The contraction of the ventricles is referred to as (1) ?and the period of ventricular relaxation is called (2). ?The monosyllables describing heart sounds during the cardiac cycle are (3). ?The first heart sound is a result of closure of the (4) ?valves; closure of the (5) ?valves causes the second heart sound. The heart chambers that have just been filled when you hear the first heart sound are the (6) ?and the chambers that have just emptied are the (7). ?Immediately after the second heart sound, the (8) ?are filling with blood and the (9) ?are empty. Abnormal heart sounds, or (10), ?usually indicate valve problems.
The Correct Answer and Explanation is:
Here are the correct answers:
- Systole
- Diastole
- “Lub-Dub”
- Atrioventricular (AV)
- Semilunar
- Ventricles
- Atria
- Atria
- Ventricles
- Murmurs
Explanation (300 words):
The cardiac cycle refers to the sequence of events that occur in the heart during one heartbeat. It consists of two main phases: systole and diastole. During systole, the ventricles contract to pump blood into the arteries — the pulmonary artery and aorta. This contraction increases pressure, forcing the atrioventricular (AV) valves (tricuspid and mitral) to close, producing the first heart sound, commonly referred to as “lub”. The AV valves prevent blood from flowing backward into the atria.
Following systole is diastole, the period when the ventricles relax and the heart fills with blood. As the pressure in the arteries becomes higher than in the ventricles, the semilunar valves (aortic and pulmonary) close, creating the second heart sound, or “dub”. This closure prevents backflow of blood from the arteries into the heart.
Right after the first heart sound, the ventricles have been filled and are starting to contract, meaning the atria have just emptied. After the second heart sound, the atria begin filling with blood again from the veins (superior/inferior vena cava and pulmonary veins), and the ventricles are now empty, preparing for the next cycle.
Abnormal heart sounds, known as murmurs, may be heard between the normal “lub-dub” sounds. These are typically caused by turbulent blood flow, often due to valve defects such as stenosis (narrowing) or regurgitation (leakage). Murmurs can be benign or indicate underlying heart disease, and they are diagnosed using a stethoscope and further evaluated with tests like echocardiography.
Understanding these basic cardiac events helps in recognizing normal versus abnormal heart function and forms the foundation for diagnosing cardiovascular conditions.
