Fetal lungs are not functioning; no organism can start to breathe while immersed in amniotic fluid. Lungs only begin to function at birth.
When the lungs do not function the backup respiratory system takes over the function of the lungs. This is true in a fetal pig.
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rib cage
Trachea
A fetal pig's lungs are similar to an adult's in the interior. The difference is that it is much smaller.
They Have Four Lobes
The pleura cover and protect the lungs in a fetal pig.
In the fetal pig, the esophageal opening is located dorsal to the glottis. The esophagus lies to the top of the stomach, in close proximity to the diaphragm.
The trachea, heart, lungs, bronchial tubes, thyroid gland, and the larynx are found in the cavity of a fetal pig.
A fetal pig's lungs are collapsed because they are filled with fluid while in the uterus. This allows for easier passage through the birth canal and prevents the lungs from being damaged during development. Once the pig is born and takes its first breath, the lungs expand and fill with air.
The diaphragm in a fetal pig attaches to the abdominal and thoracic cavity. It is used to help the pig breath.
The lungs of a fetal pig do not contain air because a developing fetus receives oxygen and nutrients from the mother's bloodstream through the placenta, not from breathing air. Therefore, there is no need for the lungs to be inflated with air until birth when the piglet starts breathing independently.