RESPIRATORY SYSTEM
• The respiratory system is represented by the following structures:
• The nose consists of the visible external nose and the internal nasal cavity
nasal septum divides the nasal cavity into right and left sides. Hair, mucus
blood capillaries, and cilia that line the nasal cavity filter, moisten, warm,
eliminate debris from the passing air.
• The pharynx (throat) consists of the following three regions;
– The nasopharynx receives the incoming air from the two internal nares. The two
auditory (Eustachian) tubes that equalize air pressure in the middle ear also ente
– The oropharyrnx receives air from the nasopharynx and food from the oral cavity
– The laryngopharynx passes food to the esophagus and air to the larynx.
,• The trachea (windpipe) is a flexible tube, 10 to 12 cm (4 inches) long an
2.5 cm (1 inch) in diameter, whose wall consists of four layers;
– The mucosa is the inner layer of the trachea. It contains mucusproducing gobl
cells and pseudostratified ciliated epithelium. The movement of the cilia swee
debris away from the lungs toward the pharynx.
– The submucosa is a layer of areolar connective tissue that surrounds the muco
– Hyaline cartilage forms 16 to 20 C-shaped rings that wrap around the submuco
The rigid rings prevent the trachea from collapsing during inspiration.
– The adventitia is the outermost layer of the trachea. It consists of areolar
connective tissue.
, • The primary bronchi are two tubes that branch from the trachea to the left and rig
lungs.
• Inside the lungs, each primary bronchus divides repeatedly into branches of small
diameters, forming secondary (lobar) bronchi, tertiary (segmental) bronchi, and
numerous orders of bronchioles (1 mm or less in diameter), including terminal
bronchioles (0.5 mm in diameter) and microscopic respiratory bronchioles. The w
the primary bronchi are constructed like the trachea, but as the branches of the tr
get smaller, the cartilaginous rings and the mucosa are replaced by smooth muscl
• Alveolar ducts are the final branches of the bronchial tree. Each alveolar duct has
enlarged, bubblelike swellings along its length. Each swelling is called an alveolus,
cluster of adjoining alveolar is called an alveolar sac. Some adjacent alveoli are
connected by alveolar pores.
• The respiratory system is represented by the following structures:
• The nose consists of the visible external nose and the internal nasal cavity
nasal septum divides the nasal cavity into right and left sides. Hair, mucus
blood capillaries, and cilia that line the nasal cavity filter, moisten, warm,
eliminate debris from the passing air.
• The pharynx (throat) consists of the following three regions;
– The nasopharynx receives the incoming air from the two internal nares. The two
auditory (Eustachian) tubes that equalize air pressure in the middle ear also ente
– The oropharyrnx receives air from the nasopharynx and food from the oral cavity
– The laryngopharynx passes food to the esophagus and air to the larynx.
,• The trachea (windpipe) is a flexible tube, 10 to 12 cm (4 inches) long an
2.5 cm (1 inch) in diameter, whose wall consists of four layers;
– The mucosa is the inner layer of the trachea. It contains mucusproducing gobl
cells and pseudostratified ciliated epithelium. The movement of the cilia swee
debris away from the lungs toward the pharynx.
– The submucosa is a layer of areolar connective tissue that surrounds the muco
– Hyaline cartilage forms 16 to 20 C-shaped rings that wrap around the submuco
The rigid rings prevent the trachea from collapsing during inspiration.
– The adventitia is the outermost layer of the trachea. It consists of areolar
connective tissue.
, • The primary bronchi are two tubes that branch from the trachea to the left and rig
lungs.
• Inside the lungs, each primary bronchus divides repeatedly into branches of small
diameters, forming secondary (lobar) bronchi, tertiary (segmental) bronchi, and
numerous orders of bronchioles (1 mm or less in diameter), including terminal
bronchioles (0.5 mm in diameter) and microscopic respiratory bronchioles. The w
the primary bronchi are constructed like the trachea, but as the branches of the tr
get smaller, the cartilaginous rings and the mucosa are replaced by smooth muscl
• Alveolar ducts are the final branches of the bronchial tree. Each alveolar duct has
enlarged, bubblelike swellings along its length. Each swelling is called an alveolus,
cluster of adjoining alveolar is called an alveolar sac. Some adjacent alveoli are
connected by alveolar pores.
