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)