Researchers have discovered that the lungs play a far more complex role in mammalian bodies than we thought, with new evidence revealing that they don't just facilitate respiration - they also play a key role in blood production. 

In experiments involving mice, the team found that they produce more than 10 million platelets (tiny blood cells) per hour, equating to the majority of platelets in the animals' circulation. This goes against the decades-long assumption that bone marrow produces all of our blood components.

Researchers from the University of California, San Francisco also discovered a previously unknown pool of blood stem cells that makes this happen inside the lung tissue - cells that were incorrectly assumed to mainly reside in bone marrow.

"This finding definitely suggests a more sophisticated view of the lungs - that they're not just for respiration, but also a key partner in formation of crucial aspects of the blood," says one of the researchers, Mark R. Looney.