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EKG Tech 2
Heart Anatomy And Electrical Conduction
Question | Answer |
---|---|
Trace a Drop of Blood from the Inferior Vena Cava to the Aorta. | Inferior and Superior vena cava->right atrium->tricuspid valve->right ventricle->pulmonic valve->pulmonary arteries->lungs->pulmonary veins->left atrium->mitral valve->left ventricle->aortic valve->aorta->rest of the body, including the heart. |
Trace the normal Electrical Conduction Pathway System Through the Heart. | Sinoatrial node (SA node)-> intraatrial and internodal pathways->atrioventricular node(AV node)->Bundle of His->Bundle Branches->Purkinje's fibers->Ventricular muscle. |
Cardiac Output (CO) | One method of measuring how efficiently the heart is pumping and circulating blood to the body cells. Cardiac output is the amount of blood pumping by the left ventricle in one minute. CO=SV X HR |
Polarization | "Readiness" muscle is relaxed and cardiac cells are ready to receive electrical impulse. Potassium (K+) is inside cell Sodium (Na+) is outside of cell. |
Depolarization | "Contraction" cardiac cells have transmitted an electrical impulse, causing muscle to contract. Potassium (K) and Sodium (NA)Switch spots. So Sodium is now inside of cell and Potassium is outside. |
Repolarization | "Recovery" muscle has contracted and cells are returning to original state. Potassium (K)and Sodium (NA) return to original spots. Potassium inside and Sodium outside of cell. |
Arteries | Carry oxygenated blood away from heart to body. Arteries have the thickest walls. Aorta is the largest artery in body |
Veins | Carry blood with carbon dioxide from body back to heart. Veins have thinner walls than arteries. Peripheral Veins are for arms and legs. |
Capillaries | The exchange of nutrients and waste products for the body cells. Have the thinnest walls. |
4 Heart Chambers | Right/Left Atrium Right/Left Ventricle |
Coronary Arteries | Give the heart muscle its blood supply. |
Epicardium | Outside "skin" of heart (thin protective membrane) |
Endocardium | Inside layer of heart, lines chambers and covers valves. Endo-Adentro-inside |
Hypoxia | Total lack of Oxygen |
Ischemia | Decreased supply of Oxygen to tissue |
Myocardial Infarction | Death of Cardiac Tissue. It can decrease ability of cardiac muscle to contract and pump blood efficiently. |
How can you determine the Cardiac Output? | CO=SV X HR SV= stroke volume HR= Heart rate example Stroke= 70ml an HR is 80. CO=70X80=5600ml=cardiac output=normal Normal is 4000-8000 |
Autonomic Nervous System | Function is to maintain the body in a normal state by controlling several organs including the heart, and blood vessels. *It can be done without the person being aware. Its divided into two parts. Sympathetic and Parasympathetic. |
Sympathetic Nervous System | Prepares the body to react in times of stress or emergencies. It increases cardiac output by increasing HR, blood pressure and force cardiac contractions."FIGHT OR FLIGHT" response. |
Parasympathetic Nervous System | Decreases the Cardiac contractions. Usually occurs AFTER stress/emergency is over, allowing body to restore energy. Can stimulate bowels, bladder, etc. |
Atria | Upper chambers of heart. Function as reservoirs or "Holding Areas" for blood. |
Ventricles | Lower chambers of heart. Left Ventricle wall is thicker because it has to pump blood throughout body. Ventricle is what causes "heartbeats" |
Myocardium | middle layer of cardiac wall. Provides pumping action needed to pump blood. |
Automaticity | Ability of cardiac pacemaker cells to generate or initiate their own electrical impulse ***Electrical Function*** |
Excitability | Irritability, ability of cardiac cells to respond to an electrical stimulus ***Electrical Function*** |
Conductivity | Ability of cardiac cells to transmit an electrical stimulus to other cardiac cells ***Electrical Function*** |
Contractility | Ability of cardiac cells to shorten, causing cardiac muscle contraction in response to electrical stimulus. ***Mechanical Function*** |
Sinoatrial node (SA) | Pacemaker of the Heart Initiates electrical impulse that travels downward. Generates 60-100 impulses per minute |
Atrioventricular node (AV) | Continues transmitting impulse of (SA) from atria to Bundle of HIs. **If (SA) fails, (AV) will work as secondary pace maker. Generates 40-60 impulses. |
Bundle of His | Continues transmitting impulse to bundle branches |
Bundle Branches | Divides into right bundle-leading to right ventricle and left-leading to left ventricle. Continue transmitting impulse to Purkinje's Fibers. |
Purkinje's Fibers | Conduct impulse to ventricular muscle. |
Ventricular Muscle | Receives Electrical Impulse.If SA or AV pacemakers did not start then it will start from the ventricles. Generates 20-40 impulses. Can come from Purkinje's fibers and bundle branches. |
P wave | Depolarization of L&R atrium |
Biphasic/Diphasic | Indicate enlargement of both atria (P wave) |
PR Interval | Represents the time it takes impulse to be conducted through atria and atrioventricular node until ventricular depolarization. Normal: 0.12-0.20 OR 3-5 small squares. |
QRS complex | Q-negative downward R-positive S-negative **Ventricular Depolarization or conduction of impulse in bundle of His Normal- less than 0.12 |
ST Segment | Normal .01 above or below base line. Can indicate cardiac problems |
T Wave | Repolarizations of Ventrcular myocardio cells. |
P-P and R-R | P-P= Length of time from one P wave to the next P wave. R-R= Length of time from one R wave to the next R wave. Determine if rhythm is regular or irregular. |
QT Interval | Depolarization and Repolarization of Ventricles. from QRS - T wave. normal is less than one half of R-R. Should be less than 0.44 If long, its Prolonged QT. |
Refractory Period | Time between Depolarization and return of the cardiac cells to the ready or polarized state. |
Absolute Refactory | Cardiac cells have not completed repolarization and CANNOT be stimulated to conduct electrical impulse and contract again (depolarize) |
Relative Refactory | Cardiac cells have repolarized to the point that SOME cells can again be stimulated to depolarize if stimulus is strong enough. Also known as Vulnerable period of Repolarization. |
Atrial Rate | Determined by Number of P waves seen |
Ventricular Rate | Determined by Number of R waves Seen |
Artifact | Interference or Static seen on the monitor screen or strip. |
6 second method | Count number of R waves in 6 sec strip and multiply by 10. Gives "approximate" number of HR. Make sure it has 6 seconds by the three lines on top of graph. If none determine 6 sec by: *5 small boxes across=1 second *30 large squares =6 seconds |
3 second method | Count number of R waves |
Division method | "More accurate, and only be used with regular rhythm" Count number of large squares between two R waves and divide by 300. ex: 300Dividedby3=100.When counting between R waves, if any small square added it equals 0.2 or 1500divided by number. |
1 minute method | *Most Accurate. Count number of R waves in a minutes long rhythm. |
Compensatory pause | Measure from R-R wave starting before the PAC till after PAC.This measurement will be EQUAL at least 2 times the R-R interval. |
Non-compensatory pause | Measure from R-R wave starting before the PAC till after PAC. This measurement will be LESS than 2 times the R-R interval. |
Bigeminy | When every other QRS complex is PVC. |
Transvenous | Through the vein Temp. Pacemaker |
Transcutaneous | Through the skin Temp. Pacemaker |
Atrial Pacemakers | inserted in right atrium. |
Ventricular Pacemakers | placed in right or left ventricle. Causes depolarizaion |