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100 Cards in this Set
- Front
- Back
What is ventilation? |
The exchange of air between atmosphere and alveoli |
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How are oxygen and carbon dioxide exchanged between alveolar air and blood in lung capillaries? |
By diffusion |
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How are oxygen and carbon dioxide transported through pulmonary and systemic circulation? |
By bulk flow |
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What is meant by bulk flow? |
When substrate is flowing through the tube and carries dissolved gas with it |
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What forms the upper respiratory tract? |
Nasal cavity, mouth, pharynx, larynx |
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What forms the lower respiratory tract? |
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Can the right lung and left lung function independently? |
Yes |
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What are some functions of the upper respiratory tract? |
Filtration Conditioning of air Speech |
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Filtration is an important defence mechanism against infection. Inhaled particles are trapped by hair and mucus in nasal passages. What do these inhaled particles activate? |
Irritant receptors triggering sneeze reflex |
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What happens to excess mucus? |
passes back to the pharynx to be removed by swallowing OR is expulsed through nose |
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Why is it necessary that air passing through the nasal cavity is warmed and humidified? |
Necessary for optimal gas exchange in the alveoli (N.B nasal passages have a rich blood supply for this purpose) |
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One function of the upper respiratory tract is speech. The larynx contains vocal cords: two folds of elastic tissue stretched across its lumen. What happens to them as air flows across them? |
They vibrate , producing sound |
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The lower respiratory tract is divided functionally into two zones. What are these two zones? |
Conducing zone and respiratory zone |
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What forms the conducting zone? |
Trachea, bronchi and bronchioles |
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What keeps the airways open in the trachea and bronchi? |
C shaped bands of rigid cartilage |
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What happens to the number of tubes in branch as you go from the trachea to bronchi? |
It increases |
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Where does the trachealis muscle span and what is its function? |
Spans gap between ends of cartilage bands It contracts to aid expulsion of blockages e.g coughing reflex N.B narrowing of airway means air comes out faster so is more effective at dislodging blockages |
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Describe the bronchioles |
No cartilage Smooth muscle bundles. Normally relaxed, allowing air to reach alveoli Contraction prevents irritants and particles from entering the alveoli |
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What forms mucus? |
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Describe the process of mucociliary transport |
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How does the amount of cilia and mucus in upper airways compare to in the bronchioles? |
Bronchioles have fewer cilia and much less mucus |
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How is bacteria and other small particles removed in bronchioles? |
Macrophages |
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What forms the respiratory zone? |
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What happens in the respiratory zone that does not happen in the conducting zone? |
Gaseous exchange |
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What do pulmonary arteries transport and from where to where? |
They carry deoxygenated blood from heart to lungs |
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How many alveoli are in each alveolar sac? |
40-50 |
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Blood that goes through capillaries is supplied by branches what vessel? |
The pulmonary artery |
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Approximately how many alveoli do the lungs contain? |
~300 x10 6 |
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What is the approximate diameter of the alveoli? |
0.2 mm |
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What are the two types of alveolar cells orpneumocytes? |
Type I flattened epithelium(gaseous exchange) Type II thicker cells(secrete surfactant) |
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What is the function of the pores inside the alveoli? |
Gaps between alveoli that allow entry of air even if duct is blocked |
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Other than providing oxygen and removing carbon dioxide, forming speech sounds, and protection from microbes and other foreign matter, what are some other functions of the lungs? |
Regulates blood hydrogen ion concentration Removal or deactivation of circulating vasoactive (affecting the diameter of blood vessels) hormones e.g bradykinin Activation of angiotensin II |
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One function of the lungs is the removal of micro-thrombi arising in systemic veins. What is meant by this? |
The lungs removed small blood clots |
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Angiotensin converting enzyme (ACE) on surface of pulmonary endothelium convertswhat into what? |
angiotensin I into angiotensin II |
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Is angiotensin II a vasoconstrictor or vasodilator? What does it trigger the release of? |
A vasoconstrictor It triggers release of aldosterone from adrenal cortex |
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In normal steady quiet breathing, the volume of air inspired is equal to the volume of air expired. What is this known as? |
Tidal volume |
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What is the volume of tidal volume? |
500 ml |
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What is the Inspiratory Reserve Volume (IRV)? |
The maximum amount that lung volume can be increased above tidal volume 3000 ml |
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What is the Expiratory Reserve Volume (ERV)? |
After expiring the tidal volume, a further maximal exertion of the expiratory muscles a further volume can be expired 1200 ml |
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What is the residual volume? |
Even after maximal expiratory effort, the lungs cannot be complete emptied, a sizeable volume always remains. 1200 ml |
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Lung volumes vary between individuals. What factors can influence lung volume? |
Age Gender Height |
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The sum of two or more volumes are known as what? |
capacities |
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The sum of the inspiratory reserve volume plus the tidal volume is....? |
Inspiratory capacity 3500 ml |
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The sum of inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume is .....? |
Vital capacity 4700 ml |
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The sum of expiratory reserve volume plus residual volume is......? |
Functional Residual Capacity 2400 ml N.B this is what is left in the lungs after a normal breath out |
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The sum of all four volumes (IRV+VT+ERV+RV) is ....? |
Total Lung Capacity 5900 ml |
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Some lung volumes and capacities can bemeasured directly using a water Spirometer. Describe how this forms a trace. |
On inspiration, pen moves up On expiration, pen moves down N.B modern versions of this decide use force transducers and record electronically |
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Because the lungs cannot be completely emptied, no 'baseline' can be recorded. What is a consequence of this? |
Residual volume, and all capacities that include RV (FRC and TLC) cannot be measured directly using this device |
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What is ventilation? |
The exchange of air between atmosphere and alveoli |
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What is |
Total ventilation per minute |
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What is |
Volume of fresh air reaching alveoli per minute |
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How can minute ventilation be calculated? |
Tidal volume x breaths per minute |
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Why is minute ventilation different from alveolar ventilation? |
Gaseous exchange occurs primarily in alveoli and minimally in respiratory bronchioles, while pharynx and conducing zone of lower respiratory tract do not contribute at all to this The volume from the top of the pharynx down to the terminal bronchioles is known as the anatomical dead space Of the 500ml tidal volume, 350 ml will reach the alveoli for gaseous exchange, while 150 ml will remain in the conducting zone and not be absorbed |
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In adults, the anatomical dead space has a fixed volume. What is this? |
~150 ml |
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How can alveolar ventilation be calculated? |
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Anatomical dead space is fixed. True or false. |
True |
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Physiological dead space is fixed. True or false. |
False. |
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In healthy lungs, anatomical dead space = physiological dead space. However, in what instance would physiological dead space not be equal to anatomical dead space? |
If some alveoli are poorly perfused (with blood) then no gas exchange occurs in those areas. This is the alveolar dead space. Physiological dead space = anatomical dead space + alveolar dead space |
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What are the SI units of pressure? |
kPa |
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What does mean? |
Fractional concentration of oxygen |
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Flow can be defined by which equation? |
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In ventilation, which are the important pressures? |
Atmospheric pressure Alveolar pressure |
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When does movement of air into and out of the lungs occur? |
When P alv is smaller or larger than P atm So in between breaths, when P alv = P atm, there is no flow of air |
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The changes in pressure inside the lungs can be explain by Boyles Law. What is this? |
The pressure (P) of a fixed amount of gas ( at a constant temperature) is inversely proportional to the volume (V) of the container in which it is placed |
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The lungs are enclosed in a fluid-filled pleural sac.Cohesive forces exerted by the fluid between the pleuralmembranes cause the lung to adhere to the thoracic cage andthus when the thorax changes its shape the lungs move with it. True or false. |
True |
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At Functional Residual Capacity (end of a normal breath out), all respiratory muscles are contracted/relaxed. |
Relaxed |
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At the end of a normal breath out, inward recoil of the lungs is balanced by what? |
Outward recoil of the chest wall. |
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At Functional Residual Capacity (end ofnormal breath out), all respiratory muscles arerelaxed and inward recoil of lungs isbalanced by outward recoil of chest wall. What does this generate? |
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What is meant by P alv = 0 |
Alveolar pressure is the same as atmospheric pressure |
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What would happen if the chest wall was opened? |
Intra-pleural pressure would be normalised with atmospheric pressure Lungs would collapse due to inward recoil Chest wall would expand due to outward recoil |
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The structure of the chest wall is such that elastic fibres in the chest tend to make the chest wall recoil ________, but _______ ______ of lungs makes lungs recoil inwards. Forces are balanced at ____ |
outwards elastic tissue FRC |
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What is trans-pulmonary pressure? |
The difference between alveolar pressure and intrapleural pressure |
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How can trans-pulmonary pressure be calculated? |
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At FRC, what is trans-pulmonary pressure equal to? |
0.5 kPa |
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What happens to intra plural pressure as the chest wall expands and why? |
It becomes more negative ( -0.7 kPa) as there is more of a force trying to pull the two membranes apart |
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As the chest wall expands, intrapleural pressure becomes more negative. How does this affect trans-pulmonary pressure and intra-pleural pressure? |
Trans-pulmonary pressure increases Alveolar pressure decreases |
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What are the sequence of events in inspiration? |
Nerves stimulate diaphragm and other inspiratory muscles to contract, expanding chest wall Intrapleural pressure falls ( becomes more negative) Alveoli are expanded Pressure in alveoli falls Increased pressure gradient from out the alveoli-air flows into lungs |
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Why do the alveoli expand during inspiration? |
Due to increased trans-pulmonary pressure difference across the alveoli |
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What are the sequence of events in normal expiration? |
Nerves decrease firing to diaphragm and intercostal muscles relax Expanded chest wall recoils inwards Intrapleural pressure goes back towards pre-inspiration level Transpulmonary pressure decreases to pre-inspiration level Expanded lungs which have a greater elastic recoil, reduce in size Air in alveoli gets compressed Air flows out of lungs |
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In forced expiration or high ventilation: abdominal muscles contract which increases/decreases recoil of diaphragm and speed/slow down shrinkage of chest wall and lungs. Intrapleural pressure may be positive/negative |
increase speed positive |
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When what two things are equal to each other is there no air flow? |
P alv = P atm |
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In mid-inspiration, expanding chest wall _______ intra-pleural pressure, making trans-pulmonary pressure more _________. This ______ the lung, making P alv __________ and results in inward/outward airflow. |
decreases postive expands negative inward |
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At the end of inspiration, chest wall is no longer expanding but has yet to passively _____. P alv = P atm and there is no ________ |
recoil airflow |
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In mid-expiration, lung is collapsing, compressing ___________ gas. So P alv becomes ________ relative to P atm, causing _______ airflow |
alveolar positive outward |
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What is the fractional concentration of nitrogen + inert gases in air ? |
~0.79 ( 79%) |
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What is the fractional concentration of oxygen in air? |
~ 0.21 (21%) |
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Why does humidified air alter the relative concentrations of other gases? |
The presence of water vapour dilutes oxygen |
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The pressure exerted by a gas is directly proportional to what two things? |
Temperature Number of gas molecules in a given volume (concentration) |
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What is the definition of partial pressure as defined by Dalton's Law? |
Individual pressure of a particular gas (e.g oxygen) in a mixture of chemically non-reactive gases |
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What is total pressure equal to? |
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What is the equation to calculate partial pressure (e.g of oxygen) ? |
P atm x fractional concentration |
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Why are the volumes different? |
Oxidation of organic fuel products water as well as CO2. CO2 produced / oxygen consumed =respiratory quotient = 0.8 |
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At rest, what is alveolar ventilation? Therefore what is the volume of oxygen inhaled per minute? |
4.2 L/min 21% of 4200ml = 882 ml |
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Of the 882 ml of oxygen in inhaled air, what happens to it? |
250 ml is absorbed into the blood and added to the reservoir of 750 ml 250 ml used by cells per min |
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How much CO2 do cells produce per minute? |
200 ml |
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What is the reservoir of CO2 in the body? |
2400 ml |
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How much CO2 is expired per minute? |
200 ml |
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How does the PO2 of oxygen vary in these places? |
PO2 reduced from atmospheric air to upper airways because of saturation |
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How does PCO2 vary in each of these places? |
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How does PH20 vary in each of these places? |
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