Heart valve chambers are lined with endocardium. Heart valves separate the atria from the ventricles, or the ventricles from a blood vessel. Heart valves are situated around the fibrous rings of the cardiac skeleton. The valves incorporate leaflets or cusps, which are pushed open to allow blood flow and which then close together to seal and prevent backflow. The mitral valve has two cusps, whereas the others have three. There are nodules at the tips of the cusps that make the seal tighter. The pulmonary valve has left, right, and anterior cusps. The aortic valve has left, right, and posterior cusps. The
How Many Birds How Many Birds "How Many Birds" is a song written by Barry Gibb, recorded by the Bee Gees in 1966 for the "Spicks and Specks" album. Recording took place at St. Clair Studios, Hurstville outside Sydney. The song was recorded on one-track tape machines and required the use of sound-on-sound for all overdubs. "How Many Birds" was recorded around April and May 1966 as part of the sessions for what became the Spicks and Specks album. The song starts with a guitar riff and the chord became E as Barry sings the introduction. After Barry sings the lines, the song