Nasal Passage: A nasal passage contains microscopic filament which secrete mucus the cilli and the mucus help to trap germs or dust particle, filter warmed and moist air.

      The epiglottis prevent food from entering the trachea.The voice box(larynx) with a vocal cord which helps to produce sound and enable you to speak fluently. The wind pipe as air passes or enters it is permanently open by tiny cartilage in it walls and this prevent the trachea from been blocked.

Bronchus : The trachea divided into 2 branches called bronchi which serve as air passage to each lungs this bronchus finally divide again and again to form a mass of small branches called bronchioles. This bronchioles are the branches that carries air to the alveoli.

      The aveoli is the site for gaseous exchange.

Pleural membrane:  This membrane surround the lungs and encloses it with pleural fluid. The pleural fluid lubrication and allowed lungs movement especially during inspiration and allowed lungs movement especially during inspiration and expiration.This ribs protect the lungs and the heart and it provide attachement for muscles.