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Defines dry-cells and batteries and explains the function. of both in relation to voltaic cells.

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Keeping the Beat

Keeping the Beat

Credit: Rosmary
Source: http://www.flickr.com/photos/94212497@N00/5343361247
License: CC BY-NC 3.0

When a person complains of chest pain or irregular heart beat, one of the first tests performed is an EKG (Greek kardio meaning “heart”). This test measures the regularity of the heart rate and the number of beats per minute. Abnormalities can be detected and appropriate treatment quickly initiated.

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  • Your heart is an impressive organ. It controls blood flow throughout the entire body and never takes a vacation. It pumps blood 24/7 to keep you functioning and healthy. Electrical impulses are generated by the heart to stimulate contraction. In order for the heart (and your body) to function properly, the contractions must be strong and regular. An EKG records those impulses to give a picture of the electrical activity of the heart.
  • Pacemakers are devices that artificially regulate the heart beat. The pacemaker is connected to the heart using tiny wires threaded through the veins and placed in specific areas of the heart. The pacemaker itself is a very small battery-operated device with a built-in computer. The computer has two basic functions: (1) to monitor the heart beat, and (2) to regulate the frequency and strength of electrical signals sent to the heart.
  • Credit: Travis Goodspeed
    Source: http://www.flickr.com/photos/travisgoodspeed/5227335032/
    License: CC BY-NC 3.0

    The "guts" of a pacemaker [Figure2]

  • Lithium batteries are the power source of choice for pacemakers. These are the same batteries that are often found in laptops, cell phones, and many other devices. They provide six times as much energy as a regular car battery and are extremely light. The power source will usually last several years before it needs to be replaced. Lithium cobalt oxide serves as the cathode, releasing electrons to flow to the carbon anode.
  • Radioisotopes were used at one time as a power source for pacemakers because they could provide a long usable life for the power needed. The heat generated by nuclear decay was sufficient to operate the device. Although there were apparently no health problems associated with radiation exposure, the development of long-lasting lithium batteries made the radioisotope power systems unnecessary. This type of pacemaker was discontinued in the early 1980s.
  • Learn more about pacemakers and the heart from the video below: https://www.youtube.com/watch?v=SMXBR_YFocs

Use the links below to learn more about heart beats and pacemakers, then answer the following questions.

  1. Where does the electrical impulse start in the heart?
  2. Why are pacemakers usually implanted?
  3. What does a pacemaker consist of?
  4. How is a pacemaker battery replaced?
  5. What does a pacemaker wearer need to avoid?

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    Image Attributions

    1. [1]^ Credit: Rosmary; Source: http://www.flickr.com/photos/94212497@N00/5343361247; License: CC BY-NC 3.0
    2. [2]^ Credit: Travis Goodspeed; Source: http://www.flickr.com/photos/travisgoodspeed/5227335032/; License: CC BY-NC 3.0

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