Source: Respiratory image, Public Domain: http://upload.wikimedia.org/wikipedia/commons/9/9f/Illu_conducting_passages.svg
Microscopic air sacs located in the peripheral parts of the lungs that consist of simple squamous epithelial tissue. Alveoli and pulmonary capillaries create the respiratory membrane where gas exchange occurs between atmospheric air and blood.
The branching tubes of the bronchial tree that distribute air throughout the lungs, all bronchial tubes (except the bronchioles) are constantly held open by cartilage to maintain an open airway.
Small tubes of the bronchial tree that connect the bronchi to the alveolar air sacs; bronchioles lack cartilage but contain walls of smooth muscle that is used to rapidly adjust airflow into and out of the lungs.
The prime mover/agonist muscle of breathing found covering the entire lower circumference of the rib cage.
Organs found in the lower respiratory tract that contains the bronchial tree and alveolar air sacs; the lungs are where gas exchange occurs. The lungs are located in the thoracic cavity/chest of the body.
The organ system of gas exchange in the body; gas exchange in the respiratory system occurs between atmospheric air we breathe in and blood in the pulmonary capillaries. The organs of the respiratory system are: nose, pharynx, larynx, trachea, bronchiole tree, bronchioles, alveoli, lungs.