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Histology
The study of tissues
Tissue
A group of similar
cells working
together to perform
a common function.
4 Types of Tissues
Epithelial
 Connective
 Muscle
 Nervous

Epithelial Tissue
Covers a body
surface or lines a
body cavity
Characteristics of Epithelial Tissue


Composed of
closely packed
cells with
specialized points
of attachment
Have a free
surface and
attached to a
basement
membrane



Avascular but
innervated
Rapid cell division
Specialized to form
glands
Functions of Epithelial
Tissue



Protection
Absorption
Secretion



Filtration
Excretion
Sensory
Classification of Epithelial
Tissue
Cell Shape:
Squamous –
flattened cells
Cuboidal- boxes
Columnar-tall
Cell Arrangement:
Simple – single
layers
Stratified –
multiple layers
Examples of Epithelial
Tissue
Simple Squamous Epithelium
(Alveoli of lungs & linings of Blood vessels)


Simple Cuboidal Epithelium
(Kidney tubules)

A.
B.
Cuboidal cells
Nucleus of cell
Simple Columnar Epithelium
(Digestive Tract)

A.
B.
C.
Columnar cells
Nucleus
Cell membrane
Pseudostratified Epithelium
(Trachea)

A.
B.
C.
Basement
membrane
Cilia
Nucleus
Stratified Squamous Epithelium
(Lining of mouth)

A.
B.
Layers of
epithelium
Surface cells
Stratified Squamous Epithelial
(Human Cheek Cells)
A.
B.
C.
Nucleus
Cytoplasm
Cell Membrane
Transitional Epithelium
(Urinary bladder)

A.
B.
Surface cells
Attached cells
Specialized for
stretching
Connective Tissue
Connective Tissue
Found everywhere
in the body; most
abundant and
widely distributed of
all the tissues.
Characteristics of Connective
Tissue

Cells widely
separated by an
extracellular
matrix

Varying degrees of
vascularization
Functions of Connective
Tissue
Binding and support
 Protection
 Insulation
 Transportation

Structural Elements

Ground Substance
– unstructured
material that fills
the space between
the cells


Cells
Fibers



Collagen fibers
Elastic fibers
Reticular fibers
Examples of Connective
Tissue
Areolar Connective Tissue
(beneath the skin)

A.
B.
C.
Fibroblasts
Collagen fibers
Elastic fibers
Reticular Tissue
(Spleen, liver, lymph nodes)

A. Reticular fibers
Adipose Tissue
(Fat)

A.
B.
Nucleus of fat cell
Fat droplet
Dense Fibrous
Connective Tissue
(Tendons)

A.
B.
Fibroblasts
Collagenous
fibers
Hyaline Cartilage
(Ends of bones, trachea, larynx)

A.
B.
C.
Chrondrocyte
Matrix
Lacuna
Bone

A.
B.
C.
D.
Central Canal
Lamellae
Osteocyte in
lacuna
Canaliculi
Blood

Leucocytes
(White Blood Cells)
Erythrocytes
(Red Blood Cells)
Sickle Cells
Muscle Tissue
Responsible for
body movements
Classification

Location



Skeletal
Cardiac
Visceral

Appearance



Smooth
Striated
Action


Voluntary
Involuntary
Skeletal Muscle:
Attached to bones for movement






A.
B.
AKA: Muscle fibers
Long, blunt,
cylindrical
Multinucleated
Striated
Voluntary
Width of cell
Nucleus
Cardiac Muscle:
Found in heart





A.
B.
Involuntary
Mononucleate
Branched
Striated
Intercalated discs
Nucleus
Visceral/Smooth Muscle:
Found in walls of hollow organs





Involuntary
Spindle-shaped
Mononucleate
No visible
striations
B. Nucleus
Nervous Tissue
Regulates and
controls body
functions
2 Major Cell Types
Neurons
Generate and
conduct nerve
impulses
Functional cells of
the nervous
system
Supporting Cells
Nonconducting
Support, protect and
insulate neurons
Neuroglia
Parts of Neuron


Cell Body
Dendrite


Receives information from sensory receptors
Axon

Carries impulses away from cell body to target structure
Neurons & Neuroglia

A.
B.
C.
Cell Body
Cell Process
(axon or
dendrite)
Neuroglia
(small dark dots)
Neuromuscular Junction

A.
B.
C.
Axon
Motor end plates
Skeletal cell