function showTab(tabName) {	
	if (document.getElementById('tab_definition')) document.getElementById('tab_definition').className = 'tab';
	if (document.getElementById('tab_entstehung')) document.getElementById('tab_entstehung').className = 'tab';
	if (document.getElementById('tab_prophylaxe')) document.getElementById('tab_prophylaxe').className = 'tab';
	if (document.getElementById('tab_risiken')) document.getElementById('tab_risiken').className = 'tab';
	if (document.getElementById('tab_symptome')) document.getElementById('tab_symptome').className = 'tab';
	if (document.getElementById('tab_diagnostik')) document.getElementById('tab_diagnostik').className = 'tab';
	if (document.getElementById('tab_therapie')) document.getElementById('tab_therapie').className = 'tab';
	
	if (document.getElementById('div_definition')) hide(document.getElementById('div_definition'));
	if (document.getElementById('div_entstehung')) hide(document.getElementById('div_entstehung'));
	if (document.getElementById('div_risiken')) hide(document.getElementById('div_risiken'));
	if (document.getElementById('div_prophylaxe')) hide(document.getElementById('div_prophylaxe'));
	if (document.getElementById('div_symptome')) hide(document.getElementById('div_symptome'));
	if (document.getElementById('div_diagnostik')) hide(document.getElementById('div_diagnostik'));
	if (document.getElementById('div_therapie')) hide(document.getElementById('div_therapie'));
	
	if (document.getElementById('tab_' + tabName)) document.getElementById('tab_' + tabName).className = 'tab_active';
	if (document.getElementById('div_' + tabName)) show(document.getElementById('div_' + tabName));
}