Final answer:
The three gases that function as chemical messengers in animals are nitric oxide, carbon monoxide, and hydrogen sulfide, playing various roles in signaling and physiological regulation.
Step-by-step explanation:
The three gases that act as chemical messengers in animals are nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S). These gases are unique among chemical messengers in that they are small, gaseous molecules that can diffuse rapidly across cell membranes.
Nitric oxide is perhaps the most well-known of these, acting as a vasodilator and neurotransmitter, and playing a critical role in the cardiovascular system. Carbon monoxide, while it can be toxic at high concentrations, serves in low concentrations as a neurotransmitter and has a role in modulating inflammatory responses.
Lastly, hydrogen sulfide has been identified as a signaling molecule in the cardiovascular and nervous systems, also influencing inflammation and cell signaling pathways.
Unlike traditional hormones, these gases are not stored but are produced on demand and act immediately on neighboring cells without the need for receptors.