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: Recently , vasopressor responses that are distinct from the cranial circulation have been demonstrated to occur in the systemic , pulmonary , and coronary circulations .
### Output Text:
Recently , vasopressor responses that are distinct from the cranial circulation have been demonstrated to occur in the systemic , pulmonary , and coronary circulations . 