If lungs are not muscles themselves, how are they able to expand and contract?

Question

i have a biology exam comming up and i dont understand this part

The resipatory system unit is more focused on the Human body

Answer 1

The lungs themselves are incredibly elastic air balloons. Their elasticity believe it or not is mostly due to a protein called surfactant, which greatly reduces surface tension, allowing the lung to expand greatly. But what causes the lung to expand? The action of muscles.

The diaphragm sits on the bottom of the chest wall cavity, but it makes NO CONNECTION WITH THE LUNGS THEMSELVES. Instead, it is just attached to the chest wall. So during inhalation, the phrenic nerve sends stimulation to the diaphragm, and it contracts. The diaphragm's contraction in essence expands the chest wall (aka thoracic cavity), which in turn increases the intra-thoracic pressure. This increased pressure pulls on the lungs, and this is what actually draws air into them. There are some accessory respiratory muscles, like the intercostal muscles and even the sternocleidomastoids for forced inspiration. (During times of extreme shortness of breath, after running for example, you'll notice people bend over to enhance their breathing. This is because from that position - almost prone position - you can aid the diaphragm and other inspiratory muscles with the powerful pectoralis muscles to expand the chest wall.)

Contraction of the lungs (expiration) is a completely passive process, i.e. there is no muscle involvement. Instead, the elastic recoil of the lung forces the air out, and this collapse actually pulls the chest wall back into place by altering the pressure in the cavity once again. The only case of muscle involvement is forced expiration, which uses the abdominal muscles to help squeeze air out.

Answer 2

Lungs Contract

Answer 3

The development of the diaphragm in mammals made it possible to exchange air much more efficiently than in either amphibians or reptiles .

Living reptiles depend on expansion and contraction of the rib cage and buccal swallowing of air for moving air in and out of lungs, which are septated and more complex in reptiles than amphibians, but still much simpler in structure than in mammals.

Respiration is also facilitated in crocodiles by the movement of the liver, which is attached to the pubis by a strand of muscle fibers that acts to expand the lungs. Unlike amphibian nostrils, reptilian nostrils are connected to the airways, but there is no hard palate and reptiles must stop breathing when there is food in the mouth

Answer 4

The diaphragm & pectoral muscles control the operation of the ribcage. The ribcage in turn contracts and expands the lungs.

Answer 5

I believe they can do this because of a muscle underneath them called the diaphragm which relaxes and contracts, forcing the muscles upwards, which expels air, when it relaxes air is inhaled into the longs filling them, and the process continues.

Answer 6

The diaphragm does the work, and the pectoral muscles move the rib cage to increase and decrease the volume available.

Answer 7

The diaphragm is below the lungs and it moves up and down to draw air into your lungs and force air out.

Answer 8

The diaphragm I believe

Answer 9

because you use ur surrounding muscles to breathe and inflate them with air and ur brain is on auto so you dont forget !!! but thats just my theory>>>