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TISSUE is a group of similarlyspecialized cells performing acommon function
TISSUES
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FUNDAMENTAL TYPES OF TISSUES
1. EPITHELIAL TISSUE
2. CONNECTIVE TISSUE
3. MUSCULAR TISSUE
4. NERVOUS TISSUE
They are interwoven to form the fabric of thebody.
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EPITHELIAL TISSUE
is the covering/lining (skin, cavities of the GI andrespiratory tracts, lining of BV), and glandular(different glands of the body) tissue of the body
made up of closely arranged cells
forming sheets with one end free (apicalsurface) and other end attached to a
basement membrane
very scanty intercellular substance
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apical surfaces of some epithelia maybe smooth, others may have some
modifications like the presence ofcilia, sterocilia or microvilli
avascular
nourished by diffusion from thecapillaries of underlying connectivetissues
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Functions of Epithelial Tissue
1. Protection
2. Absorption
3. Filtration4. Excretion
5. Secretion
6. Sensory reception
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Types of Epithelial Tissue
A. Covering and Lining Epithelium- forms the outer covering of the skin
- forms the inner lining of blood vessels, ducts, bodycavities and interior of respiratory, digestive, urinary
and reproductive systems
- classified according to
1. number ofcell layers
2. shape of the cell on free surfaceB. Glandular Epithelium
- constitutes the secreting portion of glands
ex. sweat glands
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gastric glands
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Types OfEpithelium
COVERING AND LINING EPITHELIUM
I. SIMPLE EPITHELIUM
A. SIMPLE SQUAMOUS (e.g. ENDOTHELIUM (lines the
heart,blood vessels and lymphatic vessels),
MESOTHELIUM (forms serous membranes of peritoneum,
pleura, and pericardium), Bowmans capsule of
kidney)
B. SIMPLE CUBOIDAL- THYROID,KIDNEY TUBULES
C. SIMPLE COLUMNAR- STOMACH, GALL BLADDER
small and large intestines, uterine cervix
PSEUDOSTRATIFIED CILIATED COLUMNAR
respiratory system- trachea, bronchi, larynx,
nasopharynx
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II. STRATIFIED
A. STRATIFIED SQUAMOUS- found in areas that are often
subjected to abuse or friction
KERATINIZED (lines the skin) AND NONKERATINIZED(lines the mouth, esophagus, vagina)
B. STRATIFIED CUBOIDAL and
C. STRATIFIED COLUMNAR- rare types and are found only inthe ducts of large glands
D.TRANSITIONAL- cells change in shape depending onwhether the organ is distended or contracted; cells on thesurface tend to be umbrella-shaped or dome-like when the
organ is not stretched and become large squamous whenthe organ is stretched
- lines the bladder, ureter, and renal pelvis
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Simple Cuboidal Epithelium
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Simple Columnar Epithelium
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PseudostratifiedColumnar Epithelium
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Stratified SquamousEpithelium
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Stratified squamous epithelium
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Transitional Epithelium
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Glandular Epithelia
Gland is one or more cells specialized to
manufacture and secrete particular products likehormones, mucus, perspiration, oil, earwax, milk,saliva, and digestive enzymes
Classification1. Based on route of secretion and type of product
A. Exocrine
B. Endocrine
2. Based on structure
A. Unicellular
B. Multicellular
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Classification of Multicellular Glands
1. According to duct structure
A. Simple single unbranched duct
B. Compound branched duct
2. According to structure of secretory parts
A. TubularB. Alveolar
C. Tubuloalveolar
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3. According to function
1. Merocrine
- releases its product with no part of the gland lostor damaged
ex. certain sweat glands
2. holocrine
- accompanied by cell deathex. sebaceous glands
3. Apocrine
- involves loss of some protoplasm only
ex. mammary gland
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CONNECTIVE TISSUE
most abundant
found common to all connective tissues are cells, matrix orgound substance, and intercellular fibers
If the functions are mechanical, the extracellular fibers andground substance are the major features e.g. ligaments,tendons, cartilage, and bone
If the specialized functions are protective or maintenance of
energy reserves, the cells are the major features
made up of few cells separated by great amount ofintercellular substance
most are very vascular, however, tendons and ligamentshave poor blood supply while cartilages are avascular
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Functions of Connective Tissue
1. Enclosing and separating
2. Connecting tissues together
3. Supporting and moving4. Storing
5. Cushioning and insulating
6. Transporting7. Protecting
M i T f C ti Ti
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Main Types of Connective Tissues
A. Embryonic Connective Tissues
1. Mesenchymal Connective Tissue
2. Mucous Connective Tissue
B. Connective Tissue Proper
1. Loose/ Areolar Connective Tissue
2. Adipose Connective Tissue
3. Reticular Connective Tissue
4. Dense Connective Tissuea. Dense Regular Elastic Connective Tissue
b. Dense Regular Collagenous Connective Tissue
c. Dense Irregular Connective Tissue
5. Lymphoid/ Adenoid Connective Tissue
a. Loose/ Difuseb. Dense/ Compact
C. Specialized Connective Tissues
1. Cartilage
2. Bone/Osseous Tissue
3. Blood/Vascular Tissue
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LOOSE CONNECTIVE TISSUE
1. AREOLAR CT
- most abundant
- functions as a universal packing material and
acts as a connective tissue glue that binds
organs together and keep them in their properposition
- contains several kinds of cells and all 3 types of
connective tissue fibers- contains innumerable spaces called areola that
provide reservoir of water and salts for the
surrounding tissues
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2. Reticular CT
- predominantly composed of reticular fibers which are
synthesized by reticular cells
- forms the stroma in lymphoid organs like the spleenand lymph nodes
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3. Adipose CT
- forms the hypodermis or subcutaneous tissue beneath the skin
where it serves as an insulator, protecting the body from extremeheat and cold
- contains large fat cells that are closely packed into fat lobulesseparated by trabeculae
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DENSE CONNECTIVE TISSUES
1. Dense Regular CT
- made up of an extracellular matrix that is packed with
collagenous fibers that are compactly arranged in an
organized manner
- forms a strong, rope-like structures that resist tensile forces
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2. Dense Irregular CT- consists of densely packed collagenous fibers that are
arranged in a disorderly manner- found in body areas where pulling forces are exerted in
different directions like the dermis of the skin
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CARTILAGE
Features:1. dense, firm, but pliable
2. with cells (chondrocytes), fibers (collagenous,and elastic),
and ground substance (chondromucoprotein);
* Collagenous fibers are responsible for its tensile strength
* Chondrocytes are lodged in cavities called lacunae;
cartilage capsule encloses each cell and forms its outer wall.
3. some enveloped by a fibrous tissue sheath called
perichondrium
4. avascular
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1. Hyaline Cartilage
- Is the predominant cartilage in the body- Is the precursor of most bones
- Has a glassy and homogenous appearnce
- Predominating fibers are collagenous fibers
which are not visible in stained preparationsbecause the fibers and the matrix have the samerefractive index
- Chondrocytes may appear singly or in isogenous
groups of cells called cell nests- surrounded by a perichondrium
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2. Elastic Cartilage
- Is composed of a thread-like network support of elasticfibers embedded within the matrix
- Is surrounded by a perichondrium
- Provides strength and elasticity and maintains the shape ofstructures
- Is found in areas where elasticity is desired like the externalear, auditory tubes, epiglottis
3. Fibrocartilage
- Is the only cartilage without a perichondrium
- The collagenous bundles are densely packed and arrangedin a herring bone pattern; chondrocytes are aligned in rows
between the bundles of collagenous fibers- Is the strongest type of cartilage hence,provides strength
and rigidity
- Found in the pubic symphysis and forms a cushion-like diskin between the vertebrae
-
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Hyaline Cartilage
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Elastic Cartilage
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Fibrocartilage
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BONE OR OSSEOUS TISSUE
Functions:
1. supports soft tissues2. provides attachment for muscles and tendons
3. protects vital organs
4. hematopoiesis
5. stores minerals
-is the hardest; matrix is calcified its spaces have beenimpregnated with calcium salts
-is composed of living organic components that account for itstenacity, elasticity, resilience and non- living inorganiccomponents for its hardness and rigidity
t f b ti
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types of bone tissue
1. spongy/ cancellous-contains large spaces
and in which the
extracellular matrix is
arranged as little
beams called
trabeculae
2. Compact-appears as a solid
continuous mass
structural units are
called HaversianSystems orosteons
diaphysis
epiphysis
(compact bonetissue)
(spongy bonetissue)
All bones are covered with a modified
fibrous CT called periosteum.
Endosteum lines the bone marrow cavity.
bone marrow cavity
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Osteon or Haversian System
(basic unit of compact bone)
1. concentric lamellae
- concentric rings of matrix
*types of lamellae
periosteal lamellae- at the periphery of bone
endosteal lamellae- in the innermost aspect of bone
interstitial lamellae- fill the spaces between theHaversian systems
concentric lamellae- within the Haversian system
2. lacunae
- small spaces between lamellae that contain themature bone
cells
3. canaliculi
- network of minute canals that extend from the Hcanal to the lacunae and from one lacuna toanother
- for the exchange of metabolic wastes
c/s of a compact bone
4 central (Haversian) canal
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4. central (Haversian) canal
- run parallel to the bone axis, and communicate with the external surface of
the bone and with the bone marrow cavity thru the laterally or obliquely
directed connecting Volkmanns canals
The different canals provide channels for the blood vessels
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osteocyte in lacunacentral canal
of osteon
canaliculi
The different canals provide channels for the blood vessels,
lymphatics, and nerves distributed throughout the bones.
c/s of a Haversian system
Blood or Vascular
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Blood or VascularTissue
- composed ofa. matrix
*plasma is the liquid matrixwhich bathes the cells; serum(liquid portion of clotted
blood)b. blood cells which include
wbc, rbc, and platelets
*rbc contains hgb, an ironcontaining gas-transport protein;wbc are involved inphagocytosis, immunity, andallergic reactions; platelets arefragments of giant cells called
megakaryocytes and participatein the blood clotting mechanismc. intercellular fibers whichcome in the form of solubleproteins called fibrinogenbecome evident only as fibers
when the blood has clotted
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NEUTROPHILS- most numerous- active phagocytes; numberincreases rapidly during short-termor acute infections
- pink, lilac fine cytoplasmic granules
- polymorphonuclear wbc(multilobulated, 3 to 5 lobesconnected by thin strands ofnucleoplasm)
LYMPHOCYTES- smallest
- spherical or slightly indented
nucleus
- cytoplasm appears as thin rimaround large nucleus
- part of immune system
*B lymphocytes produce antibodies;
T lymphocytes are involved in graft
rejection, fighting tumors and viruses
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. Eosinophils
-red coarse cytoplasmic granules
-fig 8 or bilobed nucleus
-increase in number during allergy
attacks, and parasitic infection
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Monocytes- largest- nucleus often kidney-shaped
- active phagocytes thatbecome macrophages in thetissues
-increase in number duringchronic infections such astuberculosis
Basophilsthe least numerous wbc
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- the least numerous wbc
- cytoplasm has a few largeblue- purple granules* granules contain histamine
(vasodilator chemical), w/c isdischarged at sites ofinflammation
- U- or S-shaped nucleus withconstrictions
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MUSCLE TISSUE
- highly cellular, well-vascularized tissue specialized to
contract and cause movement
- has the properties of extensibility, elasticity, andcontractility
- the units of histological organization are cells that havebecome elongated and are properly termed as fibers
- the 3 types of muscle tissue are skeletal, cardiac, andsmooth
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rapid, forceful, not sustained rhythmic & automatic slow & sustained
*
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* Skeletal Muscle 1000Xstriations across
muscle fiber
nucleus
long parallel fibers
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NERVOUS TISSUE
- Is found in the brain, spinal cord, and nerves
- functions to generate and conduct nerve impulses
as well as coordinate and control body activities
- 2 important properties
1. Irritability- ability to react to various stimuli
2. Conductivity- ability to transmit impulses
2 elements of nervous
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- 2 elements of nervoustissue
1. Neurons
- structural andfunctional units ofnervous tissue
- impulse-conductingcells
2. Neuroglia/ glial cells
- specialized cells of theNS that insulate,support, and protect thedelicate neurons
neuroglial cells
neuron
Types of Neurons
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A. As to Structure
1. Multipolar neuron
- with one axon and many
dendrites; most common
e.g. neurons in the CNS
2. Bipolar neuron
- with an axon and a dendrite
e.g. sensory neurons in eyes,
nose, and ears
3.Unipolar neurons
- with a single nerve fiber that
divides into 2 branches
e.g. most sensory neurons in the
ganglia outside the brain or
spinal cord
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unipolar bipola multipolar
B. As to Function
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1. sensory/afferent
- receive sensory stimuli from the environment and from within the body
Receptors- consist of naked nerve endings, capsulated receptors(Meissners and vater
Pacinian corpuscle, etc), and sense organs for the reception of nerve impulse2. motor / efferent
- control the effectors such as muscles or glands
3. association/ internuncial/ interneuron
- found in the CNS and connect between other neurons; integrate information and
responses of the CNS
NEURON
structural & functional unit of
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- structural & functional unit of
Nervous System
- composed of cell body and one or
more processes
Synapse- site of functional contact
between 2 excitable neurons
Cell Body/ soma/ perikaryon
- contains the nucleus; the
metabolic center
- neuroplasm has neurofibrils
(bundles of intermediate filaments
that provide the shape cell and
support)
and Nissls bodies (prominent
clusters of rER that produce proteins
used for growth of neurons and for
regeneration of damaged axons in the
PNS)
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Axon/ axis cylinder
- longer process that joins the
cell body at a cone-shapedelevation called the axon hillock
- occasionally gives off a
collateral branch but all axons end
up in terminal arborization
- conveys impulses away from
the cell body
Dendrites
- short branched processes
- convey impulses towards the
cell body
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2 Kinds of Nerve Fibers
1. Myelinated/medullated
- possess myelinsheath;
found in the white matterof the spinal cord
2.unmyelinated
/nonmedullated
- nerve fibers lacking thesheath ; found in the gray
matter
Nerve Fiber
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- specifies an axon plus the associated connective tissue and bloodvessels
- may acquire one or 2 coverings or ensheathments
1. myelin sheath- a multilayered lipid and protein covering that
electrically insulates the axon of a neuron and increases the speed
of nerve impulse conduction;
Oligodendrocytes myelinate axons in the CNS; Schwann cells
myelinate axons in the PNS
2. neurolemma (sheath of Schwann)- the outer nucleated
cytoplasmic layer of the Schwann cell, which encloses the myelin
sheath; found only around axons in the PNS
Structure of a Myelinated Nerve Fiber
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Structure of a Myelinated Nerve Fiber
consists of the axis cylinder which is enclosed by the myelin
sheath
gaps that segment the myelin sheath at regular intervals
are called neurofibril nodes (formerly,nodes of Ranvier )
the axon segments between 2 nodes are called internodal
segments or Schwanns segments
each segment is obliquely partitioned by narrow clefts
called incisures of Schmidt- Lantermann
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PERIPHERAL NERVE
In peripheral nervous system , nerve fibers are grouped inbundles to form the nerve
A single nerve fiber has a thin connective tissue septa called
endoneurium
Several nerve fibers forming a nerve bundle or fasciculus is
enclosed by a compact layer of connective tissue called
perineurium
Several nerve bundles are held together by loosely arranged
tissues called epineurium
epineurium
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perineuriumfascicle
Peripheral Nerve (cross section) 100X
endoneurium
Clusters of neuron cell bodies and collections of nerve fibers are named
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differently.
Nucleus- cluster of cell bodies of neurons within the Central Nervous System ;
serves as control center for a bundle of neurons
Ganglion- cluster of cell bodies of neurons within the Peripheral Nervous
System; serves as control center for a bundle of neurons; sites for possible
synapses of neurons between organs and spinal cord
Tract- bundle of nerve fibers within the CNS; interconnects structures of CNS;
conveys impulses
Nerve- bundle of nerve fibers within the PNS; conveys impulses
Nerve plexus- network of nerves within the PNS; provides overlapping
innervation (nerve supply) to certain body regions
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