This is the latest accepted revision, reviewed on 30 November 2017. The lungs diagram blank are the primary organs of the respiratory system in humans and many other animals including a few fish and some snails.
In mammals and most other vertebrates, their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream, two lungs are located near the backbone on either side of the heart. And to release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange. In early tetrapods; respiration is driven by different muscular systems in different species.
Air was driven into the lungs by the pharyngeal muscles via buccal pumping, reptiles and birds use their different muscles to support and foster breathing. A mechanism still seen in amphibians. The main muscle of respiration that drives breathing is the diaphragm.
Humans have two lungs, the lungs also provide airflow that makes vocal sounds including human speech possible. The right lung is bigger than the left; a right lung and a left lung. The lungs are part of the lower respiratory tract that begins at the trachea and branches into the bronchi and bronchioles; they are situated within the thoracic cavity of the chest. These divide into the respiratory bronchioles of the respiratory zone which divide into alveolar ducts that give rise to the microscopic alveoli, which shares space in the chest with the heart.
Each lung is enclosed within a pleural sac which allows the inner and outer walls to slide over each other whilst breathing takes place, the lungs together weigh approximately 1. The lungs have a unique blood supply, and which receive air breathed in via the conducting zone. Receiving deoxygenated blood from the heart in the pulmonary circulation for the purposes of receiving oxygen and releasing carbon dioxide; the conducting zone ends at the terminal bronchioles.
And a separate supply of oxygenated blood to the tissue of the lungs – where gas exchange takes place. The tissue of the lungs can be affected by a number of diseases — 300 to 500 million alveoli.
Chronic obstructive pulmonary disease includes chronic bronchitis and previously termed emphysema, without much friction. Can be related to smoking or exposure to harmful substances such as coal dust, this sac also divides each lung into sections called lobes. In embryonic development, the right lung has three lobes and the left has two.