Lecture Presentation by
Patty Bostwick-Taylor
Florence-Darlington Technical College
Chapter 3
Cells and Tissues
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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. Carbon
2. Hydrogen
3. Oxygen
4. 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
Plasmamembrane
(a)
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.
Nucleus
Rough ER
Nuclear envelope
Chromatin
Nucleolus
Nuclearpores
(b)
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.
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
molecules
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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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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.
Chromatin
NucleolusNuclear envelope
Nucleus
Plasma
membrane
Roughendoplasmicreticulum
Ribosomes
Golgi
apparatus
Secretion beingreleased from cellby exocytosisPeroxisome
Intermediate
filaments
Microtubule
Centrioles
Mitochondrion
Lysosome
Cytosol
Smooth
endoplasmic
reticulum
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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
1
2
34
23
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 1
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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 2
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Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
1
2
21
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 3
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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
231
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 4
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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
34
23
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 5
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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.
Golgi
apparatus
Pathway 1Secretory 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 3
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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
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.
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.
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Cytoplasmic Organelles
Centrioles
Rod-shaped bodies made of microtubules
Generate microtubules
Direct the formation of mitotic spindle during cell
division
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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.
Nucleus Flagellum
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.
Rough ER and Golgi
apparatus No organelles
Nucleus
Fibroblasts
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.
Nucleus
Intermediate
filaments
Epithelial
cells
(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.
Nuclei
Contractile
filaments
Skeletal
muscle cell
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.
Lipid droplet
Nucleus
Fat cell
(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
(e) Cell that fights
disease
Pseudo-
pods
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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
Nucleus
(f) Cell that gathers information and
controls body functions
Nerve cell
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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.
Nucleus Flagellum
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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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.
Lipid-
soluble
solutes
Extracellular
fluid
(a) Simplediffusion
of fat-solublemoleculesdirectlythrough thephospholipidbilayer
Cytoplasm
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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, diffusionof water through aspecific channelprotein (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
(b) RBC in hypertonic
solution
(c) RBC in hypotonic
solution
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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.
Lipid-
insoluble
solutes
Small lipid-
insoluble
solutes
(b) Carrier-mediatedfacilitated diffusion viaprotein carrier specific forone chemical; binding ofsubstrate causes shapechange in transport protein
(c) Channel-mediatedfacilitateddiffusion
through achannel protein;mostly ions,selected onbasis ofsize and charge
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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 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 sodium-
potassium 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.
Na+-K+ pump
2 31
321
Na+
Extracellular fluid
K+Na+
Na+
Na+
Na+
Na+
K+
K+
K+
P
P
ATP
ADP
Binding of cytoplasmic Na+
to the pump protein stimulatesphosphorylation by ATP, which causes the pump protein tochange its shape.
The shape change expelsNa+ to the outside. ExtracellularK+ binds, causing release of thephosphate group.
Loss of phosphaterestores the originalconformation of the pumpprotein. K+ is released to thecytoplasm, and Na+ sites areready to bind Na+ again; the cycle repeats.
Cytoplasm
Slide 1
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Binding of cytoplasmic Na+
to the pump protein stimulatesphosphorylation by ATP, which causes the pump protein tochange 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 2
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Binding of cytoplasmic Na+
to the pump protein stimulatesphosphorylation by ATP, which causes the pump protein tochange its shape.
The shape change expelsNa+ to the outside. ExtracellularK+ binds, causing release of thephosphate group.
Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Na+-K+ pump
21
21
Na+
Extracellular fluid
K+Na+
Na+
Na+
Na+
Na+
K+
P
P
ATP
ADP
Cytoplasm
Slide 3
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Binding of cytoplasmic Na+
to the pump protein stimulatesphosphorylation by ATP, which causes the pump protein tochange its shape.
The shape change expelsNa+ to the outside. ExtracellularK+ binds, causing release of thephosphate group.
Loss of phosphaterestores the originalconformation of the pumpprotein. K+ is released to thecytoplasm, and Na+ sites areready to bind Na+ again; the cycle repeats.
Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Na+-K+ pump
2 31
321
Na+
Extracellular fluid
K+Na+
Na+
Na+
Na+
Na+
K+
K+
K+
P
P
ATP
ADP
Cytoplasm
Slide 4
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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.
Golgi
apparatus
Pathway 1Secretory 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 3
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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 together
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Figure 3.12a Exocytosis.
Extracellular
fluid
2
3
1
Plasma
membrane
SNARE
(t-SNARE)
Vesicle
SNARE
(v-SNARE)
Molecule
to be
secretedSecretory
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 exocytosis
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Figure 3.12b Exocytosis.
(b) Electron micrograph of a
secretory vesicle in
exocytosis (190,000×)
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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 lysosome
Contents are digested by lysosomal enzymes
In some cases, the vesicle is released by exocytosis
on the opposite side of the cell
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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 1
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Figure 3.13a Events and types of endocytosis.
Plasma
membrane
Extracellular
fluid
Vesicle fusing
with lysosome
for digestion
1
(a)
Slide 2
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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 3
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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 4
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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
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Figure 3.13b Events and types of endocytosis.
Pseudopod
Bacterium
or other
particle
Extracellular
fluid
Cytoplasm
(b)
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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)
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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
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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
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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
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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
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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 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
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DNA Replication
Genetic material is duplicated and readies a cell for
division into two cells
Occurs toward the end of interphase
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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(template)strand
Newlysynthesizedstrand
Newstrandforming
Old (template)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
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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
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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 stages
Nuclear envelope breaks down and disappears
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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 seen
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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
moving
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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
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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
parts
Cleavage furrow is a contractile ring made of
microfilaments
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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 result
Common in the liver
Mitosis gone wild is the basis for tumors and
cancers
© 2015 Pearson Education, Inc.
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
spindleCentromere
Centromere
Plasma
membrane
Nuclear
envelopeNucleolus
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 1
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Figure 3.15 Stages of mitosis (1 of 6).
Centrioles Chromatin
Plasma
membrane
Nuclear
envelopeNucleolus
Interphase
Slide 2
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Figure 3.15 Stages of mitosis (2 of 6).
Chromosome,
consisting of two
sister chromatids
Centrioles
Forming
mitotic
spindleCentromere
Early prophase
Slide 3
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Figure 3.15 Stages of mitosis (3 of 6).
Spindle
microtubules
Fragments of
nuclear envelope
Centromere
Spindle
pole
Late prophase
Slide 4
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Figure 3.15 Stages of mitosis (4 of 6).
Metaphase
plate
Spindle Sister
chromatids
Metaphase
Slide 5
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Figure 3.15 Stages of mitosis (5 of 6).
Daughter
chromosomes
Anaphase
Slide 6
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Figure 3.15 Stages of mitosis (6 of 6).
Nucleolus
forming
Cleavage
furrow
Nuclear
envelope
forming
Telophase and cytokinesis
Slide 7
© 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)
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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
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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)
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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)
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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 built
Messenger RNA (mRNA)
Carries the instructions for building a protein from the
nucleus to the ribosome
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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
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Protein Synthesis
Example of transcription:
DNA triplets AAT-CGT-TCG
mRNA codons UUA-GCA-AGC
© 2015 Pearson Education, Inc.
As the ribosomemoves along the mRNA,a new amino acid isadded to the growingprotein chain.
Released tRNAreenters thecytoplasmic pool,ready to be rechargedwith a new aminoacid.
mRNA specifying one
polypeptide is made on
DNA template.
mRNA leaves
nucleus and attaches
to ribosome, and
translation begins.
Incoming tRNArecognizes acomplementarymRNA codon callingfor its amino acid bybinding via its anticodonto 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 aminoacid attached toeach species oftRNA by anenzyme
Growing
polypeptide
chain
Peptide bond
tRNA “head”
bearing anticodon
Large ribosomal subunit
Codon
Portion of
mRNA already
translated
Small ribosomal subunit
Direction ofribosome advance;ribosome moves themRNA strand alongsequentially as each
codon is read.
Met
Gly
Ser
Phe
Ala
Slide 1
© 2015 Pearson Education, Inc.
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 2
© 2015 Pearson Education, Inc.
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.
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 3
© 2015 Pearson Education, Inc.
Incoming tRNArecognizes acomplementarymRNA codon callingfor its amino acid bybinding via its anticodonto 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 ofribosome advance;ribosome moves themRNA strand alongsequentially as each
codon is read.
3
Slide 4
© 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.
Incoming tRNArecognizes acomplementarymRNA codon callingfor its amino acid bybinding via its anticodonto the codon.
As the ribosomemoves along the mRNA,a new amino acid isadded to the growingprotein 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 ofribosome advance;ribosome moves themRNA strand alongsequentially as each
codon is read.
3
4
Met
Gly
Ser
Phe
Ala
Slide 5
© 2015 Pearson Education, Inc.
Released tRNAreenters thecytoplasmic pool,ready to be rechargedwith a new aminoacid.
Incoming tRNArecognizes acomplementarymRNA codon callingfor its amino acid bybinding via its anticodonto the codon.
As the ribosomemoves along the mRNA,a new amino acid isadded to the growingprotein 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 ofribosome advance;ribosome moves themRNA strand alongsequentially as each
codon is read.
3
4
5
Met
Gly
Ser
Phe
Ala
Slide 6
© 2015 Pearson Education, Inc.
Body Tissues
Tissues
Groups of cells with similar structure and function
Four primary types:
1. Epithelial tissue (epithelium)
2. Connective tissue
3. Muscle tissue
4. Nervous tissue
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Epithelial Tissues
Locations:
Body coverings
Body linings
Glandular tissue
Functions:
Protection
Absorption
Filtration
Secretion
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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 nourished
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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 layers
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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.
Basal
surface
Apical surface
Basal
surface
Apical surface
Simple
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
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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.
Diffusion and filtration
Secretion in serous membranesProtection
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 shapeOne layer: simple epithelial
tissuesMore than one layer: stratified
epithelial tissues
Squamous
Cuboidal
Columnar
Transitional
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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 capillaries
Forms serous membranes (serosae) that line and
cover organs in ventral cavity
Fxns in diffusion, filtration, or secretion in
membranes
© 2015 Pearson Education, Inc.
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×).
© 2015 Pearson Education, Inc.
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
Fxns 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
Simple
cuboidal
epithelial
cells
Basement
membrane
Connective
tissue
(b) Diagram: Simple cuboidalPhotomicrograph: 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
Fxns in secretion and absorption; ciliated types propel mucus or reproductive cells
© 2015 Pearson Education, Inc.
© 2015 Pearson Education, Inc.
Figure 3.18c Types of epithelia and their common locations in the body.
Basement
membrane
Basement
membrane
Mucus of a
goblet cellNucleus of
simple columnar
epithelial cellSimple
columnar
epithelial cells
(c) Diagram: Simple columnar
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
Fxns in absorption or
secretion
© 2015 Pearson Education, Inc.
© 2015 Pearson Education, Inc.
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
tissue
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Stratified Epithelia
Stratified squamous
Named for cells present at
the free (apical) surface,
which are flattened
Fxns 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.
Basement
membraneBasement
membraneConnective
tissue
Stratified
squamous
epitheliumStratified
squamous
epithelium
(e) Diagram: Stratified squamous
Photomicrograph:
Stratified squamous
epithelium lining of the esophagus (140×).
Nuclei
© 2015 Pearson Education, Inc.
Stratified Epithelia
Stratified cuboidal—two
layers of cuboidal cells; fxns
in protection
Stratified columnar—surface
cells are columnar, and cells
underneath vary in size and
shape; fxns 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 ET
Shape of cells depends
upon the amnt of
stretching
Fxns in stretching with 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
Basement
membrane
Connective
tissue
Transi-
tional
epitheliumTransitional
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.
© 2015 Pearson Education, Inc.
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
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Glandular Epithelium
Two major gland types
Endocrine gland
Ductless; secretions diffuse into blood vessels
All secretions are hormones
Examples include thyroid, adrenals, and pituitary
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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 pancreas
Includes both internal and external glands
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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 jxns are formed, which vary
structurally depending on their roles
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Plasma Membrane Junctions
Membrane jxns
Tight jxns
Impermeable jxns
Bind cells together into leak-proof sheets
Prevent substances from passing through
extracellular space between cells
Found at apical region of most ET
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Membrane jxns
Adhesion/adhering jxns
Anchor/cement adjacent cells together so they fxn as
a unit
Skin and areas subjected to friction
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Plasma Membrane Junctions
Membrane jxns
Desmosomes
Bind cells together - prevent cells from being pulled as
a result of mechanical stress –Created by button-like
thickenings of adjacent plasma membranes
Intermediate filaments go across the cytoplasm and
anchor desmosomes together at opposite sides of cell
Common in cardiac muscle and ET
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Membrane jxns
Hemidesmosomes
Anchor intermediate filaments in a cell to the basal
lamina of the basal membrane
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Plasma Membrane Junctions
Membrane jxns
Gap jxns
Allow communication between cells
Smooth muscle, , and other tissues in which
activities of adjacent cells must be coordinated.
Small water soluble molecules and ions can travel
directly from one cell to the next through these
channels
© 2015 Pearson Education, Inc.
Figure 3.3 Cell junctions.
Microvilli
Connexon
Underlyingbasementmembrane
Extracellularspace betweencells
Gap(communicating) junction
Plasmamembranes ofadjacent cells
Desmosome
(anchoring
junction)
Tight(impermeable)junction
© 2015 Pearson Education, Inc.
Connective Tissue
Found everywhere in the body
Most abundant and widely distributed tissues in
body
1° Fxn: Binds body parts together
2° Fxns:
Framework for internal organs
Packages and protects organs from injury
Supports body organs
Fat and E storage
© 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 matl that accumulates and surrounds living
cells and fibers
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Extracellular Matrix
Two main elements
1. Ground substance — mostly water along with
adhesion proteins and polysaccharide molecules
2. Fibers
Produced by the cells
3 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 CT
Loose CT
Blood
© 2015 Pearson Education, Inc.
Connective Tissue Types
Bone (osseous tissue)
1° Fxns: to protect and support the body
Bone tissue stores mineral salts, produces blood
cells, and provides spaces for its own living
osteocytes.
Composed of:
Osteocytes (bone cells) sitting in lacunae (cavities)
Hard matrix of calcium salts
Large numbers of collagen fibers
© 2015 Pearson Education, Inc.
Figure 3.19a Connective tissues and their common body locations.
Bone cells
in lacunaeCentral
canal
Lacunae
Lamella
(a) Diagram: Bone Photomicrograph: Cross-sectional
view of ground bone (165×)
© 2015 Pearson Education, Inc.
Connective Tissue Types
Cartilage – a modified/specialized form of CT
Contains a dense array of fibers in a jelly-like ground
substance
Less hard and more flexible than bone
Found in only a few places in the body
Chondrocyte (cartilage cell) is the major cell type
1° Fxn
Cushion and maintain the shape of body parts
(Resists compression and is resilient)
© 2015 Pearson Education, Inc.
Connective Tissue Types
Hyaline cartilage
Hyaline cartilage is the most widespread type of
cartilage
White or “glassy” appearance
Composed of abundant collagen fibers and a rubbery
matrix
Locations:
Larynx, covers bones in joints, provides structure for
nose, connects ribs to sternum, forms ring-like trachea
and bronchi of Respiratory tract
Entire fetal skeleton prior to birth
Epiphyseal plates
Fxns as a more flexible skeletal element than bone
© 2015 Pearson Education, Inc.
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
cartilage
© 2015 Pearson Education, Inc.
Connective Tissue TypesElastic cartilage
Provides elasticity – contains many elastic fibers
Location:
Supports the external ear
epiglottis
Fibrocartilage (Fibrous Cartilage)
Highly compressible – less rigid than hyaline
Heavy bundles of collagen
Location:
Forms cushion-like discs between vertebrae of the
spinal column (intervertebral discs)
Reinforces hyaline cartilage of knee and hip
© 2015 Pearson Education, Inc.
Figure 3.19c Connective tissues and their common body locations.
Chondro-cytes inlacunae
Collagen
fibers
Chondrocytesin lacunae
Collagen fiber
Photomicrograph: Fibrocartilage of an
intervertebral disc (150×)
(c) Diagram:
Fibrocartilage
© 2015 Pearson Education, Inc.
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
© 2015 Pearson Education, Inc.
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
Tendon
© 2015 Pearson Education, Inc.
Connective Tissue Types
Loose connective tissue types
Areolar tissue
Most widely distributed CT
Soft, pliable tissue like “cobwebs”
Fxns 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 XS fluid (causes edema)
© 2015 Pearson Education, Inc.
Figure 3.19e Connective tissues and their common body locations.
Mucosaepithelium
Laminapropria
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×)
© 2015 Pearson Education, Inc.
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)
Fxns
Insulates the body
Protects some organs
Serves as a site of fuel storage
© 2015 Pearson Education, Inc.
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×)
© 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 marrow
© 2015 Pearson Education, Inc.
Figure 3.19g Connective tissues and their common body locations.
Spleen
(g) Diagram: Reticular Photomicrograph: Dark-staining network
of reticular connective tissue (400×)
Reticularcell
Bloodcell
Reticularfibers
White blood cell
(lymphocyte)
Reticular fibers
© 2015 Pearson Education, Inc.
Connective Tissue Types
Blood (vascular tissue)
Blood cells surrounded by fluid matrix known as
blood plasma
Soluble fibers are visible only during clotting
Fxns as the transport vehicle for the cardiovascular
system, carrying:
Nutrients
Wastes
Respiratory gases
© 2015 Pearson Education, Inc.
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)
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Muscle Tissue
Fxn is to contract, or shorten, to produce mvmt in
response to stimulation - then passively lengthen
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
Photomicrograph: Skeletal muscle (195×)(a) Diagram: Skeletal muscle
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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
Photomicrograph: Cardiac muscle (475×)(b) Diagram: Cardiac muscle
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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 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
Photomicrograph: Sheet of smooth muscle (285×)(c) Diagram: Smooth muscle
Skeletal Muscle Tissue
1. Skeletal muscle tissue attaches to
__________________ for voluntary movement;
it contains __________________,
_____________________, long cells.
2. Each unit, called a ___________________,
is contractile; muscle makes up ________ % of
the weight of average humans.
Cardiac Muscle Tissue1. ___________________ (heart) muscle is
composed of _______________,
______________________ branching cells that
can function in units.
2. Contraction signals pass quickly at gap junctions, and
the tissue is packed with
_________________________ to supply ATP for the
continual beating; no oxygen equals heart attack.
Smooth Muscle Tissue
1. Smooth muscle tissue contains ______________-
shaped cells.
2. Location__________________________________
_________________________________________
3. Its operation is ____________________________:
like cardiac.
4. This tissue is ____________________________,
hence the name, and its contractions are slower than
skeletal but can be prolonged.
Nervous tissue exerts the greatest
control over the body's responsiveness to
changing conditions.
1. _______________________ are
excitable cells, organized as lines of
________________________________
throughout the body.
2. ________________________ are
diverse cells that protect and
metabolically support the neurons.
Various neurons detect stimuli; others
coordinate the body’s responses; still
others relay signals to muscles and
glands for response.
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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
Conductivity
Support cells called neuroglia insulate, protect, and
support neurons
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Figure 3.21 Nervous tissue.
Brain
Spinal
cord
Nuclei ofsupportingcells
Cell body
of neuron
Neuron
processes
Nuclei of
supporting
cells
Neuronprocesses
Cell bodyof neuron
Diagram: Nervous
tissue
Photomicrograph: Neurons (320×)
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Summary of Tissues
Figure 3.22 summarizes the tissue types and
functions in the body
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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 betweendifferent environments, protects, secretes, absorbs,filters
Connective tissue: Supports, protects, bindsother 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 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 – occurs when tissues are damaged
Capillaries become permeable (↑ in diameter: dilate)
Redness, heat, ↑d blood flow, swelling (edema), pain
Clotting proteins migrate into injured area from the
bloodstream stops blood loss
Clot quarantines the injured area
Scab protects against infection
Macrophages and fibroblasts move in and remove
debris
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Events in Tissue Repair
Granulation tissue forms – delicate pink tissue
Growth of new capillaries from undamaged BVs
Phagocytes dispose of (remove) blood clot and old
fibroblasts
Rebuild collagen fibers & CT (fibroblasts scar
tissue)
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Events in Tissue Repair
Regeneration of surface epithelium begins beneath
the scab
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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Scar Tissue
Strong
Lacks flexibility
Unable to perform normal fxn of tissue it replaces
Scar tissue may severely hamper the fxning of
affected organ (ex: wall of bladder, heart, other
muscular organ)
Contracture scar
Permanent tightening
of skin that affects the
underlying
tendons/muscles when
inelastic fibrous CT
replaces the normal
elastic CT
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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
(malignant), represent abnormal cell masses in
which normal controls on cell division are not
working
Hyperplasia (↑ in size) of a tissue or organ may
occur when tissue is strongly stimulated or irritated
Atrophy (↓ in size) of a tissue or organ occurs when
the organ is no longer stimulated normally