Distending pressure and surface tension are two farces that act
upon the alveoli at all times....
Distending pressure and surface tension are two farces that act
upon the alveoli at all times. Outline how these forces are offset
in an alveolus at end-expiration and end inspiration?
Solutions
Expert Solution
Alveoli are lined with a thin layer of fluid called surfactant
which is a mixture of phospholipids that reduce surface tension and
increase lung compliance
alveoli of the lungs are highly elastic, they do not resist
surface tension on their own, which allows the force of that
surface tension to deflate the alveoli as air is forced out during
exhalation by the contraction of the pleural cavity.
The intercostal muscles relax, returning the chest wall to its
original position. During exhalation, the diaphragm also relaxes,
moving higher into the thoracic cavity. This increases the pressure
within the thoracic cavity relative to the environment
pulmonary surfactant that is secreted by type II alveolar
cells. ... Advantages of pulmonary surfactant are that it lowers
surface tension of alveolar lining-decreases the inspiratory work
of breathing and it preferentially lowers surface tension in small
alveoli-stabilizes alveolar units.
During expiration the equal pressure point moves toward the
alveoli and collapsible small airways. The lung volume decreases,
leading to smaller alveoli with less alveolar elastic recoil.
Assume that the surface tension of water is γ=70 mN/m.
(a) Calculate the internal pressure of a water droplet of radius
1μm suspended in air at atmospheric pressure.
(b) Show that if a pure fluid is assumed to be incompressible,
the chemical potential of a fluid molecule can be written as
μ(T,P) = μ0(T)+vP,
where v is the specific volume of the molecule, and P is the
pressure.
(c) The vapour pressure of bulk water is 0.02atm at temperature
20...
Pure water has a surface tension of 0.0728?/?. Soap water has a
surface tension of 0.025?/?. A soap boat was made with a mass of
0.5? and a square surface area of 2?? × 2??. Show that the soap
boat can stay afloat on both pure water and soap water solely with
the force of surface tension. Calculate the acceleration of the
boat on pure water when a drop of soap is added to the rear edge of
the boat.
(Fluid):-
Density, Specific weight, Specific gravity, Salinity,
Compressibility, Vapor pressure, and Surface tension:
Explain how these properties might explain the behavior of a
fluid, or explain something you observe every day
please give one brief sentence for each.
The surface tension of pure water is 72 dyne/cm at 20C. You are
provided with two surfactants, A and B. A 1% solution of surfactant
A reduced the surface tension of water to 35 dynes/cm and a 1%
solution of surfactant B reduces the surface tension to 44.5
dynes/cm. Now, let's assume that you are making two foams using
surfactants A and B. The total interfacial area of the foam in both
cases is 600 cm^2. What is the interfacial...
5. Surface energy (2 pts). Let’s use the concept of surface
tension as surface energy per unit area to see if we can estimate,
at least to the correct order of magnitude, the surface tension of
water.
a) Water has a molar mass of 18 g/mol and a density of 1000
kg/m3 (or 1 g/cm3). Based on this data, estimate the number of
water molecules per unit surface area of water.
b) The coordination number of water (i.e., the average...
The partial pressure of oxygen in the lung alveoli is a bit
lower than in ambient air, being about 100 mm of mercury, or 0.13
Atm (it is lower than the partial pressure in air mainly because
oxygen is continually taken up by the alveolar capillaries and
carbon dioxide is continually released into the
alveoli). In cell-free blood plasma (or a saline
solution formulated to match key characteristics of blood plasma),
which lacks red blood cells and therefore lacks hemoglobin, the...
What is the effect of transpiration on the surface tension of
the water, i.e. does it increase or decrease it? How does changing
surface tension affect water molecules below the surface? How do
you think this affects the water molecules in the xylem cells that
touch these spongy mesophyll cell walls or water in xylem cells
farther back in the leaf or stem?
8). Surface tension: A.is tendency of liquid to maximize surface
area B. decreases with decreasing strength of intermolecular force
C. increases with decreasing strength of intermolecular force D.
all are correct
9) Viscosity: A. decreases with size of molecules B. decreases
with decreasing strength of intermolecular force C. increases with
decreasing temperature D. all are correct
10) Adding salt to water does what? A. lowers freezing point C.
increases ion-dipole interactions B. increases surface tension D.
all are correct
11)...
Explain why surface tension and viscosity decrease with
increasing temperature.
Why do substances with high surface tensions also tend to have
high viscosities?
Capillary number is proportional to { (viscous force) / (surface
tension force) } and is used in momentum transfer in general and
atomization and 2-phase flow in beds of solids calculations in
particular. It is equivalent to (We/Re).
___________ Which is the friction factor for ReD = 600 and e/D =
0.002 in pipe flow?
___________ What is the friction factor for ReD= 3 x 105 and D/e
= 5000 in pipe flow?