Download Topics in PBL

University of Debrecen
Medical and Health Science Center, Medical School
Department of Physiology
Topics in PBL
Academic year 2010/2011.
Topics in PBL
1. Seminar (presentation of a supervisor chosen topic or publication for the
staff of the Physiology Department).
2. Experimental work done with a working group of the Department (previous
arrangement is necessary).
3. Changes of ECG parameters at different heart rates.
4. Comparison of cardiorespiratoric parameters of smokers and non-smokers.
5. Comparison of cardiorespiratoric parameters of trained and non-trained
persons.
6. Time dependent changes of ECG recordings of patients following
myocardial infarct.
7. Analysis of pathological (simulated) ECG recordings and preparation of
recognizing algorithms.
8. The effect of thermal load on the human body.
9.
Examination of orthostatic hypotension with Shellong′s method.
10. Time dependence of postrotatoric nystagm and nystagm initiated by
thermic stimuli.
11. Comparison of colour visual fields using perimeter.
12. Examination of dark adaptation when different wavelengths light are used
for illumination.
13. Examination of the changes of dark adaptation in persons with different
ages.
14. Examination of the accomodation and near-point of the eye.
15. The effect of external noise on the hearing threshold.
16. Test of renal mechanism for diluting.
17. Determination of action’s time.
18. Contribution of different ionic currents to the generation of cariac action
potential. Computer simulation by using HEART software.
19. Examination of buffer components of blood.
20. Analysis of the distribution of red blood cell diameter.
21. The effect of some substances on ECG registered on rat.
22. Study of the effects of extracellular ionic composition changes on the heart
contraction.
23. Study of the effects of extracellular ionic composition changes on the
skeletal muscle contraction.
24. Examination of the mechanical properties of skeletal muscle.
25. Determination of the dose-response curve of caffein applied in low and
high concenration in two types of muscle of frog (m. rectus abdominis and
m. sartorius).
26. Studies of the significance of K+, Ca2+ ions and the Na+/Ca2+ -exchanger
mechanism as well as investigation of the transmembrane signaling in the rat
uterus.
CHANGES OF ECG PARAMETERS AT DIFFERENT HEART RATES
Theoretical background:
Parameters of an ECG record can be classified, based on their frequencydependence, into to groups. Certain parameters (e.g., ST interval, TP time) possess
strong correlation with the heart rate, whereas others can be regarded as constant in
a broad frequency range.
References:
Fonyó: Principles of Medical Physiology
Physiology Laboratory Guide
Experiments to be performed: Various heart rates, generated by either physical
exercise or by the ECG simulator, are recorded. ECG curves and intervals are
analyzed with respect to the different heart frequencies.
Equipment: ECG machine, ECG simulator
COMPARISON OF CARDIORESPIRATORIC PARAMETERS OF
SMOKERS AND NON-SMOKERS
The cardiorespiratoric responses to acute physical exercise are different in
smoker and non-smoker subjects. In this exercise we compare the effect of acute
exercise on ECG, respiratory parameters and oxygen consumption between smoker
and non smoker male and female groups.
You have to find twelve to twenty volunteers from the same age group.
Subjects have to complete graded exercise tests preceded by recording of control
parameters and followed by measurements of restitution. Appropriate statistic
analysis is necessary to reveal significant differences between groups examined.
Your final report should include the following:
1, Introduction: The objectives of the current exercise.
2, Methodology: Short summary of techniques used and specific details of
applied statistic analysis
3, Results: Tables of measured data with average and standard deviation or
error.
4, Discussion of the significance of the results.
Suggested readings:
Physiology practices, a laboratory guide chapters 1.1-1.3
Any basic physiology text on exercise physiology
COMPARISON OF CARDIORESPIRATORIC PARAMETERS OF
TRAINED AND NON-TRAINED PERSONS
The cardiorespiratoric responses to acute physical exercise are different in
trained and untrained subjects. In this exercise we compare the effect of acute
exercise on ECG, respiratory parameters and oxygen consumption between trained
and non trained male and female groups.
You have to find twelve to twenty volunteers from the same age group.
Subjects have to complete graded exercise tests preceded by recording of control
parameters and followed by measurements of restitution. Appropriate statistic
analysis is necessary to reveal significant differences between groups examined.
Your final report should include the following:
1, Introduction: The objectives of the current exercise.
2, Methodology: Short summary of techniques used and specific details of
applied statistic analysis
3, Results: Tables of measured data with average and standard deviation or
error.
4, Discussion of the significance of the results.
Suggested readings:
Physiology practices, a laboratory guide chapters 1.1-1.3
Any basic physiology text on exercise physiology
ANALYSIS OF PATHOLOGICAL (SIMULATED) ECG RECORDINGS
AND PREPARATION OF RECOGNIZING ALGORITHMS
Theoretical background:
Pathological changes of cardiac function cause characteristic alterations of the
ECG. During diagnosis we try to draw conclusion from the symptoms to the cause.
Doing this we require proper knowledge of evaluating ECG recordings and the
electrophysiology of cardiac muscle (pacemaker and conducting regions).
Experiments:
Students will be given 15 pathological (simulated) ECGs. These have to be
evaluated according to the aspects given in the practical guide. Pathologic elements
have to be recognized and the possible causative must be formulated. These
pathological events should be grouped and a diagnostic algorithm must be created.
The analyzer algorithm based on the electrophysiological properties should search
pathological signs.
Experimental equipment: ECG records
THE EFFECT OF THE THERMAL LOAD ON THE HUMAN BODY
Theoretical background:
Ganong: Review of Medical Physiology (1990),pp. 204-208.
Experiments:
1, Determine the values of the blood pressure, pulse rate, breathing frequency,
perspiration (the decrease of the body weight) during thermal load. Examine
these parameters following the thermal load. Calculate the heat loss.
2, Measure the body weight, heart rate and blood pressure of the patient at rest.
3, Perform thermal load at different levels up to 80 0C temperature. Examine
the values of the previous parameters in every 3 minutes.
4, Following the termination of the load examine the restitution of the previous
parameters and the amount of water the patient has lost.
5, Examine the heat lost by the body calculated from the weight lost of the
body. (evaporation of 1 l water requires 2428 kJ).
Experimental equipment: blood pressure apparatus, sauna, chronograph, scale.
EXAMINATION OF ORTHOSTATIC HYPOTENSION WITH
SHELLONG’S METHOD
Theoretical background:
The regulation of the reaction of the living body to external stimuli includes the
blood pressure regulation. During exercise the influence of the effects of gravity
changes and results in different blood restitution in the body, which activates
vasoregulatory mechanisms. This regulatory mechanism can be easily examined by
monitoring the blood pressure. This method is used in internal medicine
(Shellong’s method), and can be easily performed (measurement of the blood
pressure in different body positions).
Ganong: Review of Medical Physiology (1994), pp. 491-503. and 523-535.
Experiments to be performed:
Examine the regulation of the venous circulation in different periods of the day.
Examine the regulation of the venous system following increased alcohol intake,
after large amount of urine excretion and in the state of sleep deprivation.
Requirements: patients, blood pressure apparatus
TIME DEPENDENCE OF POSTROTATORIC NYSTAGMUS AND
NYSTAGMUS INITIATED BY THERMIC STIMULI
Theoretical background:
Different thermal stimuli and rotation induce specific eye movements
(nystagmus). The examiner should be familiar with the types of the nystagmus and
the methods that can be used to evoke them.
Ganong: Review of Medical Physiology (1990), pp.147-149. and 177-179.
Experiments to be performed:
Examine the time dependence of the postrotatoricus nystagmus developed by
the help of rotation in different direction and at different speed (the speed of the
rotation should be constant). Perform the experiment on at least three persons.
Investigate the direction and the time dependence of the nystagmus developed by
solutions with different temperature (e.g. 25, 31, 37, 43 and 49 0C)
Requirements: patients, revolving chair and chronograph
COMPARISON OF COLOUR VISUAL FIELDS USING PERIMETER
Theoretical background: Determination of the visual field in clinical
examinations is based on the excitation of rods caused by illumination with white
light. When we change the exciting light to red, green and blue we could elucidate
the distribution of different types of scones within the retinal surface.
W.F. Ganong: Review of Medical Physiology 166-182.
Experiments:
Examination of the visual field with white light. Measuring the color visual
fields (red, green and blue) using perimeter and comparing the obtained curves.
How does the color visual fields are affected by the different background color.
Requirements: perimeter and patients
EXAMINATION OF DARK ADAPTATION WHEN DIFFERENT
WAVELENGTHS LIGHT ARE USED FOR ILLUMINATION
Aim: The determination of the dark adaptation of the eye (how does the lowest
detectable light intensity depends on the time spent in complete darkness) using
white, red and blue light. The connection between dark adaptation and the
wavelength of the light used for illumination before dark adaptation start.
Prerequisites: all equipment (a white screen and a projector with adjustable light
intensity) are provided by the department. A completely dark room is essential. No
special skills in conducting experiments are necessary.
Detailed task:
1, Determine the dark adaptation of the eye with white illumination before the
experiment using the ability to recognize different shapes of white light as a
test.
2, Repeat the measurements using red and blue shapes.
3, Repeat the experiment using red and blue illumination before starting the
experiment.
4, Fit theoretical functions to the measured curves and interpret the results.
Acceptance: constructing the graphs and determining the functions. A descriptive
report of the experiments should be submitted.
EXAMINATION OF ACCOMMODATION AND NEAR-POINT OF THE
EYE
Theoretical background
W.F. Ganong: Review of Medical Physiology 117-136.
Experiments:
1, Examination of accommodation of the eye (Scheiner’s test)
Insert two needles on a rod with centimeter scale with a distance around 60 cm.
Fix perpendicular a sheet of paper with two holes on one end of the rod. The
distance between the two holes must be smaller than the diameter of the pupil. If
you look at the tip of the nearest needle through the holes in the paper you will
have a double vision of the farther needle. If you look at the tip of the farther
needle through the holes on the paper you will have a double vision of the closer
needle. Examine the accommodation of the eye on some patient (with and without
eyeglasses) and summarize the results.
2, Determination of the near point of the eye
The special rod used in the previous experiment could be use for determining
the near point of the eye. Use the same rod with only one needle. Look at the tip of
the needle through the holes on the paper and decrease the distance between the
needle and the paper until you do not get a sharp image of the needle not even with
a maximal accommodation. In case of a 20 years old patient the near point is
around 10 cm from the tip of the cornea. Determinate the near point of the eye on
some patient (with and without eyeglasses) and summaries the results.
Tools and materials: two needles, a rod with centimeter scale, paper
THE EFFECT OF EXTERNAL NOISE ON THE HEARING THRESHOLD
Aim: To study how external noises and intensive sounds affect the sensory
function of the ear.
Prerequisites: an audiometer that is provided by the department. A completely
silent room is essential. No special skills in conducting experiments are necessary.
Detailed task:
1, Record the hearing threshold in both ears in the given frequency range.
2, Repeat the determination after changing the external noise.
3, Examine how the external noise applied to one ear affects the hearing
threshold of the same and of the other ear.
4, Examine how the hearing threshold changes (time and frequency
dependence) following an acute intensive noise.
5, Examine to what extent are the effects of these noises additive.
Acceptance: constructing the graphs. A descriptive report of the experiments
should be submitted.
TEST OF RENAL MECHANISM FOR DILUTING
Theoretical background:
W.F. Ganong: Review of Medical Physiology 581-606.
Experiments:
The experiments should be done on an empty stomach. After measuring the
body weight and emptying the vesical the patient drinks a liter of water and you
measure the body weight again. In every half an hour (8 times) we measure the
volume and the special gravity of the urine. It is very important to avoid having the
urometer contacting the wall of the measuring cylinder, and the urine filled into the
measuring cylinder must not be foamy. Fill a table with the results of the
measurements.
From a healthy patient the administered water void during 2-3 hours and the
specific gravity of the urine decreases to 1.001-1.003.
After 4 hours we measure the body weight. If the urinary output is less than the
decrease in the body weight, than the origin of the difference is the extrarenal
water extraction. If the patent is in the state of exsiccation, a part of the
administrated water will remain in the body and the volume of the urinary output
will be smaller and the specific gravity will be higher.
Repeat the measurement on 2-3 patients. A moderate exsiccation could be
induced by a light physical exercise followed by sweating.
Tools and materials: urometer, measuring cylinder, tumbler
DETERMINATION OF ACTION’S TIME
Theoretical background:
W.F. Ganong: Review of Medical Physiology 166-182.
Experiments:
The reaction time is the delay between the specific stimulus and the start of the
voluntary movement. We could continue the experiment if we measure the time
which is necessary to complete a predefined motion pattern. This time is called
time of action and it could be decreased with practice.
Use the computer program for the measurement which determines the reaction
time. Give a predefined motion pattern (for example, fold a sheet of paper and
draw a rectangular) which finishes with pressing a button on the keyboard. Repeat
the measurement at least five times and fill a table with the values. If you modify
the motion pattern (increase the number of the steps) it could be examining how
the action time depends on the syntonic action of the different part of the body.
Tools and materials: computer
CONTRIBUTION OF DIFFERENT IONIC CURRENTS TO THE
GENERATION OF CARIAC ACTION POTENTIAL. COMPUTER
SIMULATION BY USING HEART SOFTWARE
Theoretical background:
The HEART software simulates the action potentials and the contraction of the
different heart cells (nodal cells, atrial cells, ventricular cells, Purkinje cells).
This software allows to change the experimental protocol in wide range. The
user may also vary the properties of the ionic channels and the ion transporter
systems.
W.F. Ganong: Review of Medical Physiology 166-182.
Experiments:
The first step is that the user varies the conductance of a selected ion channel
between 0 and the physiological value and he/she studies the effects of the changes
on the cardiac action potentials. Next the user administers different molecules
(neurotransmitters, receptor agonists, antagonists) and compare their effects on
action potential to the results obtained by changing the conductance of ion
channels.
Requirements: computer, HEART software, printer
EXAMINATION OF BUFFER COMPONENTS OF BLOOD
Theoretical background:
Best and Taylor’s: Physiological basis of Medical Practice, Twelfth Edition,
486-507.
Experiments to be carried out:
1, Titrate 0.01 M solution of a mild acid (acetic acid) by adding the solution of
a strong base. Plot the pH measured against the concentration of the strong
base.
2, Titrate a buffer system consisting of 20 mM H2PO4- / 20 mM HPO42- using
strong acid and base respectively. Plot the pH measured against the
concentration of the strong base/acid.
3, Titrate a certain volume of anti-coagulant treated whole blood sample with
strong acid and base, respectively. Plot the pH of the whole blood measured
against the concentration of the strong base/acid. Determine the buffer capacity
of the given whole blood sample.
4, After the removal of the corpuscular elements of the blood, titrate the blood
plasma with strong acid and base, respectively. Plot the pH of the blood plasma
measured against the concentration of the strong base/acid. Determine the
buffer capacity of the plasma.
The removal of the corpuscular elements is carried out by using centrifuge. pH is
measured with using a special electrode for this purpose and a pH meter.
Measurements are carried out at room temperature, under atmospheric pressure and
at normal air gas composition.
Solutions, instruments: The required compounds and stock solutions, pH
electrode and meter, centrifuge are available. Blood sample is taken from dog, the
anti-coagulant is heparine. The processing of the acquired data happens with the
help of a computer.
ANALYSIS OF THE DISTRIBUTION OF RED BLOOD CELL DIAMETER
Theoretical background:
Best and Taylor’s: Physiological basis of Medical Practice, Twelfth Edition,
486-507.
Experiments to be carried out:
1, From human blood-smear measure the minimal and maximal diameter of the
red blood cells using ocular micrometer. Investigate at least 500 RBC!
2, From frog blood-smear repeat the previous experiment!
3, Prepare a histogram from the normalized maximal diameter data in both
cases.
4, Fit the histograms with Gauss-function and determine the most probable
diameter and the standard error.
The magnification of the microscope is calculated from the objective and the
ocular micrometer.
Solutions, instruments: Human and frog blood-smear, Microscope with oil
immersion objective, ocular micrometer, immersion oil.
THE EFFECT OF SOME SUBSTANCES ON ECG REGISTERED ON RAT
Theoretical background: Best and Taylor’s: Physiological basis of Medical
Practice, Twelfth Edition, 174-184.
Experiments to be carried out: Before starting experiment rat is anaesthetized by
administration with 50 mg / bodyweight kilogram Nembutal. During the
experiment the amount of each substance added should be increased (e.g. adding
again the same volume of it’s solution) until appreciable alterations in the ECG can
be observed. Lag phase due to absorption should be taken into account.
The steps of experiments:
1, After the rat fell to sleep ECG control curve should be registered.
2, Examine the effect of intraperitonially added acetylcholine on the parameters
of the ECG curve. Do not leave out of consideration the rapid metabolism of
acetylcholine in organism. (transient effect, 10-15 minutes).
3, After the effect of acetylcholine completely ceased, examine the effect of
intraperitonially added atropine on the parameters of the ECG curve.
4, Examine the effect of intraperitonially added isoprotenerole on the
parameters of the ECG curve. After the effect the above mentioned agent
completely developed, add Pindolol intraperitonially and continue registering
ECG curve.
5, Examine the effect of a cardiac glycoside added in single high dose on the
parameters of the ECG curve
Solutions, instruments: Rat, ECG means. Nembutal, atropine, isoprotenerole,
acetylcholine, ouabaine, Pindolol solutions. For constructing tables computer is
available.
STUDY OF THE EFFECTS OF EXTRACELLULAR IONIC
COMPOSITION CHANGES ON THE HEART CONTRACTION
Theoretical background:
The aim of the lab is to characterize the effect of changes in the extracellular
concentrations of the most significant cations in an isolated heart preparation
(Straub-heart dissected from frogs by the students). This practical requires regular
manual skills.
Best and Taylor’s: Physiological basis of Medical Practice, Twelfth Edition.
Experiments to be performed:
The design, preparation and testing of modified Ringer solutions. The
registration of effects on spontaneous cardiac function, description of the
characteristic mechanical parameters: heart rate, amplitude of contractions,
relaxation parameters.
Solutions, instruments: mechanical transducer, recorder, pH meter, osmometer,
pipettes, tools for preparation.
STUDY OF THE EFFECTS OF EXTRACELLULAR IONIC
COMPOSITION CHANGES ON THE SKELETAL MUSCLE
CONTRACTION
Theoretical background:
The aim of the lab is to characterize the effect of changes in the extracellular
concentrations of the most significant cations in a skeletal muscle preparation
(sartorius muscle dissected from frogs by the students). This practical requires
regular manual skills.
Best and Taylor’s: Physiological basis of Medical Practice, Twelfth Edition.
Experiments to be performed:
The design, preparation and testing of modified Ringer solutions. The
registration of effects on single twitches and tetani, description of the characteristic
parameters of stimulation: threshold, fusion frequency, stimulus strength and
duration.
Solutions, instruments: sartorius-dish, MINISTIM-stimulator, mechanical
transducer, recorder, pH meter, osmometer, pipettes, tools for preparation.
EXAMINATION OF THE MECHANICAL PROPERTIES OF SKELETAL
MUSCLE
Theoretical background:
W.F. Ganong: Medical Physiology
Experiments to be performed:
1. Preparation of frog skeletal (m. sartorius) muscle and skeltal muscle of the rat
(guinea pig). Put together the measuring setup and determine the length-tension
curves of the muscles. Determine the active and passive portion of the elastic
and plastic ratio of the tension.
2. Determine the temperature dependence from 40C to 370C in 5-6 steps of the
parameters above.
Tools and materials: one-two animals of a kind, transducer set, recorder, weights,
MINISTIM-stimulator, thermostated incubation chamber and thermostat.
Execution: calibration of the transducer-recorder system, determination of the
length-tension curves, determination and separation of the linear portion of the
curve. Determination of the exponent of the plastic part of the curve.
Determination of the active portion using electric stimulation.
DETERMINATION OF THE DOSE-RESPONSE CURVE OF CAFFEIN
APPLIED IN LOW AND HIGH CONCENRATION IN TWO TYPES OF
MUSCLE OF FROG (M. RECTUS ABDOMINIS AND M. SARTORIUS).
1. Theoretical background
a. comparison of the characteristics of tonic and phasic muscles
b. definition of the terms “contraction” and “contracture”
c. mechanism of caffeine effect, differences in high- and low-dose caffeine
applications
d. relationship between the strength and duration of just suprathreshold stimuli
Literature: the appropriate chapters of various textbooks concerning physiology.
2. Preparation: See “Laboratory Guide”
3. Equipment: experimental chamber, MINISTIM stimulator, amplifier, recorder
4. Solutions: Ringer’s solution; caffeine solution in 0.1; 0.5; 1; 1.5; 2; 5; 10 and
20 mM concentrations
5. The experiment:
a. determination of the amplitude of the mechanical response, the stimulus
threshold and the amplitude of the supramaximal stimulus
b. registration of 10 contractions with a low frequency (0.1 Hz) stimulus train
c. repetition of point b in 0.1 mM caffeine solution
d. wash-out in normal Ringer’s solution until the recovery of the control
contractile force
e. repetition of points b and d with increasing caffeine concentrations (the
highest concentration should be 2 mM)
f. comparison of the amplitudes of the contractions measured before and after
the caffeine applications
g. determination of the greatest achievable contraction amplitude as the
function of the applied caffeine concentration
h. determination of the stimulus strength-duration curve for contractile
threshold in caffeine free and in 2 mM caffeine solution
i. comparison of the yielded data in the two types of muscle
j. demonstration of caffeine contracture by the application of 5-10-20 mM
caffeine solutions
k. quantitative comparison of parameters of the previously recorded
contractures.
STUDIES OF THE SIGNIFICANCE OF K+, CA2+ IONS AND THE
NA+/CA2+ -EXCHANGER MECHANISM AS WELL AS INVESTIGATION
OF THE TRANSMEMBRANE SIGNALING IN THE RAT UTERUS.
1. Theoretical background
a. K+ depolarization
b. G-proteins, their significance in the signal transduction
c. definition of second messengers, the major signaling pathways
d. Ca2+ channels, their characteristics and significance
Literature: the appropriate chapters of textbooks concerning physiology and
biochemistry.
2. Preparation:
The preparation will be performed by a technician (the student may attend).
The experimental animals are given 50 ml Akrofollin injection (250 mg estradiolproprionate), intraperitoneally prior to the experiment (one injection on both of the
preceding two days). The aim of this intervention is the stimulation of estrus.
3. Equipment: water bath, experimental chamber, oxygen, amplifier, recorder,
pipette tips, automatic pipettes
4. Solutions: normal Tyrode’s solution; high K+ Tyrode’s solution; 100 mM NaF
solution; 2 mM Al2(SO4)3 solution; nitrendipine
5. The experiment:
a, Recording of spontaneous mechanical activity during a 20 minutes long
period with a chart speed of 4 cm/min. Determination the average amplitude of
the spontaneous activities; this value should be regarded as 100% throughout.
b, Activation of G-proteins in the presence of fluorid and aluminium ions.
Application of 10 ml NaF and 10 ml Al2(SO4)3 solutions rapidly after each
other. Wash-out after 10 minutes.
c, Recording of a K+ depolarization during a 20 minutes long period with a
chart speed of 4 cm/min. Comparison of the amplitudes with those recorded
under control conditions.
d, Activation of the G-proteins during K+ depolarization. Repetition of the 2nd
point at the 10th minute of the application of high K+ Tyrode’s solution. Washout after 20 minutes.
e, Application of nitrendipine solution, determination of the dose-response
curve. After a 20 minutes long recording period, the experiment should be
repeated in high K+ Tyrode’s solution.