The Physics Factbook
Edited by Glenn Elert -- Written by his students
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|The New Book of Popular Science. Connecticut: Grolier Inc, 1996.||"It beats or contracts about 70 times per minute."||1.17 Hz|
|Magill, Frank. Magill's Survey of Science. New Jersey: Salem, 1991.||"so the resting heart rate (70 beats per minute)"||1.17 Hz|
|Bender, Lionel. Human Body. New York: Crescent, 1992.||"It beats roughly 70 times a minute throughout one's life"||1.17 Hz|
|Lietz, Gerald & Anne White. Secrets of the Heart and Blood. Illinois: Gerrard, 1965.||"A baby's heart beats 120 times a minute. A man's heart beats 72."||2.00 Hz
|Berkow, Robert. The Merck Manual of Medical Information. New Jersey: Merck, 1997.||"The normal heart rate at rest is usually between 60 and 100 beats per minute."||1.00 to 1.67 Hz|
The heart is a muscular organ that is about the size of a closed fist for an average adult and weighs about 11 ounces (310 grams). When the heart muscle, called cardiac muscle, contracts it pushes blood through the chambers and into the vessels. The heartbeat is a vital, involuntary action for a living human being and the heart continues to pump throughout an individuals life stopping only at death. The heartbeat rate is controlled by the autonomic nervous system, which is composed of two parts -- the sympathetic system speeds up the heartbeat rate while the parasympathetic system slows it down.
Heartbeats vary depending on various factors such as age, physical state, and stimuli. A child has a smaller heart and therefore their heart needs to beat faster in order to pump the proper amount of blood. The heartbeat rate for infants is 120 per minute, for a child is about 90 times per minute, and for a person over age 18 is about 70 times per minute. A physically fit person has a lower heart rate as compared to an inactive person. Stimuli resulting in stress, fear or excitement will result in a rapid heartbeat. Nerves connected to the heart regulate the speed with which the cardiac muscle contracts. Interestingly, in an average lifetime, the heart continuously beats more than 2.5 billion times.
People with heart disease produce irregular sounds that are emitted for each heartbeat. Their blood flows through abnormal valves causing murmurs -- an important diagnosis for cardiac diseases. A pacemaker is an electrical device that is used to stimulate regular beating of the heart for people who have heart disease.
Frequency is denoted as the number of times a regularly recurring phenomenon occurs in one second. The number of times a heart beats in one minute is divided by 60 seconds to obtain the frequency in Hertz. The values for frequency of heartbeat that I researched were of little variation -- about 70 beats per minute for a healthy resting adult.
Take care of your heart because it is vital for your life!
Arshe Ahmed -- 1998
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