The structure of the Lower Respiratory Tract Flashcards
What is the main function of the lungs?
Gas exchange
What is the gas exchange area per lung?
20m^2
What is the minute volume?
approx 5 litres (the volume of air inhaled/exhaled a min)
What is the cardiac output?
approx 5 litres per min (volume of blood pumped out by the heart a min)
Where does the trachea run from & to?
From larynx to carina (C6 - T5)
Describe the structure of the Trachea
Oval in cross section
Semicircular hyaline cartilages (C-Shaped cartilage increases flexibility of trachea)
Pseudo-stratified ciliated columnar epithelium
Has goblet cells
What is the difference between the upper and distal trachea?
upper is more mobile than distal
What does the main bronchi consist of & and where is the sharp division?
The left & right bronchus and sharp division at the carina (T5)
Which bronchus is more vertically disposed, by how much and what does this mean?
Right main bronchus is more vertically disposed (more risk of getting things trapped=choking)
1-2.5cm long, related to the right pulmonary artery
Describe the position of the left main bronchus
comes off at more an angle, 5cm long, related to the aortic arch
Where are things more likely to get stuck & why?
More likely to get stuck in the right main bronchus as it is more vertically disposed & the left main bronchus is longer & more angled than the right
What comes after the left & right main bronchus?
The lobar bronchi
How many divisions do the left & right lobar bronchi have & what are the different segment?
Right - 3 divisions, upper lobe, middle lobe, lower lobe
Left - 2 divisions, upper lobe, lower lobe
What comes after the lobar bronchi?
The segmental branches/bronchi
How many branches does the segmental bronchi have (left & right)?
Right - 10
Left - 8
What comes after the segmental bronchi?
Terminal bronchioles, respiratory bronchioles, alveolar ducts, alveoli
What is the acinus?
The tissue supplied with air by one terminal bronchiole
Describe the alveoli (cell types)?
Type l pneumocytes Type II pneumocytes - secrete surfactant Alveolar macrophages Membrane 1 micron thick Columnar ciliated epithelium Basement membrane
Where are the nerves of the lungs derived from?
The pulmonary plexus which lies behind each hilum
What does the pulmonary plexus/lung receive innervation from?
Left and right vagus nerve (CNX) and T2-T4 ganglia of the sympathetic trunk
Where specifically does innervation come from and what does it result in?
Sympathetic NS (sympathetic trunk) - results in bronchodilation (relaxation of bronchial smooth muscle)
Parasympathetic NS (vagus nerve) - bronchoconstriction
Visceral afferent - conduct pain impulses to sensory ganglion of vagus nerve
Which lung is larger and why?
Right due to silhouette of heart
Describe the structure of the lungs
Right lung has 3 lobes - superior, middle, inferior
Left has 2 lobes - superior, inferior
How many layers are there of the lung pleura, their names, where they’re applied to and nerves
2 layers of mesodermal origin
Visceral- applied to lung surface- only has autonomic innervation
Parietal- applied to internal chest- pain sensation via phrenic
Each is a single layer of cells
Alveoli, visceral, intra pleural space (pleural fluid), parietal
