Solubility 4 diffusion principles in biological systems. Diffusion Flux, Fick's Diffusion Laws, Concentration gradient,

Concentration gradient, diffusion principles in biological systems. Diffusion Flux, Fick's Diffusion Laws,

1. SOLUBILITY –4
DIFFUSIONPRINCIPLESIN
BIOLOGICALSYSTEMS
Presented By:
Mr. S.M. Ambore
Asst. Professor,
DK Patil Institute of Pharmacy, Loha. Nanded

2. LEARNINGOUTCOMES….
Diffusion
Diffusion Flux
Concentration gradient
Diffusion Laws 2

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DIFFUSION
Diffusionisdefinedasamasstransferof
individualmoleculesofsubstancecausedby
randommolecularmotionandassociatedwith
concentrationgradient.
OR
Aphysicalprocessthatreferstothenet
movementofmoleculesfromaregionofhigh
concentrationtolowerconcentrationunderthe
influenceofconcentrationgradient.
1.Itistimedependantprocess.
2.ItiswellexplainedbyFICK’SLAWOFDIFFUSION

4. DIFFUSION
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DK Patil Institute of Pharmacy

5. DIFFUSION
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DK Patil Institute of Pharmacy

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NEED OF DIFFUSION
Ithelpstounderstand,
1.ReleaseofdrugfromPharmaceuticaldosageform
2.Ultrafiltration, microfiltration,dialysis,
hemodailysis.
3.Permeation&distributionofdruginlivingtissues.
4.Estimationofmolecularweightofpolymers.
5.Predictionofabsorption&eliminationofdrug.

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TYPES OF DIFFUSION
PASSIVEDIFFUSION:
1.Netmovementofmaterialfromanareaofhigh
concentrationtolowerconcentrationarea.
2.Thedifferencebetweenhigh&lowconcentration
iscalledasconcentrationgradient.
3.Diffusionwillcontinueuntilthegradienthasbeen
eliminatedorequilibriumisattained.

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DK Patil Institute of Pharmacy

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TYPES OF DIFFUSION
FACILITATEDDIFFUSION:
Itismovementofmoleculesacrossthcell
membraneviaspecialtransportproteinsthatare
embeddedwithinthecellularmembrane
ACTIVEDIFFUSION:
Itismovementofmoleculesacrossmembrane
fromlowerconc.tohigherconc.against
concentrationgradient.

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DK Patil Institute of Pharmacy

11. DIFFUSIONFLUX
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How many atoms moving at how much time in how much
area is called Flux(J).
The Diffusion Flux(J) is the amount of matter flowing
through a unit area in unit time.
It is denoted by J.

12. CONENTRATION GRADIENT
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1.Rate of change of concentration per unit change of
position.
2.It is denoted by dc/dx.

13. LAWS OF DIFFUSION
1.FICK’s FIRST LAW OF DIFFUSION
2.FICK’s SECOND LAW OF DIFFUSION
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DK Patil Institute of Pharmacy

14. FICK’SFIRST LAW OF DIFFUSION
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DK Patil Institute of Pharmacy
Thislawdescribestherateatwhichdiffusionoccurs.
Thislawstatesthatthediffusionfluxisdirectly
proportionaltotheconcentrationgradient.
J αdc/dx
J = -D dc/dx
Where,
J–Flux
dc/dx–Concentrationgradient
D--Diffusioncoefficientordiffusivity.

15. FICK’SFIRST LAW OF DIFFUSION
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DK Patil Institute of PharmacyJ αdc/dx
J = -D dc/dx
Negativesignindicatesthatflowoccursfrom
higherconcentrationtolowerconcentration.
Thefluxisindependentoftime.

16. FICK’SSECOND LAW OF DIFFUSION
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DK Patil Institute of Pharmacy
Changeinconcentrationwithtimeina
particularregionisproportionaltothechangein
concentrationgradientatthatpointinthesystem.
dc/dx= -dJ/dx
ThisisextensionofFirstFick’sLaw
Diffusionflux(J)isfunctionofbothspaceandtime.

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