There is no reason why you could not edit the page and also take part in the GA review however sometimes it might be simpler not to work on the page Nevertheless it is sensible to form a consensus about images if you are in doubt    The diagramme showing hormones image  is probably more suitable for the calcium metabolism page    The anatomical diagramme is quite good and could augment the a high resolution version of FileGraypng    Re FileGraypng this images in the gallery has poor resolution however the  PD version in Grays is available at a much better resolution and can be uploaded over the poor quality image