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Prepared by Patty Bostwick-Taylor,
Florence-Darlington Technical College
CHAPTER
3
Cells and
Tissues
© 2012 Pearson Education, Inc.
Concepts of the Cell Theory (no notes)
•A cell is the basic structural and functional unit
of living organisms.
•The activity of an organism depends on the
collective activities of its cells.
•According to the principle of complementarity,
the biochemical activities of cells are dictated
by the relative number of their specific
subcellular structures.
•Continuity of life has a cellular basis.
© 2012 Pearson Education, Inc.
Chemical Components of Cells (no notes)
•Most cells are composed of the following four
elements
•Carbon
•Hydrogen
•Oxygen
•Nitrogen
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Cells and Tissues
•1. Carry out all chemical activities needed to
sustain life
•2. Cells are the building blocks of all living
things.
•3. Tissues are groups of cells that are similar
in structure and function.
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Anatomy of the Cell
•1. Cells are not all the same.
•2. All cells share general structures.
•3. All cells have three main regions
•Nucleus
•Cytoplasm
•Plasma membrane
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Nucleus
Cytoplasm
Plasma
membrane
(a)
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Figure 3.1a
The Nucleus
•1. Control center of the cell
•Contains genetic material (DNA)
•2. Three regions
•Nuclear envelope (membrane)
•Nucleolus
•Chromatin
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Nuclear envelope
Chromatin
Nucleolus
Nucleus
Nuclear
pores
Rough ER
(b)
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Figure 3.1b
The Nucleus
•Nuclear envelope (membrane)
•1. Barrier of the nucleus
•2. Consists of a double bilayer membrane
•3. Contains nuclear pores that allow for
exchange of material with the rest of the cell
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The Nucleus
•Nucleoli
•1. Nucleus contains one or more nucleoli
and are the site of ribosome assembly
•2. Ribosomes migrate into the cytoplasm
through nuclear pores
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Plasma Membrane
•1. Barrier for cell contents
•2. Double phospholipid layer
•Hydrophilic heads (water-loving)
•Hydrophobic tails (water-hating)
•3. Also contains proteins, cholesterol, and
glycoproteins
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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)
Figure 3.2
Microvilli
Tight
(impermeable)
junction
Desmosome
(anchoring
junction)
Plasma
membranes of
adjacent cells
Connexon
Gap
Underlying Extracellular
basement space between (communicating)
junction
membrane cells
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Figure 3.3
Cytoplasm
•1.Contains three major elements
•A. Cytosol
•Fluid that suspends other elements
•B. Organelles
•Metabolic machinery of the cell
•“Little organs” that perform functions for
the cell
•C. Inclusions
•Chemical substances such as stored
nutrients or cell products
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Chromatin
Nuclear envelope
Nucleolus
Nucleus
Plasma
membrane
Smooth endoplasmic
reticulum
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi apparatus
Secretion being released
from cell by exocytosis
Microtubule
Peroxisome
Intermediate
filaments
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Figure 3.4
Cytoplasmic Organelles
•Mitochondria
•“Powerhouses” of the cell
•Change shape continuously
•Carry out reactions where oxygen is used to
break down food
•Provides ATP for cellular energy
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Cytoplasmic Organelles
•Ribosomes
•Made of protein and 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 tubules for carrying substances
•Two types of ER
•Rough endoplasmic reticulum
• Studded with ribosomes
• Synthesizes proteins
•Smooth endoplasmic reticulum
• Functions in lipid metabolism and
detoxification of drugs and pesticides
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Ribosome
mRNA
Rough ER
2
1
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).
Protein
3 The protein is packaged in a tiny
Transport
vesicle buds off
4
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
Ribosome
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, step 1
Ribosome
mRNA
Rough ER
2
1
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
Protein
© 2012 Pearson Education, Inc.
functional shape. Short sugar chains
may be attached to the protein (forming
a glycoprotein).
Figure 3.5, step 2
Ribosome
mRNA
Rough ER
2
1
3
Protein
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
Transport
vesicle buds off
© 2012 Pearson Education, Inc.
membranous sac called a transport
vesicle.
Figure 3.5, step 3
Ribosome
mRNA
Rough ER
2
1
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).
Protein
3 The protein is packaged in a tiny
Transport
vesicle buds off
4
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
© 2012 Pearson Education, Inc.
Figure 3.5, step 4
Cytoplasmic Organelles
•Golgi apparatus
•Modifies and packages proteins
•Produces different types of packages
•Secretory vesicles
•Cell membrane components
•Lysosomes
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Rough ER
Cisterna
Proteins in cisterna
Membrane
Lysosome fuses with
ingested substances
Transport
vesicle
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Pathway 3
Pathway 2
Golgi
apparatus
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
Plasma membrane
Extracellular fluid
Figure 3.6
Cytoplasmic Organelles
•Lysosomes
•Contain enzymes produced by ribosomes
•Packaged by the Golgi apparatus
•Digest worn-out or nonusable materials
within the cell
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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)
•Replicate by pinching in half
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Cytoplasmic Organelles
•Cytoskeleton
•Network of protein structures that extend
throughout the cytoplasm
•Provides the cell with an internal framework
•Three different types of elements
•Microfilaments (largest)
•Intermediate filaments
•Microtubules (smallest)
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(b) Intermediate filaments
(a) Microfilaments
(c) Microtubules
Tubulin subunits
Fibrous subunits
Actin subunit
7 nm
Microfilaments form the blue
network surrounding the pink
nucleus.
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10 nm
Intermediate filaments form
the purple batlike network.
25 nm
Microtubules appear as gold
networks surrounding the
cells’ pink nuclei.
Figure 3.7a-c
Cytoplasmic Organelles
•Centrioles
•Rod-shaped bodies made of microtubules
•Direct the formation of mitotic spindle during
cell division
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Cellular Projections
•Not found in all 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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Fibroblasts
Rough ER and Golgi
apparatus
No organelles
Nucleus
Erythrocytes
(a) Cells that connect body parts
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Figure 3.8a
Epithelial
cells
Nucleus
Intermediate
filaments
(b) Cells that cover and line body organs
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Figure 3.8b
Skeletal
muscle cell
Contractile
filaments
Nuclei
Smooth
muscle cells
(c) Cells that move organs and body parts
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Figure 3.8c
Fat cell
Lipid droplet
Nucleus
(d) Cell that stores
nutrients
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Figure 3.8d
Lysosomes
Macrophage
Pseudopods
(e) Cell that fights
disease
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Figure 3.8e
Processes
Rough ER
Nerve cell
Nucleus
(f) Cell that gathers information and controls body
functions
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Figure 3.8f
Flagellum
Nucleus
Sperm
(g) Cell of reproduction
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Figure 3.8g
Cell Physiology: Membrane Transport
•1. Membrane transport—movement of
substances into and out of the cell
•Cell membranes are selectively permeable
(some substances can pass through but
others cannot)
•2. Two basic methods of transport
•Passive processes
•No energy is required
•Active processes
•Cell must provide metabolic energy (ATP)
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Selective Permeability
•1. The plasma membrane allows some
materials to pass while excluding others.
•2. This permeability influences movement both
into and out of the cell.
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Passive Processes (no notes)
•Diffusion
•Particles tend to distribute themselves
evenly within a solution
•Movement is from high concentration to low
concentration, or down a concentration
gradient
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Figure 3.9
Passive Processes (no notes)
•Types of diffusion
•Simple diffusion
•An unassisted process
•Solutes are lipid-soluble materials or small
enough to pass through membrane pores
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Extracellular fluid
Lipidsoluble
solutes
Cytoplasm
(a) Simple diffusion
of fat-soluble
molecules
directly through
the phospholipid
bilayer
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Figure 3.10a
Passive Processes (no notes)
•Types of diffusion (continued)
•Osmosis—simple diffusion of water
•Highly polar water molecules easily cross
the plasma membrane through aquaporins
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Water
molecules
Lipid
bilayer
(d) Osmosis, diffusion
of water through a
specific channel
protein (aquaporin)
or through the lipid
bilayer
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Figure 3.10d
Passive Processes (no notes)
•Facilitated diffusion
•Substances require a protein carrier for
passive transport
•Transports lipid-insoluble and large
substances
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Lipidinsoluble
solutes
(b) Carrier-mediated 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
(c) Channel-mediated
facilitated diffusion
through a channel
protein; mostly ions
selected on basis
of size and charge
Figure 3.10b–c
Passive Processes (no notes)
•Filtration
• Water and solutes are forced through a
membrane by fluid, or hydrostatic pressure
• A pressure gradient must exist
• Solute-containing fluid is pushed from a
high-pressure area to a lower pressure
area
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Active Processes (no notes)
•Substances are transported that are unable to
pass by diffusion
•Substances may be too large
•Substances may not be able to dissolve in
the fat core of the membrane
•Substances may have to move against a
concentration gradient
•ATP is used for transport
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Active Processes (no notes)
•Two common forms of active transport
•Active transport (solute pumping)
•Vesicular transport
•Exocytosis
•Endocytosis
• Phagocytosis
• Pinocytosis
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Active Processes (no notes)
•Active transport (solute pumping)
•Amino acids, some sugars, and ions are
transported by protein carriers called solute
pumps
•ATP energizes protein carriers
•In most cases, substances are moved
against concentration gradients
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Extracellular fluid
Na+
Na+
K+
Na+
Na+
Na+
K+
P
K+
P
Na+
ATP
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 K+ binds,
causing release of the
phosphate group.
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
Extracellular fluid
Na+
Na+
P
Na+
ATP
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
© 2012 Pearson Education, Inc.
Figure 3.11, step 1
Extracellular fluid
Na+
Na+
K+
Na+
Na+
Na+
K+
P
P
Na+
ATP
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, step 2
Extracellular fluid
Na+
Na+
K+
Na+
Na+
Na+
K+
P
K+
P
Na+
ATP
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.
© 2012 Pearson Education, Inc.
2 The shape change expels
Na+ to the outside.
Extracellular K+ binds,
causing release of the
phosphate group.
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, step 3
Active Processes (no notes)
•Vesicular transport
•Exocytosis
•Moves materials out of the cell
•Material is carried in a membranous
vesicle
•Vesicle migrates to plasma membrane
•Vesicle combines with plasma membrane
•Material is emptied to the outside
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Extracellular
fluid
Plasma
membrane
SNARE
(t-SNARE)
Vesicle
SNARE
(v-SNARE)
Molecule
to be
secreted
Secretory
vesicle
1 The membranebound vesicle
migrates to the
plasma membrane.
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
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Figure 3.12a
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Figure 3.12b
Active Processes (no notes)
•Vesicular transport (continued)
•Endocytosis
•Extracellular substances are engulfed by
being enclosed in a membranous vescicle
•Types of endocytosis
•Phagocytosis—“cell eating”
•Pinocytosis—“cell drinking”
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Extracellular
fluid
Plasma
membrane
Lysosome
Cytosol
Vesicle
1 Vesicle
fusing with
lysosome
for digestion
Ingested
substance
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
containing ingested
material
Pit
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3 Membranes and
receptors (if present)
recycled to plasma
membrane
Figure 3.13a
Extracellular
fluid
Plasma
membrane
1 Vesicle
fusing with
lysosome
for digestion
Ingested
substance
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Figure 3.13a, step 1
Extracellular
fluid
Plasma
membrane
Lysosome
Cytosol
Vesicle
1 Vesicle
fusing with
lysosome
for digestion
Ingested
substance
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
containing ingested
material
© 2012 Pearson Education, Inc.
Figure 3.13a, step 2
Extracellular
fluid
Plasma
membrane
Lysosome
Cytosol
Vesicle
1 Vesicle
fusing with
lysosome
for digestion
Ingested
substance
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Detached vesicle
containing ingested
material
Pit
© 2012 Pearson Education, Inc.
3 Membranes and
receptors (if present)
recycled to plasma
membrane
Figure 3.13a, step 3
Extracellular
fluid
Cytoplasm
Bacterium
or other
particle
Pseudopod
(b)
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Figure 3.13b
Membrane
receptor
(c)
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Figure 3.13c
Cell Life Cycle
• Cells have two major periods
•1. Interphase
•Cell grows
•Cell carries on metabolic processes
•2. Cell division
•Cell replicates itself
•Function is to produce more cells for
growth and repair processes
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DNA Replication
•1. Genetic material is duplicated and readies a
cell for division into two cells
•2. Occurs toward the end of interphase
•3. DNA uncoils and each side serves as a
template
© 2012 Pearson Education, Inc.
C
T
G
A
G
C
T
A
Key:
C
G
= Adenine
C
G
T
A
= Thymine
= Cytosine
= Guanine
T
A
C
G
T
A
C
G
G
G
T
C
A
T
T
A
T
T
C
G
G
T
A
A
C
C
G
© 2012 Pearson Education, Inc.
A
C
G
T
Old
(template)
strand
T
A
A
T
A
G
C
A
Newly
synthesized
strand
C
G
A
New
Old (template)
strand strand
forming
DNA of one chromatid
Figure 3.14
Events of Cell Division
•Mitosis—
•A. Division of the nucleus
•B. Results in the formation of two daughter
nuclei
•Cytokinesis—
•A. division of the cytoplasm
•B. Begins when mitosis is near completion
•C. Results in the formation of two daughter
cells
PLAY
A&P Flix™: Mitosis
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Stages of Mitosis
•Prophase
•First part of cell division
•Centrioles migrate to the poles to direct
assembly of mitotic spindle fibers
•DNA appears as double-stranded
chromosomes
•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
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Stages of Mitosis
•Anaphase
•Chromosomes are pulled apart and toward
the opposite ends of the cell
•Cell begins to elongate
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Stages of Mitosis
•Telophase
•Chromosomes uncoil to become chromatin
•Nuclear envelope reforms around chromatin
•Spindles break down and disappear
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Stages of Mitosis
•Cytokinesis
•Begins during late anaphase and completes
during telophase
•A cleavage furrow forms to pinch the cells
into two parts
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Centrioles
Chromatin
Centrioles
Forming
mitotic
spindle
Plasma
membrane
Nuclear
envelope
Nucleolus
Interphase
Chromosome,
consisting of two
sister chromatids
Early prophase
Metaphase
plate
Spindle
microtubules
Centromere
Centromere
Fragments of
nuclear envelope
Spindle
pole
Late prophase
Nucleolus
forming
Cleavage
furrow
Spindle
Metaphase
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Sister
chromatids
Daughter
chromosomes
Anaphase
Nuclear
envelope
forming
Telophase and cytokinesis
Figure 3.15
Centrioles
Plasma
membrane
Interphase
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Chromatin
Nuclear
envelope
Nucleolus
Figure 3.15, step 1
Centrioles
Forming
mitotic
spindle
Centromere
Chromosome,
consisting of two
sister chromatids
Early prophase
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Figure 3.15, step 2
Spindle
microtubules
Centromere
Fragments of
nuclear envelope
Spindle
pole
Late prophase
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Figure 3.15, step 3
Metaphase
plate
Spindle
Sister
chromatids
Metaphase
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Figure 3.15, step 4
Daughter
chromosomes
Anaphase
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Figure 3.15, step 5
Nucleolus
forming
Cleavage
furrow
Nuclear
envelope
forming
Telophase and cytokinesis
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Figure 3.15, step 6
Protein Synthesis- ??
•1. Gene—DNA segment that carries a
blueprint for building one protein
•2. Proteins have many functions
•Building materials for cells
•Act as enzymes (biological catalysts)
•3. RNA is essential for protein synthesis
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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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Transcription and Translation
•Transcription
•Transfer of information from DNA’s base
sequence to the complimentary base
sequence of mRNA
•Three-base sequences on mRNA are called
codons
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Transcription and Translation
•Translation
•Base sequence of nucleic acid is translated
to an amino acid sequence
•Amino acids are the building blocks of
proteins
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Nucleus
(site of transcription)
Cytoplasm
(site of translation)
DNA
1 mRNA specifying
one polypeptide is
made on DNA template.
2 mRNA leaves
nucleus and attaches to
ribosome, and
translation begins.
Amino
acids
mRNA
Nuclear pore
Correct amino
acid attached
to each species
of tRNA by an
enzyme
Nuclear membrane
4 As the ribosome
Growing
moves along the
polypeptide
Met
mRNA, a new amino
chain
Gly
acid is added to the
growing protein chain.
Ser
Phe
Ala
5 Released tRNA
reenters the cytoplasmic
pool, ready to be
recharged with a new
amino acid.
Synthetase
enzyme
lle
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
Peptide bond
Large ribosomal subunit
C G G
G C C A U A G U C
Codon
Direction of ribosome
advance; ribosome
Portion of
Small ribosomal subunit moves the mRNA strand
along sequentially
mRNA already
as each codon is read.
translated
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Figure 3.16
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
Met
Gly
Growing
polypeptide
chain
Synthetase
enzyme
lle
Ser
Phe
Ala
Peptide bond
tRNA “head”
bearing anticodon
Large ribosomal subunit
C G G
G C C A U A G U C
Codon
Direction of ribosome
advance; ribosome
Portion of
Small ribosomal subunit moves the mRNA strand
along sequentially
mRNA already
as each codon is read.
translated
© 2012 Pearson Education, Inc.
Figure 3.16, step 1
Nucleus
(site of transcription)
Cytoplasm
(site of translation)
DNA
1 mRNA specifying
one polypeptide is
made on DNA template.
2 mRNA leaves
nucleus and attaches to
ribosome, and
translation begins.
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
Correct amino
acid attached
to each species
of tRNA by an
enzyme
Met
Gly
Growing
polypeptide
chain
Synthetase
enzyme
lle
Ser
Phe
Ala
Peptide bond
tRNA “head”
bearing anticodon
Large ribosomal subunit
C G G
G C C A U A G U C
Codon
Direction of ribosome
advance; ribosome
Portion of
Small ribosomal subunit moves the mRNA strand
along sequentially
mRNA already
as each codon is read.
translated
© 2012 Pearson Education, Inc.
Figure 3.16, step 2
Nucleus
(site of transcription)
Cytoplasm
(site of translation)
DNA
1 mRNA specifying
one polypeptide is
made on DNA template.
2 mRNA leaves
nucleus and attaches to
ribosome, and
translation begins.
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
Correct amino
acid attached
to each species
of tRNA by an
enzyme
Met
Gly
Growing
polypeptide
chain
Synthetase
enzyme
lle
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
Ser
Phe
Ala
Peptide bond
Large ribosomal subunit
C G G
G C C A U A G U C
Codon
Direction of ribosome
advance; ribosome
Portion of
Small ribosomal subunit moves the mRNA strand
along sequentially
mRNA already
as each codon is read.
translated
© 2012 Pearson Education, Inc.
Figure 3.16, step 3
Nucleus
(site of transcription)
Cytoplasm
(site of translation)
DNA
1 mRNA specifying
one polypeptide is
made on DNA template.
2 mRNA leaves
nucleus and attaches to
ribosome, and
translation begins.
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
Correct amino
acid attached
to each species
of tRNA by an
enzyme
4 As the ribosome
Growing
moves along the
polypeptide
Met
mRNA, a new amino
chain
Gly
acid is added to the
growing protein chain.
Ser
Phe
Ala
Synthetase
enzyme
lle
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
Peptide bond
Large ribosomal subunit
C G G
G C C A U A G U C
Codon
Direction of ribosome
advance; ribosome
Portion of
Small ribosomal subunit moves the mRNA strand
along sequentially
mRNA already
as each codon is read.
translated
© 2012 Pearson Education, Inc.
Figure 3.16, step 4
Nucleus
(site of transcription)
DNA
Cytoplasm
(site of translation)
1 mRNA specifying
one polypeptide is
made on DNA template.
2 mRNA leaves
nucleus and attaches to
ribosome, and
translation begins.
Amino
acids
mRNA
Nuclear pore
Correct amino
acid attached
to each species
of tRNA by an
enzyme
Nuclear membrane
4 As the ribosome
Growing
moves along the
polypeptide
Met
mRNA, a new amino
chain
Gly
acid is added to the
growing protein chain.
Ser
Phe
Ala
5 Released tRNA
reenters the cytoplasmic
pool, ready to be
recharged with a new
amino acid.
Synthetase
enzyme
lle
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
Peptide bond
Large ribosomal subunit
C G G
G C C A U A G U C
Codon
Direction of ribosome
advance; ribosome
Portion of
Small ribosomal subunit moves the mRNA strand
along sequentially
mRNA already
as each codon is read.
translated
© 2012 Pearson Education, Inc.
Figure 3.16, step 5
Body Tissues
•Tissues
•Groups of cells with similar structure and
function
•Four primary types
•Epithelial tissue (epithelium)
•Connective tissue
•Muscle tissue
•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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Apical surface
Basal
surface
Simple
Apical surface
Basal
surface
Stratified
(a) Classification based on number of cell layers
© 2012 Pearson Education, Inc.
Figure 3.17a
Classification of Epithelia
•Number of cell layers
•Simple—one layer
•Stratified—more than one layer
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Apical surface
Basal
surface
Simple
Apical surface
Basal
surface
Stratified
(a) Classification based on number of cell layers
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Figure 3.17a
Classification of Epithelia
•Shape of cells
•Squamous
•flattened
•Cuboidal
•cube-shaped
•Columnar
•column-like
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Figure 3.17b
Simple Epithelia
•Simple squamous
•Single layer of flat cells
•Location - usually forms membranes
•Lines body cavities
•Lines lungs and capillaries
•Functions in diffusion, filtration, or secretion
in membranes
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Air sacs of
lungs
Nucleus of
squamous
epithelial cell
Basement
membrane
(a) Diagram: Simple squamous
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Nuclei of
squamous
epithelial
cells
Photomicrograph: Simple
squamous epithelium forming part
of the alveolar (air sac) walls (185×).
Figure 3.18a
Simple Epithelia
•Simple cuboidal
•Single layer of cube-like cells
•Locations
•Common in glands and their ducts
•Forms walls of kidney tubules
•Covers the ovaries
•Functions in secretion and absorption;
ciliated types propel mucus or reproductive
cells
© 2012 Pearson Education, Inc.
Simple
cuboidal
epithelial
cells
Nucleus of
simple
cuboidal
epithelial
cell
Basement
membrane
Basement
membrane
Connective
tissue
(b) Diagram: Simple cuboidal
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Photomicrograph: Simple cuboidal
epithelium in kidney tubules (250×).
Figure 3.18b
Simple Epithelia
•Simple columnar
•Single layer of tall cells
•Often includes mucus-producing goblet cells
•Location - lines digestive tract
•Functions in secretion and absorption;
ciliated types propel mucus or reproductive
cells
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Simple
columnar
epithelial
cell
Nucleus of simple
columnar epithelial cell
Goblet cell
Basement
membrane
Connective
tissue
Basement
membrane
(c) Diagram: Simple columnar
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Photomicrograph: Simple columnar
epithelium of the small intestine
(430×).
Figure 3.18c
Simple Epithelia
•Pseudostratified columnar
•Single layer, but some cells are shorter than
others
•Often looks like a double layer of cells but all
cells rest on the basement membrane
•Location - respiratory tract, where it is
ciliated
•Functions in absorption or secretion
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Cilia
Pseudostratified
epithelial
layer
Pseudostratified
epithelial
layer
Basement
membrane
(d) Diagram: Pseudostratified (ciliated)
columnar
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Basement
membrane
Connective
tissue
Photomicrograph: Pseudostratified
ciliated columnar epithelium lining
the human trachea (430×).
Figure 3.18d
Stratified Epithelia
•Stratified squamous
•Cells at the apical surface are flattened
•Functions as a protective covering where
friction is common
•Locations - lining of the:
•Skin
•Mouth
•Esophagus
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Nuclei
Stratified
squamous
epithelium
Stratified
squamous
epithelium
Basement
membrane
(e) Diagram: Stratified squamous
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Photomicrograph: Stratified
squamous epithelium lining of
the esophagus (140×).
Basement
membrane
Connective
tissue
Figure 3.18e
Stratified Epithelia
•Stratified cuboidal—two layers of cuboidal
cells; functions in protection
•Stratified columnar—surface cells are
columnar, 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
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Stratified Epithelia
•Transitional epithelium
•Composed of modified stratified squamous
epithelium
•Shape of cells depends upon the amount of
stretching
•Functions in stretching and the ability to
return to normal shape
•Location - lines organs of the urinary system
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Basement
membrane
Transitional
epithelium
Basement
membrane
Transitional
epithelium
Connective
tissue
(f) Diagram: Transitional
© 2012 Pearson Education, Inc.
Photomicrograph: Transitional epithelium lining of
the bladder, relaxed state (215×); surface rounded
cells flatten and elongate when the bladder fills
with urine.
Figure 3.18f
Glandular Epithelium
•Gland
•One or more cells responsible for secreting
a particular product
•Secretions contain protein molecules in an
aqueous (water-based) fluid
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Glandular Epithelium
•Two major gland types
•Endocrine gland
•Ductless since secretions diffuse into
blood vessels
•All secretions are hormones
•Exocrine gland
•Secretions empty through ducts to the
epithelial surface
•Include sweat and oil glands
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Connective Tissue
•Found everywhere in the body
•Includes the most abundant and widely
distributed tissues
•Functions
•Binds body tissues together
•Supports the body
•Provides protection
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Connective Tissue Characteristics
•Variations in blood supply
•Some tissue types are well vascularized
•Some have a poor blood supply or are
avascular
•Extracellular matrix
•Non-living material that surrounds living cells
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Extracellular Matrix
•Two main elements
•Ground substance—mostly water along with
adhesion proteins and polysaccharide
molecules
•Fibers
•Produced by the cells
•Three types
• Collagen (white) fibers
• Elastic (yellow) fibers
• Reticular fibers
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Connective Tissue Types
•Bone (osseous tissue)
•Composed of
•Bone cells in lacunae (cavities)
•Hard matrix of calcium salts
•Large numbers of collagen fibers
•Functions to protect and support the body
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Bone cells in
lacunae
Central canal
Lacunae
Lamella
(a) Diagram: Bone
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Photomicrograph: Cross-sectional view
of ground bone (300×).
Figure 3.19a
Connective Tissue Types
•Hyaline cartilage
•Most common type of cartilage
•Composed of
•Abundant collagen fibers
•Rubbery matrix
•Locations
•Larynx
•Entire fetal skeleton prior to birth
•Functions as a more flexible skeletal
element than bone
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Chondrocyte
(Cartilage cell)
Chondrocyte
in lacuna
Lacunae
Matrix
(b) Diagram: Hyaline cartilage
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Photomicrograph: Hyaline cartilage
from the trachea (500×).
Figure 3.19b
Connective Tissue Types
•Elastic cartilage
•Provides elasticity
•Location
•Supports the external ear
•Fibrocartilage
•Highly compressible
•Location
•Forms cushion-like discs between
vertebrae
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Chondrocytes
in lacunae
Chondrocites in
lacunae
Collagen fiber
Collagen
fibers
(c) Diagram: Fibrocartilage
© 2012 Pearson Education, Inc.
Photomicrograph: Fibrocartilage of an
intervertebral disc (110×).
Figure 3.19c
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
•Dermis—lower layers of the skin
© 2012 Pearson Education, Inc.
Ligament
Tendon
Collagen
fibers
Collagen
fibers
Nuclei of
fibroblasts
Nuclei of
fibroblasts
(d) Diagram: Dense fibrous
© 2012 Pearson Education, Inc.
Photomicrograph: Dense fibrous connective tissue
from a tendon (500×).
Figure 3.19d
Connective Tissue Types
•Loose connective tissue types
•Areolar tissue
•Most widely distributed connective tissue
•Soft, pliable tissue like “cobwebs”
•Functions as a packing tissue
•Contains all fiber types
•Can soak up excess fluid (causes edema)
© 2012 Pearson Education, Inc.
Mucosa
epithelium
Lamina
propria
Elastic
fibers
Collagen
fibers
Fibroblast
nuclei
Fibers of
matrix
Nuclei of
fibroblasts
(e) Diagram: Areolar
© 2012 Pearson Education, Inc.
Photomicrograph: Areolar connective tissue, a
soft packaging tissue of the body (300×).
Figure 3.19e
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
•Functions
• Insulates the body
• Protects some organs
• Serves as a site of fuel storage
© 2012 Pearson Education, Inc.
Nuclei of
fat cells
Vacuole
containing
fat droplet
Nuclei of
fat cells
Vacuole
containing
fat droplet
(f) Diagram: Adipose
© 2012 Pearson Education, Inc.
Photomicrograph: Adipose tissue from the
subcutaneous layer beneath the skin (430×).
Figure 3.19f
Connective Tissue Types
•Loose connective tissue types
•Reticular connective tissue
•Delicate network of interwoven fibers
•Locations
• Forms stroma (internal supporting
network) of lymphoid organs
• Lymph nodes
• Spleen
• Bone marrow
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Spleen
White blood cell
(lymphocyte)
Reticular
cell
Blood
cell
Reticular fibers
Reticular
fibers
(g) Diagram: Reticular
© 2012 Pearson Education, Inc.
Photomicrograph: Dark-staining network
of reticular connective tissue (430×).
Figure 3.19g
Connective Tissue Types
•Blood (vascular tissue)
•Blood cells surrounded by fluid matrix called
blood plasma
•Fibers are visible during clotting
•Functions as the transport vehicle for
materials
© 2012 Pearson Education, Inc.
Blood cells
in capillary
Neutrophil
(white blood
cell)
White
blood cell
Red blood
cells
Red
blood cells
Monocyte
(white blood
cell)
(h) Diagram: Blood
© 2012 Pearson Education, Inc.
Photomicrograph: Smear of human blood (1300×)
Figure 3.19h
Muscle Tissue
•Function is to produce movement
•Three types
•Skeletal muscle
•Cardiac muscle
•Smooth muscle
© 2012 Pearson Education, Inc.
Muscle Tissue Types
•Skeletal muscle
•Under voluntary control
•Contracts to pull on bones or skin
•Produces gross body movements or facial
expressions
•Characteristics of skeletal muscle cells
•Striated
•Multinucleate (more than one nucleus)
•Long, cylindrical cells
© 2012 Pearson Education, Inc.
Nuclei
Part of muscle
fiber
(a) Diagram: Skeletal muscle
© 2012 Pearson Education, Inc.
Photomicrograph: Skeletal muscle (approx. 300×).
Figure 3.20a
Muscle Tissue Types
•Cardiac muscle
•Under involuntary control
•Found only in the heart
•Function is to pump blood
•Characteristics of cardiac muscle cells
•Striated
•One nucleus per cell
•Cells are attached to other cardiac muscle
cells at intercalated disks
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Intercalated
discs
Nucleus
(b) Diagram: Cardiac muscle
© 2012 Pearson Education, Inc.
Photomicrograph: Cardiac muscle (430×).
Figure 3.20b
Muscle Tissue Types
•Smooth muscle
•Under involuntary muscle
•Found in walls of hollow organs such as
stomach, uterus, and blood vessels
•Characteristics of smooth muscle cells
•No visible striations
•One nucleus per cell
•Spindle-shaped cells
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Smooth
muscle cell
Nuclei
(c) Diagram: Smooth muscle
© 2012 Pearson Education, Inc.
Photomicrograph: Sheet of smooth muscle (approx. 300×).
Figure 3.20c
Nervous Tissue
•Composed of neurons and nerve support cells
•Function is to send impulses to other areas of
the body
•Irritability
•Conductivity
•Support cells called neuroglia insulate, protect,
and support neurons
© 2012 Pearson Education, Inc.
Brain
Nuclei of
supporting
cells
Spinal
cord
Cell body
of neuron
Nuclei of
supporting
cells
Cell body
of neuron
Neuron
processes
Neuron
processes
Diagram: Nervous tissue
© 2012 Pearson Education, Inc.
Photomicrograph: Neurons (150×)
Figure 3.21
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
© 2012 Pearson Education, Inc.
Figure 3.22
Tissue Repair (Wound Healing)
•Regeneration
•Replacement of destroyed tissue by the
same kind of cells
•Fibrosis
•Repair by dense (fibrous) connective tissue
(scar tissue)
•Whether regeneration or fibrosis occurs
depends on:
•Type of tissue damaged
•Severity of the injury
© 2012 Pearson Education, Inc.
Events in Tissue Repair
•Inflammation
•Capillaries become very permeable
•Clotting proteins migrate into the area from
the blood stream
•A clot walls off the injured area
•Granulation tissue forms
•Growth of new capillaries
•Rebuild collagen fibers
•Regeneration of surface epithelium
•Scab detaches
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Developmental Aspects of Tissue
•Epithelial tissue arises from all three primary
germ layers
•Muscle and connective tissue arise from the
mesoderm
•Nervous tissue arises from the ectoderm
•With old age, there is a decrease in mass and
viability in most tissues
© 2012 Pearson Education, Inc.