When breathing for speech, exhalation is highly controlled, requiring special neurological circuitry which humans posses.
But when breathing for the purpose of speech, the exhalation process also becomes active and even more complicated. Now the breath is forced out through the vocal folds in a carefully controlled flow.
We do this effortlessly, partly because we have a large cadre of nerves devoted to the process. This is a genetic inheritance. "Ed" the "talking horse" and even "Koko" the signing gorilla could not really control the breath stream well enough to produce speech as humans do.
If you are not familiar with "Ed" check the notes.
Sometimes the process is pathologically disturbed. Cerebral Palsy children may have problems in coordinating the flow of speech and may find it difficult to get more than one word or sentence to a breath if at all.
Even some stutterers find the processes disrupted and the lack of coordination in breathing process is quite visible if not uncomfortable to watch.
NOTES: See who Ed is.
NOTES: More than you would want to know about breath control.
NOTES: And still more on breath control.
NOTES: See who Koko is.