Respiratory System

What are the main functions of the respiratory system?

-Provides a surface area for gaseous exchange

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- moves air between gas-exchange surfaces and the environment,

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-Protecting respiratory surfaces from dehydration, temperature changes, and pathogens

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-Producing sounds for speaking, singing, and other forms of communication.

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-Detecting odors by olfactory receptors in the superior portions of the nasal cavity

What are the upper and lower divisions of the respiratory system?

-Upper respiratory tract: nose, nasal cavity, paranasal sinuses, and pharynx.

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-Lower respiratory tract: larynx, trachea, bronchi, bronchioles, and alveoli.

Conducting vs Respiratory Zone

Conducting zone:

-Respiratory passages that carry air to the site of gas exchange

– Filters, humidifies and warms air

-Begins at entrance of nasal cavity and extends through the pharynx, larynx, trachea, bronchi, and larger bronchioles.

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-Respiratory zone:

-Site of gas exchange

– Composed of

• Respiratory bronchioles • Alveolar ducts • Alveolar sacs

What does the respiratory mucosa consist of?

A mucous membrane consisting of epithelium and supporting lamina propria made of areolar tissue.

What type of epithelium lines most of the upper respiratory tract, trachea, and bronchi?

Pseudostratified ciliated columnar epithelium.

What type of epithelium lines the oropharynx and laryngopharynx?

Stratified squamous epithelium.

What type of epithelium lines the small bronchioles?

Simple cuboidal epithelium with scattered cilia.

What type of epithelium lines the alveoli?

Simple squamous epithelium.

FUNCTIONS OF THE RESPIRATORY MUCOSA OF THE UPPER TRACT, TRACHEA AND BRONCHI

-Cleans inhaled air Mucus traps particles in air & cilia moves the mucus

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- Humidifies inhaled air

Water evaporates from mucus & moistens air

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-Warms inhaled air

Blood in vessels of lamina propia

How does the respiratory mucosa of the upper tract, trachea, and bronchi clean inhaled air?

Mucus traps particles in the air and cilia move the mucus toward the pharynx.

What is the function of the alveolar simple squamous epithelium?

Gaseous exchange.

What is the primary passageway for air entering the respiratory system?

The nose/nares/nostrils

What is the nasal vestibule and what is contains?

-The space contained within the flexible tissues of the nose

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-contains coarse hair traps large airborne particles such as sand, sawdust, and insects.

What is the function of the nasal septum?

It divides the nasal cavity into left and right portions.

What structures form the nasal septum?

Anteriorly, it is formed by hyaline cartilage

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posteriorly, it is formed by fusion of the perpendicular plate of the ethmoid bone and the vomer bone.

(supports the dorsum(bridge) of nase and apex(tip)

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Which bones form the lateral and superior walls of the nasal cavity?

The maxillary, nasal, frontal, ethmoid, and sphenoid bones.

What forms the hard palate and function

Paired maxillary and palatine bones

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-Floor of nasal cavity; separates it from oral cavity

What is the soft palate and what boundary does it mark?

It extends posteriorly from the hard palate and marks the boundary between the nasopharynx and oropharynx.

What is the olfactory region of the nasal cavity?

-Superior region of nasal cavity

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The areas lined by olfactory epithelium whose receptors provide the sense of smell.

What structures are included in the olfactory region of the nasal cavity?

-The inferior surface of the cribriform plate

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- superior portion of the nasal septum

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-superior nasal conchae.

What are the nasal conchae?

Turbinates

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The superior, middle, and inferior conchae are bony projections that extend toward the nasal septum from the lateral walls of the nasal cavity.

What are the meatuses?

Narrow grooves by which air passes from vestibule to nasal conchae:

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the superior, middle, and inferior meatuses.

What are the functions of the nasal conchae and meatuses?

They create turbulence of incoming air which allows:

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• Small airborne particles to contact mucosal coat

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• Provides extra time for warming and humidifying air

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• Creates eddy currents that bring olfactory stimuli to the olfactory receptor

allowing efficient cleaning, warming, and humidifying of air, and create eddy currents that bring olfactory stimuli to olfactory receptors.

What are the functions of the paranasal sinuses?

-Make skull lighter

Air filled cavities

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-Resonance chambers

Affect and amplify sound of voice

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-Mucus production

Sinuses lined with mucus membrane producing mucus to keep membranes clean and moist

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-Drainage pathway

Osteomeatal ducts connect sinuses to nasal cavity allowing mucus to drain properly

What is the function of the nasolacrimal duct?

It delivers tears into the nasal cavity through the inferior nasal concha, helping keep the nasal cavity moist and clean.

Pharynx

Throat

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-Extends between the choanae and entrance to larynx and esophagus

What are the three regions of the pharynx?

The nasopharynx, oropharynx, and laryngopharynx.

Nasopharynx characteristics

-superior portion of pharynx; connected to posterior portion of nasal cavity by choana

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- separated from oral cavity by the soft palate

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-Lined by pseudostratified ciliated columnar epithelium

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- Pharyngeal tonsil on posterior wall

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-Opening to the pharyngotympanic (auditory) tube on lateral walls;

Audioty tube opens into nasopharynx at pharyngeal opening of auditory tube

Where is the oropharynx located and what type of epithelium lines it?

-It extends from the soft palate to the base of the tongue at the level of the hyoid bone

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-lies posterior to the oral cavity

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Lined by stratified squamous epithelium.

Where is the laryngopharynx located and what type of epithelium lines it?

It is the inferior part of the pharynx, lying between the hyoid bone and the entrance to the larynx and oesophagus, and is lined by stratified squamous epithelium.

What is the larynx?

A cartilaginous structure that surrounds and protects the glottis.

Between which vertebrae does the larynx extend?

It begins at approximately C4 or C5 and ends at C6.

How are the walls of the larynx structured?

The larynx has incomplete cartilaginous walls stabilized by ligaments and muscles.

What are the three large unpaired cartilages of the larynx?

Thyroid cartilage, cricoid cartilage, and epiglottis.

What are the main characteristics and functions of the thyroid cartilage?

It is the largest laryngeal cartilage, made of hyaline cartilage, and forms most of the anterior and lateral walls of the larynx. Its anterior surface forms the laryngeal prominence (Adam’s Apple). It protects the glottis and entrance to the trachea.

What are the main characteristics of the cricoid cartilage?

It is made of hyaline cartilage, lies inferior to the thyroid cartilage, has a greatly expanded posterior portion, and supports the thyroid cartilage.

What does the cricoid cartilage protect?

The glottis and the opening to the trachea.