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Anatomy and Physiology
Chapter 3
Cells and Tissues

Cells in multicellular organisms (i
...
humans) do not
operate independently or in isolation
...

 This cell specialization allows the body to
function in very sophisticated ways
...

2
...

4
...

1
...
Body coverings & linings
b
...
Protection
b
...
Filtration
d
...
a Glandular epithelium


Fashions (forms) the glands of the body

1
...
Specialized contacts
—form continuous sheet bound to adjacent
cells by lateral contacts (including tight
junctions, desmosomes, & gap junctions
which eliminates the extracellular space b/w
tissue layers)

4

•
•
•
•
•

protection—skin (protects mechanical/
chemical/ bacterial)
Absorption—digestive tract
Filtration—kidneys (also do protection and
absorption)
Secretion—specialty of glands
Excretion, sensory reception (other functions, but
not primary functions)



Tight junctions—when adjacent
plasma membranes fuse together like
a zipper



Desmosomes—anchoring junctions
that prevent cells subjected to
mechanical stress from being pulled
apart



Gap junctions—allow communication
b/w cells

4
...
Basement membrane
—epithelials rest on thin supporting basal lamina
which separates it from connective tissue
 Basal
lamina
(epithelial)—nonliving,
adhesive material formed by glycoproteins
 Reticular lamina (connective)—extracellular
material made up of fine collagenous or
reticular fibers

3
...
Regeneration
– High capacity to regenerate
– As long as the cells receive adequate nutrition,
they can replace lost cells rapidly by cell
division

The types of epithelia are identified by:
o shape of cells
o arrangement of cells (number of cell layers
present)

All

epithelial
cells
are
irregularly
polyhedral
(many-sided)
in
cross
section, but differ in cell
height
...
Thus, nuclear shape can be very helpful
when attempting to distinguish epithelial types
Cell arrangement
(# of cell layers)
2 major types of epithelium:
Simple – one layer; typically
found where absorption &
filtration occur
Stratified – more than one
layer stacked on top of the
other; typically found in high

abrasion areas where protection
is important (skin surface &
lining of mouth)

Simple squamous
– Single layer of flat
cells
– Usually forms
membranes
o Lines body cavities
o Lines lungs and
capillaries
Simple cuboidal
– Single layer of cubelike cells
– Common in glands
and their ducts
– Forms walls of
kidney tubules
– Covers the ovaries

Simple columnar

Stratified cuboidal
– Two layers of cuboidal cells
o Stratified columnar
– Surface cells are columnar, cells underneath vary
in size and shape
– Both:
o Rare in human body
o Found mainly in ducts of large glands—
function in protection

– Single layer of tall
cells
– Often includes
goblet cells, which
produce mucous
– Lines digestive tract

Pseudostratified
– Single layer, but some
cells are shorter than others
– Often looks like a
double cell layer
– Sometimes
ciliated,
such as in the respiratory
tract
– May
function
in
absorption or secretion
Stratified squamous
– Cells at the free
edge are flattened
– Found
as
a
protective covering
where friction is
common
– Locations:
o Skin
o Mouth
o Esophagus

Transitional
epithelium




Shape
of
cells
depends upon the
amount
of
stretching
Lines organs of
the
urinary
system


...
Pleura—lining of thoracic wall &
covering the lungs
Pericardium—encloses the
heart
Peritoneum—abdominopelvic
cavity
Glandular Epithelium


Gland – one or more cells that produce &
secrete an aqueous (water-based) fluid that
typically contains proteins
...




Glands are classified as:

Mucous membranes (mucosae)
– Epithelial membranes that line the body
cavities those are open to the exterior
(digestive, respiratory, & urogenital tracts)
– In all cases, they are ―wet,‖ or moist,
membranes bathed by secretions
– Often adapted for absorption and secretion

•

Cutaneous membrane
– Your SKIN
o An organ made of keratinized stratified
squamous epithelium (epidermis) firmly
attached to a thick connective tissue layer
(dermis)
o Uniquely different b/c it is exposed to air
and is a dry membrane

•

Endocrine gland
• Ductless
• Secretions are
chemicals)

hormones

(regulatory

Exocrine gland
• Empty through ducts to the epithelial
surface
• Include sweat and oil glands, salivary
glands, liver, pancreas, mammary glands,
mucous glands, etc
...

•
Tubular—secretory cells form a
tube
•
Alveolar—(aciner) secretory cells
form small flasklike sacs
•
Tubulo alveolar—secretory parts
have both tubular and alveolar
portions

o because multicellular glands secrete their
products in different ways, they can be
classified functionally, according to their
secretory behavior
...
Connective tissue proper
(dense & loose)
2
...
Bone
4
...

2
...

4
...


Binding—connective tissue
Support—bone & cartilage
Protection—bone, cartilage, & fat
Insulation—fat
Transportation—blood

Why is matrix important?
Matrix is what enables connective
tissue to bear weight, withstand great
tension, & endure abuses such as
physical trauma or abrasion

3 main components of connective tissue:
matrix

1
...
Fibers
3
...
Ground Substance (found in matrix)
•
•

•

Amorphous (unstructured) material that fills
the space b/w cells and contains the fibers
Made of interstitial fluid, glycoproteins, &
glycosaminoglycans
(GAGs)—GAGs
coil,
intertwine, & trap water forming fluid to
semistiff gel
...
Fibers: (3 types of fibers found in matrix)
2
...
b
...
Cells
•

Primary cell types are:
o
Connective tissue proper ; fibroblast
o
Cartilage ; chondroblast
o
Bone ; osteoblast
o
Blood ; hemocytoblast (always actively
mitotic)

•

Each cell type exists in immature & mature forms
–
These cells are actively mitotic when
immature & less active when mature
o ―—blast‖ = immature cell ―—cyte‖ =
mature cell

•

Macrophages

–

•

•

Ex
...
Elastic fibers then
snap the connective tissue back
to its normal length when the
tension lets up
...
c
...

•
Construct a fine mesh around small
blood vessels, support soft tissue of
organs, and area found at junction b/w
connective tissue & other tissue types
...

Also central actors in the immune system
Macrophages may be loose & migrate freely,
or they may be fixed in matrix
...
Histiocytes ; loose connective tissue
Kupffer cells ; in the liver
Microglial cells ; brain

Dense
•
•
•

•
•

All classes consist of living cells surrounded by a
matrix
Major differences reflect cell type, fiber type, &
proportion of the matrix contributed by the fibers
Main subgroups/types
1) Connective tissue proper (dense & loose)
2) Cartilage
3) Bone
4) Blood

Embryonic Connective Tissue
1) Mesenchyme (mesenchymal tissue)
2) Mucous connective tissue (Wharton’s jelly,
which supports umbilical cord)
2 Classes—loose & dense
Loose
•
Areolar—packages organs & surrounds
capillaries
•
Adipose—reserve E, insulation, support, &
protection
•
Reticular—soft internal skeleton to support
other cell types

Dense regular—attaches muscle to bone
(tendons) or bone to bone (ligaments)
Dense irregular—provides structural
strength (dermis)
Elastic—provides durability with stretch

Loose Connective Tissue Types
Stands up to both tension and compression
Tough, but flexible (charac
...


•Hyaline cartilage remains during childhood as
epiphyseal plates (active growing regions near the
end of long bones)
•Covers the ends of long bones as articular
cartilage (helps to absorb compression at joints)
Elastic Cartilage
•maintains shape of a structure while allowing
great flexibility/elasticity
•Contains more elastin fibers than hyaline
cartilage does
•Located primarily in areas were strength &
exceptional stretchability are needed
o Example: supports the external ear & found
in epiglottis

Fibrocartilage
•Highly compressible &
resists tension
•Found where hyaline
cartilage meets a true
ligament
or
tendon;
where strong support &
ability
to
withstand
heavy
pressure
are
required
o Example:
forms cushion-like discs
between vertebrae &
spongy
cartilage
of
knees

3
...
3
...

•
Ex
...

Get rid of the harmful agent
6
...

Restore tissue to a healthy condition
Immune Response
•
Extremely specific response, takes longer to
activate
•
Immune cells attack the specific recognized
invader directly or by releasing antibodies into
the blood
...

•
This is initiated by growth factors (wound
hormones) released by injured cells
How does Tissue Repair Occur?
1
...

1
...
Mesoderm
3
...




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