GREY’S ANATOMY – “It’s the End of the World” – Meredith’s fears that she is in for a bad day are realized when a medical case arrives at Seattle Grace that threatens the lives of everyone in the O.R., on “Grey’s Anatomy,” SUNDAY, FEBRUARY 5 (approx. 10:15-11:15 p.m., ET) on the ABC Television Network. (ABC/RICHARD CARTWRIGHT)ISAIAH WASHINGTON