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: Increased secretion of vasopressin from neurohypophysis also promotes the function of the hormone as a pathogenetic factor in hypertension .
### Output Text:
Increased secretion of <span class="chemical">vasopressin</span> from neurohypophysis also promotes the function of the hormone as a pathogenetic factor in hypertension . 