Module 15 pt 2 Heart Physioology Flashcards
This system is a network of non-contractile cells that initiate and distribute impulses to coordinate the depolarization and contraction of the heart
Intrinsic cardiac conduction system
These cells have a unstable resting potential due to the open slow Na+ channels, they continuously depolarize
Autorhythmic cells
These autorhythmic cells are found in certain areas of the heart, including this node that is considered the pacemaker of the heart
Sinoatrial node
How often does the SA node beat and what is the rhythm called?
90-95 times per minute, it is called the sinus rhythm
What is unique about the SA node?
It depolarizes faster than any other part of the myocardium
This node has fewer gap junctions and has a .1 second delay
Atrioventricular Node
What is the reason for the .1 second pause of the AV node?
If there was no pause, the heart would be pumping blood against itself instead of through the valves
This is the only electrical connection between the atria and the ventricles
AV bundle, or the bundle of HIS
These are two pathways in the interverticular septum that carry the impulses towards the apex of the heart
Right and Left bundle branches
This is the complete pathway into the apex and ventricular walls
Purkinje Fibers
Irregular heart rhythms where there are uncoordinated atrial and ventricular contractions
Arrhythmias
This is a homeostatic imbalances that is a rapid irregular contraction, useless for pumping blood
Fibrillation
A defective node may result in an abnormal pacemaker takes over, like the AV node (40-60 bpm)
Ectopic Focus
A defective SA node might result in a few or no impulses from the SA actually reach the ventricles
Partial or total heart block
What is the heartbeat modified by?
Autonomic Nervous System
Where are the cardiac systems located in the brain?
Medulla oblongata
What does the Cardioinhibitory center inhibit and what through?
The SA and AV nodes through the vagus nerve
This is a composite of all the action potentials generated by nodal and contractile cells at a given time
Electrocardiogram
This is a wave in the ECG that shows the depolarization of the SA node
P wave
This is a wave in the ECG that shows the ventricular depolarization
QRS complex
This is a wave in the ECG that shows ventricular repolarization
T wave
How many sounds are there associated with closing heart valves?
Two