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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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