\begin{tikzpicture}
    \node[label={below:Médecin}] (user) {
        \includegraphics[width=1.33cm]{icons/doctor}
    };
    
    \node[system, right=of user] (system) {
        Système de\\recherche
    };
    
    \node[agent, right=of system] (kb) {
        Bases de\\connaissances
    };
    
    \draw[link]
        ([yshift=5pt]user.east)
        -- node[above=5pt, link label] {signes et\\symptômes}
        ([yshift=5pt]system.west);
    
    \draw[link]
        ([yshift=-5pt]system.west)
        -- node[below=5pt, link label] {maladies\\associées}
        ([yshift=-5pt]user.east);
    
    \draw[link]
        ([yshift=5pt]system.east)
        -- node[above=5pt, link label] {requêtes}
        ([yshift=5pt]kb.west);
    
    \draw[link]
        ([yshift=-5pt]kb.west)
        -- node[below=5pt, link label] {connaissances}
        ([yshift=-5pt]system.east);
\end{tikzpicture}