Intro to Respiratory System 2: Structures of lungs, bronchi and pleura Flashcards
What is the conducting zone ?
Nose, nasal cavity, sinuses Nasopharynx and soft palate Larynx Trachea Bronchi and bronchial tree
What is the respiratory zone ?
Bronchi and bronchial tree
Alveoli
What is the anatomical dead space ?
How large is it ?
Volume of air located in segments of respiratory tract responsible for conducting air to alveoli and respiratory bronchioles but do not take part in gas exchange itself.
100-150 mL
Where does the trachea start and where does it end ?
Starts at C6 and ends at T4/5 at the carina
What muscle is present in the trachea? Where is it located ? What is its function ?
Trachealis muscle. Located posteriorly.
Function is to altern tracheal diameter.
Where does the incision take place in tracheotomy ? What is the function of tracheotomy ?
Between the 2nd and 3rd ring of cartilage.
Bypassing airway and taking over breathing.
Where is the trachea palpable ?
Anteriorly, above the suprasternal notch.
How many lobes does each lung have ? How many bronchi ?
R lung has 3 secondary lobar bronchi while L lung has 2 secondary lobar bronchi.
Only 1 bronchus
What is the main difference between the R and L bronchus ? Why ?
R bronchus slightly more vertical, wider and shorter so foreign bodies more likely to enter R bronchus.
Because L lung needs to make room for heart and pericardium (in the cardiac notch) so dome of the R lung slightly higher.
What are the different blood supplies of the lung ? What is their function ?
Pulmonary artery system,
Bronchial artery system, keeps lung tissue alive (including bronchi)
What is the next division following the secondary lobar bronchi ?
Segmental bronchi
What is the implication of the pulmonary and bronchial systems joining ?
Most oxygenated blood in the body (just left the lungs) mixes with deoxygenated blood so as leaves the lungs, not as oxygenated as when in the lungs.
What are the next divisions following segmental bronchi ?
Conducting bronchioles, then terminal bronchioles, then respiratory bronchioles. Keep decreasing in diameter until alveoli bud from respiratory bronchioles (made up of a duct and a sac)
What is the histology of the trachea ?
Pseudo-stratified ciliated columnar epithelium with globlet cells (mucus swept up by cilia so it can be swallowed in oesophagus)
What is the histology of the bronchi ?
Similar to trachea BUT height flattened AND cartilage rings replaced by cartilage plates.
What is the histology of bronchioles (excluding Term. and Resp. bronchioles) ?
- Epithelium CHANGES from “simple ciliated columnar epithelium to simple ciliated cuboidal epithelium as bronchioles decrease in size”
- Lumen < 1 mm
- Surrounding band of smooth muscle
- Cartilage and glands disappear (bronchioles held open by surrounding lung tissue).
What is the histology of Terminal and respiratory bronchioles ?
Epithelium becomes non-ciliated cuboidal and Globet cells disappear
What is the histology of alveoli ?
Made of a duct + sac
Separated from each other by SEPTAE (alveolar wall) which is a thin, vulnerable membrane containing capillaries (air/blood barrier for exchange)
How are alveoli vascularised ?
Supplied by RBCs in capillaries for gas exchange process
What factors contribute to keeping alveoli open ?
- Lung surfactant changes surface tension which enables them to stay open for exchange to happen
- Air P also keeps them open
What is the pleura ?
Membranes covering the organs within the cavity and the walls of the cavity
What is the pleural cavity ? Why is it important ?
The space between layers of pleura.
Important because contains fluid to lubricate pleural surfaces allowing for smooth gliding movement between parietal and visceral pleura (especially when lungs expand).
What is the name of the pleura covering the lungs ?
Visceral/pulmonary pleura
What is the name of the pleura covering the cavity walls ?
Parietal pleura (different names for different for specific locations)
What side is the trachea slightly deviated towards ? What might further deviation to one side or the other indicate ?
Right.
Problem with a lung or the other.
What is strange about visceral/pulmonary pleura and parietal pleura ?
They are actually part of continuous membrane.
How come the lungs are partially expanded even without breathing?
Due to the negative Pressure in the membrane.
What separates the two lungs ?
Mediastinum
How is lung lymph drained ?
Via subpleural plexus and a plexus alongside bronchi
TO HILAR LYMPH NODES (
What are the lobes of the L lung called ? What separates these two ?
Superior and Inferior lobes
Oblique fissure
What are the lobes of the R lung called ? What separates them ?
Super (horizontal fissure) middle (oblique fissure) inferior lobes
What is the surface anatomy of the lungs ?
Superiorly, apex of lungs just above clavicle
Inferiorly, pleura extent down to costal margin but lungs end 2 rib spaces higher (so lungs only 2/3 of lung space)
In breathing, lungs do NOT extent to lower parts of pleural cavity but this allows for deep breathing.
What is the hilum of the lungs ?
Root of lungs whereby structure (main bronchus, pulmonary artery and pulmonary veins) pass into and out of the lungs (visible in anterior view of the lungs)
How does inspiration occur ?
Negative Pressure created through:
-Diaphragmatic contraction and descent (increased vertical diameter)
-Rib elevation and sternum pushed up and forward thanks to external intercostal muscles (increases anteroposterior and lateral diameters)
Hence air sucked in
How does expiration occur ?
Passive process, by muscle relaxation and elastic recoil (aided by internal intercostal muscles)
Using the anatomy of the diaphragm, explain how it is contracts in inhalation.
Diaphragm is muscular at its periphery and tendinous centrally.
Diaphragm has R and L domes.
The phrenic nerve stimulates its contraction in which the domes descend, causing negative intra thoracic pressure but raising intra abdominal pressure.
What nerves contribute to the phrenic nerve ?
Cervical (C3, C4 and C5) nerves
What is a pneumothorax ? How is it fixed ?
When air enters the pleural cavity, resulting in a collapsed lung. Occurs through trauma and some conditions.
Needle inserted just above rib to remove the air to allow lung to expand again. (Must avoid damage to neurovascular bundle running inferior to each rib)
What is the appearance of a pneumothorax on a chest radiograph ? Why ?
Increased shadow. Lungs shrink so tissue, blood supply and bronchi give it much lighter shadow.
In terms of vascular markings of the lung, what is the difference between the radiograph of a normal lung and that of a pneumothorax.
In the normal lung, lung vascular markings fill the thoracic activity.
In the pneumothorax, lung vascular markings are at the border of the lung.
