Growth- Basic Concepts

7/28/2019 Growth- Basic Concepts

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GROWTH- BASIC

CONCEPTS


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GROWTH:DEFINED AS INCREASE IN SIZE

BY RAPID MULTIPLICATION OF CELLS

Acc. to MOYERS QUANTITATIVE ASPECT OF

BIOLOGIC DEVELOPMENT PER UNIT OFTIME

DEVELOPMENT: DEFINED AS PROGRESSTOWARDS MATURITY


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Intramembranous bone formation

v/s

endochondral bone formation


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Primary secondarycartilage cartilage

It is that which has theinnate potential forgrowth i.e,if the

cartilage istransplanted to otherlocation it has thepotential to grow

Eg: Nasal cartilagetransplanted to craniumhas potential to grow

This does not havepotential to grow if

transplanted to other

site.

Eg: Condylar

cartilage


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Translation v/s Transformation

It is the movement of

bone from one

location to another

It is the surfaceremodelling of bone

by deposition &

resorption


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Deposition v/s remodelling

Is a process of bone

formation by

osteoblastic activity,

also called as

APPOSITION

Is a process that

involves shaping ofbone by both

deposition &

resorption.


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Primary displacement secondarydisplacement

This is the displacementwhich occurs due to growth ofthe same bone,by means ofappositional growth

Eg: 1.As condyle growsupwards & posteriorly itdisplaces the mandibledownwards & forwards

2.The growth of the maxillarytuberosity area & the posteriorregion as such displacesmaxilla downwards &forwards

It occurs due to thegrowth of theneighbouring bone whichin turn pushes this bone

Eg: The growth of theanticranial fossadisplaces the maxillaforward & downward


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Click to edit Master text stylesSecond level

Third levelFourth level

Fifth level


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Growth site Growth centre

Is merely a location at which

growth occurs

*ALL GROWTH

CENTRES ARE GROWTH

SITES BUT NOT VICE-VERSA

Is exact location

where independentgrowth occurs

(genetically

controlled)


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CEPHALO-CAUDAL GRADIENT OFGROWTH

It means that there is an axis of increased growthextending from head towards the feet.

A comparison of the body proportion between thepre natal & post natal life reveals that post natalgrowth of regions of the body that are away fromthe hypophysis is more.


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This figure illustrates the change in overall bodyproportions that occur during normal growth and

development.


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SCAMMONS CURVE OF GROWTH

The body tissues are classified into 4 types

1.Lymphoid tissue

2.Neural tissue

3.General tissue

4.Genital tissue

Each of these tissues grow at different times andrates


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Scammons growth curve

Click to edit Master text styles

Second levelThird level

Fourth levelFifth level


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TIMING:

GROWTH SPURTS

It has been observed that differentindividuals have varied biologic clocks in

them and they exhibit peak growth at

varying time intervals.

Growth spurts are periods of sudden

acceleration in growth seen in males &

females


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IST GROWTH SPURT- JUST BEFORE BIRTH

2ND GROWTH SPURT-

ONE YEAR AFTER BIRTH

3RD GROWTH SPURT-

7-9YRS(FEMALES)

8-11YRS(MALES)

*4THGROWTH SPURT-

11-13YRS(FEMALES)

14-16YRS(MALES)


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Fourth growth spurt is also called as

PUBERTAL GROWTH SPURT.Manipulation of skeletal discrepancies is

attempted by using myofunctional appliances

during pubertal growth spurt. Hand wrist x-rays helps to asses the level of pubertal

growth spurt


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FACTORS AFFECTING PHYSICALGROWTH

1.HEREDITY

2.NUTRITION

3.ILLNESS

4.RACE

5.CLIMATE AND SEASONAL EFFECTS


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7.SOCIO-ECONOMIC STATUS

8.EXERCISE

9.FAMILY SIZE & BIRTH ORDER

10.SECULAR TRENDS

11.PSYCHOLOGICAL DISTURBANCES


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METHODS OF STUDYINGPHYSICAL GROWTH

A.MEASUREMENT APPROACHES: (usuallyinvolves techniques for measuring livinganimals including humans)

1.CRANIOMETRY-Based on measurements of skulls found

among human skeletal remains

-Originally used to study the Neanderthaland Cro-Magnon peoples whose skulls werefound in caves

-precise measurements possible


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2.ANTHROPOMETRY:

-To measure skeletal dimensions of living individuals

-Possible to follow the growth of an individual directly,making the same measurements at a later date

3.CEPHALOMETRIC RADIOGRAPHY:

-Disadvantage of representing a 3 dimensionalstructure into a 2-D scheme

-Most popular of the above methods

-Most growth studies are based on this


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B.EXPERIMENTAL APPROACHES

1.VITAL STAINING

-Initially discovered by JOHN HUNTER

in 18th century

1)ALIZARIN:active die which react

strongly with ca++ at bone calcification

sites

2)TETRACYCLINE STAINING


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2.RADIOACTIVE TRACERS:

-99mTc-gamma emitting isotope can be used

to detect areas of rapid bone growth in humans

3.AUTORADIOGRAPHY

4.IMPLANT RADIOGRAPHY: pioneer

scientists from Copenhagen-professor

BJORK used titanium implants


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AREAS WHERE IMPLANTS AREPLACED


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MECHANISMS OF BONE GROWTH

1.Bone is a specialized tissue of

mesodermal origin

2.It forms the structural framework of the

body

3.It is a calcified tissue that supports the

body & gives points of attachment to the

musculature.


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THANK YOU

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Growth- Basic Concepts