Respiratory Organs in Human Body
I. Nasal Cavity
It opens to the exterior through nostrils.
The small hair present in the cavity help to filter particles of dust and other foreign matter.
The air in the nasal cavity gets warmed (because nasal cavity has a very good blood supply) and moistened before it enters lungs.
From the nasal cavity the air enters the pharynx. It serves as a common passage for both air and food.
The opening into the wind pipe or trachea is a narrow slit, the glottis.
The glottis is protected against the entrance of food by a triangular flap of tissue, the epiglottis.
III. Larynx (Voice Box)
Called Adam’s apple in man. It is the first part of trachea present in the neck.
When air is forced into the larynx, the vocal cords present in it vibrates and sound is produced.
The pitch of a sound is determined by the tension on the vocal cords – the greater the tension, the higher the pitch.
It is four and a half inch long tube with C – shaped ring of cartilages in its walls.
These tings of cartilage make the wall non – collapsable.
The trachea branches into two bronchi on to each lung and these branches within the lung into many smaller bronchioles.
Surrounding each lung is a double walled sac, the pleural cavity. Hence, the covering of lungs are called pleural membrane.
The right lung is divided into three lobes and left into two.
The left lung is smaller than the right and has a concavity, the cardiac notch, where the heart lies.
Inside the lung, each bronchi divides into numerous bronchioles, each of which terminates into an elongated saccule, the alveolar duct, which bears on its surface air sac or alveoli.