Question

In negative pressure breathing, inhalation results from:
A.forcing air from the throat down into the lungs
B.contracting the diaphragm
C.relaxing the muscles of the rib cage
D.contracting the abdominal muscles

Answer 1

Hint:Negative pressure breathing as the name suggests is when a negative pressure or low-pressure condition is caused within the lungs, which causes air to rush in. This is what we call inhalation. The negative pressure is induced by contracting the diaphragm which moves down, and muscles of the rib cage move up and out.

Complete answer:Inhalation is the process where we breathe in the air into our lungs. This is an autonomic as well as a somatically controllable process, where we can hold our breath or breathe faster, but can even function autonomically without needing to control or regulate.
The process of inhalation is heavily dependent on the diaphragm, intercostal muscles, and the thoracic cavity. The thoracic cavity is an airtight chamber that maintains the pressure within the lungs. During inhalation, we contract the diaphragm and the intercostal muscles in our ribs. By doing so the diaphragm moves down and the intercostal muscles move up and outwards.
This movement causes the airtight thoracic chamber to expand. Such an expansion lowers the pressure within the lungs, or as we know it creates a negative pressure environment when compared to the air pressure outside the body. This causes the air to rush into our lungs to balance out the pressure.
The opposite is the case of exhalation, where the diaphragm and the intercostal muscles relax, where the diaphragm moves up and the intercostal muscles move in which contracts the thoracic cavity creating a positive pressure within the lungs and the air rushes out to balance the pressure.
Therefore, the correct option is B.

Note:Negative pressure breathing or ventilation is when contraction of the diaphragm causes negative pressure to develop within the lungs.
To balance out the pressure air rushes into the lungs, and this is known as inhalation.
Intercostal muscles are the muscles in between the ribs, these muscles only aid in the movement of the rib cage and not the chest.
Ventilators in hospitals use this phenomenon to pump air into our lungs. Negative pressure ventilators were known as iron lungs, which mechanically contracted the chest to create negative pressure.
But ventilators used today are positive pressure ventilators that forcefully push air into the lungs, thereby forcing the thoracic cavity to expand and send air into the alveoli of the lungs.