How can I put the following events in order from 1 to 4 ?

Question

Put the following events in order from 1 to 4?

__ CNS stops sending impulses to diaphragm and external intercostals.

__Prssure gradient results in air flowing out of lungs

__ Reduced thoracic cavity results in pressure change

__Thoracic cavity decreases in three dimensions

Answer 1

The events above describe the process of passive expiration during breathing. The first step here is going to be "CNS stops sending impulses to diaphragm and external intercostals". As this occurs, the diaphragm will relax and the rib cage will also compress leading to #2 which is "Thoracic cavity decreases in three dimensions". As a reminder, the diaphragm contracts by flattening and expanding the thoracic cavity, and the external intercoastals will work to expand the ribcage for the same result. The next description of this process will therefore be "Reduced thoracic cavity results in pressure change". Lastly, "Pressure gradient results in air flowing out of lungs". As the thoracic cavity decreases in space it increases the pressure of air in the lungs which forces the air to move from the lungs to outside the body. Hope this helps you to understand, let me know if you have any questions!