Functional Anatomy of the Respiratory System

What are the different sections of the respiratory system?

The upper respiratory tract, the lower respiratory tract

What does the upper respiratory tract consist of?

Passageways from the nose to the larynx

What does the lower respiratory tract consist of?

From the trachea to the alveoli

What is the structure of the nose?

Nasal cavity is divided by the midline nasal septum.

Olfactory receptors are located in the mucosa just beneath the ethmoid bone.

The respiratory mucosa lines the nasal cavity.

The lateral walls of the nasal cavity are uneven.

The nasal cavity is separated from the oral cavity by the palate.

The nasal cavity is surrounded by a ring of paranasal sinuses

What does the respiratory mucosa do?

Moistens the air and traps incoming bacteria and foreign debris and contains lysozyme that destroy bacteria.

Ciliated cells move the contaminated mucus towards the throat to be swallowed and digested by the stomach.

Why are the lateral walls of the nasal cavity uneven?

The mucosa covered projections called concha that increase the surface area of mucosa exposed to the air

What are the different sections of the palate that separates the oral and nasal cavity?

The anterior hard palate and the posterior soft palate

Where are the paranasal sinuses?

Frontal, splendid, ethmoid, and maxillary bones

Why are the paranasal sinuses important?

They produce mucus that drains into the nasal cavities

They lighten the skull

What is the structure of the pharynx?

Continuous with the nasal cavity via the posterior nasal aperture

Three regions: nasopharynx, oropharynx, laryngopharynx

What is the importance of the pharyngotympanic tubes?

They drain into the middle ear

The mucosae are connected so ear infections may follow a sore throat

What are tonsils?

Clusters of lymphatic tissue found in the pharynx that protect the body from infection

What are the different tonsils and where are they found?

The single pharyngeal tonsil is located high in the nasopharynx

Two palatine tonsils are in the oropharynx at the end of the soft palate

Lingual tonsilsare at the base of the tongue in the oropharynx

The tubal tonsils protect the openings of the pharyngotympanic tubes in the nasopharynx

What is the larynx?

Located anterior to the pharynx it routes air and food into the proper channels and plays a role in speech

What is the structure of the larynx?

Formed of eight hyaline cartilages and the epiglottis

The largest hyaline cartilage is commonly known as the Adams apple

What is the epiglottis?

It protects the superior opening of the larynx

When swallowing, the larynx is pulled upwards and the epiglottis forms a lid over the larynx's opening, leading the food into the oesophagus

What happens when food enters the larynx?

The cough reflex is triggered to prevent the substance continuing to the lungs.

This does not happen when unconscious

What are the vocal folds?

Part of the mucus membrane of the larynx forms a pair of folds that vibrate with expelled air and allow us to speak

What is the glottis?

The slit like passageway between the vocal folds

What is the structure of the trachea?

It’s walls are reinforced with c-shaped rings of hyaline cartilage

Trachea muscle completes the wall of the trachea posteriorly

Trachea is lined with a ciliated mucosa

What is the importance of the reinforced trachea walls?

Support the trachea walls and keep it patent despite pressure changes that occur during breathing.

Open parts of the rings abut the oesophagus and allow it to expand anteriorly when we swallow large pieces of food

What is the importance of the ciliated mucus that lines the trachea?

Cilia propel the mucus that is loaded with dust particles and other debris away from the lungs and to the throat for it to be swallowed or spat out

What are the bronchi?

The right and left bronchi are formed by the division of the trachea and enter the lungs.

The right main branch is wider, shorter, and straighter than the left so it is more common for inhaled objects to become lodged here

What is the structure of the lungs?

The apex, the base, the pleura

What is the apex of the lungs?

The narrow, superior portion of each lung just deep to the clavicle

What is the base of the lungs?

The broad lung area resting on the diaphragm

What are the pleura of the lungs?

The pulmonary pleura/visceral pleura covers the surface of each lung

The parietal pleura lines the thoracic cavity

The pleural membranes produce pleural fluid

What is the importance of pleural fluid?

Allows the lungs to easily glide over the thorax wall during breathing and causes the pleural layers to cling together to anchor the lungs to the thorax wall

What is the bronchi tree?

Once in the lungs the main bronchi subdivide into smaller branches called bronchioles

What is the respiratory zone?

Includes respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

The only site of gad exchange

What is the lungs stroma?

Tissue that is mainly elastic connective tissue that allows the lungs to stretch and recoil during breathing

What is the respiratory membrane?

Gas exchange occurs by simple diffusion through the respiratory membrane

What are alveolar macrophages?

Wander in and out of alveoli collecting bacteria, carbon particles, and other debris

What are surfactant secreting cells?

Produce a lipid molecule called surfactant that coats the gas exposed alveolar surfaces