Cardiac Conduction Worksheet Flashcards
What is the function of the conduction system?
initiate and transmit the electrical impulses responsible for the coordinated contractions of each cardiac cycle.
What does it mean for a cardiac cell to be connective?
can propagate from one cell to another via gap junctions.
What does it mean for a cardiac cell to be autorhythmic?
can excite themselves spontaneously without simulation of the nervous system and contract at a regular rhythm.
Sinoatrial Node’s average beats per minute
100 beats/min
Atrioventricular node’s average beats per minute
40-50 beats/min
Ventricles average beats per minute
20-40 beats/min
What is the function of the SA node?
Sets the rate of contraction for the heart. Spontaneously contracts and generates nerve impulses that travel throughout the heart wall causing both atria to contract.
Contrast a healthy heart ECG with an abnormal one in which ventricular excitation is independent of atrial excitation
entricular excitation is independent of atrial excitation the pace of ventricular excitation is being sent by the ventricles slower natural rhythm not by stipulation from the SA node atria
Contrast the resting potential of typical myocardial cells with that of SA node cells
Typical contractile cells in the myocardium has a resting membrane potential
Cells of the SA node is not fixed and is known as the pacemaker potential
What two factors combine to determine heart rate?
Extrinsic and Intrinsic controls
Contrast the effects of acetylcholine and norepinephrine on heart rate
Acetylcholine- lowers heart rate
Norepinephrine- increases heart rate
What do parasympathetic neurons secrete?
Acetylcholine
What do sympathetic neurons secrete?
Norepinephrine
