This is an alternate content page containing a DidYouKnow Activity. It has opened in a new window.
The question and answers have an information section with a title and might have additional content and/or images.

Question:

What tissue operates in the absence of oxygen?

Answer:

Skeletal muscle, during vigorous exercise, has low oxygen levels and relies on glycolysis for energy the lactate produced while doing exercise goes into the blood where it makes us feel tired and can be turned back into pyruvate by other tissues like the heart.