Week 1 - the upper respiratory tract (URT) Flashcards
where is the URT?
the part of the respiratory tract which lies above the lower border of the cricoid cartilage (forms lower border of larynx)
what does the URT comprise of?
nose & paranasal sinuses
pharynx
larynx
what are the respiratory functions of the URT?
- conducting air from atmosphere to lower respiratory tract
- conditioning inspired air (warming, humidification and trapping of particles)
- protection of airway during swallowing (larynx)
what are other functions of the URT?
swallowing (oropharynx & larynopharynx)
smell (orfactory epithelium in nose)
speech (larynx)
what does the nose consist of?
external nose (bone & cartilage) nasal cavity (right & left)
what is the left & right nasal cavities divided by?
median nasal septum
where does each nasal cavity extend from?
nostril (anterior nares) to posterior nares
what is the function of the posterior nares?
nasal cavity communicates with nasopharynx (behind posterior nares)
what does the lateral wall of each nasal cavity contain?
3 bony projections (conchae / turbinates):
superior, middle, inferior
what is the space below each turbinate known as?
meatus:
superior, middle, inferior
what opens into the meatuses?
paranasal sinuses & naso lacrimal duct (drain tears from eyes)
what does the floor of the nasal cavity form?
roof of the mouth:
hard & soft palates
how many the paranasal sinuses are there and what are they?
4 paranasal sinuses:
frontal, ethmoidal, maxillary, spheroidal
(named from the skull bones within which they are situated)
what are paranasal sinuses?
they are air containing cavities in the skull which open into the nasal cavity
what are paranasal sinuses lined by?
respiratory epithelium (psuedostratified columnar)
what is the structure of the nose adapted to do?
filtering, warming & humidification of inspired air
how is filtering, warming & humidification of inspired air achieved by the nose>
the vascular mucosa (blood - warm air), and large surface area presented by conchae
what do the paranasal sinuses contribute to in terms of function of the nose?
the paranasal sinuses also contribute to warming and humidification of inhaled air
what is each nostril lined with?
coarse hairs trap large particles in inhaled air
what do the conchae do?
- they increase the SA for warming & humidification
2. cause turbulence (hence slow down airflow), increasing the time avaliable for warming & humidifying
what is air heated to in the nose?
approximately body temperature
how is the humidification achieved?
by transudation of fluid through the epithelium and to a lesser extent by mucus secretion
what is mucus secreted by? function?
mucus secreted by goblet cells - traps almost all particles >5 micrometers
what happens to the mucus containing trapped particles >5mm?
the cilia waft the mucus to oropharynx where it is swallowed
what happens when nose breathing becomes impossible?
the lower air passages will dry out & become more vulnerable to infection if nose breathing is impossible