Tissues
 A tissue is a group of similar cells that usually have a
common embryonic origin & functions together to carry
out specialized activities.
Connective
Tissue
Epithelial
Tissue
Muscle
Tissue
Nervous
Tissue
Tissue
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Epithelial Tissue:
 Covers body surfaces; lines hollow
organs,body cavities,and ducts;and forms
glands.
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Connective Tissue
Protects & supports body
and its organs, binds organs
together, stores energy
reserves as fats and provides
immunity.
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Muscle Tissue
Responsible for movement and
generation of force.
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Nervous Tissue
Initiates and transmits action
potentials (Nerve impulses)
that help coordinate body
activities.
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Epithelial Tissue
 Cells are very closely packed & intracellular substance
called matrix is minimal.
 Cells lie on a basement membrane.
Epithelial
Tissue
Simple
Stratified
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Single layer
of cells
Several
layer of cells
Simple Epithelium
 Found on absorptive or secretory surfaces where single
layer enhances this process.
 Types named on the shape of cells & more active the
Squamous
tissue, the taller are the cells.
Cuboidal
Columnar
Ciliated
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Squamous (Pavement) Epithelium
 Single layer of flattened cells which fit closely like flat stones,
forming a thin & smooth membrane.
 Diffusion takes place freely through this thin, smooth, inactive lining
of following structures:- heart, blood vessels, lymph vessels, alveoli
of the lungs.
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Cuboidal Epithelium
 Cube shaped cells.
 Forms the tubules of kidneys & some glands.
 Involved in secretion, absorption & excretion.
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Columnar Epithelium
 Rectangular in shape.
 Lining the organs of alimentary tract.
 Some absorb the products of digestion & some secrete mucus.
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Ciliated Epithelium
 Columnar cells with hair like processes called cilia.
 Cilia consists of microtubules.
 Wave like movement of many cilia propels the contents of the tubes,
which they line in one direction only.
 Found lining the utrine tubes & respiratory passages.
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Stratified Epithelia
 Several layers of cells of various shapes.
 Basement membranes absent.
 Protects underlying structure from wear & tear.
Stratified
Squamous
epithelium
Keratinised
NonKeratinised
Transitional
epithelium
Stratified
Epithelium
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Relaxed
&
Stretched
Stratified Epithelium:
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Stratified Squamous Epithelium
 Number of layers of cells
 Deepest cells are columnar & as they grow towards the
surface they become flattened & are then shed.
 Non keratinised stratified epithelium (Wet surfaces) they
are found in the conjunctiva of the eyes, lining of the
mouth, pharynx, vagina, oesophagus.
 Keratinised stratified epithelium (Dry surfaces) they are
found in the skin, hair & nails, surface layer consists of
dead epithelial cells to which the protein keratin has
been added, this forms a tough, relatively water proof
protective layer that prevents drying of the underlying
live cells.
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Transitional Epithelium:
 Composed of several layers of pear-shaped
cells.
 Found: Lining urinary bladder.
 It allows for stretching as bladder fills.
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Glandular Epithelium:
 Function: Secretion,accomplished by
glandular cells that often lie in clusters deep
to the covering and lining epithelium.
 Gland may consists of one cell or a group of
highly specialized epithelial cells that secrete
into ducts,onto a surface or into the blood.
 Production of such substances always require
active work by the cells and results in an
expenditure of energy.
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Types of Glands:
GLANDS
EXOCRINE
ENDOCRINE
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Exocrine Glands:
 Secrete their products into ducts(tubes) that
empty at the surface of covering and lining
epithelium or onto a free surface.
 Product may be released at the skin surface
or into lumen of hollow organs.
 Secretions: Mucous,perspiration,oil,wax and
digestive enzymes.
 Ex: Sweat glands and Salivary glands.
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Endocrine Glands:
 Are ductless.
 Secretory products enter the ECF and diffuse
into blood.
 Secretions always HORMONES,chemicals
that regulate various physiological activities.
 Ex: Pituitary,Thyroid snd Adrenal Glands.
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Connective Tissue
Cells forming are more
widely separated from each
other & intracellular
substance (Matrix) is present
in considerably larger
amounts.
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Cells of connective tissues
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Fibroblasts
 Large flat cells which produce collagen and
elastic fibers and a matrix of extracellular
material.
 Particularly active in tissue repair (wound
healing).
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Fat Cells
 Known as adipocytes these cells occur singly
or in groups.
 Vary in size and shape according to the
amount of fat they contain.
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Macrophages
 Irregular shaped cells with granules in the
cytoplasm.
 Important part of the body’s defence
mechanism as they are actively
phagocytic,engulfing and digesting cell
debris,bacteria and other foreign bodies.
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Leukocytes
 WBC’s found in small numbers in healthy
connective tissue but migrate in significant
number during infection when they play an
important role in tissue defense.
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Mast cells
 Found in liver, spleen and around blood
vessels.
 Produce granules containing heparin,
histamine etc. which are released when cells
are damaged by diseases or injury.
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Loose Connective Tissue
 Found in every part of the
body providing elasticity
and tensile strength.
 Connects and supports
other tissues.
 Example: Under the skin
Between muscles,
Supporting blood vessels
and nerve cells, Alimentary
canal, Glands supporting
secretory cells.
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Adipose Tissue
Consists of fat cells
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White Adipose Tissue
20 to 25% of body weight in adults.
It is found supporting kidneys & the
eyes, between muscle fibres & under
the skin where it acts as a thermal
insulator
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Brown Adipose Tissue
Found in newborn
When brown tissue is metabolized
produces less energy and
considerably more heat than other
fat , contributing to maintenance of
body temperature.
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Dense Connective Tissue
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Fibrous tissue
 Found forming ligaments,
which binds bones
together.
 As an outer protective
covering for bone called
periostium.
 Outer protective covering
of some organs eg.
kidneys,brain,lymph node.
 Forming muscle sheaths
called muscle facia which
extends beyond the muscle
to become the tendon that
attaches muscle to bone.
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Elastic Tissue
 Considerable extension
& recoil.
 Few cells & the matrix
consists mainly of
masses of elastic fibres
secreted by fibroblasts.
 Found in organs where
alteration of shape is
required eg. Large
blood vessels, epiglotis
& outer ears.
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Blood
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Blood
 Fluid connective tissue.
 Consists of plasma & formed elements which
include erythrocytes, leukocytes &
thrombocytes.
 Found within blood vessels (atreries, arterioles,
capillaries, venules & veins.)
 Transport oxygen & carbon dioxide; leukocytes
carry on phagocytosis & are involved in allergic
reactions & immunity, thrombocytes are
essential for the clotting of blood.
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Lymphoid Tissue
 Found in blood & in
the lymphoid tissue in
the lymph nodes,
spleen, palatine &
pharyngeal tonsils,
vermiform appendix
and wall of large
intestine.
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Cartilage
Firmer than any other connective
tissue.
Cells are chondrocytes and are less
numerous & are reinforced by
collagen& elastic fibres.
Hyaline Cartilage
Types
Fibro Cartilage
Elastic Cartilage
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Hyaline Cartilage
 Appears as a smooth bluish-white tissue.
 Chondrocytes are in small groups within cell
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nests and the matrix solid and smooth.
Found:
On the surfaces of the parts of bones that
form joints.
Forming the costal cartilages,which attach
ribs to sternum.
Forming parts of larynx,trachea and bronchi.
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Fibro Cartilage
 Tough, slightly flexible tissue.
 Found as follows:1) As pads between the bodies
2)
3)
4)
of the vertebrae called the
intervertebral discs.
Between the articulating
surfaces of the bones of the
knee joint called semilunar
cartilages.
On the rim of the bony
sockets of the hip &
shoulder joints deepening
cavities without restricting
movements.
As ligaments joining bones.
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Elastic Cartilage
Forms pinna or lobe of the ear,
the epiglotis and part of the
tunica media of blood vessel
walls.
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Bones
Connective tissue with cells (Osteocytes)
surrounded by a matrix of collagen fibres
that is strengthened by inorganic salts
especially calcium & phosphate.
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Bones
 Compact Bone: Solid or dense appearance
 Compact bone consists of osteons that contain lamellae,
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lacunae, osteocytes, canaliculi & central canals.
Cancellous or spongy bone: Spongy of fine honeycomb
appearance.
Spongy bones consists of thin plates called trabeculae.
Both compact & spongy bones comprise the various
parts of bones of the body.
Support, protection, storage, houses blood forming
tissue and serves as levers that act together with muscle
tissue to provide movement.
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Muscle tissue
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Skeletal Tissue:
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Skeletal Muscle Tissue:
 Description: Cylindrical, striated fibres with
many peripheral nuclei, voluntary control.
 Location: Usually attached bones.
 Function: Motion, posture, heat production.
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Smooth Muscle Tissue:
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Smooth Muscle Tissue:
 Description: Spindle-shaped, nonstriated fibres
with one centrally located nucleus; usually
involuntary control.
 Location: Walls of hollow internal structures such
as blood vessels, airways to the lungs, stomach,
intestines, gall bladder, and urinary bladder.
 Function: Motion (constriction of blood vessels and
airways, propulsion of foods through
gastrointestinal tract; contraction of urinary bladder
and gall bladder).
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Cardiac Muscle Tissue:
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Cardiac Muscle Tissue:
 Description: Branched cylindrical, striated
fibres with one or two centrally located
nuclei, contains intercalated discs , mainly
involuntary control.
 Location: Heart Wall.
 Function: Pumps blood to all parts of the
body.
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Nervous Tissue:
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Nervous Tissue:
 Description:
 2 Principal cells neurons and neuroglia.
 Neurons (nerve cells) consists of a cell body and
processes extending from cell body called dendrites
or axons.
 Dendrites are highly branched tapered processes of
the cell body.
 Axons are single, long processes of the cell body
that usually conduct impulses away from the cell
body.
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Neuroglia:
 Neuroglia do not generate or conduct nerve
impulses, but have other important functions;
a) Development of brain by assisting migration of
neurons.
b) Link between neurons and blood vessels.
c) Produce myelin sheath (multilayer lipid and
protein covering); this electrically isolates axon
of neuron and increases speed of nerve impulse
conduction around axons of neurons in CNS
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Neuroglia Functions:
d) Engulf and destroy microbes and cellular
debris in the CNS.
e) Assist in circulation of CSF in the areas of
brain and spinal cord by providing epithelial
lining for ventricles of brain and central canal of
spinal cord.
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Nervous Tissue:
 Location: Nervous System.
 Function: Exhibits sensitivity to various
types of stimuli; converts stimuli into nerve
impulses ,and conducts nerve impulses to
other neurons, muscle fibres , or glands.
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MEMBRANES:
MUCOUS
MEMBRANES
EPITHELIAL
MEMBRANES
CUTANEOUS
MEMBRANE
(SKIN)
SEROUS
MEMBRANE
CONNECTIVE
TISSUE
MEMBRANE
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SYNOVIAL
MEMBRANE
MUCOUS MEMBRANES
 Lines body cavity that opens to the exterior.
 Consists of a lining layer of epithelium and an
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underlying layer of connective tissue.
Lines the entire digestive, respiratory and reproductive
systems and much of urinary system.
Epithelial layer of a mucous membrane=body’s
defense mechanisms.
Certain cells of mucous membranes secrete mucous,
which prevent underlying structures from drying out.
It traps particles in respiratory passageways and
lubricates food as it moves through the GI tract.
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MUCOUS MEMBRANES
 The epithelial layer secretes enzymes needed for
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
digestion and is a site of food absorption in the GI tract.
Connective Tissue layer is called lamina propria.
It binds epithelium to underlying structures and allows
some flexibility of the membrane.
It also holds blood vessels in place and protects
underlying muscles from abrasion and puncture.
Oxygen and nutrients diffuse from lamina propria to
the epithelium covering it,while carbondioxide and
waste diffuse in the opposite direction.
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SEROUS MEMBRANES
 Lines body cavity that does not open directly
into the exterior, it lines organs within the
cavity.
 Consists of thin layers of areolar connective
tissue covered by mesothelium and they are
composed of 2 portions.
 Part attached to cavity wall=Parietal Portion
 Part that covers and attaches to organs
within the cavity=Visceral Portion.
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SEROUS MEMBRANES
 The serous membranes lining different
organs and cavities have different names:
 A) Lining thoracic cavity and covering
lungs=PLEURA.
 B) Lining the heart cavity and covering the
heart=PERICARDIUM.
 C) Lining abdominal cavity and covering
abdominal organs and some pelvic
organs=PERITONIUM.
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SEROUS MEMBRANES
 Epithelial layer of serous membrane secrete
lubricating fluid called serous fluid, that
allows organs to glide easily against one
another or against the walls of the cavity.
 The 2 layers are separated by serous fluid.
 For Example: The heart changes shape during
each beat and friction damage is prevented
by the arrangement of pericardium and its
serous fluid.
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SYNOVIAL MEMBRANES
 Lines cavities of freely movable joints.
 Line structures that do not open to the exterior.
 Composed of areolar connective tissue with elastic
fibers and varying amount of fat.
 Secrete synovial fluid,which lubricates the cartilage at
the ends of bones during their movements and
nourishes cartilage covering bones at joints. Called
articular synovial membranes.
 Other synovial membranes line cushioning sacs,called
bursae,and tendon sheaths in our hands and feet that
ease the movement of muscle tendons.
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