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Ekg- the Basic
| Question | Answer |
|---|---|
| Cardiac cells in resting state are ______polorized- their insides are_________ charged | Electrically - negative |
| When cardiac cells lose their internal negativity in a process it is called | Depolarization |
| Depolarization is | The fundamental electrical event of the heart |
| What is repolarization | After depolarization is complete, the cardiac cells restore their resting polarity- it is accomplished by the membrane pumps, which reverse the flow of ions |
| The heart consists (from a electrocardiographer standpoint) what three types of cells | Pacemaker, electrical conducting cells, and myocardial cells |
| Describe pacemaker cells | Under normal circumstances the electrical power source of the heart |
| Describe electrical conducting cells | The hard wiring of the heart |
| Describe myocardial cells | The contractile machinery of the heart |
| Pacemaker cells are able to do what | These cells are able to depolorize spontaneously over and over again the rate of depolarization is determined by the innate electrical characteristics of the cell and by external neurohormonal input |
| Each spontaneous depolarization of the pacemaker cells serves as a source of depolarization that initiates one what | Complete cycle of cardiac contraction and relaxation |
| If we record one electrical cycle of a depolarization and repolarization from a single cell we get an electrical tracing called what | Action potential |
| What is the group of dominant pacemaker cells called in the right atrium | The sinoatrial (SA) node or sinus node- fire typically rate of 60-100 x's per min |
| What are electrical conducting cells | Are long thin cells like wires of an electrical circuit the cells carry current rapidly and efficiently to distant regions of the heart the electrical conducting cells of the form distinct electrical pathways |
| The ventricular conducting fibers constitute what? | The Purkinje system |
| What is the bachmann's bundle? | Fibers at the top of the intra-atrial septum- conducting pathways in the atria have more anatomic variability |
| When cardiac cells in their resting state are electrically polarized - their insides are negatively charges- they are maintained by membrane pumps that ensure the appropriate distribution of ions- are primarily what | Potassium, sodium, chloride, and calcium |
| Myocardial cells contain an abundance of | Contractile proteins actin and myosin |
| When a wave of depolarization reaches a myocardial cell what is released within the cell | Calcium - which causes the cell to contract- which is called excitation-contraction coupling |
| The waves that appear on the ekg are primarily reflect the electrical activity of the _____ | Myocardial cells- which make up the vast bulk of the heart |
| What are the three chief characteristics of waves produced by myocardial depolarization and repolarization | Duration (measured in fractions of a second) Amplitude (measures in millivolts (mV) and Configuration (a more subjective criterion referring to the shape and appearance of a wave) |
| What is the distance in one small square & also the distance in one large square for horizontal axis | .04 sec - then 5 small to make one large so large is .20 seconds |
| What is the Verticle axis that measures voltage | 1 box is .50 mV - 2 boxes 1 mV |
| Systole | Contraction |
| Diastole | Relaxation |
| Each cycle of a normal cardiac contraction and relaxation begins when | The sinus node Depolarizes spontaneously. The wave of depolarization then propagates through both arteria causing them to contract |
Created by:
angelshari
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