Assertion: mitral valve's leaflet | /r/CapableOf | balloon up into atrium
Facets:
value: slightly
type: DEGREE
Source sentences:
text: The chordae tendineae act a bit like the strings on a parachute, and allow the leaflets of the valve to balloon up into the atria slightly, but not so much as to evert the cusp edges and allow back flow of blood.