This module introduces students to the structural, functional and pathological aspects of the respiratory system, the mechanism of breathing, gas diffusion across respiratory membrane, O2 & CO2 transport in the blood, in addition to the mechanism of regulation of respiration, respiratory changes during muscular exercise, at high altitude and in deep sea. The module also introduces the students to the pathological changes in the larynx, lungs, bronchi, pleura, pulmonary neoplasm, in addition to the infectious microorganisms that affect the respiratory system. The students also study bronchodilator, anti-allergic, and autacoids drugs. They also learn how to estimate the lung volumes, lung capacities, and how to differentiate between obstructive and restrictive lung diseases both clinically and by pulmonary function tests. Students are also introduced to clinical skills that assist them to develop the ability of focused history taking based on common diseases related to respiratory system, and chest examination in clinical skill lab. Prerequisites: FABL201, LOCO202, COHD 203, HEMA204.