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Flashcards by reynoldslaura, updated more than 1 year ago
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Created by reynoldslaura
over 11 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 |
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