documentclass[tikz,border=3.14mm]{standalone}
usetikzlibrary{chains}
begin{document}
begin{tikzpicture}[item/.style={draw,thick,text width=5cm,on
chain,join,align=center}]
 begin{scope}[start chain=going below,nodes=item,every
 join/.style={-latex,thick}]
 node {blah blah};
 node {blah blah blah blah blah blah blah blah blah blah blah blah};
 node {blah blah blah blah};
 node {blah blah blah blah blah blah blah blah};
 end{scope}
end{tikzpicture}
end{document}