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The respiratory system consists of ...

Nose, pharynx, larynx, trachea, bronchi, lungs


How is the respiratory system classified structurally?

(1) The upper respiratory system includes the nose, nasal cavity, pharynx, and associated structures; (2) the lower respiratory system includes the larynx, trachea, bronchi, and lungs.


How is the respiratory system classified functionally?

(1) The conducting zone consists of a series of inter- connecting cavities and tubes both outside and within the lungs. These include the nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles; their function is to filter, warm, and moisten air and conduct it into the lungs.
(2) The respiratory zone consists of tubes and tissues within the lungs where gas exchange occurs. These include the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli and are the main sites of gas exchange between air and blood.


What does the external nose consist of? Describe the arrangement of bone and cartilage in the nose.

The external nose is the portion of the nose visible on the face and consists of a supporting framework of bone and hyaline cartilage covered with muscle and skin and lined by a mucous membrane. The frontal bone, nasal bones, and maxillae form the bony framework of the external nose. The cartilaginous framework of the external nose consists of several pieces of hyaline cartilage connected to each other and certain skull bones by fibrous connective tissue. The components of the cartilaginous framework are the septal nasal cartilage, which forms the anterior portion of the nasal septum; the lateral nasal cartilages inferior to the nasal bones; and the alar cartilages, which form a portion of the walls of the nostrils. Because it consists of pliable hyaline cartilage, the cartilaginous framework of the external nose is somewhat flexible. On the undersurface of the external nose are two openings called the external nares or nostrils.


What are the three functions of the interior structures of the external nose?

(1) warming, moistening, and filtering incoming air; (2) detecting olfactory stimuli; and (3) modifying speech vibrations as they pass through the large, hollow resonating chambers.


What is meant by resonance?

Resonance refers to prolonging, amplifying, or modifying a sound by vibration.


What are the functions of the paranasal sinuses?

Besides producing mucus, the paranasal sinuses serve as resonating chambers for sound as we speak or sing.


What is the purpose of the bony and cartilaginous framework of the nose?

The bony and cartilaginous framework of the nose help to keep the vestibule and nasal cavity patent, that is, open or unobstructed.


Describe the nasal cavity.

The nasal cavity is a large space in the anterior aspect of the skull that lies inferior to the nasal bone and superior to the oral cavity; it is lined with muscle and mucous membrane. A vertical partition, the nasal septum, divides the nasal cavity into right and left sides. The anterior portion of the nasal septum consists primarily of hyaline cartilage; the remainder is formed by the vomer, perpendicular plate of the ethmoid, maxillae, and palatine bones.


What is the nasal cavity divided into?

A larger, inferior respiratory region and a smaller, superior olfactory region. The respiratory region is lined with pseudostratified ciliated columnar epithelium with numerous goblet cells, which is frequently called the respiratory epithelium. The anterior portion of the nasal cavity just inside the nostrils, called the nasal vestibule, is surrounded by cartilage; the superior part of the nasal cavity is surrounded by bone.


When the air first enters the nostrils, what does it pass through?

The vestibule, which is lined by skin containing coarse hairs that filter out large dust particles.


What extends out of each lateral wall of the nasal cavity?

Three shelves formed by projections of the superior, middle, and inferior nasal conchae. The conchae, almost reaching the nasal septum, subdivide each side of the nasal cavity into a series of groovelike air passageways—the superior, middle, and inferior nasal meatuses.


What lines the nasal cavity and its shelves?

Mucous membrane lines the nasal cavity and its shelves.


What are the functions of the nasal chonchae and meatuses?

Increases surface area in the internal nose and prevents dehydration by trapping water droplets during exhalation.


What happens to the air as it whirls around the chonchae and meatuses?

It is warmed by blood in the capillaries. Mucus secreted by the goblet cells moistens the air and traps dust particles. Drainage from the nasolacrimal ducts also helps moisten the air, and is sometimes assisted by secretions from the paranasal sinuses. The cilia move the mucus and trapped dust particles toward the pharynx, at which point they can be swallowed or spit out, thus removing the particles from the respiratory tract.


What cells make up the olfactory epithelium?

The olfactory receptor cells, supporting cells, and basal cells lie in the respiratory region, which is near the superior nasal conchae and adjacent septum. It contains cilia but no goblet cells.


What is the pharynx? Where is the pharynx situated?

The pharynx, or throat, is a funnel-shaped tube about 13 cm long that starts at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the larynx (voice box). The pharynx lies just posterior to the nasal and oral cavities, superior to the larynx, and just anterior to the cervical vertebrae.


What is the wall of the pharynx composed of and what is it lined with?

Its wall is composed of skeletal muscles and is lined with a mucous membrane.


Relaxed skeletal muscles help keep the pharynx __________. Contraction of the skeletal muscles assists in ___________.

Deglutition (swallowing)


What are the functions of the pharynx?

The pharynx functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils, which participate in immunological reactions against foreign invaders.


What are the three anatomical regions of the pharynx?

(1) nasopharynx, (2) oropharynx, and (3) laryngopharynx


How are the muscles of the entire pharynx arranged?

In two layers: an outer circular layer and an inner longitudinal layer.


Where is the nasopharynx found?

The superior portion of the pharynx, called the nasopharynx, lies posterior to the nasal cavity and extends to the soft palate.


What is the soft palate?

The soft palate, which forms the posterior portion of the roof of the mouth, is an arch-shaped muscular partition between the nasopharynx and oropharynx that is lined by mucous membrane.


What are the five openings in the wall of the nasal pharynx?

Two internal nares, two openings that lead into the auditory (pharyngotympanic) tubes (commonly known as the eustachian tubes), and the opening into the oropharynx. The posterior wall also contains the pharyngeal tonsil, or adenoid.


What are the functions of the nasopharynx?

Through the internal nares, the nasopharynx receives air from the nasal cavity along with packages of dust-laden mucus. The nasopharynx is lined with pseudostratified ciliated columnar epithelium, and the cilia move the mucus down toward the most inferior part of the pharynx. The nasopharynx also exchanges small amounts of air with the auditory tubes to equalize air pressure between the middle ear and the atmosphere.


Describe the location of the oropharynx.

The intermediate portion of the pharynx, the oropharynx, lies posterior to the oral cavity and extends from the soft palate inferiorly to the level of the hyoid bone. It has only one opening into it, the fauces (throat), the opening from the mouth.


What are the functions of the oropharynx?

This portion of the pharynx has both respiratory and digestive functions, serving as a common passageway for air, food, and drink.


What is the oropharynx lined with and why? What is found in the oropharynx?

Because the oropharynx is subject to abrasion by food par- ticles, it is lined with nonkeratinized stratified squamous epithe- lium. Two pairs of tonsils, the palatine and lingual tonsils, are found in the oropharynx.


Where does the laryngopharynx begin? What does it open into?

It is the inferior portion of the larynx, which begins at the level of the hyoid bone.
At its inferior end it opens into the esophagus (food tube) posteriorly and the larynx (voice box) anteriorly.