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