Respiratory System Flashcards
What are the two membrane types present in the respiratory system?
Mucous membranes - line the conducting portion of the respiratory tract (contain goblet cells)
Serous membranes - line the pleural sacs which envelope the lungs - 2 layers with lubricating fluid fluid between them
What is caused by the pleural cavity filling with air?
Pneumothorax
What is caused by the pleural cavity filling with blood?
Haemothorax
What is caused by the pleural cavity filling with pus?
Empyema
What is caused by the pleural cavity filling with watery transudate?
Pleural effusion
How can fluid be drained from the pleural cavity?
Inserting a wide- bone needle through the 7th intercostal space posteriorly under ultrasound guidance
What is the order of the respiratory tract?
Nasal cavity Nasopharynx Oropharynx Larynx Trachea Bronchi (primary and secondary) Bronchioles Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveoli
What is the conducting portion of the respiratory tract?
Nasal cavity to terminal bronchioles
What is the respiratory portion of the respiratory tract?
Respiratory bronchioles to alveoli
What portion of the respiratory tract is extra pulmonary?
Nasal cavity to primary bronchioles
What part of the respiratory tract is intrapulmonary?
Secondary bronchi to alveoli
What epithelium is the respiratory tract lined with?
Nasal cavity to secondary bronchi = pseudostratisfied epithelium (cilia and goblet cells)
Bronchioles to terminal bronchioles = simple columnar epithelium (cilia and Clara cells, no goblet cells)
Respiratory bronchioles to alveolar ducts = simple cuboidal epithelium (Clara cells and scattered cilia)
Alveoli - simple squamous epithelium
What are the olfactory regions of the nasal cavity?
Particularly thick pseudostratisfied epithelium without goblet cells. Cilia are non motile (increaseue surface area). Contains olfactory cells (containing bipolar neutrons) in which cilia respond to odours. Lamina propria and submucosa blend - contain serous glands to flush odourants from epithelial surface and olfactory nerves.
What are the non-olfactory regions of the nasal cavity?
Pseudostratisfied ciliates epithelium containing mucus glands and venous sinuses in the lamina propria. Venous plexusesswell every 20-30 mins alternating airflow from side to side to prevent over drying. Arterial blood flow warms inspired air
How many vocal cords make up the larynx?
2 “fake” vocal cords and 2 true vocal cords split by a ventricle.
What is each vocal cord lined with?
Stratified squamous epithelium and contain a vocal ligament (large bundle of elastic fibres) and a vocalis muscle (bundle of skeletal muscle)
What are the function(s) of the vocal chords?
Resonances of voice
Stop foreign objects reaching the lungs - close to build up pressure when coughing is required
What is the structure of the trachea?
Lined by pseudostratisfied ciliates epithelium and thick basement membrane
Submucosa - contains seromucous glands
C shaped hyaline cartilage ring (partly ossified to bone during aging)
What are contained in the secretions from the epithelium and submucosal glands of the trachea/bronchi?
Mucins, water, serum proteins, lysozyme, antiproteases, lymphocytes, immunoglobulins (especially IgA)
What happens to goblet cells in COPD?
Goblet cell hyperplasia - smaller proportion of ciliates cells and hypertrophy of submucous glands. So fewer cilia and less nucleus.
What’s the difference is histology between primary and secondary/tertiary bronchi?
Similar histology
Except secondary and tertiary bronchi have cartilage arranged as irregular crescent shaped islands instead of rings.
Smaller diameter
What artery carries blood to alveoli and which vein back?
Pulmonary artery carried deoxygenated blood down bronchioles (alongside bronchial artery) to alveoli.
The blood carried through capillary plexus.
Then oxygenated blood carried back to the heart via pulmonary vein
What are the features of bronchioles?
No cartilage or glands
1mm or less in diameter
Surrounded by alveoli (keep lumen open)
Surrounded by smooth muscle
What is the significance of no cartilage in bronchioles?
It allows the air passages to construct and almost close sigh smooth muscle contraction.
(This bronchoconstriction becomes excessive in asthma - cause difficultly expiring (as the bronchial walls no longer held open by surrounding alveoli)
What are Clara cells?
Interspersed between cuboidal cells in small bronchioles. They secret a surfactant lipoprotein that prevents the walls sticking together during expiration. Also secrete abundant Clara cell protein (CC16)
Low CC16 in bronchoalveolar lovage fluid means what?
Lung damages - CC16 is a measurable marker
A high CC16 in serum means what?
Leakage a cross the air - blood barrier a measurable marker in serum
What are the features of alveoli?
Alveolar walls have abundant capillaries
Supported by a basket work of elastic and reticular fibres
Have a covering composed of type 1 pneumocytes and a scattering of type 2 pneumocytes
What are type 1 pneumocytes?
Squamous cells. Cover ~90% of surface area and permit gases exchange with capillaries (across blood-air barrier)
What are type 2 pneumocytes?
Cuboidal cells. Cover ~10% of surface area and contain lamellar bodies (secretory organelles) secrete surfactant (similar to Clara cells)
What are the two main causes of emphysema?
Cigarette smoking
Alpha-1-antitrypsin deficiency
What is emphysema?
Destruction of alveolar walls and permanent enlargement of air spaces (as alveoli normally hold bronchioles open during expiration, when damaged bronchioles collapse - difficult for lung to empty, air trapped in alveoli)
What is a hallmark sign of emphysema?
Pursed lip breathing
What is pneumonia?
Inflammation of the lung caused by bacteria - lung consolidates as alveoli fill with inflammatory cells
What bacteria commonly cause pneumonia?
Streptococcus pneumoniae
H. Influenzae
S. Aureus m
What is surface tension?
Liquid has a tendency to resist rupture when placed under stress due to water molecules at surface forming strong hydrogen bonds with their neighbours
What is the function of the lubricating fluid between the pleural membranes?
Reduces friction, allowing pleura to slide easily during breathing . Fluid provides surface tension to prevent the lung recoiling and collapsing.
What is Boyles law?
When the volume of a container increases, pressure decreases.
I.e. Diaphragm down (contracted), increased thoracic cavity volume, decreased pressure - so air moves from an area of high pressure (from atmosphere into lungs)
What is an open pneumothorax?
Opening in the chest wall (with/without lung puncture), allows atmospheric air to enter pleural space
What are the potential causes of an open pneumothorax?
Penetrating trauma (stab wound, gunshot) Surgery
What is a closed pneumothorax?
Chest wall in tact, rupture of lung and visceral pleura (or airway) allows air into pleural space
what is the role of surfactant in inspiration?
When alveoli expand, surfactant molecules move apart, increased surface tension.
What is the role of surfactant in expiration?
Ehh lungs shorten, surfactant molecules move together and become more concentrated, reduced surface tension
(without surfactant alveoli can’t inflate)
