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48 Cards in this Set
- Front
- Back
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What is the definition of inspiratory reserve volume?
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The amount of "extra" air, above and beyond the tidal volume, that you can breathe in on maximum inspiration
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What is the average inspiratory reserve volume in adult males? Females?
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Males: 3100 mL
Females: 1900 mL |
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What is term for the "extra" air, beyond the tidal volume, that you can push out during maximum expiration?
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Expiratory reserve volume
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What is the average expiratory reserve volume for an adult male? Female?
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Male: 1200 mL
Female: 700 mL |
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What is the FEV1?
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Forced expiratory volume in 1 second: amount of air that can be exhaled from the lungs in 1 second with maximal effort following maximum inspiration
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What effect do obstructive respiratory diseases have on FEV1?
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Decrease FEV1 by increasing airway resistance
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What is the functional residual capacity?
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Sum of the residual volume and the expiratory reserve volume
In other words, the amount that's left after a passive expiration, the resting point 1200 + 1200 = 2400 mL in males 1100 = 700 = 1800 mL in females |
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Even after maximum exhalation some air remains in the respiratory tract. Why?
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Sub-atmospheric intrathoracic pressure keeps respiratory zone slightly inflated, non collapsable airways remain open
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What is the term for the amount of air that's left in the lungs after maximum expiration?
How much is left? |
Residual volume
=1200 mL in males =1100 mL in females |
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What is the inspiratory capacity?
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Sum of the tidal volume and the inspiratory reserve volume
500 + 3100 = 3600 mL in males 500 + 1900 = 2400 mL in females |
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What is vital capacity?
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The total amount you can breathe in (tidal volume + inspiratory reserve volume) and breathe out (expiratory reserve volume)
Male: 500 + 3100 + 1200 = 4800 mL Female: 500 + 1900 + 700 = 3100 mL |
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What is total lung capacity?
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Total amount you can breathe in and out (vital capacity) plus the residual volume
Males: 500 + 3100 + 1200 + 1200 = 6000 mL Females: 500 + 1900 + 700 + 1100 = 4200 mL |
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What is the average vital capacity for an adult male?
Female? |
4800mL
3100mL |
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What is ventilation?
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Inflow and outflow of air
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What is external respiration?
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External respiration = pulmonary respiration
Exchange of gases between the alveoli in the lungs and the blood in pulmonary capillaries across the pulmonary membrane |
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What is internal respiration?
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Internal respiration = tissue respiration
Exchange of gases between the blood in systemic capillaries and tissue cells |
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What is cellular respiration?
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Metabolic reactions that consume oxygen and give off carbon dioxide during the production of ATP
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What is atmospheric pressure at the earth's surface?
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760 mmHg or 1 atm
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What is the pressure in the alveoli just before inspiration?
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760 mmHg (atmospheric pressure)
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What is the pressure in the alveoli just before expiration?
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760 mmHg (atmospheric pressure)
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What is Boyle's Law?
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For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one doubles, the other halves)
pV = K p1V1 = p2V2 The reason is that changing the volume of the gas does not change the number of gas molecules. There are the same amount particles pushing against a smaller surface area, so the pressure goes up. |
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Describe the only reason air moves into and out of the lungs:
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Fluids flow naturally from regions of greater pressure to regions of lower pressure
Air moves into the lungs when air pressure inside the lungs is less than the air pressure in the atmosphere Air moves out of the lungs when the air pressure inside the lungs is greater than the air pressure in the atmosphere |
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In the most basic terms, how is air pressure within the lungs lowered to facilitate the flow of air from the atmosphere to the alveoli?
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The lung volume is changed. The volume increases and the pressure drops according to Boyle's law, resulting in air flowing down the respiratory tract
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How is lung volume increased to allow for inspiration?
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1) The diaphragm and the external intercostal muscles, the main muscles of inspiration, contract
2) The thoracic cavity expands 3) Intrapleural/intrathoracic pressure drops 4) Parietal pleura, adhering tightly because of subatmospheric pressure and surface tension in pleural cavity, pulls the visceral pleura along for the ride, expanding the lungs |
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What are the main muscles of inspiration and what do they do?
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Diaphragm (75% of air that enters) - flattens to increase the vertical dimension of the thoracic cavity
External intercostals (25% of air that enters) - elevate ribs resulting in increased anteroposterior and lateral dimensions of the thoracic cavity |
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How far does the diaphragm typically descend during normal quiet breathing?
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1 cm
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How far might the diaphragm descend during strenuous breathing?
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10 cm
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What does pressure within the alveoli drop to during normal quiet inspiration?
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Drops 1-3 mmHg to approximately 758mmHg
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What volume of air is inhaled during a normal quiet inspiration?
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500mL
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What does the pressure within the alveoli drop to during strenuous inhalation?
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Drops 100 mmHg to 660mmHg
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What are the accessory muscles of inhalation and what are their actions?
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Sternocleidomastoids - elevate sternum
Scalenes - elevate first two ribs Pectoralis minors - elevate the third-fifth ribs |
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What is the intrapleural/intrathoracic pressure?
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Pressure between the two pleural layers in the pleural cavity
This pressure is ALWAYS subatmospheric Just before inspiration, intrathoracic pressure = 756mmHg |
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What does intrathoracic pressure drop to during inspiration?
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Drops approx. 2 mmHg to 754mmHg
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Inhalation results from increased lung volume due to active contraction of the diaphragm and external obliques. What does exhalation result from?
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Decreased lung volume due to passive elastic recoil of chest wall and lungs, both of which have a natural tendency to spring back after they have been stretched
Why are the lungs so elastic? Elastic fibers and surface tension of alveolar fluid |
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What accounts for the elasticity of the chest wall and the lungs?
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Elastic fibers that recoil
Surface tension of alveolar fluid In one sense you could think of the chest wall as that which expands the lung (contraction of muscles expands wall, pulls adhering lung along with it) and the lung as that which contracts the chest wall (elasticity and surface tension) |
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How is air pushed out of the lungs and back into the atmosphere?
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Passive elastic recoil of lungs and chest wall results in decreased lung volume and increased intrapulmonary (alveolar) pressure (762mmHg)
Air flows from alveoli up through bronchial tree into atmosphere |
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What maximum intrapulmonary pressure is reached during passive expiration?
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762mmHg
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What are the muscles of exhalation?
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Abdominals (rectus abdominis, external oblique, transverse abdominis, internal oblique)
Internal intercostals |
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What is compliance?
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The resistance offered by a material to stretch
If a material is easily stretched, it's highly compliant If it's difficult to stretch, it's less compliant |
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What is elasticity?
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The tendency/ability of a material to return to its original shape once it's been stretched
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Besides pressure difference, what other factor determines the rate of airflow through the airways?
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Resistance
Larger diameter airways have decreased resistance Smaller diameter airways have increased resistance Airway resistance in the bronchioles thus decreases during inspiration and increases during expiration |
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What is a normal respiratory rate for a normal adult at rest?
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12-20 breaths per minute
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What is the definition of tidal volume?
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The amount of air inhaled and exhaled in a single breath
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What is an average adult tidal volume?
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500 mL
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What is the definition of minute ventilation and how is minute ventilation calculated?
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Total volume of air breathed in and out in one minute
Respiratory rate x tidal volume |
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During normal quiet breathing, which lasts longer, inspiration or expiration?
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Expiration (3s) > inspiration (2s)
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What is alveolar ventilation rate?
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Volume of air per minute that actually reaches the respiratory zone
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What is the average total lung capacity for a male? Female?
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6000 mL
4200 mL |
