This document discusses various biophysical principles including diffusion, osmosis, and dialysis. It explains that diffusion is the movement of particles from an area of higher concentration to lower concentration down a concentration gradient. Osmosis is the diffusion of water across a semipermeable membrane from a region of lower solute concentration to higher solute concentration. Osmotic pressure is the hydrostatic pressure required to prevent osmosis. These principles are important for biological processes like gas exchange and kidney function, and conditions like edema can be caused by imbalances in osmotic pressure. Dialysis techniques like hemodialysis and peritoneal dialysis are used to filter waste from blood in kidney failure patients.

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BIOPHYSICS:PRINCIPLES AND
BIOMEDICAL IMPORTANCE-2
•DIFFUSION
•OSMOSIS
•OSMOTIC PRESSURE
•DIALYSIS
DR.RITTU CHANDEL
Junior ResidentDr.Rittu Chandel

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DIFFUSION
•solute particles move from higher
concentration to a lower concentration in
order to bring a uniform concenteration
throughout.
factors affecting diffusion:
1.concentration of solute
2.temperature
3.mean moecular velocity
Dr.Rittu Chandel

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The concentration of
oxygen molecules is
greater outside the cell
than inside
So the oxygen molecules
diffuse into the cell
factor affecting diffusion-lipid solubilities of substances.Dr.Rittu Chandel

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oxygen
carbon
dioxide
pulmonarycapillary
alveolar
membrane
↓
factors affecting diffusion-partial pressure gradient,surface area,thickness of membraneDr.Rittu Chandel

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TYPES OF DIFFUSION
1.SIMPLE
2.FACILITATED
NO ENERGY REQUIRED.
Dr.Rittu Chandel

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why facilitated diffusion?
Dr.Rittu Chandel

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confirmational change of carrier
protein
Dr.Rittu Chandel

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PING PONG MECHANISM
Dr.Rittu Chandel

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FICK'S LAW OF DIFFUSION
• ds/dt = DAdc/dx
• ds/dt = rate of movement of solutes
• D = diffusion constant
• A = area
• dc/dx = concentration gradient
Dr.Rittu Chandel

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FACTORS AFFECTING
DIFFUSION
• concentration gradient
• electrical gradient of ionized solutes
• pressure gradient of gases
• mean molecular velocity
• temperature
• solubility
• viscosity
• size and shape of solute
• pore size of membrane
• time taken by diffusion is directly proportional to the square of
the distance traversed
Dr.Rittu Chandel

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ELECTROCHEMICAL GRADIENT
conc of
negative ions
is more on left
sides these
charges diffuse
to right side
•electric field is applied
when there are equal no.
of negative charges on
both side
thus electric gradient
created
concentration
difference arises
electrical difference
also present
concentration
difference rises high
enough to balance
the two effectsDr.Rittu Chandel

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BIOMEDICAL IMPORTANCE
• respiratory exchange of gases
• intestinal absorption of pentoses
• limitation of cell size
• keratinized epidermis minimizes loss of water
• pneumonia,emphysema,panting and
hyperapnea
Dr.Rittu Chandel

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DIFFUSION TRAPPING
• salicylic acid and phenobarbital are excreted
passively in distal tubule and collecting duct of
kidney by diffusion trapping
Dr.Rittu Chandel

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OSMOSIS
• the net diffusion of solvent molecules from a
dilute to concentrated solution,when seperated by
semipermeable membrane.
Dr.Rittu Chandel

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OSMOTIC PRESSURE (¶)
hydrostatic pressure which exactly balances the
osmotic influx
colligative property
the osmotic pressure exerted by particles in a
solute is determined by the number of particles
and not the mass of particles
Dr.Rittu Chandel

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van't HOFFS LAWS
• the osmotic pressure is directly proportinal to
the molar concentration of the
solute,temperature remaining constant.
• the osmotic pressure is directly proportional to
the temperature ,as long as its concentration
remains constant
Dr.Rittu Chandel

17. 17Dr.Rittu Chandel

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BIOMEDICAL IMPORTANCE
hypotonichypertonicisotonic
Dr.Rittu Chandel

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BIOMEDICAL IMPORTANCE
• osmotic distension of RBC
• kwashiorkar,nephrotic syndrome,severe
vomiting
• edema in lymphoma
• polyuria in diabetes
Dr.Rittu Chandel

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OSMOLE
• to express the concentration of solution in terms of
number of particles,the unit osmole is used.
• 1 osmole = 1 gram molecular weight of undissolved
solute.
• 180 g glucose = 1 g molecular wt.of glucose
• =1 osmole
• NaCl dissolves into two- Na and Cl
• 58.5 g NaCl =2 osmole
• 1/1000 osmole = 1 milliosmole
Dr.Rittu Chandel

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OSMOLARITY AND
OSMOLALITY
• OSMOLARITY-a solution that has 1 osmole
of solute dissolved in each litre of solution.
• OSMOLALITY- a solution that has 1 osmole
of solute dissolved in each kilogram of
solution.
• difference between osmolarity and osmolality
is less than 1%.
Dr.Rittu Chandel

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RELATION OF OSMOLALITY TO
OSMOTIC PRESSURE
• AT NORMAL TEMPERATURE,
• 1 osmole/Kg 19300 mmHg
• 1 milliosmole/Kg 19.3 mmHg
normal osmolality of ECF- 300 mOsm/Kg
and ICF
multiplying on both sides by 300,to obtain osmotic pressure of
body fluid
1*300 =19.3*300
= 5790 mmHg
approximately 5500 mmHg
osmotic pressure of body fluid is .93 times calculated value.
Dr.Rittu Chandel

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REVERSE OSMOSIS
application-purify water (to remove impurities)
to concentrate fruit juices
in wine industies
to form whey protein powder
Dr.Rittu Chandel

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DIALYSIS
Dr.Rittu Chandel

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HEMODIALYSIS
Dr.Rittu Chandel

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PERITONIAL DIALYSIS
Dr.Rittu Chandel

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•BIOMEDICAL IMPORTANCE
• seperate proteins in pure form from the
mixture with salts
• stopping enzymatic or metabolic reactions by
removing small cofactor molecules from cell
extract
• artificial kidney
Dr.Rittu Chandel

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BIBLOGRAPHY
• TEXTBOOK OF MEDICAL PHYSIOLOGY-
GUYTON (10th edition)
• TEXTBOOK OF MEDICAL BIOCHEMISTRY-
RANA SHINDE (8th edition)
• BIOPHYSICS-DEBJYOTI DAS
• MARK'S MEDICAL BIOCHEMISTRY
• LEHNINGER
• CELL AND MOLECULAR BIOLOGY
• INTERNET
Dr.Rittu Chandel

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THANK
YOU
Dr.Rittu Chandel