Four questions where you had to write something down and/ or sketch:
#) Active Ion channels?
#) Respiratory pump?
#) pRobing depth?
#) bronchial sounds vs. vesicular sounds
After 12-15 min the first people are called for the oral examination (3-4 questions in 5 minutes).
There are the grades:
1 (here you should know the answer for the questions he is asking you and also the written part should be quite good)
2 (not so many mistakes allowed, but still you can be on the wrong track)
3 (you know a little about everything, but you can make some mistakes)
and "do you want to come again?"
About the written one: It´s only one pages and you should keep it short. Sketches, keywords, schematic stuff- that´s fine. All you need. Really. Just on the surface.
Now the oral questions as far as I wrote them down for you:
1) Difference between inner and outer hair cells.
2) How is the radius and the blood pressure connected?
(p is prop. to r²) Sketch it.
Why is it like this? How are the arteries build up? (elastin for low pressure, kollagen for high pressure, muscle)
3) Inverse Respiratory pump.
4) Difference between pReflectionobing depth and peneTransmissonration depth?
5) Difference between A-delta and C- fibres? (Pain)
6) Draw an phatological EKG (in this case: AV-node is missing- where would you see the difference?)
7) Differences between primary and secondary sensing cells? Difference in function?
(primary need strong trigger, secondary need ATP as energy source).
Tell 2 examples for each: primary: everything relataed with heat: touch, pain, heat, but also smell. Secondary: vison, hearing, taste: all that is high sensitive
8 ) Vesicular (sound only during inspiration!!) vs. bronchial sound.
9) Shortly explaine betha- dispersion.
10) Sounds of heart?
frequency changes and amplitude are important! + why are they occuring
11) Why we need smooth muscles?
Want to control the blood pressure. 1/r^4-law. If we have half the radius, we have 16x the resistance!
12) Scattering? Kinds of scattering?
(Mie-anisotropic, Rayleigh-isotropic). Do we want scattering? Yes, but only for reflection, not for transmission!.
Blue light is scattered more, therefore the sky appears blue.
13) Relationship between puls transit time and blood pressure?
(Inverse linear). How long does the blood takes? (160ms for 80cm and 5m/s). What is the puls transit time?
14) Compartmental model of tissue? Does the venous blood change during inspiration?
(pulsatile arterials blood/ non-p. art. blood/ venous blood/ bloodless tissue)
(Sure it changes, as more blood is in the lungs when they expand. Therefore a stronger transmission signal and less absorbtion...)
15) How does an Osmorezeptor works? Why we need it?
(Saltreceptor, osmotic pressure,...)
16) What is your choice of frequency for an EFPG/ electrical biosignal?
(Not to high and not to low. If to high- we can´t distinguish the different kind´s of tissue <-- see graph in script!, if too low, we might risk to stimulate the nerves <-- 50Hz Problem)
17) 2 Electrodes vs 4 Electrodes. Why 2 electrodes have movement artefacts and 4 electrodes not anymore?
18) Strokevolume of the heart and bloodflow?
(80ml, 5-6l/min, I guess)
19) Interrelation between the Heart Rate Variability (HRV) and the Parasympatic Nervous System (PNS).
(PNS-> heart rate goes down as we REST. HRV goes up!)
PNS is related with the High frequency band and SNS with the Low frequency band. The deeper you sleep, the more you rest (PNS), therefore the deeper you sleep, the more HF- components....
(You get the heart rate variability from 5 min measures, where you make a graph for the frequencies. Are there a lot of high frequencies in 5 minutes, then there´s mostly the PNS active. Many low frequency components- then the SNS. Also with different intervalls possible, but mostly used 5 minutes in sports/diagnostics...).
20) What´s the reflectivity coefficient for a stethoscope on the skin? Let´s say Z_t=1, Z_A=100...
(R=1/ZTissue-1/ZAir)=0,99.
21) Different types of sleep apnoe.
(OSA, CSA, MSA, OHA (sleep hyperapnoe),...). How is apnoe defined? (Drop in oxygen saturation of 4 % and stop of breathing for at least 10 sek...).
22) How does a mechanical receptor works?
(sodium inflow for tensile, compression may podassium outflow? I´m not sure about this answer...)
23) You got high frequencies and low frequencies. Which one chooses the tissue, and which one the airway?
(Tissue: LF, Airway: HF, because of the walls.)
24) How does the EFPG Signal depends on the cardiac activity?
Sys: mü*d goes down, Dia: the product increases
25) Difference between linear and adaptive filtering?
Lin:Fixed cutt off frequency, and adapt: estimation of fC
26) Skin curvature sensor: Which methode do you use for compensating the temperature sensitivity?
2 coils methode
27) Can you measure the velocity of blood flow with an EFPG? Show me!
If blood cells are accelerated, they line up. Therefore the pathway for the signal increases. If the velocity is low, they are randomly orientated, the pathway can be short. So comparing those, we have different impedance for the two cases! Yes, we can...
28) How is the frequency coded in the ear?
We can hear up toi 20kHz, but nerv impulses can only reach 500Hz. Therefore coding needed, which happens in the cochlea. High frequ. at the beginning, low ones at the end.
29) Geometrical damping factor vs. medium damping factor? What is the frecuency range of lung sounds & obstructive snoring?
(geo: 1/r, med: e^(-alpha*r))
alpha is proportional to f²!!! Therefore Lung sounds are more damped then heart sounds.
30) EFPG: Why do we apply current and measure voltage and not apply voltage and measure current? What´s the advantage?
It´s more sensitive and has other adavantages too, which you can find in the other elaborations...
31) How high is the current in EFPG? Why not higher or lower?
()1mA. If it would be higher, we would risk to stimulate the neurons again and also we would heat up the tissue by current induced heating. And if we are too low, we can´t see anything, because the signal to noise ratio would get so small, that the noise is not distinguishable from the signal anymore...
32) Explain the Power spectral analysis for Apnoe detection.
(Just there are high frequency components, medium and low ones. 3 in total. You compare them before and after and as next step make an threshold analysis. This gives you an insight which type of apnoe you deal with.)
33) pRobing depth- How is the relationship to the distance between the sensors (dR)?
34) Can we measure respiratory activity with optical methods?
Yes, as can be seen in the graph with the reflection and the change of art & veins during inspiration, exspiration. (Changes intensity!)
That´s so far all I can remember. If you go through this questions you should be prepared quite fine. Take some time to talk with others during your preperation, they can clear up those things you won´t understand. All together I would say the professor was more then nice, the grading fair and 2 weeks of preperation should be more then enough to get out there positive.
Good luck with that one!
best wishes,
Hofi
Exam questions 2014.03.03- BMS&S
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