Short answers, pulled from the story.
The lungs are the primary organs of the respiratory system, and their main job is gas exchange. They extract oxygen from the atmosphere and transfer it into the bloodstream, while releasing carbon dioxide from the bloodstream back into the atmosphere. They also provide the airflow that makes vocalisation, including speech, possible.
The right lung has three lobes and the left lung has two. The right is divided by a horizontal and an oblique fissure, while the left has a single oblique fissure. The left lung lacks a middle lobe but has a homologous projection of the upper lobe called the lingula, meaning "little tongue."
The lungs together weigh approximately 1.3 kilograms, about 2.9 pounds. The right lung is bigger and heavier than the left, because the left lung shares space in the chest with the heart.
The lungs contain roughly 300 to 500 million alveoli, the microscopic pockets where gas exchange takes place. Together the lungs hold approximately 2,400 kilometers, about 1,500 miles, of airways. The blood-air barrier they form is about 0.5 to 2 micrometers thick.
Lung tissue can be affected by pneumonia and lung cancer, along with chronic obstructive pulmonary disease and emphysema, which can be related to smoking or harmful substances. Obstructive lung diseases include asthma, bronchiectasis, and COPD. Restrictive diseases such as pulmonary fibrosis reduce the amount of lung tissue taking part in respiration.
The lungs begin to form during the fourth week of embryogenesis from a lung bud below the foregut. Before birth the fetus is held in the fluid-filled amniotic sac, so the lungs do not breathe. At birth the newborn's nervous system reacts to the change in temperature and environment, triggering the first breath within about ten seconds of delivery.
The lungs of birds are relatively small and fixed in size, connected to eight or nine air sacs that extend through much of the body and into the bones. Air flows continuously from the rear air sacs through the lungs to the front sacs, so they are called circulatory lungs, unlike the bellows-type lungs of most other animals.