What are the 6 parts of the cardiac conduction cycle? correct answer: -SA node -Internodal pathways -AV node -Bundle of His -R and L bundle branches
... [Show More] -Purkinje fibers What is the SA node? correct answer: -Small cluster of cells located in the upper R atrium *-Pacemaker of the heart* What are internodal pathways? correct answer: Impulses sent by the SA node that travel through the atrial muscle fibers via the intra-atrial pathways Allows for simultaneous depolarization and contraction of the atria Where is the AV node located? correct answer: Lower portion of the R atria What is the inherent rate of the SA node? correct answer: 60-100 bpm What does the AV node do? correct answer: -Receives impulse from the SA node -Delays conduction to allow for the atria to contract, then conducts to the ventricle Where is the Bundle of His? correct answer: -Upper part of the intraventricular septum -Connects AV node with bundle branches What is the Bundle of His? correct answer: AV node and Bundle of His are known as the Junctional area What is the inherent rate of the Bundle of His? correct answer: 40-60 bpm What is the back up for the SA node? correct answer: AV junction Where are the R and L bundle branches? correct answer: Arise from the bundle of His and travel down the R and L side of the septum What are purkinje fibers? correct answer: Smaller branches of the bundle branches that spread throughout the myocardium and terminate there What is the inherent rate of purkinje fibers? correct answer: 20-40 bpm What is the final back up pacemaker for the SA node and AV junction? correct answer: Purkinje fibers What is automaticity? correct answer: Ability to act as an impulse, initiating electrical activity and spontaneous depolarization *Most important difference between cardiac and skeletal muscle cells* What is excitability? correct answer: Ability to respond to a stimulation and initiate an impulse What is conductivity? correct answer: Ability to transmit an impulse that has been initiated and passes along cell membranes What is contractility? correct answer: Ability of a muscle fiber to shorten in response to a stimulus What is refractoriness? correct answer: Inability of a muscle fiber to respond to a stimulus during an interval following contraction What is the absolute refractory period? correct answer: Time interval, when no matter how strong the stimulus, a cardiac cell cannot be depolarized. How do you measure the absolute refractory period? correct answer: Beginning of the QRS to the middle of the T wave What is the relative refractory period? correct answer: Time interval, when given only a stronger than normal stimulus, a cardiac cell may depolarize Why is the relative refractory period known as a vulnerable period? correct answer: Because of risk of R on T phenome [Show Less]