HAVE A HEART: The heart pumps 5.6 liters of blood through the entire body in roughly 20 seconds; each day your blood travels some 12,000 miles, and your heart beats about 100,000 times. This delivers oxygen and other essential nutrients to the body's cells and organs. A heart attack occurs when the blood supply to the heart muscle is cut off, either because part of the heart is damaged (such as the valves to the chambers), or because plaque has built up inside the arteries, narrowing them and severely restricting blood flow. Symptoms of a heart attack include a squeezing discomfort in the center of the chest, pain or tingling in the left arm, shortness of breath, and sometimes a cold sweat, nausea, or dizziness.
HEAR, HEAR: Our ears detect sound as vibrations in the air. Those sound waves cause the eardrum to vibrate, sending waves through a fluid inside the cochlea. This causes tiny hairs -- each tuned to the different pitches of the sound -- to vibrate as well, stimulating nerves which send electrical signals to the rain for processing. Having two ears makes it possible to determine from where a sound is coming. Time lag and differences in volume provide useful clues. For instance, sound coming from one direction will reach the ear furthest away about 1/500 second later than the closer ear, and the brain can detect this time lag. A difference in volume between the two ears depends on the frequency of the sounds. It is easier for us to tell the direction of high frequency sounds better than low frequency sounds, because the higher frequencies are more easily blocked by the hear, and therefore do not easily reach the far ear.
The Acoustical Society of America contributed to the information contained in the TV portion of this report.