This image shows the major organs of the lower respiratory tract of the cat.  Note that (as in humans), each lung is divided into several distinct lobes.  The muscular diaphragm that separates the abdominal cavity from the thoracic cavity can also be seen in the image.  It is the contraction and relaxation of the diaphragm (along with the muscles between the ribs) that affects a change in pressure of the space surrounding the flexible lungs, which allows them to inflate and deflate.  The  thymus gland (part of the endocrine system) that secretes hormones that affect the development of an immune system can also be seen in the image.