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Tissues:
The living
fabric
Ch 4 c
Membranes, Nervous,
and Muscle Tissue
Membranes
Cutaneous, Mucous,
and Serous
Cutaneous, Mucous, and
Serous Membranes
• Composed of epithelium
tissue bound to connective
tissue proper.
• Considered simple organs
Cutaneous
Membranes
• Skin
• Exposed to
air,
considered a
dry
membrane
Figure 4.9a
• Consists of a
keratinized
stratified
squamous
epithelium
(epidermis)
firmly attached
to a thick layer
of dense
irregular
connective
tissue (dermis)
Cutaneous
Membranes
Figure 4.9a
Mucous Membranes
• Lines body
cavities
open to the
exterior
(digestive,
respiratory,
and
urogenital
tracts)
Figure 4.9b
• Epithelial
tissue upon
a layer of
loose
connective
tissue, then
sometimes
smooth
muscle
Mucous
Membranes
Figure 4.9b
Mucous
Membranes
• Considered
Wet or
moist
membranes
Figure 4.9b
Serous membranes
• Moist membranes found in
closed ventral body cavities
• Simple squamous epithelium
resting on a thin layer of loose
connective areolar tissue
Serous membranes
• Serous fluid lubricates the facing
surfaces of the parietal (wall)
and visceral (organs).
–Remember this is a double
membrane with the serous
fluid between the layers
Serous membranes
• Serous membranes named
according to where they are and
the organs they are associated
with
Serous membranes
• Pleura – lining the thoracic wall
and covering the lungs
• Pericardium – enclosing the
heart
• Peritoneums – abdominopelvic
cavity and visceral organs
Nervous Tissue
Nervous Tissue
• Consists of branched neurons
with long cellular processes and
supporting cells
• Supporting cells are
nonconducting cells that
support, insulate, and protect
the delicate neurons.
Nervous Tissue
• Neurons transmits electrical
signals from sensory receptors to
effectors
• Found in the brain, spinal cord,
and peripheral nerves
Nervous Tissue
Figure 4.10
Muscle Tissue
Muscle Tissue
• Highly cellular
• Well-vascularized
• 3 types
–Skeletal
–Cardiac
–smooth
Skeletal Muscle
• Long, cylindrical cells, also
called muscle fibers
• Multinucleated with obvious
striations (bands)
• Initiates and controls
voluntary movement
• Found in skeletal muscles
that attach to bones or skin
Skeletal muscle tissue
• Long, cylindrical, multinucleate cells with
obvious striations
• Initiates and controls voluntary movement
• Found in skeletal muscles that attach to
bones or skin
Figure 4.11a
Cardiac Muscle Tissue
• Branching, striated,
uninucleate cells interlocking
at intercalated discs
• Propels blood into the
circulation
• Found in the walls of the
heart
Cardiac muscle
• Branching, striated, uninucleate cells
interdigitating at intercalated discs
• Propels blood into the circulation
• Found in the walls of the heart
Figure 4.11b
Smooth Muscle Tissue
• Sheets of spindle-shaped cells
with central nuclei and no
striations
• Propels substances along
internal passageways (by
peristalsis)
• Found in the walls of hollow
organs
Smooth Muscle Tissue
Figure 4.11c
Muscle Tissue
• Skeletal muscle is voluntary
muscle
• Cardiac and Smooth muscles
are involuntary muscles
What happens
when there is
trauma to tissue?
Tissue Trauma
• Causes inflammation,
characterized by:
–Dilation of blood vessels
–Increase in vessel
permeability
–Redness, heat, swelling,
and pain
Tissue Repair
• Severed blood
vessels bleed
• Inflammatory
chemicals are
released
Figure 4.12a
Tissue Repair
• Local blood
vessels dilate
and become
more permeable
• This allows
white blood cells
and clotting
proteins to
invade injured
site
Figure 4.12a
Tissue Repair
• Clotting
proteins
initiate
clotting,
surface dries
and forms a
scab
Figure 4.12a
Tissue Repair
• Granulation
tissue is
formed
• Capillary
buds invade
the clot,
restoring
vascular
supply
Figure 4.12b
• Fibroblasts
secrete
collagen,
which bridges
the gap
• Macrophages
phagocytize
dead and
dying cell
debris
Tissue Repair
Figure 4.12b
Tissue Repair
• Surface
epithelial
cell divide
and migrate
over the
granulation
tissue
Figure 4.12b
• About one
week later,
the fibrosed
area (scar)
has
contracted
and
regeneration
of the
epithelium is
in progress
Tissue Repair
Figure 4.12c
Tissue Repair
• Results in a
fully
regenerated
epithelium
with
underlying
scar tissue
Figure 4.12c
Regenerative Capacity
• Epithelial tissues, bone,
areolar connective tissue,
dense irregular connective
tissue and blood-forming
tissue regenerate extremely
well
Regenerative Capacity
• Smooth muscle and dense
regular connective tissue have
a moderate capacity for
regeneration
Regenerative Capacity
• Skeletal muscle and cartilage
have a weak regenerative
capacity
Regenerative Capacity
• Cardiac muscle and nervous
tissue in the brain and spinal
cord have NO functional
regenerative capacity
–They are replaced by scar
tissue
Regenerative Capacity
• Scar tissue is strong, but
lacks flexibility and elasticity
of most normal tissues, nor
can it perform the normal
functions of the tissues it
replaced
Developmental
Aspects
Developmental Aspects
• Primary germ layers:
ectoderm, mesoderm, and
endoderm
Figure 4.13
Developmental Aspects
These three layers of cells are
formed early in embryonic
development then specialize to
form the four primary tissues
Figure
4.13
Developmental Aspects
• Nerve tissue arises from
ectoderm (blue)
Figure 4.13
Developmental Aspects
• Muscle and connective tissue
arise from mesoderm (red)
Figure 4.13
Developmental Aspects
• Most mucous membranes
arise from endoderm (yellow)
Figure 4.13
Developmental Aspects
• Epithelial tissues arise from
all three germ layers
Figure 4.13
Developmental Aspects
• By end of second month of
development, all primary tissues
have appeared
• Tissue cells remain mitotic and
produce rapid growth until
birth, except the division of
nerve cells nearly stop during
fetal period
Developmental Aspects
• After birth, most tissues divide
until adult body size is achieved
• In adults only epithelia and
blood-forming tissues are highly
mitotic
Developmental Aspects
• With old age, the amount of
collagen declines, making tissue
repair less efficient
• With old age, bone, muscle, and
nervous tissues begin to atrophy
Quiz
next time
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16-21
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