Download Connective Tissue

Chapter 3
Cell Types
&
Tissues
What are Tissues?
Tissues are groups of cells that
have similar function
 There are 4 main tissue types:
 Epithelial Tissue
 Connective Tissue
 Muscle Tissue
 Nervous Tissue

Epithelial Tissue
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Fit Closely together to form continuous
sheets
Cells are bound together via tight
junctions and proteins called
desmosomes
Always have 1 free surface: the apical
surface, exposed to the body exterior or
cavity of an organ
Lower surface rests on the basement
membrane – structureless material
secreted by the cells
Epithelial Tissue
Avascular – having no blood
supply
 These tissues rely on diffusion of
materials through the capillaries
that lie in the connective tissue
 Easily regenerated

Epithelial Tissue
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Organized by shape and the number of layers
Shape
 Squamous – Flat, Tile-like
 Cuboidal – Cube Shape
 Columnar – Column Shape
Layers
 Simple – one layer
 Stratified – multiple layers
 Pseudostratified – columnar only, one layer of
cells with variable heights
 Transitional – vary due to stretching – cuboidal
to columnar basal membrane
Simple Squamous Epithelia
Stratified Squamous
Connective Tissue
Stratified Squamous Epithelia
Stratified Squamous Epithelia
Simple Cuboidal Epithelia
Simple Columnar Epithelia
Pseudostratified Columnar
Glandular Tissue
Secrete various products
 2 different types of glands
 Endocrine – ductless, have lost their
connection to the surface

 Secretions
diffuse into nearby
capillaries
 Example: Thyroid

Exocrine – Retain their ducts and
empty secretion on epithelial surface
 Examples:
Sweat and Oil glands, Liver,
and Pancreas
Connective Tissue

Most are highly vascularized
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Tendons & Ligaments = Poor Blood Supply
Cartilage = Avascular
 These
3 take a LONG time to heal because
of little/no blood
Made of living cells surrounded by a
non-living Extracellular Matrix (ECM)
 ECM Gives the ability
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to bear weight
to form a soft tissue around organs
to withstand stretching and other abuses
Connective Tissue
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Types:
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Bone – Osseous Tissue – Protects body
organs
Cartilage – flexible - 3 types
Hyaline – lots of collagen, ribs, larynx, joints, &
fetal skeleton
 Fibrocartilage – highly compressible,
intervertebral disks
 Elastic – flexible, outer ear & nose

Bone
Hyaline Cartilage
Stratified Squamous Epithelia
Hyaline Cartilage
Fibrocartilage
Elastic Cartilage
Connective Tissue

Loose – Fewer fibers, softer
Areolar – widely distributed, protective
wrapping of organs
 Adipose – lots of fat cells, insulation and
cushioning
 Reticular – LOTS of fibers, forms the
stroma of lymph organs to support free
blood cells – need special stain to see!


Dense – Lots of Fibers, very organized
Areolar
Adipose
Reticular Connective Tissue
Dense Regular Connective
Connective Tissue

BLOOD – made of cells
surrounded by a nonliving ECM
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Contains fibers that remain invisible
until a vessel is broken
Then these fibers come together to
form a clot
Blood
Blood
Muscle Tissue
Specialized to contract, or shorten
 Cells are elongated to provide better
contraction
 Individual Cells are called fibers
 There are 3 types:
 Skeletal
 Cardiac
 Smooth

Skeletal Muscle Tissue
Fibers are organized into sheets that
form the organs, Skeletal Muscles
 Attached to the Skeleton
 Voluntary Muscles – can be consciously
controlled
 Cells are
 Long
 Cylindrical
 Multinucleate
 Striated – Striped

Skeletal Muscle
Skeletal Muscle
Skeletal Muscle
Cardiac Muscle Tissue
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Found only in the heart
Cells are
 Uninucleate
 Branching
 Striated
Branches meet at junctions called
intercalated disks
 Allow ions to move freely from cell to
cell – creates electrical impulse
Involuntary – not under conscious control
Cardiac Muscle
Smooth Muscle Tissue
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Found in the walls of hollow organs and
vessels
Contraction causes the cavity of an organ to
either constrict or dilate
Contracts more slowly than the other 2
types of muscle
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Ex: Peristalsis – wavelike motion that keeps
food moving through the digestive system
Cells are
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Uninucleate
Spindle-shaped
Not Striated
Smooth Muscle
Connective Tissue
Nervous Tissue
Receive and conduct electrochemical
impulses
 Cells have long extensions which allow
a single neuron to reach multiple sites
 Along with numerous supporting
cells, they make up the nervous
system organs – spinal cord, brain, and
nerves
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Nervous Tissue
Nervous Tissue
Tissue Repair
2 major processes
 Regeneration
 Replacement of cells with the same
kind of cells
 Fibrosis
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Replacement of cells with Dense
Connective Tissue, or scar tissue
Depends on type of cells damaged and
what type of injury took place
Tissue Repair

Damaged tissue brings a series of events
into motion:
 Capillaries become permeable
 Allows clotting proteins to enter
damaged area to stop blood loss and
‘wall off’ the damaged area
 This prevents bacteria or other
harmful materials from entering
Tissue Repair

Granulation tissue forms
 Delicate pink tissue, full of tiny
capillaries that bleed freely when
damaged (picking a scab)
 Contains phagocytes to dispose
of the clot and collagen making
fibroblasts that synthesize scar
tissue to permanently fix the gap
Tissue Repair

Surface epithelium regenerates
Newly made epithelial cells grow just under
the scab, which will fall off
 Leaves new surface over scar tissue.
 Scar may be visible, as a white line, or
invisible depending on the wound severity

Which Tissues Repair Themselves?
Regenerate Well
 Epithelial
 Fibrous Connective & Bone
 Smooth Muscle
 Regenerate Poorly (surgical)
 Skeletal Muscle
 Cartilage
 No Regeneration (all scar)
 Nervous Tissue
 Cardiac Muscle
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Cancer
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50% of Americans will have cancer at one point
in their life
20% of Americans will die from cancer
A group of >100 diseases
All involve uncontrolled proliferation of cells
The process begins with one cell that is mutated
and begins to grow uncontrollably
Each daughter cell produced will carry the same
trait for uncontrolled cell division
Cancer
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These cells will form a tumor:
 in situ – within the original tissue
 invasive – within nearby tissue
Many in situ tumors are benign, not harmful,
and can be surgically removed.
All invasive tumors and some in situ tumors
are considered malignant, dangerous.
 Malignant tumors are likely to
metastasize, spread to other parts of the
body and establish new tumors
Cancer Growth Model