Term
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Definition
| The maintenance of a regular heart rhythm. |
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Term
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Definition
| A second reflex pathway originating from the vascular system that keeps venous pressure low and preventing pooling of blood on the venous side of the circulation. |
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Term
| Atrioventricular (AV) node |
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Definition
| Nodal fibers near the junction of atrial and ventricular septa that are spontaneously active, giving the heart a property called automaticity. |
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Term
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Definition
| Allows blood to enter the aorta. |
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Term
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Definition
| The trunk of a systemic arterial tree with many branches. |
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Term
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Definition
| Disturbances in the heart’s rhythm. |
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Term
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Definition
| Cardiovascular reflexes that regulate of arterial blood pressure. |
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Term
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Definition
| Disturbances in the duration and timing of the QRS complex (branch bundle block). |
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Term
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Definition
| Where cardiovascular reflexes that regulate arterial blood pressure originate. |
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Term
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Definition
| The difference between the current cardiac output and the maximum cardiac output the heart is capable of. |
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Term
| Ca++ induced Ca++ release |
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Definition
| A process in which free Ca++ in the cytoplasm increases Ca++ release by the SR, magnifying the effect of the additional Ca++. |
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Term
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Definition
| Strands of connective tissue attached to papillary muscles in the ventricle. |
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Term
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Definition
| The volume of blood pumped by the heart per minute. |
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Term
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Definition
| The valve through which the blood enters the left ventricle. |
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Term
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Definition
| Excitation enters the AV node and then spreads into this bundle of fibers, which divides into one branch that passes down the interventricular septum and into the right ventricle, and (usually) two branches that enter the left ventricle. |
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Term
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Definition
| A decrease in arterial blood pressure triggers a reflexive increase in heart rate/force through a simultaneous decrease in parasympathetic tone, if any is present, and an increase in sympathetic outflow to the heart and to the resistance vessels of the vascular system. |
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Term
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Definition
| Classically, the EKG was recorded from the corners of the triangle formed by the right arm, left arm, and left leg. |
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Term
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Definition
| Specialized fibers for contraction that make up the great mass of the heart. |
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Term
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Definition
| Fibers that form a conducting pathway that can rapidly transmit excitation between the atria and throughout the ventricular mass. |
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Term
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Definition
| The period in which the heart is relaxed, during which the atria and ventricles of the heart fill with venous blood. |
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Term
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Definition
| The minimum value reached just before blood ejection from the ventricle into the artery. |
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Term
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Definition
| Collects blood from the heart’s own cardiac veins. |
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Term
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Definition
| The record at the body surface of electrical currents that flow between excited and unexcited regions of the heart during a heartbeat. |
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Term
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Definition
| The sound made when damage to the aortic valves prevents them from closing tightly, blood leaks back from aorta to left ventricle during diastole. |
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Term
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Definition
| Results from the closing of the AV valves. |
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Term
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Definition
| The volume of blood in the ventricle during the point in which the ventricle undergoes isovolumetric relaxation. |
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Term
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Definition
| Within a reasonable range, the heart automatically adjusts its stroke volume so that increases in end-diastolic volume are matched by increases in stroke volume. |
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Term
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Definition
| A sheet of endothelium that is the innermost layer of the pericardium. |
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Term
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Definition
| The outermost layer of the heart wall. |
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Term
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Definition
| The outer layer of the pericardium. |
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Term
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Definition
| The point at which the ventricle contains a small amount of blood due to the contraction of the atrium (perhaps 10 percent or so under resting conditions). |
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Term
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Definition
| Separates the two atria from one another longitudinally. |
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Term
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Definition
| Divides the two ventricles. |
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Term
| Isovolumetric contraction |
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Definition
| The phase of the heart cycle during which the ventricle is contracting as a closed container. |
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Term
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Definition
| A phase in the heart cycle after ejection in which the bicuspid valve closes and the ventricle contains the end-systolic volume of blood. |
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Term
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Definition
| One of three veins the right atrium receives blood from. |
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Term
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Definition
| The contractility or force-generating potential of the heart modulated by autonomic inputs. |
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Term
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Definition
| One of the four chambers of the heart that forces blood through the aortic semilunar valve into the aorta. |
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Term
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Definition
| Carries blood to the lungs. |
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Term
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Definition
| One of the four chambers of the heart that receives blood returning to the heart from the lungs through the four pulmonary veins. |
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Term
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Definition
| Serves both ventricles, the left atrium, and the interventricular septum. |
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Term
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Definition
| Gives information about currents flowing along the dorsal-ventral axis of the heart. |
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Term
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Definition
| Gives information about currents flowing along the dorsal-ventral axis of the heart. |
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Term
| Medullary cardiovascular center |
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Definition
| With the onset of exercise or excitement, the first response of the center of the brain stem is removal of the parasympathetic tone, allowing the SA node to drive the heart at its spontaneous rate. |
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Term
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Definition
| Gives information about currents flowing in the left-right axis of the heart. |
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Term
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Definition
| A period during diastole in which blood flows through the atria and into the ventricles under the relatively low pressure of blood in veins (several mm Hg). |
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Term
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Definition
| The thickest, middle layer of the heart, composed mainly of the fibers of cardiac muscle that cause contraction. |
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Term
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Definition
| At rest and during sleep, the parasympathetic input dominates the heart. As a result, the heart rate is perhaps 60–70 beats/min instead of the approximately 100 beats/min that could be expected with no input at all. |
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Term
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Definition
| A double membrane enclosing the heart. |
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Term
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Definition
| Specialized fibers that serve as pacemakers, generating regular action potentials. |
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Term
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Definition
| The first feature of an EKG that appear when the atria depolarize. |
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Term
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Definition
| A baseline feature of an EKG that indicates when the whole mass of the atria is depolarized and there is no voltage difference between different parts of the atria; thus, no current flows around the tissue (although a current does flow across the plasma membranes of the cells). |
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Term
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Definition
| Receptors in the heart for acetylcholine (ACh). |
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Term
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Definition
| A drift due to several slowly changing membrane permeabilities, including a set of K+ channels that close slowly after each action potential and a set of Ca++ channels (T Ca++ channels) that begin to open during depolarization. |
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Term
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Definition
| The second feature of an EKG that shows the period of atrial repolarization (not seen distinctly, but part of the QRS complex) and the period of ventricular depolarization. |
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Term
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Definition
| Carries blood returning to the heart from the lungs. |
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Term
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Definition
| Branches into the right and left pulmonary arteries that carry blood to the lungs. |
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Term
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Definition
| An exploring electrode that may be attached to any of six locations ranging from near the sternum to the left lateral surface of the chest to gain information about currents flowing in the anterior-posterior axis of the heart. |
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Term
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Definition
| The conducting fibers of the ventricular mass. |
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Term
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Definition
| Serves the right atrium, right ventricle, and variable portions of the left atrium and left ventricle. |
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Term
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Definition
| One of the four chambers of the heart that receives blood from the right atrium and pumps it through the pulmonary semilunar valve that leads into the pulmonary trunk. |
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Term
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Definition
| One of the four chambers of the heart that receives blood from three veins, the superior and inferior venae cavae and the coronary sinus. |
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Term
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Definition
| Results from the closure of the pulmonary and aortic valves. |
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Term
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Definition
| Carries blood to the lungs. |
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Term
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Definition
| The inner layer of the pericardium, which is continuous with the epicardium. |
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Term
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Definition
| The pulmonary and aortic valves. |
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Term
| Right atrioventricular valve |
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Definition
| Valve through which the right atrium opens into the right ventricle. |
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Term
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Definition
| Nodal fibers in the right atrium near the opening of the superior vena cava that are spontaneously active, giving the heart the property automaticity. |
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Term
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Definition
| The muted swishing or blowing sound heard when the mitral valves fail to close tightly, and blood is forced backward from ventricle to atrium during systole. |
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Term
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Definition
| One of three veins the right atrium receives blood from. |
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Term
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Definition
| Blood that is ejected from the ventricle into the artery, rapidly raising the arterial pressure from the diastolic pressure to the systolic pressure. |
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Term
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Definition
| Atrial or ventricular contraction. |
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Term
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Definition
| A feature of an EKG that occurs when the ventricle is completely depolarized. |
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Term
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Definition
| The value achieved at the peak of blood ejection from the ventricle into the artery. |
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Term
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Definition
| Valve through which the right atrium opens into the right ventricle. |
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Term
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Definition
| The third feature of an EKG that shows the period of ventricular repolarization. |
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Term
| Total peripheral resistance (TPR) |
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Definition
| A net resistance to blood flow; a whole-body value that is affected by dilation or constriction of blood vessels (specifically the arterioles) throughout the body. |
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Term
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Definition
| Brings blood back to the heart from the superior and inferior parts of the body. |
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Term
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Definition
| Abnormal increases in the mass of the heart muscle in response to chronic overload. |
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