function abrirPag(valor){
    var url = valor;

    xmlRequest.open("GET",url,true);    
    xmlRequest.onreadystatechange = mudancaEstado;
    xmlRequest.send(null);

        if (xmlRequest.readyState == 1) {
            document.getElementById("conteudo_mostrar").innerHTML = "<p><img src='../imagens/ajax-loader.gif'></p>";
        }

    return url;
}

function mudancaEstado(){
    if (xmlRequest.readyState == 4){
        document.getElementById("conteudo_mostrar").innerHTML = xmlRequest.responseText;
    }
}

function abrirPag2(valor){
    var url = valor;

    xmlRequest.open("GET",url,true);    
    xmlRequest.onreadystatechange = mudancaEstado2;
    xmlRequest.send(null);

        if (xmlRequest.readyState == 1) {
            document.getElementById("conteudo_mostrar2").innerHTML = "<p><img src='../imagens/ajax-loader.gif'></p>";
        }

    return url;
}

function mudancaEstado2(){
    if (xmlRequest.readyState == 4){
        document.getElementById("conteudo_mostrar2").innerHTML = xmlRequest.responseText;
    }
}
function abrirPag3(valor){
    var url = valor;

    xmlRequest.open("GET",url,true);    
    xmlRequest.onreadystatechange = mudancaEstado3;
    xmlRequest.send(null);

        if (xmlRequest.readyState == 1) {
            document.getElementById("conteudo_mostrar3").innerHTML = "<p><img src='../imagens/ajax-loader.gif'></p>";
        }

    return url;
}

function mudancaEstado3(){
    if (xmlRequest.readyState == 4){
        document.getElementById("conteudo_mostrar3").innerHTML = xmlRequest.responseText;
    }
}