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AN INTRODUCTION TO BIOPHYSICS
Prof. Dr. Moustafa. M. MohamedVice Dean
Faculty of Allied Medical SciencePharos University
Alexandria
Dr. Yasser khedrBasic Science DepartmentFaculty of Physical therapy
Pharos University in Alexandria
Electricity
Within The
Body
ch1
Cardio Vascular
Instrumentation
ch2
Heat In
Medicine
ch3
Ultrasound In
Medicine And
Biology
ch4
TOPICS
Laser In
Medicine
And Biology
ch5
Human vision
ch5
Nuclear
Medicine
ch6
TOPICS
CALENDARDate Week Lecture 1
29-9-2012 1 About the biophysics
6-10-2012 - Vacation
13-10-2012 3 Ch 1
20-10-2012 4 Ch 1
27-10-2012 5 Ch 2
3-11-2012 6 Ch 2
10-11-2012 7 Ch 3
17-11-2012 8 Ch 3
24-11-2012 9 Revision
CALENDAR
Date Week Lecture 1 1-12-2012 10 Med term exam
8-12-2012 11 Ch 4
15-12-2012 12 Ch 4
22-12-2012 13 Ch 5
29-12-2012 14 Ch 5
5-1-2014 15 Ch 6
12-1-2014 15 Revision
******** ** Final Exam
What Is Biophysics?
Link BetweenBiology Physics
BIOPHYSICS
Biophysics
1. Biophysics is a bridge between
biology and physics.
2. biophysics is the study of
biological systems and
biological processes using
physics-based methods or based
on physical principles.
How Essential Is Biophysics To Progress In Biology?
1. Biophysics discovers how atoms
are arranged to work in DNA and
proteins.
2. Biophysicists are discovering how
proteins work, they use these
protein structures for discovering
how biological machines work, in
health and also in diseases.
How Essential Is Biophysics To Progress In Biology?
3. Variations in proteins make people
respond to drugs differently.
Understanding these differences
opens new possibilities in drug
design, diagnosis, , disease control
and decrease of side effects.
What Are The Applications Of Biophysics?
1. The applications of biophysics depend on society’s needs.
2. In the 20th century, great progress was made in treating disease. Biophysics helped create powerful vaccines against infectious diseases.3. It described and controlled diseases of metabolism, such as diabetes.4. Biophysics provided both the tools and the understanding for treating the diseases of growth known as cancers.
What Are The Applications Of Biophysics?
5. Biophysical methods are increasingly used to serve everyday needs, from forensic science to bioremediation6. Biophysics gives us medical imaging technologies including MRI, CAT scans and sonograms for diagnosing diseases.7. It provides the life-saving treatment methods of kidney dialysis, radiation therapy, cardiac defibrillators, and pacemakers.
Why Is Biophysics Important Right Now?1. Biophysics discovers how to modify microorganisms for biofuel (replacing gasoline and diesel fuel) and bioelectricity (replacing petroleum products and coal for producing electricity).2. Biophysics discovers the biological cycles of heat, light, water, carbon, nitrogen, oxygen, heat, and organisms throughout our planet.3. Biophysics harnesses microorganisms to clean our water and to produce lifesaving drugs.
Instrumentation AND Biophysical Methods. Measuring systems are used to provide quantitative information about parameters of biological importance.Such parameters may include bio potentials from muscles, neurons, eye, heart or brain, blood pressure or muscle forces. The signal may take different forms, such as being mechanical or electrical.. Electrical signals are the most popular and they have to be well treated so as to eliminate unwanted signals and amplified to be displayed
Examples of Electric Signals• Electrical potentials of nerves.• Electrical signals from muscles the electro-
myogram.• Electrical signal from the heart the electro-
cardiogram.• Electrical signal from the brain the electro-
encephalogram.• Electrical signal from the eye the electro-
retinogram and the electro oculogram.
Cardiovascular Instrumentation
• Bio potentials of the heart.• Electrodes.• Amplifiers.• Patient monitoring.• Defibrillators.• Pacemakers.
Applications Of Electricity And Magnetism In Medicine
• Electrical shock .• High frequency electricity in medicine.• Low frequency electricity and
magnetism in medicine.• Current research involving electricity
applied in the body.
Sound In Medicine
• General properties of the sound.• The body as a drum (percussion in
medicine).• Ultrasound pictures of the body.• Ultrasound measure motion.• Physiological effects of ultrasound in
therapy.• The production of speech (phonation).
Physics Of Ear And Hearing
• The outer ear.• The middle ear.• The inner ear.• Sensitivity of the ears.• Testing your hearing.• Deafness and hearing aids.
Light In Medicine
• Measurement of light and its units.• Applications of visible light in medicine.• Applications of ultraviolet and infrared
light in medicine.• Laser in medicine.• Application of microscopes in medicine.
Physics Of Eyes And Vision
• Focusing elements of eye.• Diffraction effects on the eye.• Defective vision and its correction.• Color vision and chromatic
aberration.• Instruments used in ophthalmology.
Physics Of Diagnostic X-ray
• Production of X-ray beam.• How X-ray are absorbed.• Making an X-ray image.• Radiation to patient from X-rays.• X-ray slices of the body.
Physics Of Radiation Therapy:
• The dose units used in radiotherapy are the rad and gray.
• Principles of radiation therapy.• A short course in radiotherapy treatment
planning.• Megavoltage therapy.
Heat And Cold In Medicine
• Physical basis of heat and temperature.• Thermometry and temperature scales.• Thermography mapping the body’s
temperature.• Heat therapy.• Use of cold in medicine.• Cryosurgery.
TUTORIAL BIOPHYSICS
INTRODUCTION OF ELECTRICITY
Dr : Yasser Ibrahim KhedrLecturer Assistant : Bohaysa
SalemBasic Science DepartmentFaculty of Physical therapy
Pharos University in Alexandria
Basic Electric Circuit Concepts
What is electricity?
Electricity is the set of physical phenomena associated with the presence and flow of electric charge.
cell switch
lamp
wires
Electric chargeThere are two types of electric charges – positive and negative.
Ion is an atom that has lost one or more electrons, giving it a net positive charge (Cation)Example : Sodium, Calcium, Potassium, and Magnesium
or that has gained one or more electrons, giving it a net negative charge (Anion). Example : Chloride, Sulfate, Phosphate, Bicarbonate
Movement or flow of electrically charged particles, typically measured in amperes. The unit of current is the ampere (A).
1 ampere = 1 coulomb/second
3
Basic Electric Circuit Concepts
QI=
t
Current
Voltage
a force that pushes the current through the circuit.
Suppose one coulomb of charge is located at point b and one joule of energy is required to move the charge to point a. Then we say that Vab = 1 volt = 1 joule/coulomb = 1 Newton.meter/coulomb.
5
Basic Electric Circuit Concepts
Friction that impedes flow of current through the circuit (rocks in the river)
Ohm’s Law
I = Current (Amperes) (amps)
V = Voltage (Volts)
R = Resistance (ohms)
Resistance:
Basic Electric Circuit Concepts
V=I.R
Another way to find resistance
The resistance varies directly with length and inversely with width (or cross-sectional area)
Short, thick wire small resistance Long, skinny wire large resistance
ρ.LR=
A
1ρ=
σ
r= Resistivity σ= Conductivity
Measuring Resistance
We can find the resistance of a component by measuring
voltage across the component using a voltmeter
current through the component using an ammeter
Measuring Resistance
or we can measure it directly using an
ohmmeter
Ω
Calculate the resistance of auniform wire of a diameter 0.32mm and length 5.0m , the resistivity of awire 5x10-7 Ωm
Solution
A=Pi r2
r=0.00016R=5.0 x10-7 x 5/(Pi x 0.000162)
R=31Ω
ρ.LR=
A
Example 1:
Solution
r = 0.14mm = 0.00014mL = 1.50 m, R = 45, A = 6.15x10-8
ρ = 45x(6.15x10-8 /a.5)=0.0000018=1.8x10-6 Ω .m
L=1x(6.15x10-8 /1.8x10-6 )=0.034 m
A wire of uniform diameter 0.28 mm and length a.50m has a resistance of 45Calculate1- its resistivity2- the length of wire that has a resistance of 1.0
Example 2:
Simple Circuits Series circuit
All in a row 1 path for
electricity 1 light goes out
and the circuit is broken
Parallel circuit Many paths for
electricity 1 light goes out and
the others stay on
Series and Parallel Circuits
What is the relationship between the three currents?What type of circuit is this?
The current is the same at each point.
321 III
What is the relationship between the four voltages?
They add to equal the supply voltage.
321 VVVVs How do you find total resistance in series?
Add each resistance together.
321 RRRRtotal
What type of circuit is this?
What is the relationship between the four currents?
The four currents add to give the total current.
321 IIIIT What is the relationship between the four voltages?
Each voltage is equal to the supply voltage.
321 VVVVS
The resistance in parallel?
321
1111
RRRRT
Find the total resistance of R1=2Ω, R2=5Ω and R3=7Ω if connected in series then in parallel
Solution In series
=2+5+7 =14 Ω
In parallel
=1/2 +1/5 +1/7 =1.2 Ω321
1111
RRRRT
321 RRRRtotal
Capacitors
A basic capacitor has two parallel plates separated by an insulating material
A capacitor stores an electrical charge between the two plates
The unit of capacitance is Farads (F) Capacitance values are normally smaller, such as
µF, nF or pF
Capacitors Basic capacitor construction
Dielectric material
Plate 1
Plate 2
The dielectric material is an insulator therefore no current flows through the capacitor
Capacitors
Storing a charge between the plates
Electrons on the left plate are attracted toward the positive terminal of the voltage source
This leaves an excess of positively charged holes
The electrons are pushed toward the right plate
Excess electrons leave a negative charge
A charged parallelplate capacitor.
Q = C V where C = ɛo A / d
for a parallel plate capacitor, where ɛo is the permittivity of the
insulating material (dielectric) between plates.
The unit of capacitance is called the Farad (F).
1 / CT = 1 / C1 + 1 / C2
11
Two capacitors in series and the equivalent capacitor.V = V1 + V2 and Q = C V
CT= C1 + C2 Two capacitors in parallel and
the equivalent capacitor.
Q = Q1 + Q2 and Q = C V
Two capacitors, C1= 5.00 µF and C2= 12.0 µF, are connected in parallelWhat is the equivalent capacitance of the combination?
Solution
C1=5 µF =5x10-6 F
C2= 12.0 µF =12x10-6 F
In parallelCeq=C1+C2
= 5x10-6 + 12x10-6 =17x10-6 F
Reference• Text books• First – Title: Physics in Biology and Medicine, – Author: Paul Davidovits• Second – Title: Medical Physics – Author: Martin Hollins• Third – Title: Medical Physics – Author: John R. Cameron and James G. Shofronck• Fourth – Title: General Physics – Morton M. Sternheim and Joseph W. Kane