Flashcards in The Respiratory System Deck (26):
How do you count the ribs?
1. Locate the 2nd rib by finding eternal angle (between manubrium and sternum)
2. Count ribs inferiorly
What is the function of the mucous membrane within the respiratory system?
Lines the conducting portion of the respiratory tract. It bears mucus-secreting cells to varying degrees.
What is the name of the serous membrane in the respiratory system?
Why is the lung 'shiny'?
- Covered in moist pleura
What can the pleural cavity fill with.
A watery transudate or exudate (pleural effusion)
How can fluid be drained from the pleural cavity?
- Inserting a wide-bore needle through an intercostal space (usually the 7th posteriorly).
- Nowadays done under ultrasound guidance.
- The needle is inserted a fraction above the superior border of the lower rib, thus avoiding the intercostal nerves and vessels, which run along the inferior border of each rib.
- Below the 7th intercostal space there is a danger of penetrating the diaphragm.
What is a pancoast tumour?
Tumor of the pulmonary apex
How can cancer cause a paralysis of the diaphragm?
- Paralysis of one side of diaphragm
- If tumour impinges on left or right phrenic nerve
- Can also lead to muscle wastage in palm (if infringes on nerve route of brachial plexus)
What is Horner's syndrome?
- Can be caused by cancer in apex of lung
- Infringes on nerves in the sympathetic trunk
- Constricted pupils, weak droopy upper eyelid and localised decreased sweating
How can cancer result in a horse voice?
- Cancer of the lung can result in a hoarse voice as a result of impingement on the left recurrent laryngeal nerve, which loops under the aorta.
- An aneurism of the aorta can also cause such hoarseness.
What makes up the conduction portion of the respiratory system?
What makes up the respiratory portion of the respiratory system?
At what point in the respiratory system does it become intrapulmonary?
Primary bronchi = extra-pulmonary
Secondary bronchi = Intrapulmonary
Which part of the respiratory system has pseudo-stratified epithelium?
Nasal cavity, pharynx, larynx, trachea and bronchi
- Lots of cilia and goblet cells
What sort of epithelium lines the bronchioles?
- Simple columnar with cilia
- no goblet cells
- Contain club/clara cells (secrete gylcosaminoglycans to protect the bronchiole lining)
Excluding the alveoli, what type of epithelium lines the respiratory portion of the respiratory tract?
- Simple cuboidal
- Some cilia
- Clara cells
How does the epithelium of the olfactory region differ to that of the non-olfactory regions?
- Much thicker epithelium
- No goblet cells
- Non-motile cilia
- Olfactory cells (bipolar neurones, causes swelling, increase surface area in response to odour)
- Located in posterior, superior region of each nasal cavity
- Serous glands (Bowman's) flush odourants from epithelial surface
In non-olfactory regions: Venous plexuses (blood vessels) swell every 20-30 minutes, alternating air flow from side to side by warming the air and preventing over drying
Describe the structure of the larynx
- False vocal cord and true vocal cord (vocalis muscle) separated by ventricles
- The ventricular folds of the larynx are lined by pseudostratified epithelium and contain mucous glands and numerous lymph nodules.
- The ventricles, together with the ventricular folds, contribute to the resonance of the voice.
- Each vocal cord, of the larynx, is lined by stratified squamous epithelium and contains:
(1) A vocal ligament (large bundle of elastic fibres, running front to back).
(2) A vocalis muscle (bundle of skeletal muscle).
- The vocal cords help stop foreign objects from reaching the lungs; they close to build up pressure when coughing is required.
Why does the mucus of sufferers of cystic fibrosis become particularly viscous?
- An ion channel molecule named cystic fibrosis transmembrane regulator (CFTR) is not present in the apical membranes of the epithelial cells of cystic fibrosis sufferers.
- As a result chloride ion transport across the membrane is substantially compromised.
- Consequently, in the respiratory tract, water does not leave the epithelium in sufficient quantities to adequately hydrate the secreted mucus. The mucus becomes viscous and can less readily be moved to the oropharynx for swallowing. Serious pulmonary infection often results.
Why is an absence of cartilage in the walls of bronchioles potentially problematic?
Absence of cartilage in walls of bronchioles can be problematic because it allows these air passages to constrict and almost close down when smooth muscle contraction becomes excessive.
Such bronchoconstriction can become excessive in asthma and cause more difficulty with expiration than inspiration (during expiration the bronchial walls are no longer held open by the surrounding alveoli).
What are clara cells?
- More abundant where there are less goblet cells
- interspersed between ciliated cuboidal cells.
- Clara cells secrete a surfactant lipoprotein, which prevents the walls sticking together during expiration.
What do Clara cells secrete and when can this be used as a measurable marker?
Clara cell protein (CC16):
- a measurable marker in bronchoalveolar lavage fluid (if lowered then lung damage).
- a measurable marker in serum (if raised then leakage across air-blood barrier).
Where can alveoli open into?
- a respiratory bronchiole
- an alveolar duct
- an alveolar sac
- another alveolus (via an alveolar pore)
Describe the key properties of alveolar wall
- have abundant capillaries
- are supported by a basketwork of elastic and reticular fibres.
- have a covering composed chiefly of type I pneumocytes (responsible for gas exchange).
- have a scattering of intervening type II pneumocytes (secrete surfactant).
What is emphysema?
- Destruction of alveolar walls and permanent enlargement of air spaces
- Can result from smoking or alpha 1-antitrypsin deficiency.
- Alveolar walls normally hold bronchioles open, allowing air to leave the lungs on exhalation.
- When these walls are damaged, bronchioles collapse, making it difficult for the lungs to empty.
- Air becomes trapped in the alveoli.
- Hallmark sign: pursed-lip breathing.