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Nervous Tissue
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
The main components of the nervous system are:
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The Brain
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The spinal cord, and
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The peripheral nerves
It contains two major types of cells:
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Neurons:
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
Branching cell that generate & conduct impulses
Supporting cells:
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Support, insulate, and protect neurons
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Nervous Tissue
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Neurons contain different processes:
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Short processes:
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Called dendrites
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Respond to stimuli
Long processes:
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Called axons
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Conduct impulses over a distance
Neurons transmit:
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Electrical signals from sensory receptors to effectors
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Nervous Tissue
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 4.10
Muscle Tissues
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
Have the following characteristics:
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Highly cellular
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Well vascularized
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Cells posses contractile elements (myofilaments)
There are three types of muscle tissue:
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Skeletal

Cardiac

Smooth
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Muscle Tissue: Skeletal
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Packaged by connective tissue sheets into organs called
skeletal muscles
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Muscle cells, also called muscle fibers, are:
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Long and cylindrical in shape
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Multinucleated
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Striated (bands due to filament alignment)
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Muscle contraction is under voluntary controls (called
voluntary muscle)
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Muscles are attached to bones or skin (occasionally)
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The main function is movement
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Muscle Tissue: Skeletal
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Figure 4.11a
Muscle Tissue: Cardiac
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Found in the walls of the heart
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Cardiac muscle cells are:
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
Branching
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Striated
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Uninucleate
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Interlocked at junctions called intercalated discs
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Under involuntary control
The main function is propelling blood into the
circulation
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Muscle Tissue: Cardiac
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 4.11b
Muscle Tissue: Smooth
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Found in the walls of hollow organs (except heart)
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Smooth muscle cells are:
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Spindle-shaped, with central nuclei
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Uninucleate
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Have no striations (smooth)
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Under involuntary control
Main function is:

Propelling substances along internal passageways
(i.e., peristalsis)
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Muscle Tissue: Smooth
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Figure 4.11c
Covering and Lining Body Membranes:
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All are:
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Continuous multicellular sheets
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Made of at least two primary tissue types
There are three types:
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Cutaneous
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Mucous
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Serous
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Figure 4.12a
Epithelial Membranes:Cutaneous Membrane

Cutaneous (skin): Consists of:

Keratinized stratified squamous
epithelium (epidermis) attached
to

Thick dense irregular
connective tissue layer (dermis)
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Figure 4.12a
Epithelial Membranes: Mucous Membranes

Mucous:

Lines body cavities
that open to the
exterior.
(e.g., digestive,
respiratory, &
urogenital tracts)
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Mostly stratified
squamous or simple
columnar

Wet or moist
membranes

Often adapted for
absorption and
secretion
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Figure 4.12b
Epithelial Membranes: Serous Membranes
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Serous:
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Found in closed
ventral body
cavities
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Moist membranes
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Simple squamous
epithelium
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Named according
to organs:

Pleura

Pericardium

Peritoneum
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Figure 4.12b
Tissue Trauma
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Tissue trauma causes inflammation
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Inflammation is characterized by:
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Dilation of blood vessels
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Increase in vessel permeability
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Redness
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Heat
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Swelling
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pain
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Tissue Repair
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Requires:
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Cell division
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Cell migration
Initiated by:
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Growth factors released by injured tissue
Damaged tissue is replaced by one of two major ways:
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By regeneration:
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
replacement by same tissue
By fibrosis:
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Replaced by connective tissue (scar tissue)
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Figure 4.13a
Defenses of Body’s External Boundaries:
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Mechanical and chemical barriers:
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Skin and mucosae
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Cilia of epithelial linings (Resp. tract)
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Strong acid of the stomach (chemical)
Barrier injury and responses:
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Injury leads to penetration of barriers
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Barrier penetration leads to stimulation of :
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Inflammatory responses: Nonspecific and quick
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Immune response: Specific but slow
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Tissue Repair: 1- Inflammatory events
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Trauma causes injured cells, and
others to release chemicals

Chemicals cause capillaries to dilate
and become very permeable
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White Cells and plasma seep into
injured area
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Clot forms and:


stops blood loss
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holds wound edges together
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walls off area
Exposed area dries forming:


a scab
Lymphatic vessels & phagocytes
remove :

excess fluid, destroyed cells,
and debris
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 4.13a
Tissue Repair: 2- Organization (blood supply
restoration)
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Granulation tissue replaces
clot
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Granulation tissue contains:
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Budding capillary bed
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Proliferating fibroblasts
(produce collagen fibers)
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Macrophages digest the clot

Upon matrix completion,
fibroblasts either revert to
resting stage or undergo
apoptosis
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Figure 4.13a
Tissue Repair: 3- Regeneration and Fibrosis
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During organization,
surface epithelium under
scab begins regenerating
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Scab soon detaches
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Fibrous tissue matures and
contracts
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Epithelium thickens and
resemble adjacent tissue
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 4.13b
Tissue Repair: 3- Regeneration and Fibrosis (cont’d)

A scar may be
visible or invisible
(based on severity of
injury)
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In simple infection
(intact epithelial
barrier), healing is
only by regeneration
(no clotting or
scarring)
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Figure 4.13c