W03 Worksheet: EKG, Pulses, & Blood PressureFollow the instructions below very carefully. Many of the items in this assignment require reading, or videos, or something else to do. Each question has either a text box that can be filled out or a box that can be checked to show completion. Be sure to type out your answers completely and expand the text boxes if you need the additional space.
Question 1 --- 4 points
EKGThe electrocardiogram (ECG or EKG) is the standard clinical tool used to measure the electrical activity of the heart. Data obtained from an EKG provides a graphical representation of the rate, rhythm, and pattern of electrical signals produced by action potentials traveling through cardiac myocytes. Recall that in a cell at rest, the inside of the cell has a negative charge with respect to the outside. That charge reverses when an excitable tissue such as a cardiac muscle cell depolarizes during an action potential. If one group of cardiac myocytes is depolarized (positive inside and negative outside) while another group is at rest (negative inside and positive outside), we have perfect conditions to generate an electrical current. If these oppositely charged areas are then connected by some sort of a conductor, an electrical current will flow. In our bodies, the extracellular fluid acts as a conductor allowing current to flow around the heart. Electrodes placed at strategic locations can then detect that current. By attaching electrodes to a galvanometer, tracings can be recorded that give us information about the magnitude and direction of the currents. Furthermore, by placing the positive and negative electrodes at different locations on the body, the EKG will give different “views” of the electrical activity. Each unique positioning of the electrodes is referred to as a lead. For example, in lead I the positive electrode is placed on near the left arm, and the negative electrode is placed near the right arm.For lead II, the positive electrode is placed on near the left leg, and the negative electrode near the right arm. By placing the electrodes in different positions, a total of 12 standard leads can beobtained, six limb leads, and six chest leads, giving 12 unique views of the electrical activity of the heart.Watch the video, “Electrical system of the heart” (links to an external site) (9:42 mins; Electrical Systems of the Heart Transcript) to learn about the electrical activity of the heart (about 10 minutes).This EKG Explained(links to an external site) video will explain the ECG waves (17:26 mins; EKG Explained Transcript(links to an external site).You can view the animation of the EKG Explained(links to an external site) here.