Respiratory System Flashcards
How do you locate the 2nd rib?
Find the sternal angle between the manubrium and the sternum - 2nd rib attaches at this point
Why is the inferior aspect of each lung curved upwards?
This is because it lies on top of the domed diaphragm
On a chest X-ray of a healthy individual, why is the domed diaphragm shown to be higher on the right?
This is on account of the liver
In the respiratory system, what does the mucous membrane line?
The conducting portion of the respiratory tract, bearing mucus-secreting cells
In the respiratory system, what do the serous membranes line?
The pleural sacs which envelop each lung
In the balloon analogy, what does the outer balloon wall represent?
Parietal serosa
In the balloon analogy, what does the inner balloon wall represent?
Visceral serosa
What is in between the two pleural layers?
A thin layer of lubricating fluid
What is the pleural cavity?
The space between the two layers
What is it called when the pleural cavity fills with air?
Pneumothorax
What is a haemothorax?
When the pleural cavity fills with blood
What is it called when the pleural cavity fills with pus?
Empyema
What is pleural effusion?
When the pleural cavity fills with a watery transudate or exudate
In a PA view of a chest X-ray, which ribs are seen more clearly?
Posterior ribs
How can fluid be drained from the pleural cavity?
Insertion of a wide-bore needle through an intercostal space - usually the 7th
When fluid is drained from the pleural cavity, why is the needle inserted a fraction above the superior border of the lower rib?
To avoid the intercostal nerves and vessels which run along the inferior border of each rib
When draining fluid from the pleural cavity, why shouldn’t the needle be inserted below the 7th intercostal space?
There is danger of penetrating the diaphragm
When can lung cancer cause a paralysis of one side of the diaphragm?
If tumour impinges on the left or right phrenic nerve
When can lung cancer cause wasting of muscles in the lower arm?
If tumour impinges on brachial plexus
What is a Pancoast tumour?
Tumour of the pulmonary apex
How is Horner’s Syndrome characterised?
Constricted pupils, weak droopy eyelids and apparent anhidrosis
How is Horner’s Syndrome often caused?
Compression of nerves called the sympathetic trunk
When can lung cancer result in a hoarse voice?
Impingement on the left recurrent laryngeal nerve, which loops under the aorta
What is the conducting portion of the respiratory tract?
Nasal cavity to bronchioles
What is the respiratory portion of the respiratory tract?
Respiratory bronchioles to alveoli
What happens to the walls of the passageways as their lumens decrease in diameter?
Their walls become thinner
How does the epithelia change in the respiratory tract?
Psuedostratified epithelia with cilia and goblet cells lines the airways from the nasal cavity to largest bronchioles
Simple columnar epithelia with cilia and Clara cells but no goblet cells line smaller bronchioles and terminal bronicholes of conducting portion
Simple cuboidal epithelia with Clara cells line respiratory bronchioles and alveolar ducts
Simple squamous epithelia line alveoli
What allows for the detection of odours?
Olfactory mucosa
Why do venous plexuses swell every 20-30 minutes?
Alternates air flow from side to side to prevent overdrying and warm inspired air
How is patency maintained?
Surrounding cartilage or bone
Which type of epithelium lines the olfactory region?
Pseudostratified epithelium
What do Bowman’s glands in the olfactory region do?
Flush odorants from the epithelial surface
What are the ventricular folds of the larynx lined by and what do they contain?
Pseudostratified epithelium and they contain ucous glands and numerous lymph nodules
Which type of epithelium is each vocal chord of the larynx lined by and what do they contain?
Stratified squamous epithelium - contains a vocal ligament and a vocalis muscle
What happens to the vocal chords when coughing is required?
They close to build up pressure
How long and wide is the trachea?
10cm long, 2.5cm wide
In the wall of the trachea, which layer is thicker in patients with COPD?
Submucosa
In COPD, what happens to the proportion of mucus to cilia?
Hyperplasia of goblet cells means more mucous is produced but a smaller proportion of ciliated cells so there is more mucous and fewer cilia to move the mucous
In cystic fibrosis, what is the result of the lack of the CFTR ion channel?
Chloride ions cannot be transported across the membrane so water does not leave the epithelium in sufficient quantities to hydrate the secreted mucous. The mucous therefore becomes thick and viscous.
Do bronchioles have cartilage or glands?
No
What do pulmonary arteries carry?
Deoxygenated blood
What is the diameter of a bronchiole?
1mm or less
What keeps the lumen of bronchioles open?
Surrounding alveoli
Why can absence of cartilage in bronchiole walls be problematic?
They can easily constrict when smooth muscle contraction becomes excessive
What becomes excessive in asthma?
Bronchoconstriction
What are Clara cells now known as?
Club cells
What do Club cells (Clara cells) secrete?
Surfactant lipoprotein which prevents the walls sticking together during expiration as well as ‘Clara cell protein’
Why are goblet cells absent in terminal bronchioles?
To prevent individuals ‘drowning’ in their own muscous
Up to what age do new alveoli continue to develop?
8 years - when there are approximately 300 million
What do alveoli walls consist of?
Abundant capillaries, supported by basketwork of elastic and reticular fibres, covering of type I pneumocytes and a scattering of intervening type II pneumocytes
How close does air in alveoli lie from blood streaming through capillaries?
0.2 micrometres
What are type I cells in alveoli?
Squamous
What are type II cells in alveoli?
Cuboidal
What is emphysema caused by?
Destruction of alveolar walls and permanent enlargement of air spaces. It is difficult for the lungs to empty
What is a distinctive sign of emphysema?
Pursed-lip breathing
What is pneumonia caused by?
Inflammation of the lung caused by bacteria. The lung consolidates as the alveoli fill with inflammatory cells
What does the parietal pleura line?
Chest wall
What does the visceral pleura cover?
The lung
Why are the two membranes separated by lubricating pleural fluid?
Fluid reduces friction, allowing the pleura to slide easily during breathing and provides the surfact tension to prevent the lung recoiling and collapsing
What is the normal pleural fluid quantity?
Approximately 25ml per lung
During inspiration, what is the approximate intrapleural pressure?
-8cmH20 (below atmosphere)
During exhalation, what is the approximate intrapleural pressure?
-4cmH20 (below atmospheric)
What does Boyle’s law state?
When the volume of a container increases, the pressure decreases
What is intrapleural pressure?
Pressure within the pleural cavity
What is intrapulmonary pressure?
Pressure within the lung
What does the pressure difference of 4cmH20 across the alveolar wall do?
It is the force that keeps the stretched lungs adherent to the chest wall
What happens when air enters the pleural space?
The -4cmH20 pressure gradient that normally keeps the lungs against the chest wall disappears so the lung recoils and collapses
What does LaPlace’s law state?
The larger the vessel radius, the larger the wall tension required to withstand a given internal fluid pressure
What is the role of surfactant?
During inspiration, surfactant molecules move apart. During expiration, surfactant molecules move together so surface tension is reduced
What does surfactant deficiency lead to?
Stiff lungs that are very difficult to ventilate
