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36 Cards in this Set
- Front
- Back
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Does a low, or high linear flow rate lead itself to laminar flow?
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A low linear flow rate
(flow rate in volume/second / Cross sectional area |
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How do you work out linear flow rate?
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Flow rate (volume/second)
/ Cross sectional area |
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In laminar flow, resistance to flow is constant for a tube of given dimensions T/F
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T
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When airflow is turbulent, resistance increases with flow rate T/F
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T
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When cross sectional area increases, resistance to flow decreases/increases
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Decreases
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The greatest resistance to airflow is found in the segmental bronchi (gen. 4). Why?
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The CSA is relatively low and the airflow is high (and turbulent)
Remember linear flow rate equation |
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Airway resistance falls as volume of the lungs increases. How?
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There is an increased total cross sectional area (imagine breathing through a woolly jumper - and remember some branches of the respiratory tree can poly-furcate (i.e. more than bifurcate)
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In the 3D respiratory system, work done =
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delta(pressure) * delta(volume)
WD = F * D |
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Why is the work of breathing increased with decreased compliance?
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More work has to be done by the inspiratory muscles to expand the chest
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Why is there increased airflow resistance in rapid, shallow breathing compared with deep and slow breathing? (In the space of a minute)
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In rapid breathing, more breaths are taken per minute. More breaths --> More resistance
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Why does pulmonary fibrosis result in increased rate and decreased depth of breathing?
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It minimises work. The work of expanding the chest is increased (because of the fibrosis). To compensate, more breaths are taken, but to a shallower degree
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State LaPlace's law
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Pressure (P) inside a hollow sphere is twice the surface tension (T) divided by the radius (r)
P = (2T)/r |
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'Pressure (P) inside a hollow sphere is twice the surface tension (T) divided by the radius (r)
P = (2T)/r' Is whose law? |
LaPlace's law
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State Poiscellie's law
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R = (8nl)/(pi)r^4
R = resistance n = viscosity l = length r = radius |
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Give three functions of surfactant
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Stabilising the alveoli by reducing the surface tension of the air-liquid interface (nice)
Increasing compliance of the lung Prevents fluid accumulating in the alveoli (and therefore plays an important role in keeping the alveolar air space dry) |
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What is surfactant made up of?
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Many phospholipid molecules
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A micelle is a monolayer T/F
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T
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Why is FEV(1) reduced in an obstructive lung disease?
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It takes longer to exhale through narrowed airways (imagine breathing as hard as you can through a McDonald's straw, then through a tube as wide as a jam-jar. Alternatively, pursed and wide mouth)
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FEV(1) is reduced in an obstructive lung disease T/F
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T
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What will the vital capacity of an individual with a restrictive lung disease be like? Normal or reduced?
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Reduced
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Those with a restrictive lung disease have a reduced PEFR T/F
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F (those with an obstructive lung disease do)
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Airways resistance increases as lung volume decreases T/F
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T
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What are the three main factors that affect lung volumes? (Generic)
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Body size
Age Sex |
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In the standing position, is the apex or base more ventilated?
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The base - Around 50% more
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What is the 'diffusion potential'?
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The potential across a membrane arising from the steady-state diffusion of an ion
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What is the 'equilibrium potential'?
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The membrane potential at which a certain ion has no net movement through a membrane.
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What is the membrane potential?
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The difference in voltage between the interior and exterior of a cell
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What is the name for the membrane potential of an unstimulated (quiescent) cell?
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The resting membrane potential
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What does the Nernst equation calculate?
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The equilibrium potential
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What is the voltage scale of a nerve cell action potential?
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-70 to +40 mV
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What last longer - nerve and skeletal action potentials, or cardiac action potentials?
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Cardiac action potentials last much longer (150 - 300 ms)
Other APs last around 1 - 2 ms |
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What is the voltage scale of the SAN?
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-60 to 0 mV (-60 immediately after an AP - threshold is at -50 mV)
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How long does a SAN action potential last for?
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150 - 200 ms
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What does membrane potential equal?
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V(inside) - V(outside)
V = voltage |
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What causes the upstroke (depolarisation) in a SAN action potential? Is it the same for atrial and ventricular action potentials?
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Diffusion of CALCIUM into the cell with SAN AP (K+ still causes the repolarisation)
Others are the normal sodium |
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What is more concentrated outside of the cell, Na+ or K+?
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Na+! (At the resting state!)
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