Phonocardiograph: Heart Sounds and Mechanisms

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What is the main cause of heart sounds?

Vibrations created by closure of the heart valves (correct)

The movement of cardiac muscle

The rhythmicity of the heart rate

The movement of blood through chambers of the heart

What is the phonocardiograph used for?

To record the sounds connected with the pumping action of the heart (correct)

To hear heart sounds more clearly

To measure the heart rate

To diagnose heart diseases

What is the purpose of phonocardiography?

To graphically record heart sounds or murmurs (correct)

To diagnose heart diseases

To record the heart rate

To measure the heart rhythmicity

What is a phonocardiogram?

A high-fidelity recording representing the rhythmicity and heart rate Signup and view all the answers

Why is phonocardiography used instead of electronic stethoscopes?

Because it can detect both heart sounds that are too low in intensity and too high in frequency Signup and view all the answers

What is the advantage of phonocardiographs over electronic stethoscopes?

They provide a recording of the waveforms of the heart sounds Signup and view all the answers

What can even subtle changes in breath sounds be detected with?

An electronic stethoscope Signup and view all the answers

What can be impaired in the absence of an airtight seal between stethoscope and skin?

Physiologic sound transmission Signup and view all the answers

What is not a capability of electronic stethoscopes?

Generating constructive interference of physiologic sound waves Signup and view all the answers

What determines the quality of sound wave transmission?

The airtight seal between stethoscope and skin Signup and view all the answers

What is the result of the mechanical working processes of the heart?

Production of sound indicating health status Signup and view all the answers

According to the valvular theory, where do heart sounds emanate from?

Point sources located near the valves Signup and view all the answers

What occurs during atrial systole in the late diastolic filling period?

Blood is forced into the ventricles Signup and view all the answers

What is the characteristic of innocent murmurs?

They are present in normal hearts without any heart disease Signup and view all the answers

What is the cause of pathologic murmurs?

Narrowing or leaking of valves Signup and view all the answers

What is necessary for heart murmurs to occur?

Blood flow above the Reynolds number Signup and view all the answers

How are heart murmurs graded?

By their intensity from I to VI Signup and view all the answers

What is characteristic of a Grade I murmur?

It is faint and heard only with special effort Signup and view all the answers

What is a common factor involved in the production of murmurs?

Decreased viscosity Signup and view all the answers

What is the primary function of the filter in the instrumentation of murmurs?

To permit selection of suitable frequency bands Signup and view all the answers

What type of microphone is often used in the instrumentation of murmurs?

Crystal microphone Signup and view all the answers

What is the typical bandwidth of the filter used in the instrumentation of murmurs?

20-2000Hz Signup and view all the answers

What is the purpose of the integrator in the instrumentation of murmurs?

To record the envelope of higher frequency signals Signup and view all the answers

Why is Rochelle salt commonly used in microphones?

It has the largest voltage output for a given mechanical stress. Signup and view all the answers

What happens when mechanical stress is placed on the crystal material in a microphone?

A voltage electromagnetic force is generated. Signup and view all the answers

Why is the sound pressure in the air chamber kept constant?

To keep a flat response in the pass band. Signup and view all the answers

What is a characteristic of dynamic microphones?

They consist of a moving coil with a fixed magnetic core. Signup and view all the answers

Why is heart sound recording with a microphone valid for a particular frequency only?

Because the microphone does not transform acoustic oscillations into electrical potentials uniformly for all frequencies. Signup and view all the answers

How is the sound wave coupled to the crystal in some microphones?

Indirectly, through a diaphragm mechanically linked to the crystal. Signup and view all the answers