Cardiac Phsiology Essay Research Paper The study

Cardiac Phsiology Essay, Research Paper

The study of cardio physiology was broken up into five distinct parts all centering on the cardiovascular system. The first lab was utilization of the electrocardiogram (ECG). This studied the electrical activities of the heart by placing electrodes on different parts of the skin. This results in a graph on calibrated paper of these activities. These graphs are useful in the diagnosis of heart disease and heart abnormalities. Alongside natural heart abnormalities are those induced by chemical substances. The electrocardiogram is useful in showing how these chemicals adjust the electrical impulses that it induces.

The second part of this lab was a computer simulation program to illustrate a frog’s electrocardiogram using various drugs in an isolated setting. The computer program entitled “Effects of Drugs on the Frog Heart” allowed experimental conditions to be set for specific drugs. The different drugs used were calcium, digitalis, pilocarpine, atropine, potassium, epinephrine, caffeine, and nicotine. Each of these drugs caused a different electrocardiogram and beats per minute reading. The calcium-magnesium ration affects “the permeability of the cell membrane”(Fox). When calcium is placed directly on the heart it results in three physiological functions. The force of the heart increases while the cardiac rate decreases. It also causes the appearance of “ectopic pacemakers in the ventricles, producing abnormal rhythms” (Fox). Digitalis’ affect on the heart is very similar to that of calcium. It inhibits the sodium-potassium pump activated by ATP that promotes the uptake of extracellular calcium by the heart. This in return strengthens myocardial contraction (Springhouse). Pilocarpine on the other hand

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acts to decrease the heart rate. It achieves this by assisting in the release of acetylcholine from the vagus nerve. Atropine on the other hand block acetylcholine receptors thus decreasing cardiac rate. By placing potassium directly on the heart, its extracellular concentration increases thus decreasing the resting potential. This brings the resting potential closer to threshold and weakens myocardial contractions. Epinephrine’s action increases the strength of contraction and of the cardiac rate. Caffeine is a stimulant that also increases the strength of contraction and of the cardiac rate. It inhibits phosphodiesterase that breaks down cyclic AMP thus causing an increase in cAMP levels. Nicotine actively binds to the nicotinic receptors causing stimulation of the parasympathetic ganglia. This in returns slows the heart rate.

By listening to chest one can hear the actual mechanical contraction of the heart. Upon the closure of the valves a lub can be heard and the semilunar valves shut a dub is heard. Using this technique, diagnosis of a heart murmur can be made. The relative opening of the foramen ovale can cause this condition. Adding a device known as a sphygmomanometer and listening to the brachial artery is how blood pressure is taken. Blood pressure is highly dependent on cardiac output and peripheral resistance. Cardiac output is the amount of blood pumped by the heart per minute. The resistance the blood receives flowing through the arterioles is peripheral resistance. As a result of this, blood pressure can be controlled by dilation and constriction of arterioles.

Upon measuring blood pressure, on should be able to hear five phases of sound.

These phases are: 1. A loud clear tapping.

2. A sequence of murmurs.

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3. A loud thumping following the murmurs.

4. The sound becomes muffled.

5. Silence.

In determining how fit we are a number of test can be used. This can include but

is not limited to the ECG, blood pressure, and/or pulse rate. By taking the pulse under various conditions the maximum cardiac rate can be estimated. Trend wise, a non-athlete will reach their maximum cardiac output at a lower workload than an athlete. Although not completely accurate, this can be a very good indicator of fitness.

MATERIALS AND METHODS

ECG

In order to carry out the electrocardiogram experiment a number of materials needed to be obtained. Three disposable electrodes along with the electrode gel were needed. The BIOPAC program, Mac Computer, and the SS 2L lead (black, red, white) were used to collect data on the subject. The electrodes were connected to the body (skin). The black lead was placed on the anterior right leg just above the ankle joint. The same was done with the red lead expect placement was on the left leg. The white lead was placed on the right wrist just above the palm. After correct placement of these electrodes, the SS 2L lead was connected to the CH 2 port. Lesson 3 was opened and the setup icon was clicked. After the setup as completed, record was clicked and the ECG recorded for 30 seconds. This was done while the subject was sitting relaxed. Using the I-beam tool, peak-to-peak measurements were taken. This value was the inter-beat interval. With that number, beat per minute was found (BPM = 60 / IBI).

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The second phase of the experiment was to connect the pulse transducer to the index finger or the right hand. The SS 2L lead was disconnected from CH 2 and placed in the CH 1 port. The SS 4L lead

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