Thorax 2 - Tracheobronchial tree Flashcards
(trachea, bronchi, bronchioles)
what are the contents of the tracheobronchial tree in order (from the trachea to alveoli)?
trachea
primary/main bronchi
secondary bronchi
tertiary bronchi
terminal bronchioles
respiratory bronchioles
acinus - clusters of alveoli
alveoli sacs - lined with ducts
what does the branching of bronchi into bronchioles allow for?
allows for more precise control of airflow and distribution of air throughout the lungs
the respiratory system consists of a CONDUCTING part & RESPIRATORY part - what does each part do?
conducting part = conducts air from the outside into the lungs
respiratory part = where gas exchange occurs (in the alveoli with the bloodstream)
where does the trachea start and end - vertebral levels?
originates at the lower border of the cricoid cartilage - C6/7
ends at the carina - T4/5
what is the carina?
a cartilaginous ridge at the level of T4/5 - marks the end of the trachea & bifurcation into the right and left main bronchi
what happens at the carina?
trachea ends & bifurcates into the right and left main bronchi
what is the shape of the hyaline cartilage rings in the trachea?
hyaline cartilage rings are C-shaped with an open posterior portion (covered by trachealis smooth muscle)
why is the posterior portion of the tracheal cartilage rings open?
prevents pressure on the oesophagus which lies immediately posterior to the trachea
why is the C-shape of the tracheal hyaline cartilage rings important?
- prevents compressing oesophagus posteriorly
- maintains patency/ prevents tracheal collapse
- allows flexibility of trachea -sympathetic innervation to the trachealis muscle can control trachea’s diameter
what fills the open posterior portion of the tracheal cartilage rings?
smooth muscle called the trachealis muscle
what is the purpose of the trachealis muscle?
- allows flexibility
- prevents compression of the oesophagus
- adjusts the tracheal diameter during coughing/ forced expiration
how does the right main bronchus differ from the left main bronchus in terms of structure?
right main bronchus is wider, shorter & more vertical
left main bronchus is narrower, more horizontal & appears more as a branching structure
why are foreign objects more likely to enter the right main bronchus in adults?
right main bronchus is wider, shorter & more vertical - more of a direct continuation of the trachea
more prone to foreign objects entering
what are the characteristics of an abnormal carina during bronchoscopy? what can this indicate?
blunted/ widened with underlying bumps - can indicate metastatic cancer spread to the inferior tracheobronchial lymph nodes
a widened and distorted carina with underlying bumps indicates problems with WHAT lymph nodes
inferior tracheobronchial LNs
in children, how do foreign objects tend to distribute between the right and left bronchi compared to adults?
in children = tend to distribute equally between both bronchi
in adults = more likely to enter the right main bronchus
what are the secondary bronchi? how do they differ between the right & left lungs?
secondary bronchi - branches of the primary/main bronchi
right lung has 3 secondary bronchi (corresponding to its 3 lobes)
left lung has 2 secondary bronchi (corresponding to its 2 lobes)
how many tertiary bronchi are there per lung? what is their function?
right lung - approx. 10
left lung - approx. 8-10
ensure efficient airflow to all parts of the lungs
what structural change occurs in the walls of terminal bronchioles compared to earlier bronchi?
terminal bronchioles no longer have hyaline cartilage in their walls - makes them more susceptible to collapse
role of respiratory bronchioles in the bronchial tree?
lead to the respiratory portion of the lungs and terminate in clusters of alveoli (acinus) - facilitate gas exchange.
what is the primary function of alveoli in the respiratory system?
alveoli are the sites of gas exchange (O₂ and CO₂) during breathing - maximise surface area for efficient gas exchange between air & blood
what happens to the structure of the bronchial tree as it progresses from tertiary bronchi to terminal bronchioles?
airways become smaller & hyaline cartilage isn’t present in the walls - makes them more susceptible to collapse
what arteries supply the upper two-thirds of the trachea? where do they arise from?
inferior thyroid arteries - branch from the subclavian artery
what arteries supply the lower one-third of the trachea? where do they arise from?
bronchial arteries - branches of the thoracic aorta (sometimes arise from the internal thoracic artery instead)