Parts of respiratory system are nose, paranasal sinuses, nasopharynx, larynx, trachea, bronchi and lungs. Nasal cavity has a septum and lateral wall, the features of which are given. Paranasal sinuses are maxillary, ethmoid, frontal, sphenoidal sinuses. Cartilages of larynx are thyroid, cricoid, epiglottis, arytenoids, corniculate and cuneiform. Trachea is the wind pipe continuing from larynx to end by dividing into two primary bronchi. Primary bronchus divides into secondary and secondary into tertiary. Further division is into bronchioles where there is absence of cartilage. The respiratory bronchiole finally gives rise to alveoli where blood-air barrier is present. Diaphragm is a musculoaponeurotic partition between thorax and abdomen with major openings for inferior vena cava, oesophagus and aorta and some minor openings. Histology of trachea and lung is illustrated.