Notes of human respiratory system

3. Larynx: It is a chamber situated in the region of neck. It is supported by four cartilages : thyroid is the largest and in the form of a broad ring incomplete dorsally, cricoid is a complete ring lying at the base of thyroid, a pair of arytenoids lying above the thyroid but in front of cricoid, and epiglottis situated behind the tongue that serves to cover the entrance to the trachea so that food particles may not enter into it. Larynx is also known as voice box since it helps in the production of sound. 4. Trachea: It is a tube starting from larynx running through the neck and the thoracic cavity. The trachea runs through the neck in front of the oesophagus. The trachea or windpipe is about 12 cm long and divided into two bronchi in the thoracic region. 5. Bronchi and bronchioles: The two bronchi enter into right and left lungs of either side. Inside the lungs they further branch into many smaller bronchioles with a diameter of about 1 mm. These bronchioles further divide into terminal and then into respiratory bronchioles. Each respiratory bronchiole divides into a number of alveolar ducts that further divide into atria, which swell up into air sacs or alveoli. 6. Lungs: A pair of conical shaped lungs is situated in the double walled sacs called pleural cavities. They are spongy and richly supplied with blood vessels and capillaries. They have about 300-400 millions of alveoli through which exchange of gases occur. Lungs have various bronchioles ending into alveoli where exchange of gases occurs. The alveoli are thin walled pouches the walls of which have epithelial linings supported by basement membrane. I hope my answers help U ☺☺☺☺

All mammals have lungs for the purpose of respiration. This is known as pulmonary respiration. The mammalian respiratory system consists of the nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles and lungs. 1. Nasal cavity: It is a large cavity lying dorsal to the mouth and is lined by mucous secreting epithelium. The nasal cavity opens outside through a pair of external nostrils or nares. Bones and cartilages support the nasal cavity. The nasal cavity is divided into two parts by a nasal septum. The cavity opens inside into pharynx through two internal nostrils. Air while passing through the nasal cavity is filtered, and only the clean air free from dust particles and foreign substances enters the pharynx. The air also gets warmed and moistened in this chamber. It is important to note that air can also be inhaled through mouth directly, but this is not advisable because the air will not be filtered, warmed and moistened. This gradually will harm the respiratory system. 2. Nasopharynx: It is a chamber situated behind the nasal cavity. At the level of soft palate, it becomes continuous with the mouth cavity or oral pharynx. It also receives the openings of eustachian tubes on its lateral sides and is thus connected to the middle ear.

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