Assertion: valve's flap | /r/CapableOf | open in only one direction
Facets:
value: to prevent the backflow of blood
type: PURPOSE
Source sentences:
text: This deoxygenated blood then passes to the right ventricle through the atrioventricular valve or the tricuspid valve, a flap of connective tissue that opens in only one direction to prevent the backflow of blood.