When the diaphragm relaxes it regains it’s domed shape causing an increase in thoracic pressure forcing air out of the lungs. To have air forced out of the lungs the pressure in the thorax must rise above _______________ pressure?
A . Trans thoracic
B . Atmospheric
C . Trans abdominal
D . Respiratory
Answer: B
Explanation:
For air to be pushed out of the lungs the trans thoracic pressure must rise above atmospheric (barometric). The diaphragm will relax and dome upward and the intercostal muscles will contract and pull the rib cage inward increasing the transthorasic pressure above atmospheric, forcing air out.