Cardiac Cycle Overview

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Questions and Answers

What is the duration of one complete cardiac cycle?

1.0 seconds

1.2 seconds

0.5 seconds

0.8 seconds (correct)

Which phase of the cardiac cycle occurs during the relaxation of the heart muscle?

Rapid ventricular ejection

Isovolumetric contraction

Diastole (correct)

Systole

During which phase does the atrial contraction take place?

Isovolumetric relaxation

Rapid ventricular filling

Ventricular diastole

Atrial systole (correct)

What event coincides with the closure of the mitral valve?

Isovolumetric ventricular contraction Signup and view all the answers

Which phase of the cardiac cycle is characterized by the ejection of blood from the left ventricle into the aorta?

Rapid ventricular ejection Signup and view all the answers

What occurs during the isovolumetric phases of the cardiac cycle?

Volume remains unchanged in the ventricles Signup and view all the answers

What is the heart sound associated with the closure of the mitral valve?

S1 Signup and view all the answers

Which ECG component coincides with the atrial systole phase?

P wave Signup and view all the answers

What physiological event coincides with the closure of the aortic valve?

Isovolumetric ventricular relaxation Signup and view all the answers

Which heart sound corresponds to the closure of the semilunar valves?

Second heart sound (S2) Signup and view all the answers

During which phase is the first heart sound (S1) primarily produced?

Isovolumetric contraction Signup and view all the answers

Which component of the second heart sound is typically delayed during inspiration?

P2 Signup and view all the answers

In which group of patients is physiological splitting of the second heart sound more likely to be detected?

Children Signup and view all the answers

What is the longest phase of the cardiac cycle?

Reduced ventricular filling (diastasis) Signup and view all the answers

Which heart sound is typically associated with the difficulties in auscultation in adults?

S3 Signup and view all the answers

Why does the second heart sound (S2) have a higher pitch compared to the first heart sound (S1)?

Resulting from the swift closure of semilunar valves Signup and view all the answers

Study Notes

Cardiac Cycle

Cardiac cycle encompasses cardiac events from one heartbeat's start to the next.
It involves both sides of the heart.
One cycle lasts 0.8 seconds, with a heart rate of 72 beats per minute.
An electrocardiogram (ECG) tracks cardiac events.
Valve openings/closings produce physiological heart sounds.

Phases of Cardiac Cycle

Diastole: Heart muscle relaxes, chambers fill with blood.
- Atrial Diastole: Atria relax, fill with blood from large veins.
- Ventricular Diastole: Ventricles relax, fill with blood from atria.
Systole: Heart muscle contracts, pumps blood from chambers into arteries.
- Atrial Systole: Atria contract, push blood into ventricles.
- Ventricular Systole: Ventricles contract, push blood into large arteries.

Isovolumetric Contraction

Left ventricle contracts, mitral valve closes.
No change in ventricle volume.
Coincides with first heart sound (S1).

Rapid Ventricular Ejection

Rapid blood flow from left ventricle into aorta.
Aortic valve opens.
Phase ends at the end of the ST segment on the ECG.

Reduced Ventricular Ejection

Reduced blood ejection rate from ventricle to aorta.
Coincides with beginning of T wave on ECG.

Isovolumetric Relaxation

Relaxation of ventricles.
Aortic valve closes.
Coincides with second heart sound (S2).

Rapid Ventricular Filling

Rapid blood filling from atrium to left ventricle.
Mitral valve opens.
Coincides with third heart sound (S3).

Reduced Ventricular Filling (Diastasis)

Slower rate of ventricular filling.
Longest phase of the cardiac cycle.

Heart Sounds

Caused by blood flow through narrow passages, valve vibrations.
Sound waves travel to skin, can be heard with a stethoscope.

First Heart Sound

Produced during isovolumetric contraction phase.
Resembles "lub".
Corresponds to mitral and tricuspid valve closure.

Second Heart Sound

Produced during isovolumetric relaxation phase.
Resembles "dub".
Corresponds to aortic and pulmonary valve closure.

Splitting of Second Heart Sound

In younger patients, physiologically, S2 may be split (A2 and P2 separately audible).
Splitting depends on inspiration/expiration. Inspiration delays the pulmonic valve closure.

Listening to Heart Sounds

Part of cardiovascular examination.
Essential components of CVS examination are general examination, inspection, palpation, and auscultation.
Requires a stethoscope:
- Bell to detect low-frequency sounds (S3&S4).
- Diaphragm to detect high-frequency sounds (S1 & S2).
Specific locations exist on the chest to listen for sounds from various heart valves.

General Principles for Listening to Heart Sounds

Quiet environment is essential.
Warm stethoscope is needed.
Follow a sequence for consistency.
Listen to each sound one at a time (rate, rhythm, S1, then S2, then abnormal sounds).
Left-side heart sounds are often louder.

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Description

Explore the intricacies of the cardiac cycle, including its phases: diastole and systole. Understand how the heart functions through contraction and relaxation, and learn the significance of electrocardiograms in tracking these events. Dive into concepts like isovolumetric contraction and rapid ventricular ejection.