HUMAN ANATOMY AND PHYSIOLOGY NOSTRILS AND NASAL CAVITY

 ANATOMY OF RESPIRATORY SYSTEM 

Respiratory organs include two lungs and the respiratory passage which includes nasal cavities nasopharynx larynx trachea and bronchi the lungs trachea bronchi and bronchioles are found in the thoracic cage whereas the respiratory passages including a part of the trachea are extrathoracic 
        The thoracic cage is a bony cartilagenous cage with the muscles situated in between the sternum and costal cartilages There are twelve thoracic vertebrae joined by the intervertebral discs made up of cartilages these are twelve pairs of ribs connected by intercostal muscles the diaphragm separates the thorax from the abdomen the whole thoracic cavity is occupied by the lungs with pleural covering and heart with peritoneal covering 
            The cavity between the two lungs is known as mediastinum it contains the heart with its pericardium oesophagus thoracic duct big blood vessels part of the trachea and bronchi 

Nostrils and Nasal Cavity ::

Nostrils are two nasal openings which serve like the gateway of the respiratory system the nasal cavity has one central septum that divides the whole cavity into two parts each half of the nasal cavity has three tubinates called chonchae which form three meatuses or cavities in the nasal cavity the superior chonchae lodges the olfactory bulb and nerve ramification alongwith olfactory receptors 
                The interior structures of the nose perform three function warming moistening and filtration of incoming air receiving of olfactory stimuli and modify speech sounds The anterior portion of nasal cavity just inside nostrils is called vestibule when air enters the nostrils it passes first through the vestibule the olfactory receptors lie in the membrane lining superior nasal conchae and adjacent septum this region is called the olfactory epithelium Inferior to olfactory epithelium mucus membrane contains capillaries and pseudostratified ciliated columnar epithelium with many goblet cells as the air goes inside nasal cavity it is warmed by blood in capillaries mucus is secreted by goblet cells which moistens air and traps dust partides the cilia move the mucus along with dust particles toward the pharynx 

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