Final

Question 1

Topic 1

1. The reasult of measurment
2. Errors
3. Mean
4. Accuracy
5. Precision
6. Standard deviation
7. SI system

Answer 1

1.Can be expressed in 3 essential elements:
- number: of giving the magnitude
- unit: in terms of which the quantity is measured
- the estimated error in the measured value
2.Systematic errors: Inaccuracy because of faulty equipment, calibration or technique. Random/statistical erros: indefinitness in result due low precision. Fluctuation in repeated experiments.
3.Expected value
4.How close the measurements comes to the real value. Low systematic error.
5.How reproducible a measurement is. Low statistical error.
6.Mean and it´s fluctations
7.International system for measures of physical units.
Length: Meter, Time: Seconds, Mass: Kilograms, Electric current: Ampere, Temperature: Kelvin, Luminous intensity: Candela, Amount of substance: Mole. All others are “derived quantities”

Question 2

Topic 2

1. Macrotransport
2. Ideal fluids
3. Archimedes principle
4. Continiuty

Answer 2

1. Transport of fliud´s/material over large distances, in tubes and vessels. E.g.respiration and circulation
2. Are incompressible and has no frictation
3. A body immersed in a fluid is acted upon by an upward force (B) (bouyant force) equal in magnitude to the weight of displaced fluid.
4. If more fliuds enter in one end of a fliud filled tube, an equal amount of fliud must enter the other end

Question 3

Topic 3

1. Bernoullis equation
2. Manometer
3. Cannulation
4. The role of gravity in the circulation
5. The effect on upward acceleration on the BP.
6. Dynamic consequences of Bernoullis equation
7. Pressure changing in narrowing artery

Answer 3

1. States that, where:
   - points 1 and 2 lie on a streamline
   - the fluid has constant density
   - the flow is steady
   - there is no friction
2. Measure pressure with the help of a fluid in a U-shaped tube where one is connected to a sealed container.
3. Like a manometer where the artery works as a sealed container.
4. When standing, the pressure is very diff. at diff. heights in the body. E.g. feets, heart and brain. Important for the brain that the flow rate are constant.
5. Could cause loss of consciousness because of collapse of vessels in the brain.
6. Giving that where the velocity of the fluid is higher the pressure is smaller. And where the area is smaller and velocity constant, the pressure is higher which gives a dangerous situation (in e.g. blood vessels).
7. The artery closes, flow stops, KE disappears and pressure builds, etc.

Question 4

Topic 4

1. Flow of viscous fliuds
2. Laminar flow
3. Parabolic velocity profile
4. Poiseuille´s law
5. Power of maintaining the laminar flow

Answer 4

1. Viscous fluid: fluid with internal friction. Higher viscosity; higher force required to maintain the flow. Viscosity depends on fluid and temp. Higher temp->less viscosity->gaseous viscosity up
2. The fluid in a tube consist of several layers, and the closer it is to the centre-the higher velocity. A flow is often laminar when the velocity is low.
3. Shows that velocity is highest in the middle, and gradually decreasing to the wall.
4. Indicating:
   - high viscosity->low flow rate
   - the flow rate is proportional to the press.
   - the flow rate is proportional to the R4
5. It is equal to the power taken by the friction between the tube and the fluid.

Question 5

Topic 5

1. Turbulent flow
2. Reynolds number
3. Measurement of blood pressure by Sphygmomanometer

Answer 5

1. Above a critical pressure, the laminar flow becomes complicated flow that is swirling
2. Determines whether a flow is laminar or not
3. Turbulent flow gives a noice in the arteries. Inflate the air stack until the artery is fully closed and then slowly let out the air again while you are listening to the arteries with a stethoscope.

Question 6

Topic 6

1. Viscous drag force
2. Stokes law
3. Measurement of the viscosity

Answer 6

1. Forces that try to retard an object in a flow.
2. Gives a nr. of the force of viscosity on a small sphere moving through a viscous fluid.
3. Fill 2 identical capillaries with 2 diff. fluids (e.g. water and blood). Then you can do a ratio between the fluids. Höppler´s viscometer and Hessler´s viscometer.

Question 7

Topic 7

1. Flow in the circulatory system
2. Transmural pressure
3. Law of Laplace
4. Work of the heart
5. Flow in elastic tubes
6. Non-Newtonian fliuds

Answer 7

1.The blood is considered as a uniform fluid. The cardiovascular system goes from heart to big arteries and branching on to smaller and smaller arteries and then capillaries and then gets bigger again in the venes.
The total cross-section of the capillaries are several 100 times larger than the great arteries but the flow resistance is much higher.
2.The pressure across the blood vessels wall
3.Tension is related to the pressure and the radius of the tube.
4.Work done by the left and right side of the heart. Proportional to the pressure and the volume.
5.Elastic walls absorb some Kinetic energy, transform it into elastic energy, causing more fliud to flow through an elastic tube over time.
6.Pseudoplastic fliuds. Will change viscosity when accelerating. Only air and water are Newtonian within the body.

Question 8

Topic 8

1. Diffusion
2. Diffusion constant
3. Fick´s 1.law
4. Fick´s 2.law
5. Medicine injected in the vein
6. Gas exchange through the alveoli-capillary membrane

Answer 8

1. A spontaneous proc. where molec. goes from high conc. to low conc. => equalizing the conc. E.g. in body, oxygen in the lungs. Are caused by that the random, thermal motion.
2. Depends on the temp, viscosity, Mr. and shape.
3. The diffusion per time unit is depending on the area, conc., the distance and a diffusion coefficient.
4. Showing the change of diffusion per time.
5. The equation allows vision of how far an injected medicine travels with time. The longer times that goes, the slower diffusion. It’s inverted proportional to the time. It’s the same amount of particles but not as quickly.
6. The oxygen diffusion goes very quickly, 0.3s. This makes it possible to exchange gases despite the high velocity of blood in the capillaries.

Question 9

Topic 9

1. Osmosis
2. The osmotic pressure
3. Isotonic solutions
4. Hypotonic solutions
5. Hypertonic solutions
6. Van Hoff´s law
7. Measurement of osmotic pressure

Answer 9

1.Diffusion of water through a semi-permeable membrane. Water will go to the concentrated solution.
2. The pressure difference needed to stop the flow of solvent across a semipermeable membrane. The osmotic pressure of a solution is proportional to the molar concentration of the solute particles in solution.
3.Solutions with an equal conc. No change in pressure. Only sol. used for infusions.
4.Inner sol. has higher conc., so water streams in. E.g. hemolysis - cell explodes.
5.Outer sol. has higher conc., so water leaves. E.g. plasmolysis - cell shrinks.
6.The osmotic pressure (Π) of a solution containing (n) moles of solute particles in a solution of volume (V).
7.Direct: Pfeffer osmometer; measure the height diff. in a cylinder connected to a solution by a membr.
Indirect: The osmotic press. can be calc. by measure the freezing or boiling point changes.

Question 10

Topic 10

1. Structure of cell membrane
2. Passiv diffusion
3. Membrane permeability
4. Correlation between the membrane permeability and the lipid solubility
5. Faciliated diffusion
6. Mechanism of faciliated diffusion
7. Active transport

Answer 10

1. Phospholipid bilayers with proteins. The lipids have one hydrophobic and one hydrophilic part. The bio. membr. are semipermeable.
2. Don’t req. energy. The membr. contain small pores where some molec. goes through.
3. It’s selective for diff. molec. Larger conc.diff.->faster diffusion. Thicker membr.->slower diffusion. Can determine the permeability by using the Fick’s law.
4. There is a definite correlation. They are proportional to each other.
5. Diffusion with the help of membr. components. No energy required. Has 4 diff. compared to passive diffusion: much faster, saturating-the solution gets more and more saturated, specific and can’t be inhibited.
6. The molec. forms a complex with a carrier molec. which goes through the membr. and there release it. The carrier molec. can’t leave the membr. but move easily inside it. Could be moving or immobile.
7. Transport against conc. gradient. Need extra energy. Hydrolysis of ATP to ADP.

Question 11

Topic 11

1. Sedimentation
2. The sedimentation velocity due to gravitation and in a centrifuge
3. Sedimentation coefficient
4. Centrifugation
5. Ultracentrifugation
6. Analytic and preparative ultracentrifuges

Answer 11

1.Used to differentitate substances, because it is depending on the radius of the sphere.
2. Affected by radius, viscosity, gravity and density.
3.The sedimentation propertiy of a particle.
4.Rotation of an object gives an outward going force, a centripetal acceleration.
5. A centrifuge with a extreme high angular velocity.
6. Analytical: ere equiped with an optical device to determine conc. distributions at any time during the measurment.
Preparative: fractionation of the content and measurment of each fraction.

Question 12

Topic 12

1. Determinations of molecular mass by desimentation-diffusion and sedimentation equilibrium methods.
2. Density gradient centrifugation

Answer 12

1.Sedimentation-diffusion method: the molec. mass is determined by combining the sedimentation coefficient and the diffusion coefficient. And extract the mass from the formed equation.
Sedimentation equil. methods: A low speed centrifugation where the sedimentation is in equilibrium with the counteracting diffusion.
2.Is used when you want to separate particles with diff. density. Use a medium with difference in its density (e.g. heavy metal salts). The part of the solution with higher density gather further from the center, and collecting those particles with same density as themselves.

Question 13

Topic 13

1. Geometric optics
2. Concept of the light ray
3. Rules of reflection and refraction
4. Relative and absolute index of refraction
5. Total reflection
6. Fiber optics
7. Light pipes
8. Light path in plane-parallel slab
9. Refraction in prism
10. Deflection of light by a small angle prism
11. Disperions of light

Answer 13

1.Describes light propagation in terms of rays. Used when the wavelight is short than the tools studying them and energies are negligible.
2. Transv. electromagnetic waves. Concept: Light propagate along a straight line, betw. 2 mediums the light reflect and/or enters the medium, the light path is reversible.
3.On a smooth surface the incident ray and the reflected ray has same angle. The angle of the refracted ray depends on the medium.
4.A measurement of how the medium is refracting light. The index of refraction is depending on the wavelength.
Defined by Snell’s law.
5.None of the incident ray enters the second medium. The angle of refraction is 90°. No energy loss.
6. Total internal refraction through a pipe.
7.Small pipe where light is totally, internally reflected in order to travel long distances with no attenuation.
8.If a ray crosses it, and it’s the same medium on both sides of the slab, the angle of the ray is unchanged but moved a distance proportionally to the thickness of the slab.
9.Since the walls of the prism is angled, the light is bending several times, according to Snell’s law.
10. The smallest deflection angle will be found in a symmetric light path case.
11.The index of refraction is depending on the wavelength of incident light ray. If it has several wavelength they will be separated in a prism and come out as a spectrum. Every part of the spectrum is monochromatic light.

Question 14

Topic 14

1. Optical image formation
2. Real and virtual images
3. Real and virtual objects
4. Image formed by a plane mirror
5. Thin spherical lenses
6. Focal points of the lens
7. Lens-maker equation

Answer 14

1. If diverging rays from a point called object, cross each other after reflection/refraction, this crossing-point is the image of the object.
2. Real images; an image where the object is where it seems to be. Virtual image; an image where the object is not is where it seems to be-the rays has been changed like with a mirror.
3. Most objects are real, the rays are coming from the location of the object. Virtual objects occur in multicomponent systems with 2 lenses or mirrors.
4. The image in a mirror is the point where the reflected light rays point at.
5. Has a small thickness compared to its radius. Can be converging or diverging.
6. Converging lens; in front-pos. value. Diverging; “behind”, where the diverging rays should “hit” each other-neg. value.
7. Calculates the focal length of a lens in air.

Question 15

Topic 15

1. Image formation by lenses
2. Ray tracing method using 3 special light rays
3. Thin lens formula

Answer 15

1.Converging lens bends light rays toward its axis, so the beam of parallel rays converges at a point (convex lens), a diverging lens bends rays outwards from its axis (concave lens).
2. Three light rays from an object are easily predictable:
-One parallell with axis - through the focus point.
-One through center of the lens - don´t change direction
-One through the “neg.” focus - when it hits the lens it goes parallell with the axis.
Where the 3 meet: image.
3. (formula) Object dist. is pos. for real objects and neg. for virtual. Image dist. is pos. for real image and neg. for virtual.

Question 16

Topic 16

1. Combination of thin lenses-lens system
2. The equivalent focal lenght of thin lenses in contact
3. Lens abberations
4. Six cardinal points for thick lenses
5. Ray-tracing for thick lenses

Answer 16

1. If you have several lenses, let the image of the first lens be the object for the following lens and so on. If the lenses are in contact, add up their powers.
2. Identical with the third one - given by an equation where the two powers of the lenses is added together.
3. Limitations of the sharpness. Spherical aberration; diff. focus in the centre and outer parts. Chromatic aberration; if the light has several wavelengths, the index of refraction will split the rays, which will have diff. focuses. Astigmation; the lens don’t focus light beam to a point but produces 2 images at diff. distances.
4. Focal points; F, F`, principal points; P1 and P2 and Nodal points; N1 and N2.
5. The real light path inside the lens can be ignored. Use the cardinal points.

Question 17

Topic 17

1. The human eye
2. Light path inside the eye
3. Role of the lens
4. Far and near points
5. Accomodation width
6. Visual acuity
7. Sensitivity
8. Colour perception
9. Optical defects of vision

Answer 17

1. Field of view is over 180 degrees. Intensity range of 10^9. Resolution close to limit and determined by wavelength.
   2.The light receptors are rods and cones situated on the retina. Blind spot where the optical nerve leaves the eye.
   Yellow spot where we have the best vision.
2. Provide fine adjustments to the focus of objects at diff. distances.
3. Far: furthest point an eye can focus, infinity for norm. eye. Near: for norm. adult 0.25 cm.
4. Ability to shift from a very short focus distance to infinity.
5. Finest detail that can be seen of the eye.
6. Minimum intensity needed to see a light depends on the wavelength.
7. Only cones register colours. 3 kinds, each w. their own pigment; red, blue and green.
8. -Emmetropia: norm.
   -Myopia: short-sightedness
   -Hypermetropia: long-sightedness
   -Presbyopia: old sight
   -Astigmatism: can focus rays better in some planes than others

Question 18

Topic 18

1. Simple magnifier
2. Principle of compound microscope
3. Image formation of - | -
4. Optical tube length
5. Magnification of the microscope

Answer 18

1. Object placed just inside focal point of the converging lens.
2. Has 2 lenses; objective and ocular.
3. The ocular magnifies the image some more and focus into the retina of the eye. Fives a convenient working height.
4. The dist. betw. the focal points and the two lenses.
5. Limited by resolution. Depends on wavelength of light.

Question 19

Topic 19

1. Wave nature of light
2. Basic wave features
3. Sinusoidal waves
4. Phase
5. EM spectrum

Answer 19

1. Transv. EM wave with changing el. and magn. fields.
2. -Frequency: nr. of waves per sec.
   - Period: time betw. 2 waves.
   - Wavelength: dist. betw. 2 peaks
   - Speed: wavelength per time
   - Amplitude: max. magnitude
   - Intensity: proportional to the square of the amplitude(I~A2 )
3. Waves with sinus or cosinus function. Repeat themselves every 2π rad.
4. Phase is the particular point in the cycle of a waveform, measured as an angle in degrees
5. Differ in wavelength only.
   - X-rays, gamma-rays and UV:700 nanom.
   - T. human eye is most sensitive to wavelengths : ~550 nm

Question 20

Topic 20

1. Principle of superposition
2. Interference of waves (light)
3. Concept of light front
4. Huygens-Fresnel´s principle
5. Diffraction of light on narrow slit
6. Requirement of visible interference
7. Coherent waves
8. Light diffraction by circular aperture
9. Diffraction disk R

Answer 20

1. When several waves are passing through the same point it’s the sum of the individual waves that forms the curve.
2. When 2 waves overlap, the can cancel, weaken or enforce each other. Depends on phase diff.
3. Surfaces where the diff. waves are in phase at every point. Spherical or plane.
4. States that each point on a wave surface can be considered as a source of secondary wavelets and the observed light intensity on a certain point is determined by the interference of these wavelets
5. A single frequency light passes through 2 narrow spaces next to each other and becomes a serie of light and dark bands on a screen. Allows to determine wavelength of light.
6. Laser
7. Phase diff. betw. interfering waves remaining constant over a long period of time.
8. Bright central region with light and dark bands surrounding it.
9. Airy disk. The image of an object point, an area with a “focus” where the image is more clearly.

Question 21

Topic 21

1. Resolving power of optical devices
2. Rayleigh´s criterion
3. Resolution of microscope
4. Abbe´s criterion
5. Numerical aperture of a microscope
6. Immersion microscope
7. UV microscope

Answer 21

1. Ability to see diff. objects sep. Expressed in formula.
2. The point where resolution is obtained is where the central maximum of one airy disk fall onto the first minima of the other airy disk.
3. Expressed by the resolving power.
4. At least 2 beams should enter into the objective to see detail in a microscope.
5. Resolving power increases with numerical aperture and with decreasing wavelength.
6. To incr. the numerical aperture and hence the resolving power, a drop of oil with high refractive index is put betw. the objective and the object.
7. Uses smaller wavelengths to improve the resolving power.

Question 22

Topic 22

1. Wave property of matter
2. The principle of electron microscopy
3. The wavelength of an electron accelerated by an electric potential difference
4. Transmission microscopes
5. Scanning electron microscopes

Answer 22

1. Like light.
2. Uses small wavelength of electrons to create an image. Shoots electrons on the object with a electron gun. The electrons are focused with magnetic lenses.
   3.Has a de Broglie wavelength of λ
3. Requires a very thin sample, less than 100 nm thick.
   Excellent resolution but no 3D structures because of the thin sample. Staining with heavy metals used to improve contrast. Entire microsc. must be in vacuum-dead sample.
4. Electrons from el.gun. focused to a small spot and swept across the sample. An el. detector counts the el. knocked out of the sample-secondary electrons. The nr. of el. changes with composition and orientation of the sample. Resolution is reduced but 3D structure seen.

Question 23

Topic 23

1. The photoelectric effect
2. The main experimental observations
3. The photon concept of Einstein
4. The photoelectric Einstein’s equation
5. The photoelectron multiplier

Answer 23

1. Release of el. from a metal surf. when illuminated by a light of certain wavelength.
2. -The max. kinetic energy of the emitted electrons depends on the frequency of light only.
   - For a given frequency and retarding potential, the intensity of the photocurrent is proportional to the intensity of light
   - The photocurrent starts to flow almost instant once light „hits” the cathode.
   - For any material there is a cut-off frequency below that no el. are emitted by the influence of light, no matter how high is its intensity.
3. Light is made up of particles (photons). Photons collide with individual electrons.
4. The “work of release” that has to be done for leaving a particular metal.
5. An el. is released and accelerated against another metal causing more el. all the way to the detector.

Question 24

Topic 24

1. Interaction of light with matter
2. Light emission
3. Rayleigh, Raman and Compton scattering
4. Absorption
5. Photoluminescence: fluorescence and phosphorescence.
6. The law of light attenuation in matter
7. the Beer-Lamber law
8. transmission, absorbance, optical density

Answer 24

1.Light emission is connected with changes in the state of outer electrons. X-radiation is a consequence of a change in state of the inner more strongly bound electrons.
2. When an electron goes from an excited state back to its ground state it releases energy in form of light. 2 ways: spontaneously or stimulated.
3. Light of any frequency may produce scattering.
Coherrent: emission of a photon with same frequency as the incoming. High probability. Raman scattering: emission of photons with higher or lower frequency. Very low probability. Compton scattering: the photon collides with a free electron and change its energy.
4.If the frequency of the incoming photon is just enough to raise the energy state to a higher level it will be totally absorbed.
5. Fluorescence: the el. goes from the excited to ground level direct. Phosphorescence: the el. goes from the excited to ground level via intermediate levels.
6. If light of intensity passes through a substance of thickness, the intensity of the transmitted light obeys the Lambert law.
7.Relates the attenuation of light to the properties of the material through which the light is traveling.
8.Absorption data is reported as either % transmission or A absorbance, which is commonly called the optical density.

Question 25

Topic 25

1. Principle of lasers
2. stimulated emission
3. inverse population
4. properties of laser lights
5. types of lasers
6. medical applications of lasers

Answer 25

1. Light Amplification by Stimulated Emission of Radiation.
2. If one atom emits a photon, that photon can collide with a second atom that is in a excited state and stimulate it to emit a photon resulting in 2 coherent photons.
3. More atoms in the upper state than in the lower state.
4. Monochromatic, coherent, directed and well focusable.
5. Lasers with fixed wavelength or tunable laser. Continous or Pulsed lasers
6. Corneal surgery, destruction of small tissue and coagulation of tissues.

Question 26

Topic 26

1. Production of X-rays
2. Properties of X-rays
3. The effects of X-rays
4. The X-ray spectrum (bremsstrahlung and characteristic X-rays)

Answer 26

1.When el. stops after striking a target at high velocity they release energy (mainly heat, some radiation).
2.High penetrating power, short wavelength (hard)
3.Ionization, luminescence, photographic, chemical effects and bio.effects.
4. Bremsstrahlung: prod. by el. colliding with the atoms. The power of radiation depends on voltage, electron current and atomic nr. of the target.
Characteristic X-rays: The el. ionize the inner atomic shells of the atom and during the rearrangement X-rays are emitted.

Question 27

Topic 27

1. Attenuation of X-rays in matter
2. The attenuation coefficient
3. The mass-attenuation coefficient
4. Photoeffect
5. Compton scattering
6. Pair production

Answer 27

1. X-ray intensity decr. similar to that of lights.
2. µ - dep. on material of medium and E of the x-ray.
3. µ/p - dep. on atomic nr. of medium and x-ray-E.
4. X-ray gives E to an el. of an inner shell.
5. The ray hits an el. and splits into 2 rays with smaller energy.
6. The photon becomes an el. and a positron.

Question 28

Topic 28

1. The behaviour of cells: tissues when low or high external electric current flows through
2. their passive electric properties
3. the Ohm’s law
4. the impedance of a resistor and a capacitor
5. harmful physiological effects of electric currents

Answer 28

1.High currents can lead to damage/death.
2.At low current intensities living matter behaves as passive elements in ordinary electric circuits (resistors, capasitors etc.)
3.States that the current through a conductor between two points is directly proportional to the voltage across the two points.
4. Resistance or capacitance cause impedance-resistance in a circuit. Capacitor: a pair of conducting sheet sep. by an insulating layer. Resistors: not good conductors such as membrane compared to fluid. The tissues and especially the membr. have electric capacity and by their impedance we can obtain physiological conditions.
5.Frequencies betw. 30 and 300 Hz are especially harmful.
Household frequency: 50 – 60Hz
It’s mainly the intensity of the current that is dangerous.

Question 29

Topic 29

1. Active electric properties of living matter
2. Excitability
3. Resting potential of cells
4. diffusion potentials
5. Donnan potential

Answer 29

1. Excitable cells in e.g. muscles and nerves.
2. Necessary for the living organism to adapt to the enviroment. The electrical potential in a cell is measured between the cytoplasm, intracellular, and the extracellular regions.
3. Electrical potential in resting cells. Depends on cell type and organism, but gen.

Question 30

Topic 30

1. The electrochemical potential
2. The Nernst-equations
3. comparison of the calculated and measured resting potentials,
4. ion currents across a typical mammalian axon membrane
5. the Na-K pump,

Answer 30

1. The sum of the electrical and chemical potentials. Depends on gas constant, faraday constant, absolute temp. and el.pot.
2. Gives a formula that relates the numerical values of the concentration gradient to the electric gradient that balances it.
3. The calculated values are not allways good, because the cell is not a closed system. The membr. puts some resistance against mobile ions. Depends on comp. of membrane. Consideres only 1 type of mobile ions at a time.
4. Ic: Ionic current due to conc. diff. Ip: Ionic current due to potential diff.
   - Na+: Both Ic and Ip are directed into the cell but the conc. is bigger outside: Must cont. be brought back against the differences.
   - Cl-: Ic = Ip, they compensate each other
   - K+: Neg. pot. in the axon. Must be returned to cell.
5. Pump Na+ out of the cell and K+ into the cell with energy from ATP.

Question 31

Topic 31

1. Changing the resting potential
2. Response to a weak stimulus
3. The action potential
4. Propagation along a non-myelinated axon
5. Propagation along a myelinated axon

Answer 31

1. When the membr. is at rest, the resting pot. is neg. due to more sodium ions outside the cell than potassium ions inside. The axon can conduct el.impulses away from the neuron´s cell body to change it.
2. Smaller than a critical threshold(-50mV), no significant axon pot. changes beyond a fem mm.
3. Stimulus above ~-50mV, shortly after the axon pot. incr. and become pos., reaching as high as +50mV. T. potential then gradually returns to resting value. T. action potential is not proportional to t. stimulus, It’s a “all-or-nothing” response.
4. Na+ permeability increases and a lot enters the cell. Pot.diff. becomes pos., inflow slows and permeability decreases again. K+ permeability goes up and flows out fast. Pot.diff. back to normal.
5. Travels faster, because of the few Na+ ions that get through the myelin sheat and at the nodes of Ranvier. The action pot. prod. a flow of pos. ions away from the node inside the axon and towards the node outside, reaching the next node and trigger next action potential at that node.

Question 32

Topic 32

1. Measurement of the membrane potential
2. electric measurements
3. voltage clamp technique
4. patch-clamp technique
5. optical measurements of the membrane potential

Answer 32

1. Can be measured by 2 diff. methods: Electrophysiological methods (electric measurments) and potential sensitive staining (optical spectroscopy).
2. If the cell is thick enough to insert the measuring electrode the membr. pot. could be measured directly. Mostly it is to thin - need to use microelectrodes.
3. To avoid pot. change. Measures it cont. by putting in an equal but opposite current that will balance the membr.pot.
4. Make it possible to measure a channel sep. A patch pipette sucking slightly at the cell membrane and measure only the current flow through the patch.
5. Specific stains or dyes used. 2 types:
   - El.pot.sensitive dyes: change their spectroscopic properties in electric field.
   - El.charged dyes: have neg. or pos. charge and are distributed on the two sides of a membrane. If the membr. potential change the dye distribution will do the same.

Question 33

Topic 33

1. Body surface biopotentials
2. electrocardiography (ECG)
3. the heart cycle
4. the Einthoven triangle
5. a typical Lead II ECG signal
6. Wilson-type arrangement
7. electroencephalography (EEG)
8. classification of the EEG signals (δ, Θ, α and β waves)

Answer 33

1.Weak el.signals detectible on the body surf.
Divided by their origin:
-Muscle movement => electromyogram (EMG)
-Heart operation => electrocardiogram (ECG)
-Brain operation => electroencephalogram (EEG)
-Eyes => electroretinogram (ERG)
2.The rythmical action of the heart controlled by electrical signals. Initiated by spontaneous stimulation of sinoatrial node (pacemaker in right atrium).
3.SA node initiate depolarization of nerves and muscles of both atria causing the atria to contract and pump blood into the ventricles. Repolarization follows. The signal then passes into the atrioventricular(AV) node, which initiate the depolarization of the ventricles causing them to force blood into the pulmonary trunc and general circulation. The ventricles nerves and muscles repolarize and the sequence begins again.
4.Most common locations of electrodes: right arm(RA), left arm(LA) and left leg(LL).
5. (graph) -0.25s: small increase-depolarization. 0.5s: high peak-ventricle depolarization and contraction. Just after peak-another small increase-ventricle repolarization. Begins again.
6.The RA, LA and LL electrodes are connected to a common point of a constant potential, considered as zero potential = the indifferent electrode.
7. Electrodes on the scalp, to measure elect. activity.
8. -α: Resting phase - 8-13Hz
-β: Brain activity >13Hz
-δ: Observed very seldom (e.g. deep sleep) 0.5-3.5Hz
-θ: Ill conditions 4-7Hz

Question 34

Topic 34

1. Structure of cathode-ray oscilloscope.
2. operation of cathode-ray oscilloscope.
3. High frequency electric diathermy (the capacitance method, the inductance method and microwave diathermy)
4. high frequency electric surgery

Answer 34

1. Used to study ECG, EEG. El. gun(cathode) with an accelerating anode. Horizontal and vertical deflection plates. Finally a flourescent screen that the el. are hitting and produce a light.
2. With no electric field there are only a bright spot on the screen. With a field the spot moves and creates a pattern on the screen. The pattern is based on the pot. diff. which prod. vertical deflection. With the horizontal “sweep” you adjust the frequency so that the signal repeat itself on the same spot, creating a stable pattern.
3. Electric power transferred into heat in the body tissue at high frequencies.
   - Capacitance: the tissue is placed between 2 capacitors with a oscillating electric field making the ions in the tissue move
   - Inductance method: the tissue is placed within/near the inductor which prod. alternating magnetic fields.
   - Microwave diathermy: the tissue absorbes electromagnetic waves that are upon it.
4. Using a probe to rapid boil cell fluids => explosions of cells

Question 35

Topic 35

1. Natural radioactivity
2. alpha, beta and gamma radiation
3. composition of the atom
4. composition of the atomic nucleus
5. definition of isotopes
6. size and binding energy of nuclei
7. possible way to gain nuclear energy; fission and fusion

Answer 35

1.Emit high penetrating invisible radiations without any external influence.
2.-α-radiation: positively charged particles (e.g.He2+)
-β-radiation: electrons
-γ-radiation: neutral EM radiation(e.g.light, X-rays)
3.Positive charged nuclei surrounded by an electron cloud.
4.2 kinds of nucleons: protons and neutrons. Protons: pos. charged (equal to el. but opposite sign). Neutrons: Electrically neutral. A nucleus is specified by:
- Atomic number Z - nr of protons
- Mass number A, nr of nucleons.
Nr. o. neutrons N = A-Z
5.Same atomic number but diff. nr. of neurons.
6.Size very small compared to atom. 3 types of interactions:
- Strong interactions: Holding nuclei together
- EM forces: Has infinite range
- Weak interactions: Are responsible for certain nuclear transformations
7. Fission of heavy nuclei or fusion of light nuclei will lead to energy being released.

Question 36

Topic 36

1. Properties of radioactivity
2. the radioactive decay law
3. decay constant
4. half-life
5. biological and effective half-life
6. radiocarbon dating
7. nuclear reactions
8. chain reactions
9. transmission of nuclear radiations (α, β and γ-radiation, neutrons) through matter and their ionising capabilities

Answer 36

1. Natural; caused by instability in nuclei. Artificial; result of unstable isotopes from nuclear R.
2. Predicts how the nr. of the not-decayed nuclei decreses in time.
3. The λ proportionality constant
4. Time required for half of the nuclei present to decay.
5. Estimates the rate of excretion in two diff. formulas.
6. 14C is always present in the environment and ingested by all living organisms. When the organism dies, the 14C intake stops and begins to decay. By measure the amount of 14C we can calculate the date of death.
7. A nucleus is changed by the interaction with an other nuclear particle.
8. A neutron divides a large atom and give rise to energy and more neutrons which each one of them will give rise to an other division resulting in several divisions at the same time and so on…
9. When radiation passes through matter it leaves a trail of ionized atoms along its path.
   - α: small mass, long range, specific ionization
   - β: higly penetrating, no definite range
   - γ: short range, straight path, ion-pair distribution
   - neutrons: deeply penetrating, interacts with nuclei, indirect ionization, long range

Question 37

Topic 37

1. Radiation units (source activity, radiation exposure, absorbed dose, dose equivalent, effective dose)
2. The biological effects of ionising radiations, “transferred energy – induced effect” non-proportionality

Answer 37

1.-Source activity: nr. of decays in unit time. Unit: Bequerel
-Exposure: amount of radiation reaching the material. Only defined for X-rays and gamma-rays. Unit: 1 Röntgen
-Absorbed dose: the amount of radiation absorbed in the material from the beam. SI-unit: gray (J/Kg)
-Biologically equivalent dose: the effect of radiation on bio. system depends on type of radiation, its energy and quality factor. Unit: SI-unit: Sieverts, Sv (J/Kg)
-Effective dose: the weighted sum of the dose equivalent of diff. organs.
2.Non-proportional to E transferred.
If the whole body is exposed to 0.25C/Kg-death.
The molecules essential structures gets changed-can`t function properly anymore.
Some cells/tissues more susceptible than others.
Many Gross effects.

Question 38

Topic 38

1. Stochastic effect
2. Deterministic effects
3. .basic principles of radiation protection (justification, optimization (ALARA), dose limits)
4. gas filled radiation detectors
5. the scintillation detector

Answer 38

1. Frequency of damage but not severity depends on dose without threshold. Heritable and carcinogenic.
2. Damage that result from the collective injury of many cells in the affected tissues. E.g. Cataract of the lens.
3. -Justification: should provide more benefit than detriment
   - Optimization: It means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as is practical. ALARA: As Low As Reasonably Achievable
   - Dose limits: primary dose limits with respect to average industrial risk which limits should not be exceeded.
4. Ionisation chamber, proportional chamber, GM counter – All has same design but different voltage ranges
5. Scientillation crystal and a photomultiplier (radiation released, multiplies in chamber, then measured)

Question 39

Topic 39

1. The radioactive tracer method
2. preferences in the selection of radioisotopes
3. In vitro and in vivo uses of radioisotopes
4. radioimmunoanalysis (RIA)
5. diagnosis of the thyroid gland

Answer 39

1. Radioactive isotopes movements, accumulation and fate traced by radiation. Because they form comp. the same as stable isotopes they can be used tol bael a mol./comp.
2. -Minimum exposure to organs.
   - Short half-life-mainly gamma-radiation is advantageous.
   - Harder Y-rays (less E in tissue).
   - Technetium isotope obtained via moly cow R.
3. In-vitro: used to determine amounts of hormones. Mainly RIA. In-vivo: diagnostic of thyroid gland (iodine-uptake measurement)
4. E.g. known quantity of labelled antigen added to blood serum - some bind to antibodies within the serum. These complexes is extracted - radioactivity measured and amount of initial antigen determined with calibration.
5. NaI adm. orally, then scintillation counter used to measure the radioactivity.

Question 40

Topic 40

1. Ultrasound
2. reflection of ultrasound
3. the Doppler effect
4. the effects of ultrasound
5. diagnostic use of ultrasound
6. echoencephalography

Answer 40

1.Frequency above 20000 Hz. Longitudinal mechanical waves, can´t propagate in vacuum.
2.Mostly the ultrasound is sent in short pulses and betw. the pulses the reflection is measured by the emmitting device. The reflection depends on the density differences.
Shorter wavelength => larger attenuation.
3.The observed sound is depending if the source or observer are in motion and at which direction they are moving.
4.Heat effect (vibration transformed to heat), cavitation,
emulgation and dispersing effect, chemical effect (water ionized and excitated-OH, OH-, H+ etc. are prod.), biological effect (bacteria, viruses, fungi, smaller organisms killed)
5.A-scan: the oscilloscope display the emitted pulse and then also the reflected pulse. B-scan: a spot will be observed only at reflected pulse
6.An A-scan taken to find the midline betw. the hemispheres of the brain.

Question 41

Topic 41

1. Conventional linear and axial tomography
2. computer tomography.
3. Image formation using radioisotopes
4. the rectilinear scanner
5. the gamma camera
6. thermography

Answer 41

1. Conventional linear: x-ray tube+film linked together. Object in plane of cut casts shadow appears as a image.
   Axial: Image of a slice of the body. Film and tube rotate around the patient. Improved by CT.
   2.Improves resolution via repeatedly crossing paths.
2. To examine functions of organs and glands.
   4.Measures radiation distribution. Detector moves over a pattern over the target area, which gives a image.
   5.Measures amount of gamma radiation in a large area. Carries out scans quickly. Used to diagnose diseases in many organs.
   6.Infrared used to form image based on the body surface temperature - influenced by internal metabolic proc. and ext. factors.

Question 42

Topic 42

1. Positron emission tomography (PET)
2. nuclear magnetic resonance (NMR) imaging

Answer 42

1.A radionuclei that decay through positron emission are introduced into the body. Gamma-rays are prod. when the positrons encounter and annihilates with el. E carried away by emitted x-rays.
2. Uses the fact that many nuclei behaves in magnetic fields as small magnetic dipols.
A resonance occure and can be orientated. In diff. tissues the atoms behaves diff. giving a possibility to give a image of the diff. tissues.