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Flashcards on Respiratory, created by reynoldslaura on 05/02/2013.

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Created by reynoldslaura almost 6 years ago
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Question Answer
What is the difference between functional residual capacity and residual volume? Functional residual capacity is the volume of air remaining in the lungs after passive expiration however residual volume is the amount of air remaining in the lungs after maximal exhalation
What is the value for vital capacity? 4.8L (4800ml)
What is the value for functional residual capacity? 2.2L (2200ml)
What is the normal value for expiratory reserve volume? 1.0L (1000ml)
What is the value for inspiratory capacity? 3.8L (3800ml)
What does alveolar ventilation rate tell us? The amount of fresh gas avaliable for gas exchange
How can compliance be measured graphically? By taking the gradient of a volume vs transpulmonary pressure graph
What measurements cannot be taken using a spirometer? Functional residual capacity, total lung capacity, residual volume
What is the normal value for tidal volume? 0.5-0.6L (500-600ml)
What is the value for vital capacity? 4.8L ( 4800ml)
What is the value for residual volume? 1.2L (1200ml)
What is the normal value for inspiratory reserve volume? 3.2L (3200ml)
What is the value for total lung capacity ? 6.0 L (6000ml)
What is happening if the VA:Q ratio is 0? Blood is passing through the lung without coming into contact with alveolar air
Give two functions of the pulmonary circulation. Any two from: provides nutrition to the alveoli and airways, acts as a blood reservoir, provides filtration of the blood and metabolises vasoactive substances
If a VA:Q ration is ∞, where is this? An anatomical dead space or ventilated alveolus that isn't perfused
How are pulmonary arterial walls different from other arterial walls? They are very thin and contain little smooth muscle
What are the responses that help maintain low pressure that dont require any muscle/nervous input? Recruitment of capillaries - act to increase the surface area of lungs and increase passage through lungs and distension of capillary segments- acts to reduce resistance
What is the equation for vascular resistance? input pressure-output pressure ÷ blood flow
How is vascular resistance affected when the lungs are fully inflated? Vascular resistance decreases as the vessels are pulled open by surrounding lung parenchyma
Name two things that can result from pulmonary hypertension? Hypertrophy of R.V which can lead to right ventricular heart failure and pulmonary oedema (blood goes out of vessels and into the lungs)
What is the pressure difference between the top and bottom of the lungs? 23mmHg or 30cm H₂O
What does hypoxia mean? Reduced pO₂ levels, the fall below the usual 98mmHg- can occur at high altitude.
What occurs in response to hypoxia? pulmonary vasoconstriction
What does hypercapnia mean? Raised pCO₂ of >40mmHg. CO₂ dissolves in water to give H+ therefore it causes a drop in blood pH. It usually occurs where there is inadequate gas exchange e.g. breathing disorders
What occurs in response to hypercapnia? Vasoconstriction
How is RAW (airway resistance) affected by change in lung volume? Airway resistance increases with decrease in lung volume
What is radial traction? As the lung expands, connective tissue pulls on bronchioles so their diameter expands and RAW (airway resistance) falls
Where does dynamic compression occur? From the bronchioles downwards. It can only occur where there are no-cartilaginous rings holding the airways open
Name two things that cause bronchioconstriction. Parasympathetic innervation (vagal stimulation), a fall in pCO₂, asthma, and irritants causing bronchioconstriction e.g. inflammation of airways
Name two things that cause bronchiodilation. Autonomic stimulation, local mediators, sympathomimetic agents (β₂ agonists)
Name two things that can increase RAW (airway resistance)? Mucus and inflammation (causes a narrowing and occlusion of the airways)
What is the mean arterial pressure in the pulmonary circulation? 25/10mmHg
Why is the diaphragm the most important muscle for respiration? Because contraction of the intercostal muscles aren't sufficiently strong to change the volume of the thorax (damage to the phrenic nerve results in the need of a ventilator to breathe)
What happens to intrapleural pressure when the volume of the thorax increases? It falls/becomes more negative allowing air to flow into the lungs as alveolar pressure < atmospheric pressure
By what method can we estimate the anatomical dead space? Via Fowler's method of N₂ washout from the lungs
By what method can we measure the physiological dead space? Via the CO₂ content of the expired and alveolar air via the Bohr equation
Why is the work of inspiration greater than the work of expiration? Because of resisitive forces that oppose the airflow- energy is required to overcome the airways resistance (also pulmonary tissue resistance and inertia of air and tissues)
Why is energy required for expiration so much less? Because the energy for expiration is largely derived from the stretching of the elastic elements in the lungs and chest during inspiration. Resistive forces asist airflow
In a healthy person, what is the volume of air in the anatomical 'dead space'? 150-180ml- this is the volume inside the upper respiratory tract to the terminal bronchioles (doesn't take part in gas exchange)
What effects can diseases which increase the physiological dead space (e.g. damages to the chest wall and paralysis of respiratory muscles have on ventilation rate? They can cause hypoventilation
What is meant by the term hyperventilation? Ventilation that is in excess of metabolic needs. CO₂ exhaled at a greater rate than production. pCO₂ falls <40mmHg and pO₂ rises >98mmHg.
What conditions or under what cirumstances can hyperventilation occur? During an acute asthma attack or under conditions of stress or altitude and during forced expiration e.g. blowing a balloon or musical instrument
What is meant by the term 'physiological dead space'? The sum of the anatomical and alveolar dead space. However in HEALTH all of the alveoli take part in gas exchange so physiological dead space EQUALS anatomical dead space
What is meant by the term 'dead space'? A volume of the lung that doesn't participate in gas exchange e.g. the trachea
What do we mean by air conditioning? Warming up of the air before it enters the lungs and the purifying of it. (cilia and mucus trap particulates preventing them from going onto gas exchange surfaces)
What is the average breathing rate? 12 breaths/min
What is alveolar ventilation rate? (tidal volume-dead space)x breathing rate
What is the normal value for tidal volume? 500ml
What is the conducting zone primarily made up of? Dead space
What structures of the bronchial tree are found in the transitional and conducting zones? Respiratory bronchioles, alveolar ducts and alveolar sacs
What is the normal value of O₂ in arterial blood? 98mmHg (13kPa)
What is the normal value for CO₂ in arterial blood? 40mmHg (5.3kPa)
What is the definition of hypoventilation? Inadequate ventilation of the lungs. CO₂ is being produced and isn't being expelled. O₂ is being used up but isn't being replaced
What is used to reduce surface tension in the liquid lining of the alveoli? Surfactant. It is a special fluid produced in the lungs that acts as a 'detergent' to reduce surface tension in the liquid layer of the alveoli. Makes it alveolar collapse less likely at lower pressures
What is meant by the term compliance? The elasticity or distensibility of the lung
What is the equation for compliance? Change in volume ÷ change in pressure
When is compliance reduced? When elasticity is impaired e.g. fibrous tissue in the lungs ad when surface tension is increased (decrease in the production of surfactant- premature birth) This keeps alveoli small