Why would the digestive tract be considered outside of the body?

1 Answer
Dec 7, 2015

because there is a continuous lumen starting and ending with openings to the outside of the body.
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you can see in the image the body is represented by the big oval shape, and the alimentary tract is the long tube going through this body from one side to another.
In a 3D body imagine the oval shape to be a sphere and the tube is a hollow space passing this sphere from one end to another, so you can see through as if it is not part of the body ( the hollow space).