Ch 22 - Respiratory System

The Respiratory System function primarily to:

provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and maintain acid-base balance

for non-vital functions:

sensing odors, speech production, and straining, such as during childbirth or coughing

What are the two main zones of the respiratory system?

• Conducting zone

• Respiratory zone

What are the functions of the nose in the respiratory system?

• Provides a route for incoming and outgoing air

• Removes debris and pathogens from incoming air

• Warms and humidifies incoming air

What are the two major sections of the nose?

• External nose

• Nasal cavity (internal nose)

root

region located between the eyebrows

bridge

part that connects the root to the rest of the nose

dorsum nasi

is the length of the nose

apex

is the tip of the nose

ala

is a cartilaginous structure that forms the lateral side of each naris (plural = nares), or nostril opening

philtrum

concave surface that connects the apex of the nose to the upper lip

What divides the nasal cavity in the internal nose?

The nasal septum, which is:

• Formed anteriorly by septal cartilage

• Formed posteriorly by the perpendicular plate of the ethmoid bone

What are the three bony projections on the lateral wall of the nasal cavity?

The superior, middle, and inferior nasal conchae

What is the function of the nasal conchae?

• Increase the surface area of the nasal cavity

• Disrupt airflow, causing air to bounce along the epithelium

• Helps clean and warm the air

What structures in the internal nose help conserve water and prevent dehydration?

The conchae and meatuses

What are the four paranasal sinuses?

• Frontal sinus

• Maxillary sinus

• Sphenoidal sinus

• Ethmoidal sinus

What are the functions of the paranasal sinuses?

• Warm and humidify incoming air

• Produce mucus

• Lighten the weight of the skull

What type of epithelium lines the respiratory tract?

Pseudostratified ciliated columnar epithelium

What is the role of goblet cells in the respiratory epithelium?

They produce mucus to trap debris in the nasal cavity.

What is the function of cilia in the respiratory epithelium?

move mucus and trapped debris out of the nasal cavity.

What is the pharynx made of and what is it lined with?

• Formed by skeletal muscle

• Lined by a mucous membrane

How is the pharynx connected to the nasal cavities?

The pharynx is continuous with the nasal cavities.

What are the three major regions of the pharynx?

• Nasopharynx

• Oropharynx

• Laryngopharynx

What is the function of the nasopharynx?

serves only as an airway.

What is the pharyngeal tonsil (adenoid), and what is its function?

• Located in the nasopharynx

• Contains a rich supply of lymphocytes

• Covered with ciliated epithelium

• Traps and destroys pathogens that enter during inhalation

What tubes open into the nasopharynx, and what is their purpose?

The auditory (Eustachian) tubes connect to each middle ear cavity and help equalize pressure.

What is the function of the oropharynx?

a passageway for both air and food.

What are the fauces?

opening between the oral cavity and the oropharynx.

Where is the palatine tonsil located?

laterally in the oropharynx, near the fauces.

Where is the lingual tonsil located?

at the base of the tongue.

Where is the laryngopharynx located?

It is inferior to the oropharynx and posterior to the larynx.

What is the function of the laryngopharynx?

It serves as a route for both ingested material and air until its inferior end.

What does the laryngopharynx connect to?

Posteriorly: continues into the esophagus

What three large cartilage pieces form the larynx?

• Thyroid cartilage

• Epiglottis

• Cricoid cartilage

What is the thyroid cartilage and its key features?

• Largest cartilage of the larynx

• Forms the laryngeal prominence ("Adam’s apple")

• More prominent in males

• Located anteriorly

What is the function of the epiglottis?

• Located superiorly, attached to the thyroid cartilage

• Covers the opening of the trachea during swallowing to prevent aspiration

What is the cricoid cartilage?

• Located inferiorly in the larynx

• Forms a ring with a wide posterior and thinner anterior portion

What are the paired cartilages of the larynx?

• Arytenoid, corniculate, and cuneiform cartilages

• Attach to the epiglottis, vocal cords, and muscles involved in speech production

What structures make up the glottis?

• Vestibular folds (false vocal cords)

• True vocal cords

• The space between these folds

What is the vestibular fold?

• Also called the false vocal cord

• One of a pair of folded sections of mucous membrane

What are the true vocal cords?

• White, membranous folds

• Attached by muscle to thyroid and arytenoid cartilages

• Inner edges are free to oscillate and produce sound

What forms the structure of the trachea?

16 to 20 stacked, C-shaped pieces of hyaline cartilage

What is the fibroelastic membrane in the trachea?

• Formed by the trachealis muscle and elastic connective tissue

• Closes the posterior surface of the trachea

• Connects the C-shaped cartilages

• Allows the trachea to stretch and expand during inhalation and exhalation

Where does the trachea branch into the primary bronchi?

At the carina, where the trachea splits into the right and left primary bronchi.

What is the carina, and what is its function?

• A raised structure containing specialized nervous tissue

• Triggers violent coughing if a foreign body (like food) is present

Where do the primary bronchi enter the lungs?

At the hilum of each lung.

How does the bronchial tree branch beyond the primary bronchi?

• Primary bronchi branch into secondary (lobar) bronchi, then into tertiary (segmental) bronchi

• Tertiary bronchi branch into bronchioles

• Bronchioles become terminal bronchioles

• Terminal bronchioles lead to structures involved in gas exchange

Which structures are directly involved in gas exchange?

• Alveolar duct

• Clusters of alveoli

What is the respiratory bronchiole?

The smallest type of bronchiole, beginning the portion of the airway involved in gas exchange.

What does the alveolar duct open into?

A cluster of alveoli.

What is an alveolus?

One of the many small, grape-like sacs attached to alveolar ducts.

What is an alveolar sac?

One of the many small, grape-like sacs attached to alveolar ducts.

What is an alveolar sac?

A cluster of individual alveoli responsible for gas exchange.

What are alveolar pores, and what is their function?

• They connect alveoli to each other

• Help maintain equal air pressure throughout the alveoli and lungs

What are the three major cell types in the alveolar wall?

• Type I alveolar cells

• Type II alveolar cells

• Alveolar macrophages

What is the role of type I alveolar cells?

They are squamous epithelial cells that make up the alveoli walls.

What do type II alveolar cells do?

They secrete pulmonary surfactant, which reduces surface tension in the alveoli.

What is the function of alveolar macrophages?

Phagocytic immune cells that remove debris and pathogens from the alveoli.

What is the general shape and covering of the lungs?

• Pyramid-shaped

• Enclosed by the pleurae

How are the lungs connected to the trachea?

By the right and left bronchi.

What borders the lungs inferiorly?

The diaphragm.

How does the right lung differ from the left lung?

• The right lung is shorter and wider.

• The left lung is smaller in volume.

What is the cardiac notch?

An indentation on the left lung that provides space for the heart.

What is the function of fissures in the lungs?

separate the lobes of the lung.

How many lobes and fissures does the right lung have?

• Three lobes: superior, middle, and inferior

• Two fissures: horizontal and oblique

How many lobes and fissures does the left lung have?

• Two lobes: superior and inferior

• One fissure: oblique

What is a bronchopulmonary segment?

• A division of a lung lobe

• Each segment receives air from its own tertiary bronchus

• Supplied with blood by its own artery

What does the pulmonary artery do?

• Arises from the pulmonary trunk

• Carries deoxygenated blood to the alveoli

How is blood supplied and drained in the pulmonary lobule?

• One arteriole supplies it

• One venule drains it

• These become the pulmonary capillary network near the alveoli

What effect does the parasympathetic nervous system have on the bronchi?

It causes bronchoconstriction.

What effect does the sympathetic nervous system have on the bronchi?

It stimulates bronchodilation.

What is the pulmonary plexus?

• A region on the lung root formed by nerves entering at the hilum

• Nerves follow the bronchi and branch to innervate muscle fibers, glands, and blood vessels

What is the visceral pleura?

• The layer superficial to the lungs

• Extends into and lines the lung fissures

What is the parietal pleura?

• The outer layer

• Connects to the thoracic wall, mediastinum, and diaphragm

What is the pleural cavity?

The space between the visceral and parietal pleura layers.