Page 4 - EKG STUDY GUIDE

The Heart Valves:
The purpose of the heart valves is to prevent backflow of blood thereby assuring uni-directional
flow thru the heart.

The atrioventricular valves (AV): so-called because they are located between the atria and
ventricles.
a.) Tricuspid valve – located between the right atrium and the right ventricle. As the name
connotes, it has three cusps.
b.) Mitral valve – located between the left atrium and the left ventricle. It has two cusps
and it also called the bicuspid valve.

The semilunar valves: called semilunar because they have half-moon shaped cusps
a.) Pulmonic valve – located between the right ventricle and the pulmonary trunk.
b.) Aortic valve - located between the left ventricle and aorta

Murmurs are caused by diseases of the valves or other structural abnormalities.

The heart sounds are produced by the closure of the valves:
S1 – first heart sound is due to the closure of the mitral and tricuspid valves.
S2 – second heart sound is due to the closure of the aortic and pulmonic valves.

Vessels of the Heart
The arteries supplying the heart are the right and left coronary from the aorta. The veins
accompany the arteries, and terminate in the right atrium.

Neural Influences of the Heart
The heart is influenced by the autonomic nervous system (ANS) which is subdivided into the
sympathetic and parasympathetic nervous systems.

Sympathetic nervous system: affects both the atria and the ventricles by increasing heart rate,
conduction and irritability.

Parasympathetic nervous system: affects the atria only by decreasing heart rate, conduction and
irritability.

National Healthcareer Association EKG Study Guide (Ea) 6