ANAT41 – Lecture Notes
HISTOLOGY
Histology is the study of tissues.
What is a tissue?
A group of ____________.
Major or principal types of tissues
1. Epithelium or epithelial tissue: covers body surfaces and lines structures (e.g.
organs, glands, etc.)
2. Connective tissue: protects, supports, binds, provides immunity, stores fat
3. Muscle tissue: contraction
4. Nervous tissue: detects stimuli and transmits nerve impulses
1. Epithelial tissue
 Two basic types:
epithelium that covers and lines
glandular epithelium
General features:
1. Cellular = consists of cells arranged in continuous sheets, either in single or multiple
layers
2. Has surfaces:
(a) free surface (apical surface); barriers, secretory surfaces and protective
surfaces
(b) lateral surfaces
(c) basal surface
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ANAT41 – Lecture Notes
3. Avascular - no blood supply
4. Innervated - has nerve supply
5. Mitotically active - cells divide to produce a new population
Epithelium is classified based on the cell shape and number of layers.
Layers: Simple vs. Stratified
Basic Shapes:
 Squamous - thin, flattened cells (resembles a fried egg)
 Cuboidal - equal widths and lengths, cube or hexagon shaped
 Columnar - taller than they are wide
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ANAT41 – Lecture Notes
Types of Epithelium
Simple squamous
Characteristics
Location
Function
Single layer of
flat cells, with a
centrally located
nucleus
Lines heart,
blood vessels,
lymphatic
vessels, air
sacs of lungs,
capsule of
kidney, serous
membranes
Filtration,
diffusion,
secretion,
osmosis
Single layer of
cubed shaped
cells, with a
centrally located
nucleus
Covers
surface of
ovary, lines
cornea, forms
pigmented
area of retina,
lines kidney
tubules, small
ducts and
glands
Secretion
and
absorption
Single layer of
columnar
shaped cells,
with basally
located nucleus;
can be ciliated
or non-ciliated
Non-ciliated:
Lines GI tract,
ducts of many
glands,
gallbladder
Ciliated:
Bronchioles,
uterine tubes,
uterus, central
canal of spinal
cord, ventricle
of brain
Secretion
and
absorption
Several layers
of cells,with
varying shapes;
apical cells are
squamous
shaped
Epidermis of
skin, Lining of
mouth,
esophagus,
part of
epiglottis, part
of pharynx,
vagina, and
tongue
Protection
Simple cuboidal
Simple columnar
Moves
mucus
and other
substance
s by ciliary
action
Stratified squamous
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ANAT41 – Lecture Notes
Stratified cuboidal
Typical two or
layers of cubed
shaped cells;
can be more
than 2
Ducts of sweat
glands,
esophageal
glands, and
parts of male
urethra
Protection
, and
some
secretion
and
absorption
Several layers
of cells, only the
apical looks
columnar
shaped
Parts of
urethra,
excretory
ducts of some
glands, anal
mucous
membrane,
part of the
conjunctiva of
the eye
Protection
and
secretion
Only 1 cell layer
thick, but has
the appearance
of multi-layers
because the
nuclei of the
cells lie at
different levels
Ciliated: Lines
airways of the
respiratory
tract
Non-ciliated:
large glands,
epididymis,
parts of male
urethra
Secretion
and
movement
of mucus
by cilia
Lines urinary
bladder, parts
of ureters, and
urethra
Allows for
distention
or
stretching
Stratified columnar
Ciliated Pseudostratified columnar
Transitional
Has several
layers, but there
is transitional
shapes of cells
from cuboidal to
squamous;
apical layer has
dome shaped
cells that may
be binucleated
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ANAT41 – Lecture Notes
Glands = function in secretion; one or more specialized cell types that release their contents
into ducts, onto a surface or directly into the blood.
Classified as either exocrine or endocrine.
a. exocrine =Secrete their products into ducts and onto body surfaces or
cavities
Examples:
b. endocrine = Secrete their products directly into the blood
Examples:
2. Connective Tissue (CT)
General characteristics:

Ground substance

Protein fibers (3 types)
Collagen
Elastic
Reticular

Specialized cells
Ground substance + protein fibers = extracellular matrix
Types of Cells found in connective tissue:
1. Fibroblasts
2. Macrophages
3. Plasma cells
4. Mast cells
5. Adipocytes
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ANAT41 – Lecture Notes
Types of Loose
Connective Tissue
Areolar
Adipose
Reticular
Types of Dense
Connective Tissue
Dense regular
Characteristics
Location
Contains all 3 types
of fibers, several
kinds of cells; most
predominant type
of connective
tissue proper in the
body
Subcutaneous
layer of skin,
papillary layer of
dermis, lamina
propria of
mucous
membranes,
around blood
vessels, nerves,
body organs
Subcutaneous
Adipocytes that
layer of the skin,
store lipids; the
around heart and
cytoplasm and
kidneys, yellow
nucleus are pushed bone marrow,
to the periphery by padding around
lipid droplet
joints and
sockets of the
eye
Network of reticular Liver, spleen,
fibers and cells
lymph nodes, red
bone marrow,
around bloods
vessels and
muscle
Function
Strength,
elasticity and
support
Reduces heat
loss, energy
storage,
supports, and
protects
Characteristics
Location
Forms stroma
of organs,
binds smooth
muscle, filters
and removes
worn out blood
cells
Function
Collagen fibers
densely arranged,
with fibroblasts
between them
Tendons,
ligaments,
aponeuroses
Provides
strong
attachments
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ANAT41 – Lecture Notes
Dense irregular
Elastic
Densely packed,
randomly arranged
collagen fibers
Fasciae,
Reticular layer of
the dermis,
Fibrous
pericardium of
heart,
periosteum of
bone,
perichondrium of
cartilage, joint
capsules,
membrane
around many
organs, heart
valves
Provides
strength
Densely packed
elastic fibers, with
fibroblasts between
them
Lung tissue,
walls of elastic
arteries, trachea,
bronchiole tubes,
true vocal cords,
suspensory
ligaments of the
penis, ligaments
between
vertebrae
Allows
stretching of
various organs
Types of Supportive Connective Characteristics
Tissue
Hyaline Cartilage
Chondrocytes in
lacuna, "glassy"
like matrix that
resembles a
water picture
Location
Function
Ends of long
bones,
anterior ends
of ribs, parts
of larynx,
trachea,
bronchi,
bronchiole
tubes,
embryonic
Smooth
surface for
articulating
structures,
support, and
flexibility
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ANAT41 – Lecture Notes
tissue, and
fetal skeleton
Elastic Cartilage
Chondrocytes in
a lacuna, with
elastic fibers in
the background,
appears "dirty"
Fibrocartilage
Bone
Chondrocytes in
the lacuna that
are arranged in
rows, wave like
collagen in the
matrix
System of
osteons, with
features that
include lamellae,
lacunae,
osteocytes,
canaliculi and
haversian canal
Types of Fluid Connective Characteristics
Tissue
Blood
Consists of
plasma, red blood
cells, white blood
cells and platelets
Epiglottis, Ear,
Auditory or
Eustachian
tube
Support and
maintain
shape
Pubic
symphysis,
Intervertebral
discs, menisci
of the knee
Support and
fusion
Compact and
spongy bones
of the skeletal
system
Support,
protection,
storage,
houses
blood
forming
tissues, aids
in movement
Location
Function
Within bloods
vessels, and
chambers of
the heart
Transports,
phagocytosis,
involved in
allergic
reactions,
immune
response and
blood clotting
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ANAT41 – Lecture Notes
3.
Muscle Tissue
General functions:
Produces body movements
Generates heat
Maintains posture
There are 3 different types of muscle tissue:
1. Skeletal (voluntary or striated) muscle: parallel fibers, multi-nucleated, striated
Location:
2. Smooth (visceral) muscle: spindle shaped cells, with a centrally located nucleus;
involuntary
Location:
3. Cardiac muscle: Branched cells, with centrally located nuclei, striated; involuntary
Location:
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ANAT41 – Lecture Notes
4. Nervous Tissue
A. Neuron or nerve cells = send and receive messages
What is the basic structure?
Location: brain, spinal cord, nerves
B. Neuroglia = support and nourish nervous tissue
Location: brain, spinal cord only
Membranes - combination of epithelial and connective tissue
Definition: a sheet of tissue which lines a body cavity or covers a body surface
Types of membranes:
Epithelial membranes
1. Mucous membranes - lines body cavities that open to the exterior
2. Serous membranes - has two parts: parietal and visceral layers
 line body cavities and covers the organ that lie within the cavities
3. Synovial membrane - lines cavities of the joints
3. Cutaneous membrane (skin) - We'll talk about this one in more detail In the next
chapter.
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