tricuspid valve
Summary
The tricuspid valve is the three-leaflet atrioventricular valve between the right atrium and right ventricle. It opens passively when atrial pressure exceeds ventricular pressure and closes at the start of ventricular systole, preventing backflow into the right atrium.
Detail
Meaning: The tricuspid valve is the right atrioventricular (AV) valve, between the right atrium and right ventricle. It has three leaflets. It opens and closes passively with pressure: when right atrial pressure exceeds right ventricular pressure it opens and the ventricle fills; when the ventricle contracts, pressure reverses and the valve shuts, so blood leaves through the pulmonary valve rather than flowing back. Chordae tendineae anchored to papillary muscles keep the leaflets from everting into the atrium.
On the MCAT: Expect blood-flow tracing: vena cava → right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs. Graphs of the cardiac cycle show the AV valves closing at the start of ventricular systole (first heart sound, S1) and the semilunar valves closing at the start of diastole (S2). For a leaky tricuspid valve, predict regurgitation into the right atrium during systole, raising right atrial pressure.
Common confusion: The tricuspid has three cusps and is on the right; the bicuspid (mitral) valve has two and is on the left. Both are AV valves, so both close at S1; the pulmonary and aortic valves are semilunar. Papillary muscles do not open the valves; pressure differences open and close them.
Sources
- Campbell Biology
- Human Physiology: An Integrated Approach
- Principles of Anatomy and Physiology
Written for the MCAT and checked before it was published. For study reference only. Spotted an error? Let us know.