More Learning: The Heart Headline Heart Beating Below is an open heart surgery.  You can see a human heart beating within the chest. Actin Myosin Crossbridge Below is the myosin molecule interacting with the actin molecule causing muscle contraction.  Abdominal Aortic Aneurysm Featured below is a severe abdominal aortic aneurysm Abdominal Aortic Aneurysm Abdominal Aortic Aneurysm