PATH 222 Cardiac Dysrhythmias
, PATH 222
Cardiac Dysrhythmias (Arrhythmias)
VanMeter and Hubert Chapter 12; LeMone et al. p. 895-897; Adams, Chapter
55 Week 2
Review the cardiac conduction system.
Figure 55.1 Adams et al. (2nd Canadian ed.) p. 697
a) sino-atrial node (pacemaker) in the right atrium
• generates impulses at approximately 70/minute (automaticity = the ability to
spontaneously generate an action potential without direction from the nervous system
• called sinus rhythm
• can be affected by the autonomic nervous system and by hormones such as epinephrine
b) impulses spread through the atrial pathways and the atria contract
c) atrio-ventricular node located on the floor of the right atrium
d) impulses continue into the ventricles through the Bundle of His, right and left bundle
branches and Purkinje fibers, resulting in ventricular contraction
Review the cardiac cycle in VanMeter and Hubert 5th ed. page 227 - 228.
Cardiac output
• the volume of blood ejected by a ventricle in one minute
• depends on heart rate and stroke volume
• stroke volume varies with sympathetic stimulation and venous return, eg. increased
venous return leads to increased force of contraction
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, PATH 222
Cardiac Dysrhythmias (Arrhythmias)
VanMeter and Hubert Chapter 12; LeMone et al. p. 895-897; Adams, Chapter
55 Week 2
Review the cardiac conduction system.
Figure 55.1 Adams et al. (2nd Canadian ed.) p. 697
a) sino-atrial node (pacemaker) in the right atrium
• generates impulses at approximately 70/minute (automaticity = the ability to
spontaneously generate an action potential without direction from the nervous system
• called sinus rhythm
• can be affected by the autonomic nervous system and by hormones such as epinephrine
b) impulses spread through the atrial pathways and the atria contract
c) atrio-ventricular node located on the floor of the right atrium
d) impulses continue into the ventricles through the Bundle of His, right and left bundle
branches and Purkinje fibers, resulting in ventricular contraction
Review the cardiac cycle in VanMeter and Hubert 5th ed. page 227 - 228.
Cardiac output
• the volume of blood ejected by a ventricle in one minute
• depends on heart rate and stroke volume
• stroke volume varies with sympathetic stimulation and venous return, eg. increased
venous return leads to increased force of contraction
Downloaded by Quiz Grade
()
