HMM1414 Chapter 5 Part 1

8/9/2019 HMM1414 Chapter 5 Part 1

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CHAPTER 5

TISSUE ORGANIZATION5.1 ORGANIZATION OF THE ANIMALBODY5.1.1 General Body Architecture Animal body plan tube within a tube

Digestive tract tube running from mouth

to anus.

Tube suspended in coelom internalbody cavity.

Coelom divided into two cavities by

diaphragm:

Thoracic cavity heart andlungs.

Abdominal cavity stomach,intestine, and liver.

Body supported by endoskeleton -jointed bones that grow as body grows:

Skull surrounds brain

Vertebrae,column consisting of separatebones surrounds spinal cord.

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4 levels of organization in

vertebrate body:

Cells tissues organs organsystems5.1.2 Tissues Structure And Function Most animals composed of

specialized cells organized into tissues

with different functions

Tissues make up organs, which

make up organ systems

Tissues = a group of cells similar

in structure and function.

3 fundamental embryonic tissues,

the germ layers:

Endoderm innermost

Mesoderm middle

Ectoderm outermost

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Ectoderm

Mesoderm

Endoderm

Primitive gut


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(ii) Stomach(Figure 40.6, Campbell, page 827)

Organ systems = a group of organs that

function together to carry out major

activities of bodies.

Example: Digestive system

Organ systems (Table 40.1, Campbell, page 827)

5.2 EPITHELIAL TISSUES

5.2.1 Covering Epithelium Occur in sheets of tightly packed cells.

Covers outside of body and lines organs

and cavities within body.

Cells closely joined.

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Digestive

tractLiver Gallbladder Pancreas

DIGESTIVE SYSTEM


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In many epithelia, cells riveted together

by tight junctions.

Functions - barrier protects againstmechanical injury, invasive

microorganisms, and fluid loss.

Cells at base of epithelial layer attached to

basement membrane, a dense mat ofextracellular matrix. Free surface of epithelium exposed to air

or fluid.

Epithelia classified by

(i) Number of cell layers

Simple epithelium - single layer ofcells.

Stratified epithelium - multipletiers of cells.

Pseudostratified epithelium -single-layered but appears stratified

because cells vary in length.

(ii) Shape of cells on free/exposed surface. Cuboidal (like dice) Columnar (like bricks on end) Squamous (flat like floor tiles).

(Figure 40.5, Campbell, page 826)

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Characteristics:1. Epithelium (epithelial membrane)

covers internal and external surfaces of

vertebrate body.

Derived from all three germ layers:

Ectoderm epidermis outer portion

of skin

Endoderm inner surface of digestivetract

Mesoderm inner lining of blood

vessels = endothelium. True epithelium arises from ectoderm

or endoderm

Epitheliums arising from mesodermare not true epithelium.

2. Provides barrier that prevents passage of

some substances while facilitating

passage of others.

Example: Epidermis

Protects from dehydration relatively

impermeable to water.

Protects from airborne pathogens.

Epithelium of digestive tract.

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Allows selective entry of digestive

products.

Barrier to toxins.

Lungs Allows rapid gaseous diffusion.

3. May be modified into glands secretion.

4. Cells tightly bound very littleintercellular spaces. Lower layers of cell rest on

basement membrane compose ofnetwork of collagenous fibers.

Have free surface on other side. Blood vessels cannot pass through

adjacent cells.

Depends on diffusion of nutrient and

O2 from blood vessels in nearby tissues.

This limits thickness of epithelium

one or a few layers thick.

Cells can regenerate.

Cells constantly replaced. Example :

Liver gland formed from epithelium

Can regenerate after portions of it are

surgically removed.

Epidermis renewed every two weeks

Epithelium inside stomach replaced

every two to three days.

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Shape of

cells

Number of layers of cells

SIMPLE STRATIFIED

SQUAMOUS Simple squamous Stratified squamous

CUBAIDAL Simple cuboidal Stratified cuboidal

COLUMNAR Simple columnar Stratified cuboidal

Pseudostratified Transitional

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Squamo u

s

(Flat)

Cuboidal

(Samewidth&

height)

Column a

r

(Tallert h

anw

ide)

Epithelium

Simple(1 cell thick)

Stratified(> 1 cell thick)

Squamous

Cuboida

l

Columnar


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1. Simple epitheliuma) Squamous epithelium

Cells thin and flattened.

Little cytoplasm encloses centrally

placed disc-shaped nucleus.

Margins tessellated (irregular).

Adjacent cells often bound firmly

together by protoplasmic connections. Location and function:

Bowmans capsules, alveolar lining of lungs,

and blood capillary walls enables diffusion

of materials through it.

Blood vessels and heart chambers provides

smooth lining that allows relatively friction-free passage of fluid through them.

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b) Cuboidal epithelium Least specialized epithelia.

Cube shaped.

Pentagonal/hexagonal from surface view.

Central spherical nucleus.

Location: Pancreatic duct, collecting duct

of kidney, and salivary duct, salivary, mucus,

sweat, and thyroid glands

Function: secretion and absorption

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c) Columnar Epithelium Cells tall and quite narrow.

Have more cytoplasm.

Nucleus at basal end.

Mucus-secreting goblet cells areinterspersed amongst the cells.

(Mucous membrane ormucosa = alayer of moist epithelium containing goblet

cells, together with the underlying

connective tissue.)

Epithelium may be secretory and/or

absorptive in function.

Free surface end of cell usually has

microvilli increases surface area forabsorption and secretion.

Location and function:

Stomach lining mucus secreted by

goblet cells protects stomach lining from

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Cuboidal cell

Central spherical

nucleus

Basement

membrane


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acidic contents of stomach and from

digestion by enzymes.

Intestine lining protects from

digestion by enzymes, lubricates passage of

food, and absorption of digested food (small

intestine).

Kidney ducts protection.

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d) Ciliated epithelium Columnar, but with cilia at free surface.

Mucus-secreting goblet cells produce

fluids.

Movement of cilia produces current in

fluid.

Location and function: Oviducts,

ventricles of brains, spinal canal, andrespiratory passages moves materials from

one location to another by ciliary action.

e) Pseudostratified epithelium13


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Cells appear to be at different layers

because not all cells reach free surface.

All cells attached to basement

membrane.

Location:

Linings of urinary tract, trachea, epididymis

pseudostratified columnar.

Linings of respiratory passages pseudostratified columnar ciliated.

Olfactory mucosa

Function: Secretion and movement by

ciliary action

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2. Stratified Epithelium Several layer of cells.

Forms tough impervious layer.

Cells formed by mitotic division of

germinal layer on basement membrane.

First-formed cells cuboid in shape.

As cells are pushed towards free surface,

they become flattened and are calledsquames. Squames eventually flake off and

replaced by new ones from beneath.

Types (depending on shape of uppermost

layer cells):

Stratified squamous outer layerof skin, parts of esophagus, lining of mouth

protection

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Stratified cuboidal sweat glandducts protection

Stratified columnar mammarygland ducts protection and secretion.

Stratified transitional lining ofurinary bladder permits distention

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Transitional epithelium Modified stratified epithelium.

3 4 layers of cells of similar size except

free surface cells, which are more

flattened.

Free surface cells do not flake off.

Cells able to change shape under

differing condition. Example : urinary bladder and ureter.

Cells change shape when wall of bladder

is stretched as it fills up with urine.

Thickness of tissues prevents urine

escaping in surrounding tissues.

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5.2.2 Glandular Epithelium Absorb or secrete chemical solutions.

Glandular epithelia lining lumen ofdigestive and respiratory tracts form a

mucous membrane - secretes a slimysolution called mucus lubricates surfaceand keeps it moist.

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Exocrine gland Epithelial connection between gland &

surface epithelium remains as a tube

(duct). Deepest cells become secretory cells

discharge secretions into duct.

Secretory cells may form spherical sack

or tube, which may show various degree of

branching (to increase area of secretory

surface).

Example: sweat, oil, wax, mammary and

digestive glands, pancreas produces

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mucus, oil, wax, milk, or digestive

enzymes.

Endocrine gland Epithelial connection disappears.

Secretory cells forms close association

with blood capillaries.

Secretion (hormones) passes intobloodstream. Example: pituitary and thyroid glands,

pancreas, ovary, and testes produces

hormones.

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5.3 CONNECTIVE TISSUES Function - bind and support other tissues.

Structure: Have a sparse population ofcells

scattered through an extracellularmatrix.

Matrix consists of a web offibersembedded in a uniform foundation that

may be liquid, jellylike, or solid.

Matrix usually secreted by connective

tissue cells.

Functions:1. Provides supportive framework for body,

for example, skeletal, bone, and cartilage

tissue.

2. Binds other tissues together, example

binds skin with underlying tissues. (Thus,

tissue is strong.)

3. Forms sheath around organs of body,

separating them so that they do not interfere

with each others activities.

4. Embedding and protecting blood vessels

and nerves where they enter or leave organs.

5. Protection against wounding or bacterial

infection areolar tissue.

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6. Insulation of body against heat loss

adipose tissue.

7. Producing blood

Three kinds of connective tissue

fibers: collagenous, elastic, and reticular

fibers all are protein.

(i) Collagenous fibers Made of collagen (most abundant

protein in animal kingdom).

Non-elastic, do not tear easily when

pulled lengthwise.

(ii) Elastic fibers Long threads of elastin. Provides a rubbery quality -

complements non-elastic strength of

collagenous fibers.

(iii) Reticular fibers Very thin and branched.

Composed of collagen and continuous

with collagenous fibers, they form a

tightly woven fabric that joins

connective tissue to adjacent tissues.

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5.3.1 Connective Tissue Proper1. Loose connective tissue

Binds epithelia to underlying tissuesand functions as packing material, holding

organs in place.

Loose connective tissue has all three

fiber types.

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Connective Tissue

Connective

Tissue Proper

Specialized

Connective Tissue

Loose

Connective

Tissue

Dense

Connective

Tissue

Areolar

Adipose

Dense

Regular

Dense

Irregular

B

lood

Ca

rtilag

e

Bone


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Two cell types predominate in the

fibrous mesh of loose connective tissue.

Fibroblasts - secrete the proteiningredients of the extracellular fibers.

Macrophages - amoeboid cells thatroam the maze of fibers, engulfing

bacteria and debris of dead cells by

phagocytosis.

(a) Areolar Tissue Matrix transparent semi-fluidcontaining:

Mucin

Hyaluronic acid Chondroitin sulphate

Fibres: Collagen In wavy bundles.

Scattered throughout matrix. Flexible but inelastic.

Elastin Thin straight fibres.

Forms a loose anastomosing network.

Flexible but elastic

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Both provide considerable tensile

strength and resilience to tissue.

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Cells interspersed in the matrix:

1. Fibroblast Flattened, spindle-shaped, with oval nucleus.

Produce fibres.

Located close to fibres but can migrate

towards wounded tissues secretes fibres to

seal injured area.

2. Macrophage (histiocyte) Polymorphic cell capable of amoeboid

movement engulf bacteria or foreign

particles.

Generally immobile but at times can

wander to areas of bacterial invasion

provides body defense.

3. Mast cell Small, oval shaped, with granular cytoplasm.

Secretes matrix, heparin and histamine. Found close to blood vessels.

Heparin anticoagulant preventsconversion of prothrombin to thrombin.

Histamine released from injured/disrupted

tissues causes vasodilation, contraction of

smooth muscle and stimulates gastric

secretion.

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Rare.

Products of mitotic cell division by migratory

lymphocytes.

Components of body immune system -

produce antibodies.

5. Chromatophore In specialized areas skin and eye.

Branched and densely packed with melanin

granules.

6. Fat cell Contains large lipid droplet.

Cytoplasm and nucleus confined to margins.

7. Mesenchyme cell Reserve of undifferentiated cells.

Can be stimulated to transform into one of

the above cell types when needed.

Location: upper dermis, blood vessels,

nerves, around body organs. Function: Gives strength, elasticity, and

support.

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1. Nucleus of fibroblast

2. Collagen fiber

3. Elastic fiber

(b) Adipose Tissue Specialized form of loose

connective tissue that stores fat in adipose

cells distributed throughout the matrix.

Pads and insulates body and stores fuel

as fat molecules.

Each adipose cell contains a large fat

droplet that swells when fat is stored and

shrinks when the body uses fat as fuel.

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2. Dense/Fibrous ConnectiveTissue

Dense - due to its largenumber of collagenous fibers.

Fibers are organized into parallel bundles,

an arrangement that maximizes

nonelastic strength.

This type of connective tissue forms

tendons, attaching muscles to bones,and ligaments, joining bones to bones at

joints.

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Skeleton of a shark and embryonic

skeletons of many vertebrates are

cartilaginous. Human retain cartilage as flexible

supports in certain locations, such as

nose, ears, and intervertebral disks.

Three types of cartilage:

1. Hyaline cartilage

2. Yellow elastic cartilage

3. White fibrous cartilage

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http://www.botany.uwc.ac.za/sci_ed/grade10/mammal/cart.htm

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Hyaline CartilageMatrix semi-transparent consist ofchondroitin sulphate and finecollagen fibrils.Peripheral chondrocytes are flattenedand arranged in parallel rows.Those situated internally are biggerand scattered.Chondrocyte is contained in lacunae each encloses one, two, four, or eightchondrocytes.No blood vessels exchange ofmaterials between chondrocytes andmatrix is by diffusion.Elastic and compressible tissue.Location: ends of bones (sternum ofribs), nose, air passages ofrespiratory system (larynx andtrachea) and in parts of ear.Function: Provides movement atjoints, flexibility, and support.

Yellow Elastic CartilageSemi-opaque matrix containingnetwork of elastic fibres.Chondrocytes close to one another.

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Very elastic and flexible allowstissue to recover its shape afterdistortion.Location: External ear, eustachiantube, epiglottis, and cartilages ofpharynx.Function: Gives support andmaintains shape.

(iii) White Fibrous Cartilage Matrix contains large numbers of densely

packed collagen fibres.

Very little chondrocytes.

Have great tensile strength and a smalldegree of flexibility.

Location: intervertebral discs (provides

cushioning effect), symphysis pubis (the

region between two pubic bones of the

pelvis), and ligamentous capsules of joins.

Function: Support and fusion.

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2. Bone Skeleton supporting most vertebrates is

made ofbone, a mineralized connectivetissue.

Bone-forming cells called osteoblastsdeposit a matrix of collagen.

Calcium, magnesium, and phosphate ions

combine and harden within the matrix

into the mineral hydroxyapatite. Combination of hard mineral and flexible

collagen makes bone harder than

cartilage without being brittle.

Microscopic structure of hard mammalian

bones consists of repeating units called

osteons. Each osteon has concentric layers

of mineralized matrix deposited around

a central canal containing blood

vessels and nerves that service the

bone.

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Two types of bone: compact and spongy

bone.

(i) Compact bone Consists of units called Harvesiansystem orosteon. Characteristic of the Harvesian system:

Has central Harvesian canal containingnerves, arteries, veins and lymph vessels.

Canal surrounded by numerous

concentric cylinders called Harvesianlamellae.

Interspersed between lamellae are

numerous lacunae containingosteoblasts. When not active, they are called

osteocytes can be activated anddifferentiate into osteoblasts.

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Fine channels called canaliculi radiatefrom each lacuna.

Canaliculi contain cytoplasm and may

link up with Haversian canal, with other

lacunae or pass from one lamella toanother.

Capillaries branch from arteries and veins

in Haversian canal and pass via canaliculi

to the osteoblasts in lacunae facilitate

passage of nutrients, metabolic waste

and respiratory gases towards and awayfrom the cells.

In longitudinal section, Haversian canals

linked to one another by transverse canals

called Volkmann canals.

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Haversian

canal

Vein Artery

Nerve

Haversian

lamellae

Lacuna

Osteocyte

Canaliculi


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Bone covered by a dense connective

tissue called periosteum.(ii) Spongy bone Found in larger bones and is always

surrounded by compact bone.

Consists of sheets of bones called

trabeculae, interspersed with largespaces occupied by bone marrow.

Trabeculae contain osteoblasts.

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3. Blood Functions differently from other

connective tissues Have extensive extracellular matrix.

Plasma liquid matrix consisting ofwater, salts, and a variety of dissolved

proteins.

Liquid matrix enables rapid transport of

blood cells, nutrients, and wastes.

Suspended in plasma are erythrocytes

(red blood cells), leukocytes (white blood

cells), and cell fragments called platelets.

Red cells carry oxygen.

White cells function in defense

against viruses, bacteria, and other

invaders.

Platelets aid in blood clotting.

(i) Plasma

Pale yellow liquid. 90% water and 10% solutes.

Solutes:

Metabolites glucose, amino acids,

vitamins.

Wastes nitrogen compounds, CO2.

Hormones (regulate cellular activities).

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Ions especially sodium, chloride, and

bicarbonate.

Proteins albumin, globulins (carriersof lipids and steroid hormones), and

fibrinogen (blood clotting). If fibrinogen is removed, blood plasma is

called serum. Function: Provides medium for exchange

of substances.

(ii) Cells

http://www.biosbcc.net/doohan/sample/htm/Blood%20cells.htm

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Erythrocytes (Red blood cells) 5 million per mm3 blood.

Diameter: 7 - 8 m. No nucleus (and organelles).

Shape: biconcave disc.

Plasma membrane thin and flexible.

Cell filled with haemoglobin lack of

nucleus permits more haemoglobin to bepacked into cell 250 million molecules of

haemoglobin per cell.

Life span: 120 days.

New cells manufactured in red bone

marrow 1 million per second.

Function: O2 and CO2 transport biconcave disc provides a large surface-

volume ratio for absorption.

b) Leukocytes (White blood cells) Larger the erythrocytes. 7000 per mm3 blood.

Have nucleus.

Short life span a few days.

Function: Body defenses.

Two main groups: granulocytes and

agranulocytes.

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1.Granulocytes Contains lobed nucleus and granular

cytoplasm.

Capable of amoeboid movement.

Three types:

(i) Neutrophils 7 9 m.

70% of leukocytes.

Nucleus with 3 5 lobes.

Can squeeze between cells of capillary

walls (diapedesis) and move toinfected area.

Function: Phagocytosis - engulf and

digest pathogen

(ii) Eosinophils (Granules stained red with eosin dye.)

1.5% of leukocytes.

9 12 m.

Nucleus sometimes Z shaped.

Function: Anti-histamine properties.

(iii) Basophils (Granules stained blue with methylene

blue.)

0.5% of leukocytes.

10 m.

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Nucleus sometimes S shaped.

Function: Produce heparin and

histamine (causes inflammatory

response).

2.Agranulocytes Non-granular cytoplasm.

Oval or bean-shaped nucleus.

Two types:

(i) Monocytes 4% of leukocytes.

9 12 m.

Bean-shaped nucleus.

(Can migrate from bloodstream to

inflamed areas, acting in same manner

as neutrophils.)

Function: Phagocytosis - engulf

bacteria.

(ii) Lymphocytes 24% of leukocytes. 6 8 m.

Big, rounded nucleus with little

cytoplasm.

Function: Antibody production and

cellular immune response.

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(c) Platelets Irregularly shaped membrane-bound cell

fragments.

Formed from megakaryocytes , largebone marrow cells.

0.25 million per mm3 blood.

Usually without nucleus.

Life span: 7 8 days.

Function: Blood clotting.

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5.4 MUSCLE TISSUES Composed of long cells called muscle

fibers - capable of contracting whenstimulated by nerve impulses.

Most abundant tissue in most animals.

Myofibrils - arranged in parallel withincytoplasm of muscle fibers.

Made of contractile proteins, actin andmyosin.

Muscle contraction accounts for most of

energy-consuming cellular work in active

animals.

Three types of muscle tissue in

vertebrate body: skeletal muscle, cardiac

muscle, and smooth muscle.

5.4.1 Skeletal Muscle Attached to bones by tendons.

Responsible for voluntary movements.

Consists of bundles of long cells called

fibers.

Each fiber is a bundle of strands called

myofibrils.

Multinucleated.

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Also called striated muscle due toarrangement of contractile units

(sarcomeres) - gives cells a striped(striated) appearance under the

microscope.

5.4.2 Smooth Muscle Lacks striations

In walls of digestive tract, urinary

bladder, arteries, and other internal organs.

Spindle-shaped cells.

Contraction slower than skeletal muscles

but can remain contracted longer.

Controlled by different kinds of nerves

than those controlling skeletal muscles,

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Responsible for involuntary body

activities.

Example, churning of stomach and

constriction of arteries.

5.4.3 Cardiac Muscle Forms contractile wall of heart.

Striated.

Contractile properties similar to those of

skeletal muscle.

Performs unconscious (voluntary) task of

contraction of heart.

Muscle fibers branch (anastomose) and

interconnect via intercalated disksrelay signals from cell to cell during

heartbeat.

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5.5 NERVOUS TISSUES Senses stimuli and transmits signals from

one part of animal to another. Functional unit of nervous tissue =

neuron (nerve cell) Uniquely specialized to transmit nerve

impulses.

Consists ofcell body and 2/moreprocesses called dendrites and axons. Dendrites transmit impulses from their

tips toward rest of neuron.

Axons transmit impulses toward

another neuron or toward an effector,

such as muscle cell that carries out a

body response.

In many animals, nervous

tissue is concentrated in brain.

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5.5.1 Neurons

.

http://www.botany.uwc.ac.za/sci_ed/grade10/mammal/nervous.htm

Cell body contains nucleus andcytoplasm.

Enclosed within a plasma membrane.

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Also contains Nissls granules (involved

in protein synthesis), ribosomes, and

other organelles.

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D endrites are cytoplasmic processesextending from cell body they make

synaptic connections with other neurons.

Nerve fibre is a long cytoplasmicextension from cell body that transmits

impulse.

Nerve fibres that transmit impulses away

from cell body are called axons whilethose that transmit impulses towardscell body are called dendrons .

Cytoplasm of cell body contains large

amount of ribosomes synthesize proteins

which is supplied to nerve fibres.

Cytoplasm of nerve fibre continuous with

cytoplasm of cell body & lacks ribosomes.

Plasma membrane of nerve fibre is

continuous with that of cell body.

Nerve fibres may or may not be

surrounded by a fatty myelin sheath,formed from Schwann cells. Sheath is constricted at intervals along

nerve fibre by nodes of Ranvier. Sheath insulates nerve fibre and speed up

transmission of impulses along it.

Neurilemma, a tough elastic membrane,surrounds the sheath.

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Classification of neuron(i) Based on function (direction in

which impulse is transmitted)

http://www.abbysenior.com/biology/nervous_system.htm

(a) Sensory orafferentneuron Transmits impulse from the receptor

to the central nervous system.(b) Motor orefferentneuron

Transmits impulse from the central

nervous system to the effector.

(c) Intermediaryneuron Transmit impulse from sensory to the

motor neuron.

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(d) Neurosecretory neuron* Specialized neurons that synthesize

and secrete hormones

(ii) Based on structure (number of

fibres)

(A) Pseudo-unipolarneuron Neuron has only one extension that

divides into two, dendrite and axon.

(B) Bipolarneuron Neuron has one axon and one

dendrite at opposite ends of the cell

body.

(C) Multipolarneuron Neuron has one axon and several

dendrites.

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5.5.2 Neuroglia Ten times more numerous than neurons.

Found throughout central nervoussystem.

Function:

1. Provides mechanical support to

neurons.

2. Supply nourishment to neuron fibres.

3. Some are involved in the memory

process stores information in the form

of RNA.

4. Some form the myelin sheath.

Neuroglia cells

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HMM1414 Chapter 5 Part 1