In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The abruptness of the renal failure and its reversibility within days suggests that there was a functional component to the renal dysfunction .
### Output Text:
The abruptness of the renal failure and its reversibility within days suggests that there was a functional component to the renal dysfunction . 