Chapter 4 – Tissues: The Living Fabric
• Epithelial Tissue (Epithelium) – A sheet of cells that covers a
body surface or lines a body cavity.
• Two Purposes:
• 1. Covering and lining epithelium
• 2. Glandular epithelium
• Six roles:
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1. Protection
2. Absorption
3. Filtration
4. Excretion
5. Secretion
6. Sensory reception
• 1. Cellularity – composed of mostly tightly packed cells. Only
a small amount of extracellular material
• 2. Specialized contacts – Epithelial cells fit close together to
form continuous sheets. Adjacent cells are bound together at
many points by lateral contacts (tight junctions and desmosomes)
• 3. Polarity – Epithelial cells have:
• Apical surface – a free surface exposed to the exterior or cavity
• Can contain microvilli – fingerlike extensions of the plasma membrane
• Basal surface – an attached surface
• Basal lamina – a thin supporting sheet
• 4. Epithelial tissue is supported by connective tissue
• Reticular lamina – a thin layer of extracellular material of collagen
protein fibers that is part of underlying connective tissue
• Together these form the Basement Membrane.
• 5. Innervated but avascular
• Does contain nerve tissue
• Does not contain blood vessels
• 6. Regeneration – Epithelial tissues easily regenerate based on
what they’re exposed to.
• Simple epithelia
• Composed of a single cell layer
• Typically found where absorption and filtration occur (a thin layer is
desirable)
• Stratified epithelia
• Consists of two or more cell layers stacked one on top of the other
• Common in high abrasion areas (ex. skin and lining of the mouth)
• Three types of cells:
• Squamous cells
• Flattened and scalelike
• Disk-shaped nucleus
• Cuboidal cells
• Boxlike (about as tall as they are wide)
• Spherical nucleus
• Columnar cells
• Tall and column shaped
• Elongated nucleus
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Simple Squamous Epithelium
Simple Cuboidal Epithelium
Simple Columnar Epithelium
Pseudostratified Columnar Epithelium
• Flattened laterally
• Endothelium – provides a
slick, friction-reducing lining
in lymphatic vessels as well
as hollow organs of the
cardiovascular system
• Mesothelium – the
epithelium found in serous
membranes lining the
ventral body cavity and
covering its organs
• Location: Kidney glomeruli;
air sacs of lungs; lining of
heart; blood vessels;
lymphatic vessels; lining of
ventral body cavity
• Function: allows materials in
and out via diffusion;
lubrication of surfaces
• Single layer of cubical cells
• Cuboidal cells in the kidneys
may contain dense microvilli
(uncharacteristic of simple
cuboidal cells)
• Location: Kidney tubules;
ducts and secretory portions
of small glands; ovary
surface
• Function: secretion and
absorption
• Characterized by a single
layer of tall, closely packed
cells
• Contain dense microvilli on
the apical surface of
absorptive cells
• This tissue also contains
goblet cells which secrete a
protective lubricating mucus
• Location: Nonciliated type
lines most of the digestive
tract, gallbladder and
excretory ducts of some
glands; ciliated variety lines
small bronchi, uterine tubes,
and some regions of the
uterus
• Function: Absorption;
secretion of mucus, enzymes,
and other substances;
ciliated type propels mucus
• All cells rest on the
basement membrane, but
only the tallest reach apical
surface of the epithelium
• Nuclei are at different
levels which makes the
tissue appear stratified.
Not actually stratified.
• Location: Nonciliated type
in ducts of large glands and
parts of the urethra;
ciliated variety lines the
trachea, most of the upper
respiratory tract.
• Function: Secretion,
particularly of mucus;
propulsion of mucus by
ciliary action
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Stratified Squamous Epithelium
Stratified Cuboidal Epithelium
Stratified Columnar Epithelium
Transitional Epithelium
• Most common type of
stratified epithelium.
• Composed of multiple
layers.
• Free surface cells are
squamous, cells of the
deeper layers are cuboidal
or less commonly columnar
• Location: Nonkeratinized
type forms the moist linings
of esophagus, mouth, and
vagina; keratinized variety
forms the epidermis of the
skin, a dry membrane
• Function: Protects underlying
tissues in areas subjected to
abrasion
• Rare type of tissue
• Forms large ducts of some
glands
• Location: Largest ducts of
sweat glands, mammary
glands, and salivary glands
• Function: Protection
• Similar to stratified
cuboidal epithelium
• From large ducts and some
glands
• Rare type of tissue
• Location: Rare in the body;
small amounts in male
urethra and in large ducts
of some glands
• Function: Protection;
secretion
• Tissue will line urinary
organs. These areas are
subjected to a lot of
stretching and different
internal pressures as organ
fills with urine.
• Base layer – cuboidal or
columnar
• Apical layer – vary in
appearance
• Location: Lines the ureters,
bladder, and part of the
urethra
• Function: Stretches readily
and permits distension of
urinary organ by contained
urine
• Gland – consists of one or more cells that make and secrete a
particular product
• Secretion – an aqueous fluid that usually contains proteins
• Two Types of Glands:
• Endocrine Glands
• Exocrine Glands
• Eventually lose their glands – Ductless Glands
• Produce hormones, regulatory chemicals – Secreted into
extracellular space
• More numerous
• Multicellular glands secrete their products through a duct into
body surfaces or into body cavities
• Include:
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Mucous
Sweat
Oil
Salivary glands
Liver
Pancreas
• Connective tissue – found everywhere in the body
• Major functions include:
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1. Binding and support
2. Protection
3. Insulation
4. Transportation
• 1. Common origin
• Arise from Mesenchyme – embryonic tissue derived from the mesoderm
germ layer
• 2. Degrees of vascularity
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Some very vascular; some not vascular
Cartilage – avascular
Dense connective tissue – poorly vascularized
Others richly vascularized
• 3. Extracellular Matrix
• Nonliving
• Strong
• Ground substance – an amorphous material that fills the space
between the cells and contains fibers
• Made of interstitial fluid, cell adhesion proteins, and
proteoglycans
• Fibers of connective tissue provide support
• Collagen fibers – made of collagen proteins
• Secreted into extracellular space
• Elastic fibers – made of elastin proteins
• Like rubber bands
• Reticular fibers – fine collagenous fibers
• 1. Fibroblast – connective
tissue proper
• 2. Chondroblast – cartilage
• 3. Osteoblast – bone
• 4. Hemocytoblast – blood
• Mixed throughout connective tissues
• In charge of consuming foreign substances and cells
• Embryonic Connective Tissues
• - Mesenchyme
• Connective Tissue Proper – Loose connective tissue
• 1. Areolar Connective Tissue
• 2. Adipose Tissue
• 3. Reticular Connective Tissue
• Connective Tissue Proper – Dense connective tissue
• 1. Dense Regular Connective Tissue
• 2. Dense Irregular Connective Tissue
• Cartilage
• 1. Hyaline Cartilage
• 2. Elastic Cartilage
• 3. Fibrocartilage
• Others
• 1. Bone
• 2. Blood
• Embryonic connective
tissue, gel-like ground
substance containing
fibers, star-shaped
mesenchymal cells
• Location: Primarily in the
embryo
• Function: Gives rise to all
other connective tissue
types
• Flat branching cells that
appear spindle shaped
• Gel-like matrix with all
three fiber types; cells;
fibroblasts;
macrophages, mast cells,
and some white blood
cells
• Location: Widely
distributed under
epithelia of body
• Function: Wraps and
cushions organs; its
macrophages
phagocytize bacteria;
plays important role in
inflammation; holds and
conveys tissue fluid
• Fat cells
• Closely packed cells
• Nucleus pushed to the
side because of large
fat droplets within the
cell
• Location: Under skin;
around kidneys and
eyeballs; in bones and
within abdomen; in
breasts
• Function: Provides
reserve food fuel;
insulates against heat
loss; supports and
protects organs
• Network of reticular
fibers in a typical loose
ground substance;
reticular cells
predominate
• Location: Lymphoid
organs (lymph nodes,
bone marrow, and
spleen)
• Function: Fibers form a
soft internal skeleton
(stroma) that supports
other cell types
• Primarily parallel
collagen fibers; a few
elastin fibers
• Mostly contains
fibroblasts
• Location: Tendons, most
ligaments, aponeuroses
• Function: Attaches
muscles to bones or to
muscles; attaches bones
to bones
• Thicker collagen fibers
• Structure is more
irregular
• Major cell type:
fibroblast
• Location: Dermis of the
skin; submucosa of
digestive tract; fibrous
capsules of organs and
of joints
• Function: Structural
strength; withstand
tension
• Similar to bone and dense connective tissue
• Surrounded by perichondrium – a dense irregular connective
tissue membrane
• Come from chondroblasts
• Provides support
• Some flexibility
• Between bones
• Location: Forms most of
the embryonic skeleton;
covers the ends of long
bones; forms costal
cartilages of the ribs;
nose, trachea, and
larynx
• Function: Supports and
reinforces; has resilient
cushioning properties;
resists compressive stress
• Like hyaline cartilage
• More elastic fibers in
matrix
• Location: Supports the
external ear; epiglottis
• Function: Maintains the
shape of a structure
while allowing great
flexibility
• Matrix is similar to
hyaline cartilage but less
firm; thick collagen
fibers predominate
• Location: Intervertebral
discs; pubic symphysis;
discs of knee joint
• Function: Tensile strength
with the ability to absorb
compressive shock
• Hard, calcified matrix
• Lots of collagen fibers
• Well vascularized
• Location: Bones
• Function: Supports and
protects; provides levers
for muscles to act on;
stores calcium, minerals,
and fat; marrow inside
bone is site for blood cell
formation
• Red and white blood
cells in a fluid matrix
• Location: Contained
within blood vessels
• Function: Transport of
respiratory gases,
nutrients, wastes, and
other substances
• Epithelial Membranes – a continuous multicellular sheet
composed of at least two primary tissue types:
• An epithelium bound to an underlying layer of connective tissue proper
• Cutaneous Membrane – skin
• Epidermis – keratinized stratified squamous epithelium
• Dermis – dense irregular connective tissue
• Mucous Membranes – line body cavities that are open to the
exterior (hollow organs of digestive, respiratory, and urogenital
tracts)
• Always wet or moist membranes bathed by secretions, or in the case of
urinary mucosa, urine
• Serous Membranes (serosae) – are moist membranes found in
closed ventral body cavities
• Parietal layer – lines the cavity wall and then reflects back as visceral
layer
• Visceral layer – covers outer surfaces of organs within the cavity
• Consists of:
• Mesothelium – squamous epithelium resting on loose connective tissue
(areolar)
• Serous fluid – lubricates the facing surfaces of the parietal and visceral
layers
• Makes up the nervous
system which controls the
body
• Made of two types of
cells:
• Neurons – highly specialized
nerve cells that generate and
conduct nerve impulses
• Supporting Cells –
nonconducting cells that
support, insulate, and protect
the delicate neurons
• Location: Brain, spinal
cord, and nerves
• Function: Transmit
electrical signals from
sensory receptors and to
effectors (muscles and
glands) which control
their activity
• Highly cellular, well-vascularized tissues that are responsible for
most types of body movement
• Muscle cells are called muscle fibers because of their elongated
shape – allows for better contractile function
• Myofilaments – elaborate versions of actin and myosin filaments
that allow for movement
• Three types:
• Skeletal muscle
• Cardiac muscle
• Smooth muscle
• Packaged by connective
tissue sheets into organs
known as skeletal
muscles – attached to
bone of the skeleton
• Allow for movement
• Cells are striated in
appearance
• Location: In skeletal
muscles attached to
bones or occasionally to
skin
• Function: Voluntary
movement; locomotion;
manipulation of the
environment; facial
expression; voluntary
control
• Occurs in the walls of the
heart – found no where
else
• Contractions help propel
blood throughout the body
• Appear striated with two
differences to skeletal
muscle:
• Uninucleate
• Branching cells that fit
together at junctions –
intercalated discs
• Location: walls of the
heart
• Function: as it contracts, it
propels blood into the
circulation; involuntary
control
• No externally visible
striations
• Spindle shaped and contain
one centrally located nucleus
• Found in walls of hollow
organs (digestive and urinary
tract organs, uterus, blood
vessels)
• Acts to propel substances
through
• Involuntary muscle (not
voluntary which we can
control)
• Location: mostly in the
walls of hollow organs
• Function: Propels
substances or objects
(foodstuffs, urine, a
baby) along internal
passageways;
involuntary control
• Regeneration – replacement of destroyed tissue with the same
kind of tissue
• Fibrosis – proliferation of fibrous connective tissue called scar
tissue
• Occurs in Three stages:
• 1. Inflammation – surrounding tissues swell; blood clots
• 2. Organization restores blood supply – blood clot is replaced by
Granulation tissue
• Composed of: extremely permeable capillaries (makes capillary bed),
macrophages, and fibroblasts
• 3. Regeneration and/or fibrosis effects permanent repair – surrounding
cells reproduce through mitosis
• 1. The tissue injured
• 2. The type of injury and immediate care given to the injured
site
• 3. Nutrition
• 4. Adequacy of blood supply
• 5. State of health
• 6. Age
• Ectoderm
• Mesoderm
• Endoderm