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TCN A&P Ch. 11
The Heart
79
Anatomy
Professional
03/18/2012

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Term
Automaticity
Definition
The maintenance of a regular heart rhythm.
Term
Bainbridge reflex
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.
Term
Atrioventricular (AV) node
Definition
Nodal fibers near the junction of atrial and ventricular septa that are spontaneously active, giving the heart a property called automaticity.
Term
Aortic valve
Definition
Allows blood to enter the aorta.
Term
Aorta
Definition
The trunk of a systemic arterial tree with many branches.
Term
Arrhythmias
Definition
Disturbances in the heart’s rhythm.
Term
Aortic baroreceptors
Definition
Cardiovascular reflexes that regulate of arterial blood pressure.
Term
AV block
Definition
Disturbances in the duration and timing of the QRS complex (branch bundle block).
Term
Carotid sinus
Definition
Where cardiovascular reflexes that regulate arterial blood pressure originate.
Term
Cardiac reserve
Definition
The difference between the current cardiac output and the maximum cardiac output the heart is capable of.
Term
Ca++ induced Ca++ release
Definition
A process in which free Ca++ in the cytoplasm increases Ca++ release by the SR, magnifying the effect of the additional Ca++.
Term
Chordae tendinea
Definition
Strands of connective tissue attached to papillary muscles in the ventricle.
Term
Cardiac output
Definition
The volume of blood pumped by the heart per minute.
Term
Bicuspid
Definition
The valve through which the blood enters the left ventricle.
Term
Bundle of His
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.
Term
Baroreceptor reflex
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.
Term
Einthoven's triangle
Definition
Classically, the EKG was recorded from the corners of the triangle formed by the right arm, left arm, and left leg.
Term
Contractile fibers
Definition
Specialized fibers for contraction that make up the great mass of the heart.
Term
Conducting fibers
Definition
Fibers that form a conducting pathway that can rapidly transmit excitation between the atria and throughout the ventricular mass.
Term
Diastole
Definition
The period in which the heart is relaxed, during which the atria and ventricles of the heart fill with venous blood.
Term
Diastolic pressure
Definition
The minimum value reached just before blood ejection from the ventricle into the artery.
Term
Coronary sinus
Definition
Collects blood from the heart’s own cardiac veins.
Term
Electrocardiogram (EKG)
Definition
The record at the body surface of electrical currents that flow between excited and unexcited regions of the heart during a heartbeat.
Term
Diastolic murmur
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.
Term
First heart sound
Definition
Results from the closing of the AV valves.
Term
End-systolic volume
Definition
The volume of blood in the ventricle during the point in which the ventricle undergoes isovolumetric relaxation.
Term
Frank-Starling law
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.
Term
Endocardium
Definition
A sheet of endothelium that is the innermost layer of the pericardium.
Term
Epicardium
Definition
The outermost layer of the heart wall.
Term
Fibrous pericardium
Definition
The outer layer of the pericardium.
Term
End-diastolic volume
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).
Term
Interatrial septum
Definition
Separates the two atria from one another longitudinally.
Term
Interventricular septum
Definition
Divides the two ventricles.
Term
Isovolumetric contraction
Definition
The phase of the heart cycle during which the ventricle is contracting as a closed container.
Term
Isovolumetric relaxation
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.
Term
Inferior venae cavae
Definition
One of three veins the right atrium receives blood from.
Term
inotropic effect
Definition
The contractility or force-generating potential of the heart modulated by autonomic inputs.
Term
Left ventricle
Definition
One of the four chambers of the heart that forces blood through the aortic semilunar valve into the aorta.
Term
Left pulmonary artery
Definition
Carries blood to the lungs.
Term
left atrium
Definition
One of the four chambers of the heart that receives blood returning to the heart from the lungs through the four pulmonary veins.
Term
left coronary artery
Definition
Serves both ventricles, the left atrium, and the interventricular septum.
Term
Lead III
Definition
Gives information about currents flowing along the dorsal-ventral axis of the heart.
Term
Lead II
Definition
Gives information about currents flowing along the dorsal-ventral axis of the heart.
Term
Medullary cardiovascular center
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.
Term
Lead I
Definition
Gives information about currents flowing in the left-right axis of the heart.
Term
Passive filling
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).
Term
Myocardium
Definition
The thickest, middle layer of the heart, composed mainly of the fibers of cardiac muscle that cause contraction.
Term
Parasympathetic tone
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.
Term
pericardium
Definition
A double membrane enclosing the heart.
Term
Nodal fibers
Definition
Specialized fibers that serve as pacemakers, generating regular action potentials.
Term
P wave
Definition
The first feature of an EKG that appear when the atria depolarize.
Term
PQ interval
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).
Term
Muscarinic
Definition
Receptors in the heart for acetylcholine (ACh).
Term
Prepotential
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.
Term
QRS complex
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.
Term
Pulmonary veins
Definition
Carries blood returning to the heart from the lungs.
Term
Pulmonary trunk
Definition
Branches into the right and left pulmonary arteries that carry blood to the lungs.
Term
Precordial leads
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.
Term
Purkinje fibers
Definition
The conducting fibers of the ventricular mass.
Term
Right coronary artery
Definition
Serves the right atrium, right ventricle, and variable portions of the left atrium and left ventricle.
Term
Right ventricle
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.
Term
Right atrium
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.
Term
Second heart sound
Definition
Results from the closure of the pulmonary and aortic valves.
Term
Right pulmonary artery
Definition
Carries blood to the lungs.
Term
Serous pericardium
Definition
The inner layer of the pericardium, which is continuous with the epicardium.
Term
Semilunar valve
Definition
The pulmonary and aortic valves.
Term
Right atrioventricular valve
Definition
Valve through which the right atrium opens into the right ventricle.
Term
Sinoatrial (SA) node
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.
Term
Systolic murmur
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.
Term
Superior venae cavae
Definition
One of three veins the right atrium receives blood from.
Term
Stoke volume
Definition
Blood that is ejected from the ventricle into the artery, rapidly raising the arterial pressure from the diastolic pressure to the systolic pressure.
Term
Systole
Definition
Atrial or ventricular contraction.
Term
ST segment
Definition
A feature of an EKG that occurs when the ventricle is completely depolarized.
Term
Systolic pressure
Definition
The value achieved at the peak of blood ejection from the ventricle into the artery.
Term
Tricuspid
Definition
Valve through which the right atrium opens into the right ventricle.
Term
T wave
Definition
The third feature of an EKG that shows the period of ventricular repolarization.
Term
Total peripheral resistance (TPR)
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.
Term
Vena cava
Definition
Brings blood back to the heart from the superior and inferior parts of the body.
Term
Ventricular hypertrophy
Definition
Abnormal increases in the mass of the heart muscle in response to chronic overload.
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