Respiratory Flashcards
What is Charles’ law?
Pressure increases as temperature increases
What is the universal gas law?
How does alveoli maintain ventilation/perfusion ratio?
How does alveoli maintain ventilation/perfusion ratio?
Hypoxic pulmonary vasoconstriction - Diverts blood away from poorly ventilated areas Hypoxic alveoli vasoconstrict pulmonary vessels
What is boyle’s law?
Pressure inversely proportional to volume
What is the consequence of chronic hypoxic vasoconstiction?
Right ventricular failure Chronic increased resistance causes high after-load for right side of heart - cor pulmonale
What cells do alveoli contain and what are their function?
Type 1 pneumocytes - gas exchange Type 2 pneumocytes - produce surfactant to reduce surface tension
What is surface tension?
Elastic tension of liquids which makes them acquire the least surface area possible
What is the epithelial lining of the upper respiratory tract?
Pseudostratified ciliated epithelia with goblet cells
What are the muscles of inspiration?
Diaphragm External intercoastals
What are the muscles of expiration?
None - elastic recoil
What factors determine rate of diffusion?
Surface area Resistance - nature of barrier, nature of gas Gradient of partial pressure
What is the partial pressure of O2 and CO2 in lungs?
pO2 - 13.3kPa pCO2 - 5.3kPa
What are the muscles of forced inspiration?
Diaphragm External intercostals Scalene Serratus anterior Sternocleidomastoid Pectoralis minor
What are the muscles of forced expiration?
Internal intercostals Innermost intercostals Abdominal muscles
What is residual volume and how can it be measured?
Volume left in lungs after maximal expiration Measured via helium dilution test
What is anatomical dead space?
The air in the upper airways that is unavailable for gas exchange
What is physiological dead space?
Anatomical dead space + alveolar dead space Alveolar dead space is the alveoli that have insufficient blood supply as those that are damaged by accident or disese
How do you measure a patient’s anatomical dead space?
Nitrogen washout test
Explain nitrogen washout test
Patient takes breathe of 100% O2 The O2 reaches the alveoli and mixes with residual atmospheric air that contains nitrogen, but air in conducting airways remains 100% O2. Person exhales through one way valve and gas content is measured. Nitrogen concentration initially 0 as exhaling dead space 02 but then gradually rises
What is the alveolar ventilation rate and how is it calculated?
Amount of air that reaches the alveoli = pulmonary ventilation rate (tidal vol x RR) - dead space ventilation rate (dead space volume x RR)
What ribs are atypical?
1, 2, 10, 11, 12
What does the bucket-hand type movement of the external intercostals cause?
Expansion of anteroposterior and transverse diameters of chest
What is the innervation of intercostal muscles?
Intercostal nerves from anterior rami of T1-T12
What are the openings of the diaphragm and at what level do they occur?
T8 - vena cava T10- oesophagus T12- aorta (aortic hiatus)
What is the innervation of the diaphragm?
Phrenic nerve (C3, 4, 5)
Where do the neurovascular supply to intercostal muscles run? State in which order they lie
Intercostal groove of rib (lower border) Between internal and innermost intercostal muscles Vein, artery, nerve (VAN)
What do the intercostal nerves supply?
Intercostal muscles, parietal pleura, overlying skin
Describe course of intercostal arteries
Thoracic aorta - posterior intercostal artery Subclavian artery - internal thoracic artery - anterior intercostal artery Anterior and posterior intercostal arteries anastomose