Sentence:  In type 3 , this general relationship is maintained peripherally but not centrally where the pulmonary vein follows a more independent path to the hilum as is the case throughout the <WSD>lung</WSD> in type 2 , . 
Meaning of the word marked with <WSD> tags:  either of two saclike respiratory organs in the chest of vertebrates; serves to remove carbon dioxide and provide oxygen to the blood