Illustration of the human respiratory tract. At top is the larynx with the trachea, which divides into two main bronchi in the lower part. The lungs themselves consist of multiple smaller sections, the lobes, divided by fissures. The right lung has three lobes: the superior, the middle and the inferior lobe. The left lung has only two lobes: the superior and the inferior lobe. This is because the left lung must make space for the heart and is therefore smaller than the right lung.