Heart Valves Overview

Overview

This lecture explains the structure, location, and function of the heart's valves, focusing on how they maintain unidirectional blood flow.

Heart valves ensure unidirectional blood flow by opening and closing in response to pressure changes.
Two main types: atrioventricular (AV) valves and semilunar valves.

Located between atria (receiving chambers) and ventricles (pumping chambers).
Tricuspid valve: right side, between right atrium and right ventricle, made of three cusps.
Bicuspid (mitral) valve: left side, between left atrium and left ventricle, made of two cusps.
AV valves prevent backflow into atria when ventricles contract.
Chordae tendineae anchor AV valve cusps to papillary muscles, holding valve flaps closed during ventricular contraction.
Papillary muscles and chordae tendineae prevent valve flaps from everting into the atria under high pressure.

Located between ventricles and major arteries (aorta and pulmonary trunk).
Pulmonary valve: between right ventricle and pulmonary trunk.
Aortic valve: between left ventricle and aorta.
Semilunar valves prevent backflow from arteries into the ventricles.
Each semilunar valve consists of three half-moon shaped cusps.
Open when ventricular pressure rises and close when pressure falls, preventing blood return to heart.

AV valves open when atrial pressure exceeds ventricular pressure, allowing ventricles to fill.
Semilunar valves open during ventricular contraction and close during relaxation to prevent arterial backflow.

Atrioventricular (AV) valves — valves between the atria and ventricles (tricuspid and bicuspid/mitral).
Semilunar valves — valves at the exit of each ventricle (pulmonary and aortic).
Tricuspid valve — right AV valve with three cusps.
Bicuspid (Mitral) valve — left AV valve with two cusps.
Chordae tendineae — tendon-like cords anchoring AV valve flaps to papillary muscles.
Papillary muscles — muscles attached to chordae tendineae, stabilizing AV valves.
Trabeculae carneae — internal ridges within the heart chambers.
Cusp — a flap or segment of a heart valve.