Anatomy
Tissues- Four Basic Types
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Epithelial Tissue
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Connective Tissue
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Muscular Tissue
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Nervous Tissue
Epithelium
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Characteristics
Epithelial tissue- covers surfaces with an
uninterrupted layer of cells.
Epithelial cells- are attached to one another.
Intercellular spaces in epithelium are small.
Epithelial cells- are separated from the
underlying tissue by a basement membrane.
Epithelium- is named according to the number of
cell layers and the shape of the cells.
Epithelium
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Cell Layers (stratification)
Simple: There is a single layer of cells.
Stratified: More than one layer of cells. The superficial layer is used to
classify the layer. Only one layer touches the basement membrane.
Stratified cells can usually withstand large amounts of stress.
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Pseudostratified Columnar: There is only a single layer of cells, but
the position of the nuclei gives the impression that it is stratified. All cells are
in contact with the basement membrane, but all do not reach the free
surface.
Epithelium
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Cell Shapes
Squamous- Flat
cells (like pancakes)
Cuboidal- Cells that
are about as wide
as they are tall (cubelike)
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Columnar- Cells
that are tall (columns)
Epithelium
Simple Squamous
Model (surface view)
Epithelium
Simple Squamous
(surface view)
Location
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lungs (alveoli)
capillary endothelium
(inner lining)
lining of pleural cavity,
the pericardium, and the
peritoneum
Bowman's capsule
(Kidney)
Epithelium
Epithelium
Stratified Squamous
Location
 From lining of the
esophagus
Epithelium
Stratified Squamous
(Thin Skin)
Location
The stratified squamous
epithelium of thin skin has thin layers
of keratin on the upper surface. Note
that the epithelium rests on dense
irregular connective tissue below (light
pink).
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Epithelium
Simple Cuboidal
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follicle of thyroid
gland
collecting ducts of
kidney
salivary glands
pancreas
Epithelium
Stratified Cuboidal
Location
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ducts of sweat
glands
Epithelium
Simple Columnar
Location
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gall bladder
surface epithelium of
stomach
Uterine glands
small intestine
Epithelium
Stratified Columnar
Location
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1.
2.
3.
large excretory duct of
salivary glands
parotid
submandibular
sublingual
Epithelium
Pseudostratified
Location
Our large airways are
lined by ciliated Pseudostratified epithelium.

The cilia beat towards
the throat. They propel a
thin layer of mucus, so that
you can cough it up when
you "clear your throat.“
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Epithelium
Transitional
(Changes from an
empty relaxed urinary
bladder to a stretched
full bladder)
Empty Bladder
(relaxed)
Location

urinary bladder
Full Bladder
(distended)
Connective Tissue
 Connective tissue consists of cells separated by varying amounts of extracellular
substance.
 In connective tissues cells typically account for only a small fraction of the tissue volume
unlike epithelial tissue.
 The extracellular substance consists of fibers which are embedded in ground substance
containing tissue fluid.
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Fibers in connective tissue can be divided into three types: collagen fibers, elastic
fibers and reticular fibers.
Collagen fibers are the most abundant protein fibers in the body.
Elastic fibers are made of elastin and are "stretchable.“
Reticular fibers are very fine collagen fibers that join connective tissues to other
tissues.
The principle roles of connective tissue are to bind or strengthen organs or other tissues.
It also functions inside the body to divide and compartmentalize other tissue structures.
Connective Tissue Types
 Areolar (loose connective tissue) holds organs and epithelia in place.
 Adipose tissue contains adipocytes, used for cushioning, thermal insulation, lubrication
(primarily in the pericardium) and energy storage. [fat]
 Dense connective tissue (or, less commonly, fibrous connective tissue) forms ligaments
and tendons Its densely packed collagen fibers have great tensile strength.
 Reticular connective tissue is a network of reticular fibers (fine collagen, type III) that
form a soft skeleton to support the lymphoid organs (lymph nodes, bone marrow, and
spleen.)
 Blood functions in transport. Its extracellular matrix is blood plasma, which transports
dissolved nutrients, hormones, and carbon dioxide in the form of bicarbonate. The main
cellular component is red blood cells.
 Bone makes up virtually the entire skeleton.
 Cartilage is found primarily in joints, where it provides cushioning. The extracellular
matrix of cartilage is composed primarily of collagen.
Loose Connective Tissue
 As the name implies, loose
connective tissue consists of a
loosely woven mix of fibers, cells,
and ground substance.
 Areolar, a more technical name
used for this tissue type means
"spaces".
 Loose connective tissue therefore
possesses randomly arranged
protein fibers with abundant
intercellular spaces.
 Scattered within the spaces are 7 cell
types.
Loose Connective Tissue
 Macrophages arise from precursor cells called monocytes.
 They are actively mobile and leave the blood stream to enter connective tissues, where
they differentiate into macrophages.
 Macrophages change their appearance depending on the demand for phagocytotic
activity.
 Mast cells are - like macrophages, lymphocytes and eosinophils - in demand when
something goes wrong in the connective tissue.
 Mast cells facilitate an immune response to antigens which triggered the release of
histamine and heparin.
 Lymphocytes play an important and integral role in the body's defenses.
 Fibrocytes are the most common cell type in connective tissues.
 Fibroblasts contain large amounts of the organelles which are necessary for the synthesis
and excretion of proteins needed to repair the tissue damage.
Loose Connective Tissue
 The loose CT in the
duodenum is a "space filler"
that provides the flexibility
the GI tract needs.
 Many of the nuclei present
are probably fibroblasts, but
other cell types common in
loose CT include plasma
cells, mast cells, and
lymphocytes.
Loose Connective Tissue
 Two types of adipose cells are found in
fat tissues, white and brown adipocytes.
 These adipose cell types vary in their
ability to mobilize energy from stored
fat.
 Brown fat cells are smaller and more
efficient at converting fat into available
energy.
 Brown fat is more typical in infants,
being replaced gradually by white fat as
we age.
 In both cell types fat droplets enlarge to
push nuclei and cytoplasm to the
periphery.
Loose Connective Tissue
 Although present as the supportive
tissue of lymph nodes, glands, organs,
and bone marrow, reticular connective
tissue is not that obvious.
 Small, branching, collagen fibers that
form the reticular connective tissue are
usually hidden from view by the
numerous lymphatic, epithelial, or bone
marrow cells anchored to them.
 The stroma, or supporting network of
reticular fibers is best seen with special
stains.
Loose Connective Tissue
 Loose connective tissues of membranes are important sites of
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inflammation due to mast cells.
Mast cells release histamine, heparin(an anticoagulant), and other
vasoactive agents.
Vascular effects of histamine are important initiators of
inflammation.
These include vasodilation in vessels and increased permeability in
capillaries.
The visible signs of inflammation are explained by keeping
histamine's vascular effects in mind.
Loose Connective Tissue
The sign:
Caused by:
1. Redness
vasodilation of blood vessels
2. Edema
fluid loss from more permeable
capillaries
3. Sensitivity to touch
pressures and chemical shifts in
interstitial fluids sensitizing receptors
neurons
4. Elevated temperature
heat carried to site from the body core
by blood
Dense Regular Connective Tissue
Tendon
Ligament
Supportive Connective Tissue- Cartilage
 Cartilage is a flexible but strong supportive connective
tissue.
 Unlike bone and all other connective tissue types,
cartilage is avascular, lacking blood vessels.
 Three varieties of cartilage: hyaline; elastic; and
fibrocartilage
Supportive Connective Tissue
Three Types of
Cartilage
Location and Function
Hyaline
The most abundant type, found as supportive tissues in the
nose, ears, trachea, larynx, and smaller respiratory
tubes. Found covering the articular surfaces of bones in
synovial joints. Forms the costal cartilages where ribs attach
to the sternum and is the precursor to bone in most of the
embryonic skeleton.
Elastic
Has dark-staining elastic fibers embedded in ground
substance. These fibers are clearly visible and this trait is the
single, best way to differentiate elastic cartilage from hyaline.
Found in the eusatachian tubes, epiglottis, and ear lobes
where needs dictate supportive tissues possess elasticity.
Fibrocartilage
Type of cartilage that contains fine collagen fibers arranged in
layered arrays. Spongey structure makes a good shockabsorbing material in the pubic symphysis and intervertebral
disks.
Supportive Connective Tissue- Cartilage
Hyaline
Elastic
Fibrocartilage
Supportive Connective Tissue- Bone
 Bone is the major structural and supportive connective tissue of the
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body.
The matrix of bone contains abundant collagen fibers and these impart
strength, some flex, and resistance to twisting or torsional forces.
Surrounding these "reinforcing rods" of collagen is a cement-like
ground substance called hydroxyapatite.
This mineral complex of calcium phosphate salts makes bone highly
resistant to compression forces.
Together, collagen fibers and hydroxyapatite make bone one of the
strongest and lightest materials known.
Supportive Connective Tissue- Bone
Bone Tissue Functions
 support - for muscles, organs, and soft tissues
 leverage and movement - the synovial joints
 protection - for critical organs
 calcium phosphate storage - mineral balance
 hematopoiesis - formation of blood cells
Supportive Connective Tissue- Cancellous Bone
 During bone formation, the first
bone to form is always cancellous.
Cancellous (Spongy) Bone
 Have no Haversian Systems or
Osteons
 Open spaces between trabeculae of
cancellous bone are typically
occupied by red bone marrow.
 Red Marrow is the source for all
"formed elements" of the blood.
 Found at the end of long bones
and in the middle of flat bones
trabeculae
Supportive Connective Tissue- Bone
 Compact bone is a highly structured,
dense type of bone found where
maximum strength is required.
 There are many lacunae(the small dark
spots) where mature bone cells or
osteocytes are found.
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Bone forming cells or osteoblasts are
never found in lacunae but rather along
the edges of bone where new lamellae
form. When an osteoblast is completely
surrounded by the forming
hydroxyapatite, it becomes an
osteocyte.
 A third type of bone cell to remember is
the osteoclast, also found along the
edges of bone.
 Osteoclasts are active where bone or
calcified cartilage is being resorbed and
restructured.
Compact Bone
Bone Tissue
Cancellous (Spongy)
Bone
Compact
bone
Cancellous (Spongy)
Bone
Muscle Tissue
Skeletal Muscle Tissue
•
Skeletal muscle is a type of striated
muscle, usually attached to the skeleton.
•
Skeletal muscles are used to create
movement, by applying force to bones
and joints; via contraction.
•
They generally contract voluntarily (via
somatic nerve stimulation), although they
can contract involuntarily through
reflexes.
•
Muscle cells (also called fibers) have an
elongated, cylindrical shape, and are
multinucleated.
Smooth Muscle Tissue
•
•
Smooth muscle is a type of non-striated
muscle, found within the "walls" of hollow
organs and elsewhere like the bladder and
abdominal cavity, the uterus, male and
female reproductive tracts, the
gastrointestinal tract, the respiratory tract,
the vasculature, the skin and the ciliary
muscle and iris of the eye.
Smooth muscle fibers are spindle shaped,
and like all muscle, can contract and relax.
Cardiac Muscle Tissue
•
Cardiac muscle is the muscle that makes
up the wall of the heart.
•
Cardiac muscle is similar to skeletal
muscle in that it is striated and similar to
smooth muscle in that the nuclei are
centrally located and many cells are
required to span the length of the
muscle.
•
It differs from both skeletal muscle and
smooth muscle in that its cells branch
and are joined to one another via
intercalated discs.
Nervous Tissue
•
Neurons (also known as neurones
and nerve cells) are electrically
excitable cells in the nervous system
that process and transmit
information.
•
Neurons are the core components of
the brain, spinal cord and peripheral
nerves.
•
Neurons are typically composed of a
soma, or cell body, a dendritic tree
and an axon.