Flashcards in Resp Deck (127)
What is partial pressure and how is it calculated?
-The pressure which a gas exerts within a mixture
-Proportional the the volume of gas in the mixture ie air is 21% oxygen so will generate a partial pressure of 21kPa
Describe the intrathorasic pressure changes during inspiration and expiration
-Inspiration = lungs expand and volume increases whilst pressure falls below atmomspheric pressure allowing air to flow into lungs
-Expiration = lungs deflate and volume decreases whilst pressure rises forcing air out
What is saturated vapour pressure?
-The amount of pressure exerted by liquid molecules as they evaporate at a liquid-gas interface after equilibrium is reached
What is the effect of saturated water vapour on nitrogen and oxygen as it is breathed in?
-Lowers the partial pressure as it contributes to the total pressure in the airways
What is gas tension? What dertermines gas tension
-The amount of pressure exerted in a liquid by gas condensing into it
-Same as partial pressure in the air as it will reach equilibrium
What epithelium lines the upper respiratory tract?
-Pseudostratified columnar ciliated epithelium with goblet cells
What are the function of the conchae/turbinates?
-To increase the surface area in order to warm and humidify air, to mix air
What are the functions of the nose?
-Organ of smell
-Filter (hairs and mucus) and humidify air
-Receive local secretions form sinuses and nasolacrimal duct
Which sinuses correspond to which meatus in the nose?
-Frontal, anterior ethmoid and maxillary into middle
-Sphenoid and posterior ethmoid into superior
-Nasolacrimal to inferior
Why can upper resp tract infections cause middle ear infections?
-Track up eustachian tube
Describe the positioning of the vocal cords during respiration, swallowing, speech and coughing
-Respiration -> open
-Swallowing -> closed
-Speech -> partially closed
-Coughing -> initially closed then open
What is the glottis?
-Two vocal cords and opening between them
What moves the vocal cords and what nerve supplies these muscles? How can this relate to a horse voice?
-Intrinsic muscles of larynx
-Recurrent laryngeal nerve (branch of vagus)
-Any damage to the RLN eg thyroid goitre, apical lung tumour, stroke, can lead to hoarse voice
Which bronchi is most likely to aspirate a foreign body and why?
-Right as the path is more vertical
Describe the defect in CF and how this causes symptoms
-Defective ion channel named cystic fibrosis transmembrane regulator causing comprimised cl transport across the membrane
-Water does not leave epithelium producing thick, viscous and sticky mucus which is hard to clear. this produces severe pulmonary infections, pancreatitis and gi disturbances
How do the bronchioles remain open during inspiration if they have no supporting cartilage? What happens during expiration? In which pathology can this be problematic and why?
-The tension from the surrounding alveoli keep them open. during expiration they willl collapse as the alveoli are not filled with air
-COPD/emphysema- Increased airway resistance due to destruction of supporting alveolus tissue causing early closure of the bronchioles during expiration
What cells secrete surfactant and why is it so crucial to lung function?
-Clara cells/type II pneumocytes
-Surfactant decreases the surface tension in alveoli in order to keep the pressures in each alveolus similar and prevent bullae formation. This is because smaller alveolus will have a larger surface tensio.Surfactant has a greater effect in smaller alveoli as there is less surface area for it to cover therefore the pressure in each alveolus becomes equal
What is emphysema?
-Desctruction of the alveolar walls as a result of a1-antitrypsin deficiency or smoking
-results in difficulty breathing due to early closure of bronchioles
-Air become trapped within the alveoli
In which direction do the upper and lower ribs move?
-Upper increase AP diameter
-Lower increase transverse diameter
Describe the intercostal muscles and their function
-External -> end close to costal cartilage and elevate the ribs during quiet inspiration
-Internal -> end close to vertebral column and depress the ribs during forced expiration
-Innermost -> only lie laterally and depres the ribs in forced expiration
Where would you place a chest drain and why?
-5th intercostal space mid axillary line at the superior border of 6th rib
-Avoid any thick musculature and avoid neurovascular bundle which runs along each inferior rib
From where do the intercostal arteries arise?
-Posterior from thoracic aorta
-Anterior from internal thoracic (from subclavian)
What is the main source of venous drainage of the thoracic wall?
What is the function of the diaphragm? Where/why are the openings in the diaphragm
-Main muscle of inspiration
-T8 -> IVC aperture
-T10 -> oesophageal aperture
-T12-> Aortic aperture
Where is the upper border of the liver during expiration?
Describe the nerve supply of the diaphragm and why this can cause shoulder tip pain?
-Referred pain upon diaphragmatic irritation to dermatomes C3,4,5
State the muscles used in normal inspiration. What are the accessory muscles of inspiration?
-Diaphragm and external intercostals
What are the muscles of quiet and forced expiration?
-Quiet expiration is by elastic recoil of lungs and chest wall -> passive, no muscles involved
-Forced -> abdominal muscles and internal/innermost intercoastals
What are the four parts of the pleura?
-Cervical, mediastinal, costal and diaphragmatic