Lab 4 - Heart Flashcards
How is the hormonal regulation of heart function demonstrated?
Through effect of... Epinephrine Propanolol Acetylcholine Atropine Verapamil Strophantine
How are the experiments of hormonal heart regulation carried out?
In situ heart preparation, using a multimedia program
How is the main characteristics of the pulse determined?
- Palpating
2. Electrical recording
How do you gain the ECG traces?
By using dif. bipolar leads
How do you determine the cardiac axis?
By analyzing the ECG traces
Then bases of vectorcardiography are discussed.
How do you examine the in situ heart function?
With a virtual laboratory
- SimHeart
What is another word for in situ heart?
Langendorff Heart
How do you perform the dissection in the program?
- Opening chest cavity
- Remove heart
- Insert a cannula into the aorta
- The heart is perfused with an oxygenated isotonic solution (“Krebs solution”)
What is the route along where the solution(Krebs) will flow?
Reservoir –> Tubes –> Aorta
- -> Coronary arteries –> Cappiraries –> Coronary veins
- -> Right atrium –> Right ventricle –> a.pulmonalis
- -> The outer surface of the heart.
How do we register the heart function ?
By measure the changes in the intraventricular pressure
How do we measure the changes in the intraventricular pressure?
Through vv. cords, minimal blood gets into the left ventricle, therefor both ventricle are filled with the fluid.
- Insert a balloon catheter into left vetricle through the left atrium and the pulmonary veins.
In the virtual laboratory, what are the 3 devices that is switched on?
Thermostat (keeps temp conctant at 37 degrees)
Amplifier
Perfusor
How is the velocity of the nutrient solution?
The flow is constant (10ml/min)
Wich means that it passes through the heart with constant pressure.
When connecting the ballon catheter, what are the further steps?
The ballon catheter is connected to a mechano-electrical transducer which converts the pressure changes generated by cardiac contractions into electrical signals. (2mmHg/1mV)
And passes it into the amplifier
Using 5mV/Div resolution, a deflection of one division almond the Y-axis is equal to 10mmHg pressure change
What is the Acetylcholine effect on the heart function?
Parasympathetic transmitter
What is the Atropine effect on the heart function?
Competitive antagonist of acetylcholine
What is the Epinephrine effect on the heart function?
Sympathetic hormone
PQ!!! What is the Propanolol effect on the heart function?
beta-receptor BLOCKER (B1 and B2)
What is the Verapamil effect on the heart function?
Calcium chanel BLOCKER
What is the Strophantine effect on the heart function?
Na+ / K+ ATPase BLOCKER
What can you base the calculation change of drug-concentration (Q) in the nutrient solution on?
Flow rate of drug administered (I, mikroliter/min)
Concentration of drug solution used (C, mol/l)
One unit on the recording paper with 1/cm/sec paper-speed is equivalent to how many cm on the paper?
One unit on the paper is 1cm along the x-axis,
1cm/sec speed paper
= 1 unit = 1 cm on paper
Why should you wait until the effect of the drug is developed?
Because the heart reacts to dif. substances with a certain delay
What is Epinephrine and where does it come from?
Epinephrine is a natural sympathetic hormone liberated from the adrenal medulla
What kind of effects can Epinephrine have on the heart?
Several stimulating effects:
Increases the ….
Pacemaker
Heart rate (Positive chronotropic effect)
Velocity of contraction (Vmax)
Maximal isometric tension (Sm) - (+ Inotropic effect.)
Lowers the…
Threshould potential of pacemaker cells (+ bathmotropic)
Facilliates the.... Stimulus conduction ( +dromotropic efect)
PQ!! What kind of effects can Propanolol have on the heart?
Its a sympathicolyticum that inhibits type B1 and B2 adrenoreceptors.
What differentiates Systolic and Diastolic?
Systolic: Contraction/Exties
Diastolic: Relaxation/releases
In the experiment with epinephrine and propanolol - what are we recording?
The heart rate during resting state and with epinephrine ´
Pressure in the left chamber(mm/Hg) Systole and Diastole
How long epinephrine has bin administered and time for the heart to return to resting state.
Then…
Observe how the heart function goes back to normal when adding propanolol (Functional antagonism)
What is acetylcholine and where does it come from?
A natural parasympathetic neurotransmitter liberated from the synapses in the n. vagus,
What kind of effects can acetylcholine have on the heart function?
Extretes negative
Chrono, Bathmo, Dromo and inotropic effect on the heart through type 2 muscarinic receptors.
What is Atropine and where does it come from?
The competitive antagonist of acetylcholine
It binds to the muscarinic acetylcholine receptors with ought stimulating them.
When looking for the effects of acetylcholine and atropine, what do we do?
Determine the systolic and diastolic pressure(lft chamber)
Calculate heart rate during normal functions
Calculate heart rate under the influence of acetylcholine
How long does it take from acetylcholine has bin administered to the heart returns to its resting state.
Competitive antagonist to acetylcholine, what is observable?
Administer as acetylcholine as before, but…
After stopping the administration, immediately add atropine, determine how long it takes until the heart will go back to resting state,
What is Verapamil, and what does it do?
It is a Ca2+ channel blocker drug.
It primarily blocks the L type of calcium channels
It also blocks the power of the muscle fibers
By dilating the coronaries it facilities the nutrient supply for the heart.
What happens when Verapamin blocks the Ca2+ channels?
It delays the elicitation of spontaneous diastolic depolarization (mainly in the AV node).
It leads to irregular heart beats (arrhythmia)
When blocking the power of muscle fibers, it also decreases the power of the heart
How do we examine the Verapamin effect?
by applying its solution of dif. conc. according to a table.
- Determine the time taken for the effect to develop
- Determine the quantity for the drug given
- Calculate the HR and changes in systolic and diastolic pressure in the left chamber.
- Note the time taken for the heart to return to its resting state
What is strophanine, and what does it do?
A cardiac glycoside
Is a specific inhibitor of the cardiac Na+/K+ ATPase
It increases the intracellular Na+ conc. and
Decreases the intracellular K+ concentration in the heart
As a result of the intracellular Na+ conc increasing, the intracellular Ca2+ conc increases as well.
The Strophanine effect of the heart function
-The Latter increases the heart power (+ inotropic effect)
-Strophanine stimulates the sarcoplasmic Ca2+-ATPase (responsible for muscle relaxation-enchants both phases of muscle function)
- Decreases the arterial refractory period - frequency of atrial contraction will increase (Langendorf heart)
- In AV node, it delays stimulus conduction
(-dromotropic effect)
- Frequency of ventricular contraction will decrease
(-chronotropic effect)
- Improves the spreading of atrial arrythmias
- Protects the ventricles if atrial stimuli become too freq.
- Overdose may lead to AV block
What does a insufficient heart mean?
Positiv Inotropic effect is pronounced in a insufficient heart
Strophanthine can induce cardiac arrhythmia in various ways, name some
-By decreasing the ventricular refractory period by delaying intracardial stimulus conduction.
- Enchantes the so called secondary (latent) stimulus generation
(lead to extrasystoles+consequently arrhythmia).
- Decreased intracellular K+ conc. causes resting pot. of heart muscle cells to increase. (Spontainliously diastolic depolarization - result in extrasystoles)
- Oversaturation of intracellular calcium stores
- Fluctuation of free plasmatic calcium level enhance late post-depolarization - (lead to extrasystoles)
- Higher doses than therapeutical ones - HEART FAILURE
Due to the experiment regarding Strophanthine, what do we perform?
Heart failure therapy by observing the effect go strophantine on heart failure caused by acetylcholine
What is the pulse?
The volume of blood expelled by the heart into the aorta during systole dilates the aortic wall.
What happens during diastole pressure?
The aorta contracts again and the blood proceeds in it further.
This pressure fluctuation spreads in the arterial system in the form of a wave.
What happens with the pulse pressure in the pheriferry?
Its modified because of the appearance of reflection waves.
How can you examine the pulse?
Palpation
Then you can determine
- Pulse frequency (Normally the pulse rate is equal to HR,
Pulsus frequents/fast and Pulsus rarus/slow)
- Ryhythmicity - Pulsus regulars or Pulsus irregularis
- Hardness - Pulsus durus (hard) or Pulsus Mollis (soft)
Puls pr min when resting and exited.
Normal puls values women
70/min
Normal puls values men
80/min
How can we palpate the puls?
Usually by placing you’re fingertips over a major artery running under the skin superf. over a bony base. (radial a. in humans)
Using the palpation method you can determine The frequency, Rythmicity and hardness of the puls.
What is the plus frequency?
Normally the pulsate is equal to heart rate related to the same unit of time.
With respect to frequent, fast puls(pulsus frequens) or slow puls (pulsus rarus) pulses can be determined.
What is the rythmicity of the pulse?
In case of rhythmic pulse, there are uniform cycles of the pulse pressure waves.
(Pulsus regularis)
If these cycles are irregular, the pulse is arrhythmic (Pulsus irregulars)
PQ!!! What is the hardness of the pulse?
The power needed to compress it. Hard pulse (Pulsus durus) Soft pulse (Pulsus Mollis)
What are the steps of evaluating the pulse?
Amplitude of the pulse waves
Equality
Length
Slope of the pulse
What are the dif pulse waves?
Amplitude of pulse waves:
Big (pulsus alsus)
Small (Pulsus parvus)
What is equality of the pulse?
Whether the amplitude of each pulse wave is same:
Equal (Pulsus equalis)
Unequal (Pulsus inequalis)
What is the length(duration) of the pulse?
Long/short and none equal to the pulse rate
What is the slope of the pulse(angle)?
Fast acending (pulsus celer) Slowly ascending (pulsus tardus)
What are the parts of the pulse curve?
- Anarcotic limb with the steepness of it.
- Pulse pressure (top of the curve)
- Dicrotic noch
(small drop before it raises and then decreases again) - Catarotic limb (drop)
When measuring the pulse in class, what do we measure=?
Frequency
Rythmicity
Equality
Length
All of them at rest and after exercise
What is ECG used for?
Used to record electrical potential differences generated by the heart and conducted to the body surface
When can the ECG inform about?
Position of the heart
The heart rate
The pacemakers rhythm and its origin
The propagation of depolarization and repolarization
What are the standard bipolar leads?
The ECG is obtained by the bipolar standard leads
Lead I
Lead II
Lead III
Nowdays,unipolar leads are also used (precordial or limb)
What is lead I
Potential difference between right and left arm (RA,LA)
PQ!!! What is lead II
Potential difference between right arm and left leg(RA, LL)
What is lead III
Potential difference between left arm and left leg (LA,LL)
How does the ECG of the unipolar limb leads work?
An refference point is formed by connecting the electrodes on to limb together through a string recistor.
The ECG is recorded between this reference point and a so called different electrode is placed on another limb.
What are the unipolar leads of the ECG?
They are named after different places of the electrodes
VR: Right arm
VL: Left arm
VF: Left leg
What does the VR lead measure?
The VR measures the voltage difference between the right arm and the two other limbs that is connected electrically
What does it mean that the Goldbergs unipolar leads are obtained?
The signals obtained can be amplified by setting up special connections among the different points. These labels are labeled with a prefix “a”. E.g “aVR”
Where is standard lead I and II ECG recorded?
Chanel 1 and 2
Where is standard lead III ECG calculated?
Calculated from lead I and II
Displayed in channel 3.
Where does the heart rate signal derive from?
From the lead II ECG
Displayed in channel 4
How to attach the electrodes?
Attach the main cable to the main unit
Apply a small am. of electrode cream to the electrode
Attach subjects as followed:
Lead II: The negative (red) electrode to the right wrist.
The positive (black) electrode to the left ankle
The earth (green) to the right ankle
Voluntaire has to sit still
What is the isoelectric line
The physiological baseline (0mV) of the ECG trace
What are the waves above and under the isoelectric line?
The waves over: Positive
The waves under: Negative
What is a segment?
A part of the ECG trace that falls between waves
What is parts that may contain larger parts with one or more waves called?
Intrevalls or
Complexes
What are the names of the different waves?
P, Q, R, S, T
How is e.g.. a segment labeled?
ST segment : by using the first and last waves
What is the name of the positive wave in the cardiac cycle that indicated the atrial depolarization?
P wave
Can atrial depolarization be seen on the ECG trace?
No!
Because it coincides with the QRS complex.
What is a bifid P wave?
A wave that may occur in case of asynchronous activation of the atria.
What is the PQ segment?
It represent the propagation of the action potential through the AV node (Atrioventricular conduction)
What is the Q wave?
- Detected on the body surface.
- Its asosiated with the ventricular electrical actions.
1st. part: a small downward deflection is termed the Q wave. - It indicates the transmission of excitation from the HIS bundle to the ventricular muscle.
What is the R wave?
- The largest deflection of the ECG trace.
- Indicates depolarization of the major mass of the ventricles
- During standard leads its a positive deflection
- Amplitude ranges to 1,5mV
- Based on the amplitude of the R wave, the cardiac axis can be determined
- Its followed by a small S wave.
What is the S wave?
A small negative wave that follows after the R wave
Originates from the depolarization in the right ventricle
Spreading from the endocardium towards the epicardium
What is QRS all together?
The process of ventricular depolarization result in a special pattern in the ECG trace.
Called the QRS complex
What is ST together called?
ST segment
For the duration of ST segment the whole ventricle is depolarized, so the ST segment is an isoelectric line.
PQ!! What is the T-wave?
The pattern of ventricular repolarization
PQ!! What are the variation of the T-wave within the species?
Humans and carnivores:
Upward deflection - like P wave(depolarization)
PQ!!What is the background of the phenomenon of T-waves in Humans and carnivores?
Because depolarization begins where cells were depolarized last.
ie. Repolarization start at ventricular epicardium and propagates towards the endothelium
What is the baseline?
The isoelectric line 0mV
What are the different waves, segment, complexes?
Waves: PQRST
Segment: PQ, ST
Complex: QRS
On what do you evaluate the ECG according to?
Quality of recording Heartrate Rytmicity P wave PQ segment QRS complex ST segment T wave
How do you determine the quality of the recording?
Can the diff waves be distinguished?
Is the baseline on the isoelectric line (0mV)
How do you determine the heart rate?
The length of RR intervals (sec)
Heartrate calculated from RR intervals
HR= 60/RR (sec)
(men: 80/min, women: 70/min)
How do you determine Rhythmicity?
Do R waves follow each other at regular intervals?
(Normaly the heart function is rhythmical)
Are P, T waves, and the QRS complex present during the cardiac cycle?
PQ! What are the characteristics of the P wave?
Pressent in Lead I and II Positive Amplitude: 0,25mV Duration: 0,05-0,1 sec Shape: Rounded, never sharp Not bifid
PQ! What are the characteristics of the PQ segment?
Shape: On the isoelectric line
Duration: 0,05-0,1 sec
What are the characteristics of the QRS complex?
All waves present in the QRS complex
Positive R wave in Human and carnivores
Amplitude of R wave: 1,5mV
Duration of R-wave: 0,06-0,12 sec
What are the characteristics of the ST segment?
Shape: On the isoelectric line
What are the characteristics of the T-wave?
Present
Same polarization as R wave (+, human,carnivores)
Amplitude: Max. The 2/3 of the R-wave.
How do you perform lead I?
Besides the electrodes attached (lead II), place 2 other ones to perform Lead I.
- Negative (white) on right wrist
- Positive (black) on left wrist
- Eath is same as before
How do you calculate lead III?
From lead I and II by the software.
compare the three standard limb leads
Why is potential difference generated in the course, cardiac depolarization, vector nature?
Potential difference generated in the course of cardiac depolarization are vector nature because they have different Size and Direction
What is an integral vector?
Adding up he potential differences measured at the same moment on different leads = Integral vector
What is a vector cardiogram?
The size and direction of integral vectors steadily changes, creating vector loops that correspondent to diff waves. The sum of all those vector loops = Vector cardiodiagram
During normal heart function, on the summit of the R wave, where does the integral vector always point?
Cardiac Axis
Depends on the position and weight of the heart.
What does cardiac axis refer to?
Size of the heart
How to determine the cardiac axis?
- Measure the peaks in the value of R-waves in each standard lead
- Construct at least two out of three vectors projected to the plane of the given electrodes
The integral vector of these projected vectors is termed the R vector in frontal plane
The direction of this integral vector is the cardiac axis in the frontal plane.
The direction of cardiac acid ranges from?
-30 - 110 degrees
What is the cardiac deviation of cardiac axis if it is less than -30 degrees?
Left cardiac axis deviation
What is the cardiac deviation of cardiac axis if it is more than +110 degrees?
Right cardiac axis deviation
What is cardiac deviation mainly caused by?
A change in the spreading of the depolarization. (Cardiac dilation, brach block etc)
what is the function of peripheral circulation?
Ensure material exchange between the intra- and extra cellular space
How is material transport mainly released?
By diffusion
How does the material exchange happen in the microcirculatory bed
Diffusion
Filtration
Resorbtion
How does the microcirculatory bed run ?
In the arterioles of the MCB it runs towards the capillaries while the blood flowing from the capillaries converges in the venules.
In the arteries the blood flow is fast + pulsation
The capillaries are entirely filled with flowing blood cells separated by plasma plugs
What can we distinguish in the large vessels?
Quicker axial flow
Slower mural flow
(Plasmatic zone)
What does the axial flow do to RBC and WBC?
Comprises red blood cells
White bloodcells float predominantly in the mural flow
Who has the highest density? RBC or WBC?
RBC
What is exchanged by diffusion
Water, gasses, small molecular substances.
What does the rate of diffusional exchange depend on?
The conc. gradient
Transit time of the substance being exchanged (permeability and diffusion surface of the area of the capillary wall)
What plays a definite role in formation and volume of intestinal fluids(ISF)
Filtration and
Reabsorbtion
Woh is the actual volume of ISF determined?
Ratio of filtration Resorbtion that depends on: - Blood pressure - Hydrostatic pressure - Oncotic pressure - Tissue turgur
(other pathological cases: permeability of capillaries also effect the formation of ISF)
How to calculate the effective filtration pressure?
Peff is the difference between the Pheff and Poef pressures:
Peff= pheff-poeff
Effective filtration pressure (Peff)
Effective hydrostatic pressure (Pheff)
Effective oncotic pressure (poeff)
What is the blood pressure?
The pressure in the arterial system
What are the most important pressure values that determine the BP?
Systolic
Diastolic
Mean arterial and
Pulse pressure
How to measure Systolic pressure
Measured at the summit of the systole.
Repressent the maximal pressure during cardiac cycle
Humans: 110-120 mmHg (14,5-16.0 kPA)
How to measure Diastolic pressure
Measured at the end of the diastole
Repressent the minimal pressure
Human: 75-80 mmHg (10-11 kPa)
How to measure Mean arterial pressure?
Average blood pressure over a period of time.
Duration of diast is longer than syst = Mean arterial not equal to arithmetic average.
Empirical equation
Paverage = (Psystolic+2*dyastolic)/3
Decreases towards the periphery
Maintains the blood flow in the circulatory system
What is pulse pressure?
Difference between systolic and diastolic pressures
in humans: 40 mmHg
Pulse pressure increases towards the periphery as a result of the appearance of reflection waves.
What is the pulse pressure a function of?
Cardiac output
Pheripheral resistance
Total of circulating blood volume in arterial system
Compliance of the vessels (decreases with age)
Indirect measuring of bloodpressure
- An artery is being compressed (brachial), then released slowly.
- Determined by different sounds originating from turbulent bloodflow and clapping of the walls of the artery.
- The sounds appear between systolic and diastolic blood pressure values.
- Method based in an inflatable cuff in order to compress the brachial artery.
How can the sound between systolic and diastolic blood pressure indicate the value?
A clear tapping head at every pulse beat = Indicates the value of systolic pressure
The disapairance of the tapping sound indicates the value of diastolic pressure.
What is Ausculatory methode?
Measures Systolic Diastolic Mean arterial pressure Pulse pressure
Riva-rocci sphygometer, consist a inflatable cuff, an inflatable balloon with a bulb for pumping it up, an a mercury manometer.
Inflate cuff to 160-180 mmHg.. Sound present/disapeared?
