
 Location:
 Supports the external ear
 Fibrocartilage
 Highly compressible
 Location:
 Forms cushionlike discs between vertebrae of the
spinal column
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Figure 3.19c Connective tissues and their common body locations.
Chondrocytes
in lacunae
Chondrocytes in
lacunae
Collagen
fibers
Collagen fiber
(c) Diagram:
Fibrocartilage
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Photomicrograph: Fibrocartilage of an
intervertebral disc (150×)
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 bone
 Ligaments—attach bone to bone at joints and are
more elastic than tendons
 Dermis—lower layers of the skin
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Figure 3.19d Connective tissues and their common body locations.
Ligament
Tendon
Collagen
fibers
Collagen
fibers
Nuclei of
fibroblasts
Nuclei of
fibroblasts
(d) Diagram: Dense
fibrous
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Photomicrograph: Dense fibrous
connective tissue from a tendon (475×)
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 place
 Layer of areolar tissue called lamina propria underlies
all membranes
 All fiber types form a loose network
 Can soak up excess fluid (causes edema)
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Figure 3.19e Connective tissues and their common body locations.
Mucosa
epithelium
Lamina
propria
Elastic
fibers
Collagen
fibers
Fibroblast
nuclei
Fibers of
matrix
Nuclei of
fibroblasts
(e) Diagram: Areolar
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Photomicrograph: Areolar connective tissue,
a soft packaging tissue of the body (270×)
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)
 Functions
 Insulates the body
 Protects some organs
 Serves as a site of fuel storage
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Figure 3.19f Connective tissues and their common body locations.
Nuclei of
fat cells
Vacuole
containing
fat droplet
Nuclei of
fat cells
Vacuole
containing
fat droplet
(f) Diagram: Adipose
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Photomicrograph: Adipose tissue from the
subcutaneous layer beneath the skin (570×)
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 marrow
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Figure 3.19g Connective tissues and their common body locations.
Spleen
White blood cell
(lymphocyte)
Reticular
cell
Blood
cell
Reticular
fibers
Reticular fibers
(g) Diagram: Reticular
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Photomicrograph: Dark-staining network
of reticular connective tissue (400×)
Connective Tissue Types
 Blood (vascular tissue)
 Blood cells surrounded by fluid matrix known as
blood plasma
 Soluble fibers are visible only during clotting
 Functions as the transport vehicle for the
cardiovascular system, carrying:
 Nutrients
 Wastes
 Respiratory gases
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Figure 3.19h Connective tissues and their common body locations.
Blood cells
in capillary
Neutrophil
(white blood
cell)
Red blood
cells
White
blood cell
Red
blood cells
(h) Diagram: Blood
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Monocyte
(white blood
cell)
Photomicrograph: Smear of human
blood (1290×)
Muscle Tissue
 Function is to contract, or shorten, to produce
movement
 Three types:
1. Skeletal muscle
2. Cardiac muscle
3. Smooth muscle
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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
expressions
 Characteristics of skeletal muscle cells
 Striations (stripes)
 Multinucleate (more than one nucleus)
 Long, cylindrical shape
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Figure 3.20a Type of muscle tissue and their common locations in the body.
Nuclei
Part of muscle
fiber
(a) Diagram: Skeletal muscle
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Photomicrograph: Skeletal muscle (195×)
Muscle Tissue Types
 Cardiac muscle
 Involuntarily controlled
 Found only in the heart
 Pumps blood through blood vessels
 Characteristics of cardiac muscle cells
 Striations
 Uninucleate, short, branching cells
 Intercalated discs contain gap junctions to connect
cells together
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Figure 3.20b Type of muscle tissue and their common locations in the body.
Intercalated
discs
Nucleus
(b) Diagram: Cardiac muscle
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Photomicrograph: Cardiac muscle (475×)
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 activity
 Characteristics of smooth muscle cells
 No visible striations
 Uninucleate
 Spindle-shaped cells
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Figure 3.20c Type of muscle tissue and their common locations in the body.
Smooth
muscle cell
Nuclei
(c) Diagram: Smooth muscle
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Photomicrograph: Sheet of smooth muscle (285×)
Nervous Tissue
 Composed of neurons and nerve support cells
 Function is to receive and conduct electrochemical
impulses to and from body parts
 Irritability
 Conductivity
 Support cells called neuroglia insulate, protect, and
support neurons
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Figure 3.21 Nervous tissue.
Brain
Nuclei of
supporting
cells
Spinal
cord
Nuclei of
supporting
cells
Cell body
of neuron
Neuron
processes
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Cell body
of neuron
Neuron
processes
Diagram: Nervous
tissue
Photomicrograph: Neurons (320×)
Summary of Tissues
 Figure 3.22 summarizes the tissue types and
functions in the body
© 2015 Pearson Education, Inc.
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
• Muscles attached to bones (skeletal)
• Muscles of heart (cardiac)
• Muscles of walls of hollow organs (smooth)
Epithelial tissue: Forms boundaries between
different environments, protects, secretes, absorbs,
filters
• Lining of GI tract organs and other hollow organs
• Skin surface (epidermis)
Connective tissue: Supports, protects, binds
other tissues together
• Bones
• Tendons
• Fat and other soft padding tissue
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Tissue Repair (Wound Healing)
 Tissue repair (wound healing) occurs in two ways:
1. Regeneration
 Replacement of destroyed tissue by the same kind of
cells
2. Fibrosis
 Repair by dense (fibrous) connective tissue (scar
tissue)
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Tissue Repair (Wound Healing)
 Whether regeneration or fibrosis occurs depends
on:
1. Type of tissue damaged
2. Severity of the injury
 Clean cuts (incisions) heal more successfully than
ragged tears of the tissue
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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 area
 Granulation tissue forms
 Growth of new capillaries
 Phagocytes dispose of blood clot and fibroblasts
 Rebuild collagen fibers
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Events in Tissue Repair
 Regeneration of surface epithelium
 Scab detaches
 Whether scar is visible or invisible depends on
severity of wound
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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 poorly
 Skeletal muscle
 Tissues that are replaced largely with scar tissue
 Cardiac muscle
 Nervous tissue within the brain and spinal cord
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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 puberty
 Nervous tissue becomes amitotic shortly after birth.
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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 causes
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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
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