Final answer:
The assertion that the sounds of Korotkoff are produced by the closing of the heart valves is false. Korotkoff sounds are related to the measurement of blood pressure and signify the resumption of blood flow, whereas heart sounds are indeed caused by the closing of the heart valves.
Step-by-step explanation:
The sounds of Korotkoff are not produced by the closing of the heart valves but are instead associated with measuring blood pressure using a sphygmomanometer and a stethoscope. The Korotkoff sounds are the noises that a clinician hears through a stethoscope as the cuff of the sphygmomanometer is gradually deflated on a limb. Initially, no sounds are heard because there is no blood flow.
However, when the cuff pressure is lowered, the first Korotkoff sound occurs, corresponding to the systolic pressure, and marks the return of blood flow through the brachial artery. The last Korotkoff sound corresponds to the diastolic pressure, indicating that blood flow has returned to normal and is no longer constricted by the cuff.
In contrast, the heart sounds ("lub-dub") are indeed caused by the closing of the heart valves: the atrioventricular valves produce the first heart sound (S1), and the semilunar valves produce the second heart sound (S2), which can be heard during a cardiac examination.