Laminar and Turbulent Flow Flashcards
What does flow equal
pressure/resistance
What is the equation for cardiac output?
CO= Blood pressure (ABP-CVP)/ resistance (TPR)
Look at Poiseuille’s Law
on slides
What is flow proportional to?
driving pressure
What is flow inversely proportional to?
resistance
What type of flow does Poiseuille’s law apply to?
laminar
What is laminar flow?
An organised pattern of flow in a parabolic flow profile
Describe the parabolic flow profile
On the outside, there is an immobile layer of fluid, this is due to high resistance. The next layer slips fast the immobile layer faster. Each successive layer goes past faster The layer of fluid in the middle of the tube moves at the fastest velocity.
Can you heart laminar flow?
no because it is highly organised
What is turbulent flow?
Disorganised flow made up of cross currents and epicurrents. More kinetic energy required
- mixing of fluid streams
- generation of sound (energy lost as sound)
How can you determine if a flow is laminar or turbulent?
-using Reynolds number (high number=turbulent)
What factors is the Reynold’s number related to?
- density of the fluid (more dense= more likely to be turbulent)
- diameter of the tube (larger=turbulent)
- velocity of flow (faster=turbulent)
- viscosity of the fluid (less viscous=more likely to be turbulent)
Once you have calculated a Reynold’s number how do you determine whether it is laminar or turbulent?
- less than 2000= laminar
- greater than 3000=turbulent
(between=increasing chance of turbulent)
Where does turbulent flow occur in the airways?
-trachea (high velocity, large radius)
What type of flow is it in most of the bronchial tree?
transitional (mixture of both types)
In the airways, where is there laminar flow?
in the very small airways
When does laminar flow occur in the blood vessels?
most of the time
When does turbulent flow occur in CV system?
- when there is an irregularity in the vessel e.g valves or clot
- when blood velocity is high
- stenosis (narrowing of blood vessels leading to increased flow velocity)
- anaemia decreased haematocrit decreases blood viscosity
What is murmur?
when there is turbulent blood flow (google) heart sounds don’t sound the same
What is the first heart sound?
AV valve closure
What’s the second sound?
pulmonary valve closure
How do you measure blood pressure?
- tighten cuff to prevent blood flow
- slowly ease cuff off allowing the blood to flow through as the pressure in the cuff is equal to the blood pressure. As the blood vessel is partly occluded you set up turbulent blood flow which you can hear through the stethoscope
- first sound=systolic blood pressure
- point at which you no longer hear any sound= diastolic blood pressure (laminar)
