The Physics Factbook™
Edited by Glenn Elert -- Written by his students
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|Bibliographic Entry||Result |
|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 closedfist for an average adult and weighs about 11 ounces (310 grams).When the heart muscle, called cardiac muscle, contracts it pushesblood through the chambers and into the vessels. The heartbeatis a vital, involuntary action for a living human being and theheart continues to pump throughout an individuals life stoppingonly at death. The heartbeat rate is controlled by the autonomicnervous system, which is composed of two parts -- the sympatheticsystem speeds up the heartbeat rate while the parasympatheticsystem slows it down.
Heartbeats vary depending on various factors such as age, physicalstate, and stimuli. A child has a smaller heart and thereforetheir heart needs to beat faster in order to pump the proper amountof blood. The heartbeat rate for infants is 120 per minute, fora child is about 90 times per minute, and for a person over age18 is about 70 times per minute. A physically fit person has alower heart rate as compared to an inactive person. Stimuli resultingin stress, fear or excitement will result in a rapid heartbeat.Nerves connected to the heart regulate the speed with which thecardiac 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 areemitted for each heartbeat. Their blood flows through abnormalvalves causing murmurs -- an important diagnosis for cardiac diseases.A pacemaker is an electrical device that is used to stimulateregular beating of the heart for people who have heart disease.
Frequency is denoted as the number of times a regularly recurringphenomenon occurs in one second. The number of times a heart beatsin one minute is divided by 60 seconds to obtain the frequencyin Hertz. The values for frequency of heartbeat that I researchedwere of little variation -- about 70 beats per minute for a healthyresting adult.
Take care of your heart because it is vital for your life!
Arshe Ahmed -- 1998
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