Respiratory tract Flashcards
Function of respiratory tract
respiration (gas exchange). Conducts, warms and humidifies air and protects against pathogens
What 2 components make up the respiratory tract?
Upper and lower respiratory tract
Which components make up the upper respiratory tract?
nose, paranasal sinuses, mouth (inc tonsils), pharynx, larynx
What forms the protuberance of the nose?
nares (nostrils)
What forms the nasal septum?
Vomer bone (and bit of ethmoid) and hyaline cartilage
What tissues make up the nose?
skin, muscle, bone, hyaline cartilage (where nasal septum is found)
Where is muscle found in the nose?
in the corner of the nose (for flaring)
What is the internal portion of the nose referred to?
nasal cavity
Where is the nasal cavity located?
superior and posterior to the nose, inferior to the anterior cranial fossa, superior to the mouth
Which other aspects of the respiratory tract is the nasal cavity continuous with?
nares (external nose) and pharynx
Which ducts open up in the nasal cavity?
ducts from the paranasal sinuses and the nasolacrimal duct
Where does the nasolacrimal duct run from and to?
from the medial canthus of the eye (corner) to the inferior nasal meatus
What is the inferior nasal meatus?
A small space beneath the inferior nasal concha where the nasolacrimal duct opens up
Which gland produces tears?
Lacrimal gland
How do tears pass from the eye to the nose?
Via the nasolacrimal gland which connects the medial canthus of the eye to the inferior nasal meatus
What epithelium makes up the external portion of the nose?
Stratified squamous keratinised epithelium (with hairs)
What are the two segments of epithelium within the nose?
Respiratory and olfactory segments/epithelium
What epithelium is found in the nose (making up the respiratory and olfactory segments)?
ciliated pseudostratified columnar epithelium
What is the difference between the olfactory and respiratory segments in the nose?
The olfactory segment has olfactory receptors
Where is the olfactory epithelium/segment located?
At the roof of the nasal cavity, superior and posterior to the nose
Function of the olfactory segment/epithelium
detect airborne odour molecules (smell)
How do we detect smell?
Airborne odour molecules enter the nasal cavity and bind to olfactory receptors. The receptors are activated and send an impulse via the olfactory nerve (CNI) to the olfactory system.
What forms the first line of defence to prevent particles entering further into the nose?
nasal hairs found near nares
What are the functions of the nose?
Warms and filters the air (via conchae/turbinates) and sense of smell
What are the conchae?
Folds of cartilage in the nasal cavity that warm and filter the air
What are the names of the conchae?
Superior, middle and inferior concha
Function of the paranasal sinuses
vocal resonance and speech modification, lighten weight of head, support immune defence of nasal cavity, humidify air.
What are paranasal sinuses?
Air filled spaces within the bones of the skull and face
What are the 4 paired paranasal sinuses?
Frontal, ethmoid, sphenoid and maxillary sinuses
Which are the most superior paranasal sinuses?
frontal sinuses
Where are the frontal sinuses located?
in frontal bone (triangular roughly in shape), superior and slightly medial to eye sockets
Where are the sphenoid sinuses located?
Sphenoid bone (most posterior of the paranasal sinuses), posterior to ethmoid sinuses
Where are the ethmoid sinuses located?
Ethmoid bone (posterior and medial to eye sockets)
Which are the largest of the paranasal sinuses?
Maxillary sinuses
Where are the maxillary sinuses located?
In the maxilla, inferior to eye socket, slightly inferior and lateral to nasal cavity
Where do the maxillary sinuses drain into?
Nasal cavity just inferior to frontal sinus opening
What is a potential pathway for the spread of infection between the paranasal sinuses?
Fluid draining from the frontal sinuses into the maxillary sinuses
Fistula definition
an abnormal communication between 2 epithelium lined orans that do not normally connect
Name given for an opening created between a paranasal sinus and the mouth
oro-antral fistula
Which paranasal sinus is typically involved in an oro-antral fistula?
Maxillary sinus
Potential causes of an oro-antral fistula
molar tooth extraction (accidentally removing floor of maxillary sinus), trauma, bone disease (e.g. osteomyelitis), radiotherapy
What is the pharynx?
A 12-15cm muscular tube that extends from the skull base to oesophagus (~C6)
Function of the pharynx
conducts air, muscles contract to direct food to oesophagus
What are the 3 parts of the pharynx?
Nasopharynx, oropharynx, laryngopharynx
Where does the nasopharynx extend from and to?
From the base of the skull (sphenoid sinus) to soft palate (uvula)
Where does the oropharynx extend from and to?
From the soft palate (uvula) to epiglottis (elastic cartilage)
Where does the laryngopharynx extend from and to?
Epiglottis to the bifurcation into the trachea and oesophagus
What components make up the lower respiratory tract?
(continuation of larynx), trachea, R and L bronchi, lungs, blood-air barrier
What is the larynx commonly known as?
Voicebox
Which vertebrae does the larynx extend along?
C3-6
Function of larynx
generates sound, acts as a sphincter, air conduction, airway protection (closes off trachea during swallowing)
What is the superior-most region of the larynx?
epiglottis
Which bone is the epiglottis attached to?
hyoid bone
What is unique about the hyoid bone?
It is the only bone in the body to not be connected to another bone
Where is the larynx located?
Anterior aspect of the neck, superior to the trachea and inferior to the pharynx
How long is the larynx?
4-5 cm
Which aspect of the respiratory tract grows in puberty?
larynx
What connects the hyoid bone to the thyroid cartilage?
thyrohyoid membrane
How are the thyroid and cricoid cartilages held in place?
By muscles (cricothyroid muscles) and ligaments (cricothyroid ligament)
What is the larynx composed of?
9 cartilages, ligaments, muscle and mucous membranes
What are the 9 cartilages of the larynx?
3 paired cartilages: arytenoid, corniculate and cuneiform cartilages. 3 unpaired cartilages: thyroid, cricoid and epiglottis cartilages.
How is the larynx able to move?
There are joints between the cartilages e.g. arycorniculate joint connects arytenoid and corniculate cartilages, cricoarytenoid joint, cricothyroid joint.
Which is the largest cartilage of the laryngeal skeleton?
thyroid cartilage
Function of the thyroid cartilage
forms a protective shield for the anterior larynx
Where do the 2 halves of the thyroid cartilage meet?
At the midline to form the laryngeal prominence (Adam’s apple)
Which is the only laryngeal cartilage that forms a full circle?
cricoid cartilage
What is the anterior part of the cricoid cartilage known as?
the arch
What is the posterior aspect of the cricoid cartilage known as?
the lamina
Which is the most inferior cartilage of the laryngeal skeleton?
Cricoid cartilage
What is the name of the elastic leaf-shaped laryngeal cartilage?
Epiglottis
Function of the epiglottis
allows the passage of air through the larynx into the trachea, closes over the laryngeal inlet during swallowing.
Where is the epiglottis attached?
To the internal surface of the thyroid cartilage
What is the name of the cartilages that sit over the posterior portion of the cricoid cartilage?
Arytenoid cartilages
What is the structure of the arytenoid cartilages?
pyramid-shaped, small, hard, flexible cartilages
What are the 2 processes in the base of the arytenoid cartilages?
vocal process (anterior angle), muscular process (lateral angle)
What are corniculate cartilages also known as?
cartilages of Santorini
Structure of the corniculate cartilages
small, elastic, cone-shaped cartilages
What are cuneiform cartilages also known as?
Wrisberg cartilages
Where are the corniculate and cuneiform cartilages located?
within the aryepiglottic fold
Function of the cuneiform cartilages
support vocal folds and the lateral aspects of the epiglottis
Location of the aryepiglottic fold
extends from the epiglottis to the arytenoid cartilages
Function of the arytenoid cartilages
attach vocal cords
What is the name of the ‘false vocal cord’?
Vestibular fold (comprised of vestibular ligament and mucous membrane)
What is the name of the emergency procedure which establishes an airway?
Cricothyroidotomy
Why may a cricothyroidotomy be necessary?
if the patient cannot breath due to a foreign object in upper airway, facial trauma, oedema of glottis (throat swelling)
What does a cricothyroidotomy involve penetrating?
Skin and cricothyroid membrane (but avoids vocal cords)
How long is the trachea?
10-12 cm
At which vertebrae level does the trachea start?
C6
How many incomplete (C-shapes) cartilaginous rings make up the trachea?
15-20
What is the function of the cartilage in the trachea?
to maintain a patent airway
Why is there no cartilage in the posterior trachea?
To allow food to pass smoothly down the oesophagus
What is present in place of cartilage at the posterior trachea?
Smooth muscle (trachealis)
What is the name of the smooth muscle in the posterior trachea?
trachealis
What is a tracheostomy?
a form of long term mechanical ventilation which involves creating an opening below the 1st tracheal ring and inserting a tube into the trachea (balloon used to maintain position)
When would a tracheostomy be required?
When endotracheal incubation has failed
If a foreign object is inhaled, which bronchus is it more likely to enter?
Right bronchus
What is the difference between the left and right bronchus?
the right bronchus is more vertical, has a greater diameter and is shorter than the left bronchus.
What type of epithelium lines the bronchi?
Respiratory epithelium (continues)
What lobes does the left bronchus divide into?
Superior and inferior lobe bronchus
What lobes does the right bronchus divide into?
superior, middle and inferior lobe bronchi
How does the epithelium change from the lobular bronchiole to the terminal bronchiole?
Transition from ciliated columnar to more non-ciliated cuboidal epithelial cells
What are the divisions of each bronchus (L+R)?
L/R (primary) bronchus -> lobular (secondary) bronchus -> segmental (tertiary) bronchus -> terminal bronchus -> lobular bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar duct -> alveolar sac
What percentage of cells in the alveolar sac are type 1 pneumocytes?
95%
What are type I pneumocytes also known as?
Alveolar air cells
What makes up 5% of the cells in the alveolar sacs?
Type II pneumocytes (surfactant cells)
Function of type II pneumocytes
produce surfactant
Function of surfactant
acts as a detergent to minimise friction and ensure lubrication
Which cells have a shared basement membrane?
Alveolar and endothelial cells
What is the advantage of having a shared basement membrane?
minimises diffusion distance for gas exchange
