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HISTOLOGY
Intercellular organization
Types of Tissues
The cells of the body are arranged into various groups having
similar structural and functional characteristics.
These groups are called tissues.
Epithelium
Connective tissue
Muscle tissue
Nervous tissue
Epithelial Tissue
Tissues that cover and line all
surfaces and cavities of the body.
• These cells are close together
with very little intercellular
material.
• Can be arranged in one layer
(simple) or more than one layer
(stratified)
• Functions include: protection,
absorption, and secretion
• Some possess specialized
structures, such as cilia and
microvilli.
3 cell shapes of epithelium
• Squamous (looks like a fried egg)
• Cuboidal cube shaped
• Columnar column shaped
Epithelium (cont.)
• There are no blood capillaries
present in epithelium
• So all nutrients and oxygen reach
these cells by diffusion
• They also have the ability to
replace themselves at a very high
rate.
Epithelium (cont.)
Connective Tissue
• Consists of various types of
cells, fibers, and proteins
known as intercellular
material. (matrix)
• Functions include: support,
flexibility, and binding of
tissues, transport and storage
of materials and protection
against foreign substances.
• There are many diverse
forms . It can be a liquid, gel,
fibrous, or solid.
• Connective tissue has the
capacity to repair and
regenerate damaged areas of
the body.
MUSCLE TISSUE
• Displays contractility, the ability to
shorten when stimulated.
• It accounts for 40-50% of the total
body weight.
• Functions in the production of
movement.
3 types of Muscle:
• Skeletal-produces movement of the
bones of the skeleton acting as levers
• Smooth-produces movement within
the hollow organs of the body and
the blood vessels.
• Cardiac- found only in the heart,
causes the contraction of the heart to
pump blood.
NERVOUS TISSUE
• Is specially adapted to collect and
transmit information by means of
different types of nerve cells.
• Nerve cells are called NEURONS
Nerve cells differ a great deal in
structure and function
• Some are sensitive to changes in the
environment and can receive stimuli.
• Others are adapted for sending
impulses or messages down their
length.
• Other nerve cells are responsible for
carrying out the proper responses.
• Nervous tissue plays a vital role in
the maintenance of homeostasis.
Types of Epithelial Tissue
Simple Squamous Epithelium –
squamous cell is a flattened (fried
egg) shaped cell.
• Found lining the blood vessels.
endothelium
• Makes up the tissues of the lungs,
the sac around the heart.
• Functions in absorption/diffusion,
and the secretion of fluids.
Stratified Squamous Epithelium
• Makes up the skin, lines all body
orifices.
• Many layers of squamous cells.
• The skin is cornified (keratin) a
protein which makes the cells
tougher and impervious to water
in its more superficial layers.
• Functions in protection and
secretion.
Simple Cuboidal Epithelium
• One layer of cube shaped cells.
• Found making up glands, tubules of
the kidneys, and the ovaries.
• Functions in secretion.
Simple Columnar Epithelium
• One layer of column shaped cells.
• They are packed close together to
form a protective covering over the
inner surface of a hollow organ.
• The lining of the digestive tract is
composed of these types of cells.
• Found within this epithelium are
goblet cells which secrete mucous
which allows for lubrication and
protection of these cells.
• Functions in protection, secretion
and absorption.
Ciliated Columnar Epithelium (Pseudostratified)
• Appear to be stratified but are not.
• Free border of the cell is covered with
cilia, which moves material. (mucous)
• Found lining most of the respiratory
tract and the fallopian tubes.
• Functions in protection and secretion.
CONNECTIVE TISSUES
3 cell types found in connective tissue.
1. fibroblast-long star shaped cell
produces elastin(yellow) and
collagen (white) fibers.
2. Macrophages-phagocytic cell.
3. Mast Cells- function in immunity still
not clearly understood.
Loose Connective Tissue (areolar)
• Forms delicate thin membranes with
many yellow and white fibers.
• Binds skin to underlying tissue and
organs
• Has numerous blood vessels running
through it to supply the epidermis
with nourishment.
• Fills in spaces, repairs damaged
tissues.
Adipose Tissue
• Fat storage tissue
• Found deep to the skin, around
kidneys, heart, behind eyeballs and in
abdominal membranes, and in
various joints.
• Acts as a protective cushion, heat
insulator, and a reserve energy
source.
Fibrous Connective Tissue
• Consists of closely packed thick white
fibers. (collagen) very few cells.
• Makes up ligaments, tendons, outer
membrane of the eye (sclera), and
deeper portions of the dermis.
• Very low blood supply so healing is
very slow.
Cartilage
• Very rigid, supports, provides framework,
serves as attachments for muscles, and
protects.
• Very abundant intercellular matrix with
collagen fibers imbedded in it.
• Cells are called chondrocytes, which
produce a clear milk-glass like matrix.
• No direct blood supply so healing is slow.
3 types found in the body.
1.
2.
3.
hyaline-most abundant found on the ends
of bones in joints, nose, rings of trachea
and the fetal skeleton.
Elastic- more flexible found in the external
ear, and larynx
Fibrocartilage-very tough shock absorber.
Found in the intervertebral discs, knees,
and bones of the pelvic girdle.
Bone (Osseous Tissue)
• Most rigid of all tissues.
• Contains mineral salts of calcium
and phosphorus.
• Very large intercellular matrix like
cartilage.
• Functions to provide support,
serves as attachment for muscles,
forms blood cells, protects internal
organs, and stores inorganic salts.
• Cell are called osteocytes
Blood
• The only true liquid tissue of the
body
• Actually is cells suspended in a liquid
intercellular matrix. (plasma)
• Blood cells are produced in
hemopoietic tissue called red
marrow in the bones of the skeleton.
MUSCLE TISSUE
Displays irritability, ability to respond to a
stimulus. contractile
• Contracts or shortens when stimulated
3 types:
1. skeletal-striated, multinucleated, very
large cells. Responsible for voluntary
movements of the skeleton. voluntaryyou consciously control its contractions.
2. Smooth-nonstriated, involuntary found
in the walls of hollow organs and blood
vessels. Pushes food through the
alimentary canal and controls the flow
of blood thru the vessels.
3. Cardiac-striated, involuntary muscle
makes up the heart, singlely nucleated,
possess intercalated discs.
NERVOUS TISSUE
• Also displays irritability, made up of
neurons, which are sensitive to
certain changes in the environment.
• They respond by transmitting
electrical impulses down cytoplasmic
extensions to other neurons or
muscles or organs.
• Makes up the brain and spinal cord
and the rest of the peripheral nerves
and receptors.
• Neuroglial cells function to bend,
support and supply nutrients to
neurons.