Structural Organization of Life

7/26/2019 Structural Organization of Life

1/34

Structural Organization Of

Life

The Discovery of Cell and Cell Theory

Discovery of Cell

In 1665, an English biologist Robert Hooke invented frst compound microscope and

observed the sections o corks and leaves under this microscope. He noticed in

them small bo like chambers o same si!e "hich he called #cells$. %ter this,

biologists observed di&erent organisms under the microscope. 'he( ound that

structure o cells "as comple.

Cell Theory

In 1)th centur(, the compound microscope "as highl( advanced and biologists

observed things *ust a micrometer apart. %ter this, a series o discoveries started,

"hich provided basic inormation or cell theor(.

1. In 1+1 - , Robert ro"n discovered nucleus in cells o plants.

/. In 1++, a 0erman botanist athias 2cheiden observed that all plants "ere made

up o cells.

. In 1+), 'heoclor 2ch"ann obsrved that the bodies o o animals "ere made upo cells "hich "ere similar to plant cells.

3. 'hus, 2chleiden and 2ch"ann ormulated the #4ell 'heor($. %ccording to this, all

organisms are made up o cells.

5. In 1+3, . 7urkin*i gave the name #7rotoplasm$ to the things ound inside the

cells. %t that time, cell "as considered as a bag o thick dense substance containing

a nucleus.

8ater on, resolving po"er and 9ualit( o microscopes "ere highl( improved. 2ection

cutting o tissues and cells and their staining became easier and better. It revealed

that cell "as not a simple mass o granular substance: instead it contained man(

sub cellular bodies called #;rganelles$. Each organelle has a defnite *ob in the cell.

6. Human is made up o about 6 trillion cells.


2/34

1. %ll animals and plants are made up o cells and cell products. %mong these some

organisms are unicellular and some are multicellular.

/. 4ell is structural and unctional unit o living organisms.

. >e" cells come rom the divisions o pre?eisting cell.

Electron Microscope

'his is the most advanced orm o microscope. Its resolving po"er is /5 times or

more that o a compound microscope. In this microscope, a beam o electrons under

high voltage is passed through the ob*ect and its image is re@ected on to a screen

through an electro magnetic lens to make a photograph.

ABiagramC

Dith the help o microscope, an( ob*ect an be magnifed up to /5, its original

si!e.

Comparison of Light Microscope and Electron Microscope

Light Microscope

'he radiation source is light so it is called light microscope.

Davelength o light is 3 - nm.

aimum resolution is / nm.

aimum useul magnifcation is F 15 "ith e(e.

8enses are used.

Electron Microscope

'he radiation source is beam o electrons, so it is called Electron icroscope.

Davelength o beam o electrons is .5 nm.

aimum resolution is .5 nm.

aimum useul magnifcation is F. /5, on screen as image or photograph.

Electromagnets are used.


3/34

Structure of Eukaryotic Cell

2tructure o 4ell

'here are t"o t(pes o cellsG

1. 7rokar(otic cell

/. Eukar(otic 4ell

7rokar(otic cell lacks a membrane bound nucleus and membraned organelles e.g.

bacterial cell "hile eukar(otic cell has a membrane bound nucleus and membraned

organelles e.g. cells o plants and animals.

Dith the help o light microscope and electron microscope, a t(pical Eukar(otic cell

sho"s the ollo"ing structural details.

ABiagramC

1. 4ell Dall

/. 4ell embrane

. >ucleus

3. 4(toplasm

1. 4ell Dall

It is the outer most boundar( o plant cells. It is rigid and non?living. It is chemicall(

composed o 4ellulose. 'he cell "all o ungi is made up o 4hitin. 'he "alls o some

cells are thick and "alls o some cells are thin.


4/34

It is a thin membrane "hich is also called 7lasma membrane. It is present in cells o

all plants and animals. It is outer most boundar( o animal cell "hile in plant cells: it

is present inner to cell "all. oth nucleus and c(toplasm are surrounded b( cell

membrane. %ccording to @uid mosaic model, cell membrane is composed o t"o

la(ers o lipids in "hich protein molecules are partiall( or completel( embedded.


5/34

'he( re oval or rod like in shape. 'heir membrane is doubled. ;uter membrane is

smooth "hile inner membrane has enolding in the mitochondrial matri. 'hese

enolding are called cristae. 'he cristae bear small rounded bodies "hich are called

particles.

'here are about one million elementar( particles in one mitochondrian. 'he( areinvolved in oidative phosphor(lation. 'he( also have man( respirator( en!(mes.

>umber o itochondria

'heir number is di&erent in di&erent cells o di&erent animals. In more active cells,

their number is more than 1 e.g. liver cell.s 'he cells o ear lobes have a e"

number o mitochondria.


6/34

It is also called granular endoplasmic reticulum because ribosomes are attached on

it.


7/34

'hese are second t(pe o plastids. 'hese are o various colours other than green. In

plants, colours other than green are due to chromoplasts. 'hese are present in the

petals o the @o"ers and in the ripened ruit.


8/34

'hese cells lack a membrane bound nucleus. 'he hereditar( material AB>%C is ound

in c(toplasm.

'hese cells lack membrane bound organelles.

Ribosomes are o small si!e in and reel( scattered c(toplasm.

4ellulose is absent in cell "all, rather it is made up o peptido?gl(can or murein.

'hese cells are simple and o smaller si!e Aaverage diameter .5 - 1 nmC

Eukar(otic 4ell

'he organisms mae o Eukar(otic cells are called Eukar(otes, e.g. animals, plants

ungi and protists.

'hese cells have a membrane bound nucleus: and hereditar( material is ound

inside the nucleus.

'hese cells have membrane bound organelles.

Ribosomes are o large si!e and are present in endoplasmic reticulum ree in

c(toplasm.

4ellulose is present in cell "all o plant cells. 'he cell "all o most o ungi is

composed o chitin.

'hese cells are comple and o larger si!e A%verage diameter 1?1nmC

itosis

It is that cell division in "hich the number o chromosomes in both daughter nuclei

remains same as in parent nucleus.

ABiagramC

Events o itosis

itosis has the ollo"ing phasesG

1. 7rophase

/. etaphase

. %naphase

3. 'elephase

5. 4(tokinesis


9/34

7rophase

1. In this phase, coiling o chromosomes starts and their length decreases but

diameter increases. It means that chromosomes become shorter and thicker, this

process is called condensation.

/. icrotubules arrange to orm a structure called spindle.

. In animal cell, there are also present centrioles on both poles o spindle. uclear membrane is broken do"n. >ucleolus disappears and chromosomes

scatter over the spindle fber.

6. Each chromosome consists o t"o similar threads like structure called chromatids,these chromatids are united to each other b( means o centromere.

etaphase

1. 'he chromosomes arrange themselves on e9uator o the spindle to orm an

e9uatorial plate. In this condition, chromosomes become more visible.

/. 'he chromosomes are attached at their centromere to one spindle fber rom

each pole.

%naphase

1.


10/34

4(tokinesis

'he division o c(toplasm is called c(tokinesis. It begins at the last stages o nuclear

division. In plant cell, c(toplasm divides b( ormation o cell plate "hich is also

called phragmoplast. It graduall( etends out"ard and fnall( t"o daughter cells are

separated.

In animals, c(toplasm divides b( urro"ing. Buring this, there occurs in"ard

pinching o cell membrane resulting into t"o daughter cells. In mitosis, t"o

daughter cells are ormed rom one parent cell "hich are identical to their parent

cell.

2ignifcance o itosis

1. itosis occurs in all t(pes o somatic cells.

/. Baughter cells ormed as a result o mitosis have same number o chromosomes

as that o parent cell. In this "a(, all cells o bod( o an organism have samenumber o chromosomes.

. J(gote divides b( mitosis to orm embr(o and ater hatching or birth, mitosis

continues up to maturit( o an individual.

3. itosis also results in gro"th and repairing o damaged or "orn out tissues.

5. Healing o "ounds is also due to mitosis

eiosis

It is that t(pe o cell division in "hich c(toplasm and nucleus divides t"ice and as a

result o this, our daughter cells are ormed and chromosome number is reduced to

hal. It means that one diploid A/nC parent cell divides to orm our haploid AnC

daughter cells.

eiosis consists o t"o sub divisionsG

1. eiosis I

/. eiosis II

1. eiosis I

It has ollo"ing stagesG

7rophase I


11/34

1. It is length( than prophase o mitosis. It is ver( important phase. It is divided into

fve stages during "hich there is continuous condensation o chromosomes.

/. 'he important process o this phase is s(napsis in "hich homologous

chromosomes pair "ith each other length "ise.

. Each pair consists o our chromatids or t"o chromosomes.

3. %ter s(napsis, the process o crossing over takes place. In this, homologous

chromosomes echange their chromatids parts at certain places.

5. %t end o this phase, nuclear membrane breaks up. >ucleolus disappears and

chromosomes scatter over the spindle.

6. 8ike mitosis, mitotic apparatus is also ormed here.

ABiagramC

etaphase I

1. 'he chromosomes arrange on scatter o the spindle.

/. Here, homologous bivalents arrange at e9uatorial plate o spindle.

. ;nl( one spindle fber is attached to each chromosome.

%naphase I

1. Homologous pairs o chromosomes are separated.

/. 2pindle fbers contract.

. 4hromosomes begin to move to"ards the opposite poles.

3. 'his phase is di&erent rom metaphase o mitosis because hal the number o

chromosomes moves to"ards each pole and each chromosome still has t"o

chromatids.

'elephase I

1. Hal the number o chromosomes reach at opposite poles.

/. 4hromosomes again increase their length.

. >ucleolus reappears. >uclear membrane is reormed and in this "a( t"o

daughter nuclei are ormed.

3. >o" c(toplasm divides and t"o daughter cells are ormed. Each cell is haploid

AnC.


12/34

/. eiosis II

It is similar to mitosis. 'he haploid cells ormed in meiosis I pass through phases o

meiosis II and ultimatel( our haploid AnC daughter cells are ormed. 'hese cells

ater"ards change into spores Ain plants or gametes AanimalsC

2ignifcance o eiosis

1. eiosis takes place onl( in germ mother cells "hich orm gametes or spores.

/. It maintains the chromosome number o a species constant generation ater

generation.

. I gametes had the same number o chromosomes as in somatic cells, the

number o chromosomes "ould have doubled ater each generation in a species.

3. 'he number o chromosomes is constant or each species. Buring meiosis:

gametes Aboth andC ormed are haploid.

5. 0ametes unite to orm a diploid !(gote.

6. Buring meiosis, pairing o chromosomes takes place "hich is called s(napsis.

. Echange o genetic material occurs during meiosis. In this "a( variations are

produced "hich are ra" material or evolution.

'issues

'issues

% group o cells "hich perorm same unction is kno"n as tissue. 'he tissues are

divided into di&erent t(pes on the basis o their orm and structure or unction.

7lant 'issues


13/34

i. eristematic or embr(onic tissues

ii. 7ermanent 'issues

i. eristematic 'issues

1. 4ells o this tissue have abilit( to divide.

/. 4(toplasm is dense nd nucleus is big in these cells.

. acuoles are smaller i present other "ise absent.

3. %ll cells are identical.

5. 'here are no intercellular spaces.

6. 'heir "alls are thin and nucleus is present in centre o cell.

. 'hese tissues ound on ape o root or shoot are called apical meristems. 'hecells o these tissues divide: and redivide to add primar( tissue or elongation o

setm or root.

'his t(pe o gro"th is called primar( gro"th.

+. eristematic cells are also ound on the lateral sides o roots and stems as

lateralAcambiumC or intercalar( meristem, and these add, secondar( tissues. In this

"a(, thickness o stem or root is increased. 'his t(pe o gro"th is called secondar(

gro"th.

ii. 7ermanent 'issues

'he cells o this tissue lack the abilit( to divide and the( originate rom meristems.

'hese are given belo"G

a. Epidermal 'issues

b. 0round 'issues

AaC Epidermal 'issues

1. 'he( are ound as the outermost covering o lea, stem or root.

/. 'here are non intercellular spaces.

. 4ells are rectangular in shape.

3. In the epidermal tissues o stem and leaves, there are small openings called

stomata or gaseous echange.

AbC 0round 'issues


14/34

1. ost o the portion o bod( o herbaceous plants consists o ground tissues i.e.

parench(ma.

/. 'he( are thin "alled.

. 4ells are large in si!e.

3. 4ells sometimes ma( develop the abilit( to divide.

5. 'heir main unctions are to prepare and store ood and "ater.

2upporting or echanical 'issues

'hese provide strength @eibilit( to the plant. 'he( are o ollo"ing t"o t(pesG

a. 4ollench(ma 'issues

b. 2clerench(ma 'issues

AaC 4ollench(ma 'issues

1. 'hese consist o living cells.

/. 'heir "alls are not uniorml( thickened.

. suall( "alls are thickened at angles.

3. 'hese are more @eible or elastic than sclerench(ma.

5. 'hese tissues are ound in stem, in midrib o leaves and in corte o petiole.

AbC 2clerench(ma 'issues

1. 'hese consist o dead cells.

/. 'heir "alls are highl( thickened due to deposition o lignin.

. 8ignin provides hardness and strength to the cell.

3. 'hese cells are "ithout protoplasm.

5. 2clerench(ma cells are o t"o t(pes,

2tone cells having uniorml( thick cell "alls: ound in testa o seeds.


15/34

'hese are the tissues "hich consists o t"o or more than t"o t(pes o cells. ut all

cells perorm a common unction.

'hese 'issues are o ollo"ing t(pesG

F(lem 'issue

1. 'his vascular tissue transports "ater in the plants and provides strength to the

plant.

/. In this tissue, there are present (lem parench(ma and t"o t(pes o thick "alled

dead cells.

8ong cells "hich are called vessel elements or cells. 'he( are *oined together to

orm long pipe?lines. 'hese transport "ater rom roots to leaves.

2pindle shaped cells, "hich are called tracheicts. 'hese provide strength to root and

shoot etc.

. F(lem conducts "ater in one direction that is rom roots to"ards the stem and

leaves.

7hloem 'issues

1. 'his vascular tissue transports ood in the plants.

/. It helps in t"o directional conduction o ood material i.e. rom leaves to roots and

vice?versa.

. 'his tissue mostl( consists o living cells. 'here are three t(pes o cells

AaC 7hloem 7arench(ma

AbC 2ieve 'ube 4ells

AcC 4ompanion 4ells

AaC 7hloem 7arench(ma

'hese cells store surplus "ater and ood. 'he( can start to divide "hen needed.

AbC 2ieve 'ube 4ells

'heir end "alls have small pores called sieve plates. 'hese cells *oin to orm long

pipelines, "hich are called sieve tubes. 'here is no nucleus in these cells. 'heir

main unction is to transport ood.

AcC 4ompanion 4ells


16/34

In some plants, each sieve tube cell is accompanied b( a companion cell. 'he

companion cell has a nucleus. 'he corn cell controls the movement o ood through

sieve tubes.

%nimal 'issues


17/34

3. 'hese are o t"o t(pesG

2ot connective tissues e.g. att( tissues and tendons.

Hard connective tissues e.g. cartilage and bone.

5. lood is also a special connective tissue "ith cells suspended in the @uidmedium. It transports materials in the bod(.

/. uscular 'issues

1. 'his tissue is made up o special contractile cells or fbers.

/. 'he cells are elongated and are called muscle fbers.

. 'hese cells have the abilit( to contract and rela "hich results in movements o

bod( and the organs.

3.


18/34

5. 'his tissue also orms brain and spinal cord

nicellular ;rganism A%moebaC

'he organisms consisting o onl( one cell are called unicellular organisms e.g.

%moeba, 7aramecium etc.

%moeba

1. It is mostl( ound in resh "ater pond or pool.

/. In the ponds, it is ound moving about around the "eeds and stones. 2ome

species are ound in the moist soil.

. %moeba is a large protist.

3. It does not have the permanent shape.

5. Its si!e is about the end o pin or it measures about ./5mm. 'hereore it is

observed under the microscope.

6. Its structure is ver( simple.

. It consists o nucleus and c(toplasm, "hich are surrounded b( a cell membrane.

+. 4ell membrane protects it.

). 4(toplasm is divided into t"o parts. ;uter clear and transparent part is called

ectoplasm "hile the inner, viscous, translucent and granular part is called

endplasm.

1. Endoplasm contains ood vacuoles o di&erent si!es. 'hese ood vacuoles help in

the digestion o ood.

11. 'he ood o %moeba consists o microbes present in the "ater o pond.

1/. 4ontractile vacuole maintains the concentration o "ater in the bod(. It removes

surplus "ater out o the cell.

1. In %moeba, the echange o gases and removal o "aste.

13. In %moeba, there are also present mitochondria, golgi bodies and ribosomes.

15. >ucleus changes its place "ith the movement o the organism.

ABiagramC


19/34

ulticellular ;rganism Arassica 7lantC

ulticellular ;rganism

'he organisms consisting o man( cells are called multicellular organism. e.g.

rassica 7lant, rog, man etc. diagramK

rassica 7lant Austard 7lantC

1. 'his plant is so"n in "inter and at the end o season, it produces seeds and then

dies.

/. 'his is an annual plant.

. %n oil is etracted rom seeds o this plant "hich is kno"n as mustard oil.

5. 'he scientifc name o this plant is rassica 4ampestris.

ABiagramC

>on?Reproductive 7arts or egetative 7arts

'hese parts do not directl( take part in seual reproduction e.g. root, stem,

branches and leaves.

Reproductive 7arts

'hese parts directl( take part in seual reproduction e.g. @o"er, ruit and seed.

Root o rassica

'he root is that part plant "hich is present inside the soil. It is produced rom radical

o seed. 'he frst ormed root is called 7rimar( root. Buring its gro"th, it gives o&

secondar( and tertiar( root. Each root has a root cap at its tip or ape. ehind the

root cap, root hairs are present "hich absorbs "ater and salts rom the soil. Roots

also anchor the plant frml( in the soil.

ABiagramC

Internal 2tructure o Root o rassica

Dhen transverse section o root o rassica is observed under the microscope, the

ollo"ing parts are ver( prominent.


20/34

Epidermis

It is outermost and protective la(er. It is single celled. 2ome cells gro" out"ard to

orm root hair.

4orte

It is present inner to epidermis. It is made up o several la(ers o thin "alled living

cells Aparench(ma cellsC. 'here are present intercellular spaces. 'hese cells store

ood.

Endodermis

it is the innermost la(er o corte. 'here are no intercellular spaces. 'here are

thickenings o special materials around the cell "hich check di&usion o "ater rom

(lem to corte.

7eric(cle

'he la(er present inner to endodermis is called peric(cle. 'here are also no

intercellular spaces. %ll the branches o roots arise rom peric(cle.

ascular undles

F(lem is present in middle o root "hich etends to peric(cle in the orm o our

ra(s and controls one "a( transport o "ater and salts. In bet"een the (lem ra(s,

phloem bundles are present "hich transport ood in t"o directions.

2tem o rassica

'he stem is that part o the plant "hich gro"s above ground. It arises rom plumule

o seed. It is herbaceous and branched. It bears leaves and @o"ers. 'he part o

stem or its branch rom "here a lea arises is called node. 'he part bet"een t"o

nodes is called internode. the important unction o stem is the conduction o

prepared ood rom leaves to other parts and that o "ater absorbed rom roots to

leaves. It supports leaves, @o"ers and ruits like a pillar. It keeps the leaves in such

a position that the( can get light to prepare ood.

ABiagramC

Internal 2tructure o 2tem o rassica

Dhen transverse section o stem o rassica is observed under the microscope,

ollo"ing parts are visible.

Epidermis


21/34

It is the outermost protective la(er o stem. ;uter to epidermis, there is la(er o

cutin "hich reduces loss o "ater rom stem. 'he cells are compactl( arranged and

there are no intercellular spaces.

4orte

It is inner to epidermis. It is made up o man( la(ers o parench(ma and

collench(ma tissues. 'he main unction o corte is storage o "ater and ood.

Endodermis

It is innermost la(er o corte. It is not prominent in stem. It allo"s suitable 9uantit(

o "aer to enter corte rom (lem.

7eric(cle

It is in the orm o bundles in bet"een the endodermis and vascular bundles. It is

composed o sclerench(ma cells. It orms bundle cap.

ascular undles

In stem, vascular bundles are arranged in the orm o ring. ascular bundle consists

o phloem and (lem. 7hloem is to"ards outside and (lem is to"ards inside.


22/34

5. In the middle o lea there is a thick midrib.

6.


23/34

oth t(pes o cells have chloroplasts containing chloroph(ll. 2o, photos(nthesis

takes place here. 'he unction o mesoph(ll is to manuacture ood or the plant.

ascular 'issue

It consists o midrib and veins. 'he midrib is bundle. pper part o midrib is (lem

and lo"er part is phloem. 7eric(cle and endodermis surround this bundle. esides

this 8amina has other bundle "hich are called veins.


24/34

insects and are transerred rom one @o"er to the other. 'his process is called

pollination.

0(noecium

It is the inner most part o @o"er. It is emale reproductive part. It consists o t"o

carpels, "hich are used. Each carpel has three parts. 'he basal s"ollen part is

called ovar(. 'he stalk like part above the ovar( is called 2t(le. 'he top o st(le is

some"hat s"ollen and it is called 2tigma. ;ver( contains man( ovules. ;vules are

ripened to orm seeds "hile ovar( is ripened to orm ruit. 'he ruit o rassica is

called 2ili9ua.


25/34

t"o large bulges indicate the position o e(es. 'he tongue o rog is stick(. 'he

tongue is attached at anterior end o buccal cavit(. 'he posterior end o tongue is

ree and bifd. the rog eeds on di&erent insects. 'o capture its pre(, it suddenl(

thro"s its tongue on to the pre(, "hich sticks to the tongue and is brought to the

buccal cavit(, "hen the tongue is dra"n back.

>ear the maillar( *oints, pair o opening o eustachian tubes are present. In male

rog, there is also, present a pair o opening o vocal, sacs on the lateral side o @oor

o the buccal cavit( "hich help the croaking. uccal cavit( narro"s, posteriorl( to

orm phar(n. 'he digestive s(stem, respirator( s(stem and ears are linked to

phar(n. In posterior part o phar(n, there is another opening called 0lottis. 'his

leads to lungs through tachea. It closes at the time o digestion o ood but remains

open "hen animal is respiring.

ABiagramC

;esophagus, 2tomach and Intestine

7har(n leads into a small but "ider tube called oesophagus or gullet. 'he

oesophagus opens into the stomach. 'he anterior end o stomach is called 4ardiac

end "hile the posterior end is called 7(loric end. 'he "alls o stomach are muscular

and glandular.

'he muscles o "alls o stomach contract and rela, b( "hich ood is broken do"n

into tin( pieces. 'he secretions o stomach have di&erent en!(mes "hich help in

chemical digestion. In stomach, digestion o protein o ood is started. %ter

stomach, frst part o intestine begins "hich is called duodenum. 'he ducts rom

liver and pancreas open into the duodenum. 'hese ducts bring *uices rom these

glands. 'he second part o intestine is Ilium are called 2mall intestine. 'he secretion

o pancreas is called 7ancreatic uice. 7ancreatic *uice enters the bile duct b( small

duct. 'his *uice digests the ood and brings in such orm "hich can be absorbed b(

the blood through intestine. Bigested ood is absorbed b( illium and surplus "ater is

absorbed b( recturm. Remaining undigested ood is epelled though cloacal

aperture. % membrane keeps the intestine intact at a place and prevents

strangulation o small intestine. 'his membrane is called mesenter(.

Respirator( 2(stem o


26/34

ABiagramC

7ulmonar( Respiration

'he echange o gases through lungs is called pulmonar( respiration. In this

process, rog keeps its mouth closed. %ir reaches buccal cavit( through nostrils.

>ostrils are closed @oor o buccal cavit( is raised: glottis opens, and air is pushed

into the lungs. 'he intake o air is called inspiration. In rog, there is a pair o balloon

shaped lungs. Each lung consists o small thin "alled chambers called alveoli "hich

greatl( increase the surace area o the lungs. ;n each alveolus, there are man(

blood capillaries. Dhen lungs are flled "ith air, then echange o gases occurs

bet"een blood and air in lungs at the site o alveoli. Buring this, the echange o

gases occurs bet"een blood and air present in buccal cavit(. %ter this air is

removed rom the lungs.


27/34

Heart is conical organ. It is muscular. It has three chambers. It is present in the bod(

cavit( bet"een the oesophagus and sternum. 8ike a pump, it contracts and is

relaes. %s a result o this, blood continuousl( circulates in the bod(. 'he heart is

surrounded b( a membrane "hich is called pericardial "hich protects the heart.

A


28/34

%rterial 2(stem o


29/34

enous 2(stem

'he blood vessels "hich bring the blood rom di&erent bod( parts, back into the

heart are called veins. 'he s(stem containing o veins is called enous s(stem.

ear the liver a branch o

abdominal vein combines "ith it. 'hen it enters the liver and divides and redivides

to orm capillaries. 'he, blood entering the liver through hepatic portal veins goes to

the post caval b( means o hepatic veins. 'he blood rom post caval goes to heart

through sinus venosus.

'he blood coming back into the heart is o t"o t(pes.


30/34

;(genated blood "hich comes rom lungs b( pulmonar( veins.

Beo(genated blood rom all parts o the bod( enters sinus venosus through

precavals and post caval and then enters the right atrium.

ABiagramC

8(mphatic 2(stem o


31/34

Reproductive 2(stem o


32/34

'his is central part o brain. 'his is associated "ith e(es and vision.

AcC Hind rain

'his is the posterior part o brain. It controls and coordinates bod( movements and

maintains balance o the bod(. It also controls respiration, circulation, taste and

digestion.

2pinal 4ord

'he posterior part o the brain is continuous "ith spinal cord. It runs through the

vertebral column. 'he spinal cord controls the movements o trunk region.

7eripheral >ervous 2(stem

It consists o nerves. 'hese nerves connect the central nervous s(stem A4>2C "ith

various parts o the bod(. 2ome nerves originate rom brain. 'hese are called cranial

nerves other nerves originate rom spinal cord. 'hese are called spinal nerves. Inrog, there are 1 pairs o cranial nerves and ) or 1 pairs o spinal nerves.

4ranial

asicall(, nerves are o three t(pesG

2ensor( >erves

'hese take messages rom sensor( organs to 4>2.

otor >erves

'hese take messages rom 4>2 to glands and muscles.

ied >erves

'hese do both above mentioned unctions.

4ranial >erves

In these nerves, frst, second and eight pairs are sensor( nerves "hich are

associated "ith senses o smell, sight and hearing. 'hird, ourth and sith pairs are

motor nerves "hich carr( message rom brain to the e(e. >ine and ten pairs are

mied nerves, "hich are supplied to *a", ace, tongue and heart.

2pinal >erves

'hese are all mied nerves. 'hese control unctions o di&erent organs.

Ear o


33/34

2tructure o Ear o


34/34

"hich light passes beore it strikes retina. ;ptic nerve takes the sensor( messages

rom the e(e to the brain.

ABiagramC

Documents

Structural Organization of Life