Pulmonary Circuit
blood vessels that carry blood to and from the lungs
Systemic Circuit
blood vessels that carry blood to and from all body tissues
Mediastinum
medial cavity of the thorax
Apex of the heart
is the lowest superficial part of the heart, points toward lest hip
Apical Impulse
also called the point of maximum impulse (PMI), is the furthermost point outwards (laterally) and downwards (inferiorly) from the sternum at which the cardiac impulse can be felt. The cardiac impulse is the result of the heart rotating, moving forward and striking against the chest wall during systole.
Pericardium
doubled-walled sac that encloses the heart.
Fibrous Pericardium
superficial part of pericardium, protects, anchors and prevents the heart from overfilling
Serous Pericardium
deep to the fibrous pericardium, a thin, slippery, two-layer serous membrane that forms a closed sac around the heart.
Parietal Layer
lines the internal surface off the fibrous pericardium and attaches to the large arteries exiting the heart.
Pericardial Cavity
cavity between the serous pericardium that’s filled with serous fluid
Epicardium
Visceral layer of the Serous Pericardium that lines the external heart surface, the first layer of the heart wall.
Myocardium
middle layer of heart wall, composed mainly of cardiac muscle, the layer that pumps
Cardiac Skeleton
connective tissue fibers that reinforce the myocardium internally and anchor the cardiac muscle fibers
Endocardium
inside layer of the heart wall, sheet of endothelium, lines the heart chambers and covers the fibrous skeleton of the valves
Left Atria
left superior chamber of the heart that receives oxygenated blood from the lungs
Right Atria
right superior chamber of the heart the receives oxygen-poor blood from the body
Left Ventricle
left inferior chamber of the heart that pumps oxygenated blood to the body
Right Ventricle
left inferior chamber of the heart that pumps oxygen-poor blood to the lungs
Interatrial Septum
internal partition that divides the heart longitudinally
Interventricular Septum
internal partition that divides the ventricles
Coronary Sulcus
groove in the exterior heart that separates the atria from the ventricls
Anterior interventricular Sulcus
cradles the anterior interventricular artery and marks the anterior position of the septum separating the right and left ventricles
Posterior interventricular Sulcus
cradles the posterior interventricular artery and marks the posterior position of the septum separating the right and left ventricles
Auricles
wrinkled, protruding appendages which increase the atria volume
Pectinate Muscle
muscle bundles on anterior wall of the right ventricle that look like teeth on a comb, exist on the left atria only in the auricle.
Fossa Ovalis
a shallow depression that marks the spot where a small opening existed in the fetal heart
Super Vena Cava
vein returns blood from the body regions superior to the diaphragm into the right atrium
Inferior Vena Cava
vein returns blood from the body regions inferior to the diaphragm into the right atrium
Coronary Sinus
vein collects blood draining from the myocardium into the right atrium
Pulmonary Veins
four veins entering the left atrium transport blood back to the heart from the lungs, best seen on the posterior side
Trabeculae Carneae
irregular ridges of muscle mark the interior walls of the ventricles
Papillary Muscle
cone-like muscle bundles, which play a role in valve function, project into the ventricular cavity.
Pulmonary Trunk
routes blood pumped from the right ventricle to the lungs
Aorta
the largest artery in the body, routes blood pumped from the left ventricle to the body
Atrioventricular (AV) Valves
prevents backflow into the atria when the ventricles contract
Tricuspid Valve
the right (AV) atrioventricular valve, has three flexible cusps (flaps of endocardium reinforced by connective tissue cores)
Mitral Valve
the left (AV) atrioventricular valve, has two flexible cusps (flaps of endocardium reinforced by connective tissue) resembles the two-sided bishop’s miter
Chordae Tendineae (heart strings)
tiny white collagen cords attach each AV valve, anchor the cusps to the papillary muscles. Serve as guide wire
Semilunar Valves
guards the bases of the large arteries from the ventricles, prevents backflow into the ventricles when the ventricles relaxes.
Aortic Semilunar Valve
valve between the left ventricle and the aorta
Pulmonary Semilunar Valve
valve between the right ventricle and the pulmonary trunk
Coronary Circulation
the functional heart supply of the heart, the shortest circulation of the body.
Left Coronary Artery
runs toward the left side of the heart and then divides into two major branches
Anterior Interventricular Artery
follows the anterior interventricular sulcus and supplies blood to the interventricular septum.
Circumflex Artery
supplies the left ventricle and the posterior walls of the left ventricle.
Right Coronary Artery
courses to the right side of the heart, where it also gives rise to two branches
Right Marginal Artery
serves the myocardium of the lateral side of the heart
Posterior interventricular Artery
runs to the heart apex and supplies the posterior ventricular walls
Cardiac Veins
any of the veins returning the blood from the tissues of the heart that open into the right atrium either directly or through the coronary sinus
Coronary Sinus
A venous sinus that opens into the right atrium of the heart and serves to drain the coronary veins.
Great Cardiac Vein
one of three large tributaries of the coronary sinus
Middle Cardiac Vein
one of three large tributaries of the coronary sinus
Small Cardiac Vein
one of three large tributaries of the coronary sinus
Anterior Cardiac Vein
empty directly into the right atrium.
Angina Infarction
a thoracic pain caused by fleeting deficiency in blood delivery to the myocardium
Myocardial Infarction (MI)
Commonly called a Heart Attack, caused by prolonged coronary blockage.
Cardiac Muscle Cells
short, fat, branched, interconnected, striated and contracts by sliding filament mechanism
Differences in Cardiac and skeletal contraction
Means of Stimulation – each skeletal muscle fibers must be stimulated to contract but some cardiac muscle cells are self-excitable
•Organ vs. Motor Unit Contraction – Only muscle fibers stimulated by nerve fibers contract. In cardiac muscle, either all fibers in the heart contract as a unit or the heart does not contract at all.
•Length of Absolute Refractory Period – in skeletal muscle contractions lasts 15-100ms with brief refractory period 1-2ms. In Cardiac muscle the refractory period lasts over 200ms nearly as long as the contraction
Intrinsic Cardiac Conduction System
consists of non-contractile cardiac cells specialized to initiate and distribute impulses throughout the heart
Cardiac Pacemaker Cells
make up the intrinsic conduction system have an unstable resting system potential.
Pacemaker Potentials
the spontaneously changing membrane potentials
Atrioventicular (AV) Node
located in right atrial wall just inferior to the entrance of the superior vena cava, is a part of the electrical control system of the heart that coordinates the top of the heart. It electrically connects atrial and ventricular chambers, generates impulses and sets the pace of the heart as a whole. The Pacemaker
Sinus Rhythm
the rhythm set by the atrioventicular (AV) node that determines heart rate.
Atrioventricular (AV) Bundle
The bundle of His is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches
Right & Left Bundle Branches
The AV bundle persists only briefly before splitting into these two branches which course along the interventricular septum toward the apex
Subendocardial Conducting Network (Purkinje fibers) -
are located in the inner ventricular walls of the heart, just beneath the endocardium, completes the pathway through the inventricular septum, penetrate into the heart apex, and then turning superiorly into the ventricle wall.
Arrhythmias
irregular heart rhythms
Fibrillation
a condition of rapid and irregular heart contractions in which the control of heart rhythm is taken away from the SA node by rapid activity in other heart regions
Ectopic Focus
an abnormal pacemaker appears and takes over heart rate
Junctional Rhythm
describes an abnormal heart rhythm resulting from impulses coming from a locus of tissue in the area of the atrioventricular node, the "junction" between atria and ventricles.
Extrasystole
Ectopic heartbeats are small changes in an otherwise normal heartbeat that lead to extra or skipped heartbeats. They often occur without a clear cause and are most often harmless. The two most common types of ectopic heartbeats are:
•Premature ventricular contractions (PVC)
•Premature atrial contractions (PAC)
Heart Block
is a problem that occurs with the heart's electrical system. This system controls the rate and rhythm of heartbeats. Heart block occurs if the electrical signal is slowed or disrupted as it moves through the heart.
Cardioacceleratory Center
a group of neurons in the medulla from which cardiac sympathetic nerves arise; nerve impulses along these nerves release norepinephrine that increases the rate and force of the heartbeat
Cardioinhibitory Center
a group of neurons in the medulla from which arise parasympathetic fibers that reach the heart via the vagus (X) nerve; nerve impulses along these nerves release acetylcholine that decreases the rate & force of the heartbeat
Electrocardiography
a recording of the electrical changes accompanying the cardiac cycle that can be recorded on the body's surface; may be resting, stress, or ambulatory
QRS Complex
combination of three of the graphical deflections seen on a typical electrocardiogram (ECG). It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the right and left ventricles of the human heart. In adults, it normally lasts 0.06 - 0.10 s
T wave
represents the repolarization (or recovery) of the ventricles.
P wave
during normal atrial depolarization, the main electrical vector is directed from the SA node towards the AV node, and spreads from the right atrium to the left atrium.
P-R Interval
measured from the beginning of the P wave to the beginning of the QRS complex. It is usually 120 to 200 ms long. On the usual 25 mm/s ECG tracing, this corresponds to 3 to 5 small boxes. The PR interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node where it enters the ventricles. The PR interval is therefore a good estimate of AV node function.
P-Q interval
the time between the beginning of atrial depolarisation and the beginning of ventricular depolarization.
S-T Segment
the time between the end of S-wave and the beginning of T-wave. Significantly elevated or depressed amplitudes away from the baseline are often associated with cardiac illness.
Q-T interval
the time between the onset of ventricular depolarisation and the end of ventricular repolarisation. Clinical studies have demonstrated that the QT-interval increases linearly as the RR-interval increases