Lecture 2: Fluids/Solutions Study Guide for Quiz
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What are two types of fluids?
Liquids and gases
Fluids take the ___
Shape of their container
What does Pascal’s principle state about pressure?
Pressure is exerted equally regardless of the size of the container—i.e.: arterial blood pressure monitoring
What do hydrometers measure?
Density of fluids
What is hydrodynamics?
The study of fluids in motion
What is laminar flow?
Flow that is smooth, orderly
What is turbulent flow?
Flow that is chaotic, always changing
In anesthesia, we strive for ___ flows
Laminar flows
What is the venturi flow meter?
• Venturi flow meter was originally used to measure speed in a pipe—they found that the speed was greatest at the narrowest part of the pipe • Today, Venturi flow meters are the basis behind nebulizers
What is Pouisielle’s Law?
The laminar flow rate is proportional to the fourth power of the pipe’s radius
Pouiseuille’s Law applies to ___ flow only
Laminar flow only
What two things have the greatest effect on laminar flow?
Radius and length
What are 3 possible ways to increase the fluid flow rate through a catheter or needle (based on Poiseuille’s Law)?
• Raise IV bag height or add a pressure bag • Use a large gauge IV catheter • Use a shorter length IV catheter
What is Bernoulli’s Principle?
Pressure of a fluid varies inversely with speed—as the speed of a fluid increases, the pressure exerted by the fluid decreases
Bernoulli’s principle—an increase in speed = a ___ in pressure
Decrease
Bernoulli’s principle—a decrease in speed = ___ in pressure
Increase
According to Bernoulli, pressure is ___ in the narrow part of the tube
Lower (because speed increases in the narrow part of the tube)
Bernoulli’s principles are seen in the ___
Venturi tube flowmeter
What is viscosity?
Measure of a fluid’s resistance to flow
Fluids with a high viscosity…
Do not flow very readily (i.e.: honey)
Fluids with a low viscosity…
Flow more easily (i.e.: water)
The closer a molecule is to a wall, the ___ it moves
Slower (speed is essentially zero)
Molecules in the center move…
The fastest (parabolic shape, laminar flow)
Less viscosity =
Better flow