<prompt> Anatomical dead space is equivalent to:13rd of tidal volume25th of tidal volume10 mlkg of body weight15 mlkg of body weight  <response>: Anatomic dead space refers to the volume of the conducting airways and is around 130 - 180ml 2mlkg throughout life in the adult i.e about 13rd of tidal volume. Physiologic dead space: It refers to the propoion of the tidal volume that does not paicipate directly in gas exchange. It consists of the anatomic dead space and the alveolar dead space. It comprises 25 - 35 of of the normal tidal volume. 