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Heart Sounds & ECG Basics
Two of the oldest tools in medicine are still used at almost every cardiac check-up: the stethoscope, which hears the valves closing as the familiar lub-dub, and the ECG, which traces the electrical signal that drives each beat. This quiz covers the foundations — what makes each heart sound, the normal resting heart-rate range, what the waves on an ECG tracing stand for, and what a murmur actually is. It is written for students, patients who have had an ECG, and anyone curious about what the squiggles mean.
✓ Medically reviewed by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist · Last reviewed: October 2026
How it works: five questions, one best answer each. Tap an answer and you will see straight away whether it is right, with a short explanation of the reasoning. Your score builds as you go — there is no timer and no account needed.
Question 1 of 5
The familiar "lub-dub" of the heartbeat: what produces the first sound (lub)?
The first heart sound (S1) is made by the mitral and tricuspid valves closing at the start of ventricular contraction. The second sound, the "dub" (S2), is the aortic and pulmonary valves closing at the end of that contraction.
Question 2 of 5
What is generally considered the normal resting heart-rate range for a healthy adult?
A resting adult heart rate of about 60–100 beats per minute is the usual reference range; trained athletes often sit lower at rest. A rate is always interpreted together with symptoms and the person's usual baseline.
Question 3 of 5
On an ECG tracing, the P wave represents…
The P wave is atrial depolarisation — the electrical wave that triggers the two upper chambers to contract. It is followed by the QRS complex, which triggers the ventricles, and the T wave, which is the ventricles resetting (repolarising).
Question 4 of 5
A standard 12-lead ECG uses how many electrodes placed on the body?
Despite the name "12-lead", a standard ECG uses 10 electrodes: four on the limbs and six across the chest. The 12 leads are twelve different electrical viewpoints calculated from those ten electrodes.
Question 5 of 5
A heart murmur is…
A murmur is an extra whooshing sound heard between or instead of the normal sounds, caused by blood flowing turbulently — for example through a narrowed or leaky valve. Some murmurs are harmless ("innocent"), which is why a new murmur is examined and, if needed, scanned rather than guessed about.
Your result
Keep learning
ECG & Stress Test — Preparation GuideWhere the stickers go, what the treadmill stages feel like, and the rules about medicines on the day.Open → Heart Attack — Condition HubHow ECG changes help diagnose a heart attack, and what treatment and recovery involve.Open → Nursing: Monitoring & AssessmentHeart sounds, pulses, blood pressure and the other bedside observations nurses rely on.Open →Frequently asked questions
What is the difference between heart sounds and an ECG?
Heart sounds are mechanical: they are the noise of valves closing and blood moving, heard with a stethoscope. An ECG is electrical: it records the signal that triggers each beat, which is generated before any movement happens. The two tests answer different questions, so clinicians often use both.
Can listening to the heart replace an ECG?
No. A stethoscope can reveal murmurs and obvious rhythm problems, but it cannot show the heart's electrical patterns — heart block, strain patterns or the signs of a heart attack on a tracing. An ECG takes only a few minutes and adds information no amount of listening can provide.
These quizzes are for learning only. They are not medical advice, cannot diagnose anything, and do not replace assessment by a qualified clinician. If you have symptoms now — especially chest pain, severe abdominal pain, or sudden weakness or speech problems — seek urgent medical care.