Cardiac Anatomy & EKG Fundamentals

Flashcards covering cardiac anatomy, blood flow pathways, the conduction system, EKG fundamentals, and cardiac electrophysiology.

Human heart size

Approximately the size of a fist.

Epicardium

The outermost layer of the heart where the coronary arteries lie.

Intraventricular septum

The band of tissue that separates the right and left ventricles.

Atrial kick

The phase during diastole where the atria contract to squeeze the remaining blood into the ventricles.

Heart chambers

There are $4$ chambers inside the human heart.

Superior and inferior vena cava

The two main vessels through which deoxygenated blood returning from the body enters the heart.

Tricuspid valve

The valve through which blood passes when flowing from the right atrium into the right ventricle.

Pulmonary artery

The structure carrying deoxygenated blood from the right ventricle to the lungs, making it the only artery in the body carrying deoxygenated blood.

Mitral valve

The valve through which oxygenated blood coming from the left atrium enters the left ventricle.

Aorta

The largest artery leaving the left ventricle that delivers oxygenated blood to the rest of the body.

Sinus node (SA node)

Known as the normal pacemaker of the heart because it fires fastest and maintains control.

Sinus node firing rate

The standard pacemaker firing rate of the sinus node, which is $60\text{ to }100\text{ bpm}$.

AV junction firing rate

The inherent firing rate range of the AV junction pacemaker cell, which is $40\text{ to }60\text{ bpm}$.

Purkinje fibers

The structures at the end of the electrical conduction pathway sequence after impulse conduction proceeds from the SA node, interatrial/internodal tracts, AV node, Bundle of His, and bundle branches.

Bundle of His

The structure to which impulse conduction travels directly from the AV node before dividing into the left and right branches.

EKG small block width

The width of one small block on EKG graph paper, representing $0.04\text{ seconds}$ of time.

EKG big block width

The width of one big block on EKG graph paper, representing $0.20\text{ seconds}$ of time.

Intervals

The general term for measurements of time between EKG waves and complexes.

PR interval duration

The normal duration range for a PR interval, which is $0.12\text{ to }0.20\text{ seconds}$.

PR interval measurement

Measures the time required for an impulse to travel between the atrium and ventricle.

Escape beat

A cardiac beat that fires after a pause longer than the normal R-R interval.

Absolute refractory period

The specific refractory period during which a cardiac cell cannot respond to another impulse no matter how strong.

Relative refractory period

The period during which a cardiac cell will respond only if the incoming impulse is very strong.

Supernormal period

A hyper period in which a cardiac cell can respond even to a very weak impulse.

Depolarization

The discharge of electricity that occurs when a cardiac cell becomes positively charged.