Module 7 Flashcards
Any material that has the ability to flow
fluid
Hydrostatics definition
study of fluids that are not moving (density & pressure)
Hydrodynamics definition
study of fluids in motion
(T/F) Fluids can be either liquids or gases
True
(T/F) Hydrostatic pressure does not depend on volume, container shape, or total mass
True
(T/F) Hydrostatic pressure only depends on the depth of fluid, its density, and the acceleration of gravity
True
Used to measure the specific gravity of liquids
hydrometer
Smooth and orderly flow of fluid
laminar flow
Chaotic and abruptly changing flow of fluid
Turbulent flow
A mixture of laminar flow along the walls and turbulent flow in the center
Transitional flow
volume of fluid that flows past a point per unit time
Flow rate
SI unit for flow rate
m^3/s (cubic meters per second)
In laminar flow, the flow velocity at the center is ____ times the velocity of the mean flow
2 times
This type of flow predominates in the terminal bronchioles (smaller airways)
Laminar
Blood flow is an example of ______ flow
laminar
Large airway flow is an example of ______ flow
Turbulent
Name 5 variables that can cause laminar flow to turn into turbulent flow
- increased velocity
- change in viscosity
- change in density
- change in diameter
- rough, irregular vessel walls
- kinked tubing angled >25 degrees
- medium to large airways
- coughing and phonation
- orifice constriction such as glottic closure
As the speed of the fluid increases, the pressure of the fluid _______. This is explained by the _______ equation.
Decreases
Bernoulli equation
The basis of the venturi effect when using venturi masks
Bernoulli equation - higher speeds = lower pressure
Nebulizers use the ________ to deliver both humidification and medications such as albuterol.
venturi effect
Explains the tendencies of fluid flow in a bifurcated tube after passing a constriction
Coanda effect
During the coanda effect, the path with the _____ flow velocity will receive a higher volume of fluid or gas at the expense of the path with ______ flow velocity.
greater
lesser
(think about this almost like a vacuum. The faster velocity pathway will draw more of the fluid volume towards it)
This law mathematically describes laminar flow
Poiseuille’s Law
List the 4 components of Poiseuille’s Law
- Radius
- Viscosity
- Length
- Pressure
This variable has the most dramatic effect on flow according to poiseuille’s law
Radius
Doubling the radius increases flow by ___ times
16
Increased viscosity = ______ flow rate
decreased
Increasing the radius = ______ flow rate
increased
Increasing the length of tubing = ______ flow rate
decreased
Increased pressure exerted on tubing = _____ flow rate
increased
If tube length decreased by 1/2, then the flow rate increases by ____ times.
2 times
This class of drug increases bronchial tube diameter, improving gas flow
B2 agonists
Glottic closure & irregular wall or angles >25 degrees cause ______ flow in the medium to large airways
turbulent
Increasing peak inspiratory pressures (PIPs) increases the pressure gradient, improving gas flow and tidal volume (Vt). However, this increases the risk of what?
converting laminar flow to turbulent flow
Determines the presence of laminar, transitional, or turbulent flow
Reynold’s number
Re
Reynold’s number
Reynold’s number equation incorporates factors of Poiseuille’s Law and fluid ______
density
Reynold’s number is ______ related to viscosity
inversely
Re < or = 2000 reflects ______ flow
laminar
Re >2000 reflects _____ flow
turbulent
In status asthmaticus pts., the addition of helium (heliox) to the breathing gas results in a decrease in the _____ of the gas and increases flow through airways
density
Describes the relationship of wall tension (T) to pressure (P) and radius (r) in cylinders and spheres
Law of LaPlace
stress force exerted over a given area
Tension
Law of LaPlace equation for cylinders (blood vessels, aneurysms, ventricles)
T = Pr
Law of LaPlace equation for spheres (alveoli)
2T = Pr
In cylinders, wall tension increases with ______ radius
increasing
This law shows why smaller capillaries don’t burst during periods of hypertension, whereas larger vessels and aneurysms may
Law of LaPlace
Increased pressure = ______ tension
increased
Increased wall tension at end diastole = _____ stroke volume
increased
Without surfactant, _____ alveoli would collapse, as they would require higher pressure to open compared to _____ alveoli.
smaller
larger
If surface tension was the same, pressure is ______ in smaller alveoli than larger alveoli
greater
Lack of surfactant _____ wall tension
increases
what is the equation used for total pressure calculations of fluids on the bottom of cylinders when given height, atmospheric pressure and density of the fluid?
P2 = P1 + pgh
P1 = atmospheric pressure (in Pa) p = density in kg/m3 g = gravity constant (9.81 m/s2) h = height in m
