Which ONE of the following statements about mechanisms of breathing is CORRECT?Group of answer choicesMovement of air out of the lungs occurs via a pressure gradient created by expanding the thoracic cageWhen surface tension between parietal and visceral pleura is broken, lungs may collapse and this is largely due to elastic recoilThe diaphragm is responsible for quiet breathing because its attachments to the ribs help expand the thoracic cageRhythmic contractions of the diaphragm are controlled by the brainstem and transmitted from the thoracic spinal cord via the phrenic nerveUpper ribs tend to expand the thoracic cage by increasing its tranverse diameter and lower ribs tend to expand it in the anteroposterior dimension Flag question: Question 5Question 51 ptsWhich ONE of the following statements regarding the trachea is CORRECT?Group of answer choicesIt is posterior to the oesophagus in the neckIt divides into the main bronchi at the at vertebral level T3It contains cartilaginous rings that are deficient anteriorlyIt is lined by respiratory epitheliumIt begins at the level of the hyoid bone Flag question: Question 6Question 61 ptsWhich ONE of the following statements regarding the thoracic aorta is correct?Group of answer choicesThe ascending aorta arises from the left ventricle in the middle mediastinumThe descending aorta passes through the aortic hiatus of the diaphragm at the level T‑10The ascending aorta does not have any branchesThe descending thoracic aorta is located in the middle mediastinumThe aorta arches over the right main bronchus

Let's go through each statement one by one:

1. "Movement of air out of the lungs occurs via a pressure gradient created by expanding the thoracic cage" - This statement is INCORRECT. Movement of air out of the lungs occurs when the thoracic cage contracts, not expands. This contraction increases the pressure in the lungs, forcing air out.

2. "When surface tension between parietal and visceral pleura is broken, lungs may collapse and this is largely due to elastic recoil" - This statement is CORRECT. The surface tension between the parietal and visceral pleura helps keep the lungs inflated. If this tension is broken, the lungs may collapse due to their natural elastic recoil.

3. "The diaphragm is responsible for quiet breathing because its attachments to the ribs help expand the thoracic cage" - This statement is INCORRECT. While the diaphragm does play a crucial role in breathing, it is not solely responsible for quiet breathing. Other muscles, such as the intercostal muscles, also contribute to the expansion and contraction of the thoracic cage during quiet breathing.

4. "Rhythmic contractions of the diaphragm are controlled by the brainstem and transmitted from the thoracic spinal cord via the phrenic nerve" - This statement is INCORRECT. The rhythmic contractions of the diaphragm are indeed controlled by the brainstem, but the signals are transmitted via the phrenic nerve, which originates in the cervical spinal cord (C3-C5), not the thoracic spinal cord.

5. "Upper ribs tend to expand the thoracic cage by increasing its transverse diameter and lower ribs tend to expand it in the anteroposterior dimension" - This statement is INCORRECT. The upper ribs primarily increase the anteroposterior diameter of the thoracic cage (pump handle movement), while the lower ribs primarily increase the transverse diameter (bucket handle movement).

So, the correct answer is: "When surface tension between parietal and visceral pleura is broken, lungs may collapse and this is largely due to elastic recoil".