Cardiac Electrophysiology Flashcards
What is the function of the Sinoatrial node and where is it located
The SA node Is the dominant Pace maker in the heart
* Located in the right atrium near the superior venae cavae
* It spreads electrical impulses through the heart that cause the heart to beat
What is automaticity of the myocardium
the ability to grenerate its own electrical impulses without stimulation of nerve impulses
What is the heart tissue called that can create electrical impulses
Pacemaker tissues
Specialized conduction tussye
What is the Electrical conduction system
The ability for the heart muscles to create and conduct their own electrical impulses
What is the Atrioventricular node and where is it found
- Transmitting the impulse from the atria to the ventricles
- synchronisation of atrial and ventricular contractions by a varying delay;
- and protection of the ventricles from rapid atrial arrhythmias
- LOCATION: in the Koch triangle near the coronary sinus on the interatrial septum.
What is the Bundle of HIS and where is it located
Connection segment for the AV nodes and the Left/Right Bundle branches
* Assists in conducting and transmitting electrical impluses
What is the Bundle branches and where are they located
They are off shoots of the Bundle of HIS and branch down the Left & right side of the Interventricular system
What are Purkinje fibers and where are they located
They are thousands of ting branched fibers that carry electrical impulses into the ventricles and allow the ventricals to contract
What are the Heart rates of the 3 pacemakers
- Sinoatrial node : 60-100 beats/min (it is the most rapid pacemaker)
- Atrioventricular Junction (AV junction): 40-60/min
- Purkinje fibers :20-40/min
How is a impulse from the SA node transmitted down the heart
- Receives impulse and transmits it through both atriums by the Internodel pathway
- Then travels down to the Atrioventricular node and the surrounding tissue including the Bundle of His (Impulse is delayed .12s to allow atria to empty into the ventricle)
- Impulse passes from the Bundle of HIS through the Bundle branches and down both sides of the interventricular system
- Impulse spreads through the Purkinje fibers and through thousands of fibers in the ventricle ( roughly .08s causing both ventricles to contract simultanously
What is the Dromotropic effect
Changes to the conduction speed
* + effect = increase conduction speed
* Epinepherine causes a + dromotropic effect
What is Depolarization
Process of which a muscle fiber are stimulate to contract due to changes in the concentraction of electrolytes across the cell membrane
- Is a cell going from (-) to (+)
What is Repolarization
The process of a cell becoming negative again
-going from (+) to (-)
What is the Refactory period of a cell and what are the 2 stages
When the myocardial cell is either undergoing repolarization or depoliarization
1. Absolute refactory period : cell is still highly polarized and a new action potenial cant be initated
2. Relative refactory period : a cell is partially depolarized and a new action potential will be inhibitied but is not imposible
How does Depolarization and repolarization occur
- A resting (Polarized) cell when stimulate opens voltage gate channels
- Na+ rushes in from these channels and causes Ca2+ voltage gates to open causing Ca2+ to also enter the cell
- This Influx of positive ions causes mechanical contraction of the myocardium
- Both Na+ and Ca2+ gates close and Potassium gates open causing K+ ions to rush out of the cell
- The rapid removal of K+ ions restores the (-) charge of the cell making the cell Polarized again
- Once repolarized a sodium-potassium pump moves K+ and Na+ ions against the concentration gradient back to their respective spots (this is driven by ATP)
