Voc 8 Dr yordy
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spankybax320 Plus on April 1, 2011
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60 terms
Terms | Definitions |
|---|---|
 arterioles | small blood vessels that carry blood to the capillaries; walls contain smooth muscle that contracts and relaxes to regulate blood flow |
| arteries | large vessels that carry blood away from the heart |
| capillaries | the smallest blood vessels in the body; possess thin walls that permit material exchange between blood and tissues |
| venules | blood vessels that carry blood from capillaries to veins |
| veins | large blood vessels that carry blood toward the heart |
| resistance | any mechanical force that tends to retard or oppose motion |
| R=1/r4 | RESISTANCE IS INVERSELY PROPORTIONAL TO THE FOURTH POWER OF THE VESSEL RADIUS. |
| F= Pressure difference/R | ... |
| myocardium | the entire cardiac muscle mass |
| pericardium | a double-layered serous membrane that surrounds the heart |
| endocardium | thin membrane lines inner surface, inner layer of heart - part of circulatory system |
| atrium | the heart's two upper chambers, which receive blood carried to the heart in veins; singular, atrium |
| ventricle | in the heart, the two lower chambers, which pump blood into the arteries; in the brain, chambers that contain cerebrospinal fluid |
| AV valves | a heart valve made up of membranous flaps or cusps that allows blood to flow in one direction only, from an atrium into a ventricle:::: lie between atria and ventricles, are the tricuspid valve on the right side of the heart and the bicuspid (mitral) valve on the left |
| semi-lunar valves | valves located between the ventricles and arteries on either side of the heart and that prevent blood from flowing back into the ventricles when the ventricles are relaxed |
| pulmonary circulation | the portion of the cardiovascular system which carries oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood back to the heart. |
| systemic circulation | circulation of blood throughout the body via arteries, arterioles, capillaries, venules, and veins to deliver oxygen and nutrients to body tissues |
| cardiac muscle | Name the muscle type based on the histological features: • Actin and myosin in sarcomeres; striated; uninuclear; gap junctions; troponin:calcium binding complex; T tubules and SR forming dyadic contacts; voltage-gated calcium channels |
| pacemaker potential | A self-initiating action potential that occurs in the conduction system of the heart and triggers action potentials (and thus contraction) in the cardiac muscle cells Tee pacemaker potential is triggered by the regular, spontaneous depolarization of the cells of the conductions system, due to slow inwar leak of positive ions (Na+ and Ca2+). Because the SA node has the fastest leak, it typically reaches the threshold for the pacemaker potential before any other region of the conduction system, and thus sets the pace of the heart |
| pacemaker potential | spontaneous depolarization in the resting membrane potential |
| SA (sino-atrial) node | Pacemaker of the heart, 60-80 beats located superior right atriuma region in the wall of the upper right atrium where pacemaker cells are concentrated; normally determines the heart rate |
| AV (atrio-ventricular node) | part of the conduction system of the heart located near the tricuspid valve |
| bundles of His | run up and down the divider between the ventriclespart of the conduction system of the heart located in the interventricular septum |
| Purkinje fibers | specialized conductive fibers located within the walls of the ventricles. They are responsible for relaying cardiac impulses to the cells of the ventricles, which allow the ventricles to contract |
| gap junctions | areas where two adjacent cells are connected together by membrane proteins called connexons that form small channels between the cells, enabling ions and small molecules to move freely between them .communication channels |
| intercalated discs | specialized junction between cardiac muscle cells that contain both desmosomes and gap junctions |
| AV nodal delay | AP conducted slowly so complete ventricular fillings so atria becomes complelety depolarized and to contract and empty contents into ventricles |
| functional syncitium | cells of heart can become excited and contract at the same time |
| refractory period | Time period during an action potential in which a cardiac cell is less excitable than at its RMP ~Requires a stronger than normal stimulus to generate an action potential Absolute RP Relative RP |
| electrocardiogram | a record of the electrical activity of the heart that, if abnormal, may indicate heart disease |
| P wave | corresponds with depolarization of SA node; impulse through the atria; small upward wave |
| QRS complex | The QRS complex represents the electrical activity associated with the contraction of the ventricles, or ventricular depolarization and consists of the Q wave, the R wave and the S wave |
| T wave | in ECG last wave of cardiac cycle corresponding to repolarization of ventricle |
| PR interval | Time required for conduction from the SA node to AV node. The time between atrail and ventricular deplarization. This is normally 0.12 to 0.2 seconds. |
| normal sinus rhythm | heart rhythm originating in the sinoatrial node with a resting rate of 60 to 100 beats per minute |
| bradycardia | slow heart rate (less than 60 beats/minute) |
| tachycardia | abnormally rapid heartbeat (over 100 beats per minute) |
| arrhythmia | Condition in which there is a lack of rhythm of the heartbeat; also called dysrhythmia |
| first degree heart block | atrioventricular (AV) block in which the atrial electrical impulses are delayed by a fraction of a second before being conducted to the ventricles |
| second degree heart block | AV block in which occasional electrical impulses from the SA node fail to be conducted to the ventricles |
| third degree heart block | (Complete heart block) No artial impulses are conducted through the AV node. Heart has regular atrial activity and regular ventricular activity, but the activities are not coordinated with each other. R-R always regular |
| flutter | extremely rapid but regular contractions of the heart, as in atrial or ventricular flutter (typically from 250 to 350 beats/minute) |
| fibrillation | extremely rapid contractions of the heart that lack the power needed to pump blood around the body. |
| defibrillation | termination of ventricular fibrillation by delivering an electrical stimulus to the heart; most commonly done by applying electrodes of the defibrillator externaly to the chest wall but can be performed internally during open heart surgery or via an implanted device |
| sick sinus syndrome | also called Sinus node dysfunction, a malfunction of the sinus node, the heart's "natural" pacemaker. |
| ectopic pacemakers | Pacemakers other than the SA node are called? |
| extrasystoles | Beats from an ectopic source |
| re-entry | an arryhthmogenic mechanism in wich the impulse does not die out; it instead continues to circulate and re-excite tissue (circus rhythm) |
| circus movements | same impulse travels around & around (damaged heart does not depolarize efficiently, abnormal movement caused by reentry) |
| stroke volume | the volume of blood ejected from each ventricle during a single heartbeat |
| systole | the period of ventricular contraction during a cardiac cycle |
| diastole | the period of ventricular relaxation during a cardiac cycle |
| end diastolic volume | the amount of blood in each ventricle at the end of its relaxation period, about 130 mL |
| end systolic volume | the amount of blood remaining in each ventricle at the end of ventricular contraction, about 60 mL |
| cardiac output | the volume of blood pumped per minute by the left ventricle of the heart |
| CO = SV X HR | Formula for calculating cardiac output |
| inotropic action | ... |
| chronotropic action | Drugs that change the HR by affecting signals to the SA node |
| extrinsic controls | long reflexes that involve CNS and extrinsic autonomic nerves |
| intrinsic controls | the heart beat control maintained from within the heart that establishes the usual, day-in, day-out, pace of heart beats |
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