Hi please use the figure 7-1 to answer all parts of the questions. Describe what

Question

Hi please use the figure 7-1 to answer all parts of the questions. Describe what happens when the events are recorded.Describe the general cause of electrical events for cardiac cycle. Think about he events that ivcur between electricke and auditory events from question 2( the first question) the electricke events lead to what. Which causes what to happen? Describe the general cause of the auditory events.

Refer to Figure 7-1 on p. 99 of your lab manual. Draw and label the electrical and auditory events (the letters and sounds) you will record in lab in the correct sequence as they occur in the cardiac cycle. For each event drawn above, briefly describe what happens as the events are recorded (i.e. the first wave is a recording of what event?) Based on your answers for the previous question, describe the general cause of the electrical events, not each individual electrical event, for the cardiac cycle. HINT: The cardiac cycle has multiple electrical events with the same cause. Before answering, recall the name and the cause of the electrical event for skeletal muscles in Exercise 5. Think about the events that occur between the electrical and auditory events from question 2. The electrical event leads to what, which causes what to happen? Etc. Describe the general cause of the auditory events, not each auditory event

Explanation / Answer

The given picture is of Electrocardiogram-ECG. The electrical events in the heart can be detected by electrodes on the surface of the body. A recording of these events is an electrocardiogram and the instrument used to record the electrical changes is an electrocardiograph. ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle.

Each peak in the ECG is identified with a letter from P to T that corresponds to a specific activity of the heart.

i. The P- wave represents the atrial depolarization. i.e., the electrical excitation of the atria, which leads to the contraction of both atria.

ii. The QRS-complex represents ventricular depolarization, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.

iii. The T-wave represents the repolarization of ventricles. i.e., the return of the ventricles from excited to normal state. The end of T-wave marks the end of systole. ( Atrial repolarization is not apparent because it takes place while the ventricles are depolarizing and the QRS complex masks the electrical events).

By counting the number of QRS complexes that occur in a given time period, one can determine the heart rate of an individual.

The auditory sounds are 'LUB' and 'DUP' are heard during the cardiac cycle.

The first sound 'LUBB' is heard after the atrial contraction. When the atria contract, the blood is pumped into the ventricles and the bicuspid and tricuspid valves close to prevent the back flow. The sound is due to closure of cuspid valves.

The second sound 'DUP' is heard after the ventricular contraction. When the ventricles contract, the blood goes to the two arteries attached to the heart- the aorta from left ventricle and pulmonary artery from right ventricle. When the ventricles contract, the aortic and pulmonary semilunar valves (present at the bae of these two arteries) close. The closure of these semilunar valves is heard as 'DUP'.

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