In this subchapter:
(1) "Emergency medical services personnel" has the meaning assigned by Section 773.003, Health and Safety Code.
(2) "Firefighter" means a firefighter who is a permanent, paid employee or a volunteer of a state agency or the fire department of a political subdivision.
(3) "First responder" means emergency medical services personnel or a firefighter.
(4) "Peer" means a person who is a first responder or retired first responder.