Outline the key functions of the respiratory system
Define the term upper respiratory tract
• The part of the respiratory tract above the lower border of the cricoid cartilage (which forms the lower border of the larynx) is termed upper respiratory tract.
Define the term lower respiratory tract
• The parts of the respiratory tract below the lower border of the cricoid cartilage, including the lungs and associated structures.
What are the four main structures found in the URT?
Describe the pulmonary circulatory system of the lungs
Low resistance system which is ‘supply driven’ rather than demand led
Low pressure
eceives entire cardiac output
What is the purpose of resistance vessels in the pulmonary circulation?
• Do not influence total flow through pulmonary circulation, only distribution of blood within it
Why is tissue fluid not normally formed in the lungs?
Capillary pressure in the normal pulmonary circulation is always less than the colloid osmotic pressure
Give three main functions of the URT
Give three minor functions of the URT
• Swallowing (oropharynx and laryngopharynx)
• Smell (olfactory epithelium in nose)
Speech (larynx)
What two main parts make up the nose?
* the nasal cavity
Describe the structure of the nasal cavity
Outline the structure of the lateral wall of each nasal cavity
Contains three bony projections known as the choncae (superior, middle and inferior)
• The space below each conchae is known as the meatus (superior, middle and inferior)
What structures drain into the meatus of the nasal cavity?
The paranasal sinus
The nasolacrimal duct
What does the floor of the nasal cavity form?
• The roof of the mouth
What are the three main functions of the nose?
• Respiration ○ Filters air ○ Humidifies and warms air • Organ of smell • Receives local secretion ○ Sinuses ○ Nasolacrimal duct
How does the structure of the nose relate to its function?
Aside from humidification of air, what is the function of secreted nasal mucus and associated cilia?
Mucus secreted by goblet cells traps almost all particles. Cilia waft mucus to oropharynx where it is swallowed
Name the four paranasal sinuses
The frontal, ethmoidal, maxillary and sphenoidal sinuses
Give five possible functions of paranasal sinuses
What are the three parts of pharynx?
What is the key function of the pharynx?
• Prevent aspiration of food during swallowing, which can lead to life threatening airway obstruction or infection
How is the nasopharynx connected to the middle ear cavity?
• By the auditory tube (eustachian tube)
What does the connection of the nasopharynx to the middle ear cavity allow?
• Air pressure in middle ear cavity to be equalized to atmospheric pressure
What issue can the connection of the nasopharynx to the middle ear cavity cause?
• URTI can be spread to the middle ear cavity via the auditory tube, resulting in middle ear infection. More likely in children than adults.