Respiratory Study Guide

Respiratory System

The major function of the respiratory system is to supply the body w/ oxygen and dispose of carbon dioxide.

Four processes called respiration:

1.) Pulmonary ventilation: movement of air into and out of the lungs so that the gases there are continuously changed and refreshed (commonly called breathing)

2.) External respiration: movement of oxygen from the lungs to the blood and of carbon dioxide from the blood to the lungs.

3.) Transport of respiratory gases: transport of oxygen from the lungs to the tissue cells of the body, and of carbon dioxide from the tissue cells to the lungs. This is accomplished by the cardiovascular system using blood as the transporting fluid.

4.) Internal respiration: movement of oxygen from blood to the tissue cells and of carbon dioxide from tissue cells to blood.

Respiratory Zone: the actual site of gas exchange, is composed of the terminal bronchioles, respiratory bronchioles, alveolar ducts and alveoli sacs, alveoli, all microscopic structures.

Conducting Zone: includes all other respiratory passageways, which provide fairly rigid conduits for air to reach the gas exchange sites: secondary bronchi, tertiary bronchi, bronchioles.

The Nose and Paranasal Sinuses

The nose is the only externally visible part of the respiratory system.

The nose:

1.) provides an airway for respiration

2.) moistens and warms entering air

3.) filters and cleans inspired air

4.) serves as a resonating chamber for speech

5.) houses the olfactory "smell" receptors

The structures of the nose are divided into the external nose and the internal nasal cavity.

External nose includes the root (area between the eyebrows), bridge and dorsum nasi (anterior margin), apex (tip of the nose), nostrils

The internal nasal cavity lies in and posterior to the external nose. During breathing air enters the cavity by passing through the nostrils, or external nares. The nasal cavity is divided by a midline nasal septum.

Olfactory mucosa: lining the slitlike superior region of the nasal cavity, contains smell receptors.

Respiratory mucosa (RM): is pseudostratified ciliated columnar epithelium, containing scattered goblet cells. The ciliated cells of the RM create a gentle current that moves the sheet of contaminated mucus posteriorly toward the throat, where it is swallowed and digested by stomach juices.

*When the inspired air is cold, the vascular plexus becomes engorged w/ blood, thereby intensifying the air-heating process.*

The conchae and nasal mucosa not only function during inhalation to filter, heat and moisten the air, but also act during exhalation to reclaim this heat and moisture.

The nasal cavity is surrounded by a ring of paranasal sinuses located in the frontal, sphenoid, ethmoid and maxillary bones. The sinuses lighten the skull, and together with the nasal cavity they warm and moisten the air.

The Pharynx

* funnel shaped

* connects the nasal cavity and mouth superiorly to the larynx and esophagus inferiorly.

* Divided into three regions (superior to inferior)- nasopharynx, oropharynx, and laryngopharynx.

The Nasopharynx

* Posterior to the nasal cavity inferior to the sphenoid bone and superior to the level of the soft palate.

* Lies above the point where food enters and serves ONLY as an air passageway.

* High on the posterior wall is the pharyngeal tonsil (adenoids) which traps and destroys pathogens entering the nasopharynx in air.

* The pharyngotympanic (auditory) tubes, drain the middle ear cavities and allow middle ear pressure to equalize with atmosphere pressure open into the lateral walls of the nasopharynx.

The Oropharynx

* Lies posterior to the oral cavity and is continuous with it through an archway called the fauces (throat).

* Extends inferiorly from the level of the soft palate to the epiglottis, both swallowed food and inhaled air pass through it.

* Pseudostratified columnar to a more protective stratified squamous epithelium.

* The palatine tonsils lie in the lateral walls of the fauces. The lingual tonsil covers the base of the tongue.

The Laryngopharynx

* Oropharynx is above laryngopharynx serves as a passageway for food and air and is lined with a stratified squamous epithelium.

* Lies directly posterior to the upright epiglottis and epiglottis and extends to the larynx, where the respiratory and digestive pathways diverge.

The Larynx

* The larynx or voice box attaches superiorly it attaches to the hyoid bone and opens into the laryngopharynx.

* Inferiorly it is continuous with the trachea.

* Has three functions: 1.) provide a patent (open) airway, 2.) act as a switching mechanism to route air and food into the proper channels and 3.) voice production.

* Laryngeal prominence, which marks the fusion point, is obvious externally as the Adam's apple.

* Laryngeal cartilages are hyaline cartilage.

* The large shield-shaped thyroid cartilage is formed by the fusion of two cartilage plates.

* Inferior to the thyroid cartilage is the ring-shaped cricoid cartilage perched atop and anchored to the trachea inferiorly.

* Three pairs of small cartilages, arytenoids, cuneiform and corniculate cartilages, form part of the lateral and posterior walls of the larynx. The most important of these are the pyramid shaped