Protostar
cytoskeleton
The term is "protostar", not "prostar". Yes. A protostar is an early stage of a star.
Plasmolysis is the reason because it always has water to keep it full.
They produce surfactant, a substance that reduces surface tension. Alveoli are very small, only 80 nanometers wide, and are flat. Therefore they have a tendency to curl up. The surfactant reduces this tendency, hence keeps the alveoli from collapsing.
The pressure within a protostar counters gravity and prevents the star from collapsing further.
Protostar
The uterus keeps the trachea from collapsing in a fetal pig.
Its cytoplasm.
Its surface temperature and luminosity increase.
cytoplasm
hydrostatic
Transpulmonary pressure
Dynamic equilibrium.
cytoskeleton
gravity maybe?
The trachea has a series of cartilage rings that prevent it from collapsing.