Equations
What is Bernoulli's equation, and what does it explain?
It describes the inverse relationship between pressure and velocity.
What are the 3 main types of blood flow?
Plug
Laminar
Turbulent
What shape do the veins become when someone is standing?
Circular
(Increased transmural pressure causes a circular shape. Decreased transmural pressure/supine position causes elliptic/collapsed shape)
Velocity is at its maximum
Pressure drops significantly
What is the name of the waveform that displays a slow upstroke (time) and a weak amplitude (velocity)?
Tardus Parvus
What is the Ohm's Law equation, and what does it explain?
Explains the relationship between flow, pressure, and resistance
(Relates to Poiselle's equation)
What flow occurs in large vessels and at the entrance of vessels?
Plug Flow
(Occurs because there is minimal friction loss happening in those areas)
What is the term for the pressure applied to the veins from the outside?
Extrensic Pressure
What happens to the pressure gradient near a stenosis?
The pressure gradient increases
What type of flow waveform coincides with arterial circulation?
Pulsatile Flow
(Accelerates/Decelerates with contraction)
What are the "positive" components of the Pouisille's equation?
(What is in the numerator?)
(Full Equation: 𝑄 = Δ𝑃𝜋𝑟^4/8𝜂𝐿)
(An increase in pressure gradient and radius promote a faster flow rate)
What type of flow has a parabolic pattern?
Laminar flow
(Due to the center of the vessel being the fastest)
Where would you find a negative hydrostatic pressure in relation to the heart?
Anywhere above the heart
(Pressure is negative because gravity is working with the blood to bring it back to the heart)
What kind of flow occurs just distal to the stenosis?
Turbulant flow
What type of flow waveform would show with the lack of respiration?
Continuous Flow Waveforms
What is the continuity equation, and what does it explain?
Q=vA
The continuity equation explains that flow rate remains constant despite changes in velocity or area.
What is used to quantify the degree of turbulence in blood flow?
Reynold's number
(Turbulance flow has a Reynold's number of >2,000)
Inspiration increases venous return from where?
From the upper extemities
What is collateral flow?
An alternative route that is formed due to the high pressure proximal to a stenosis
(Collaterals indicate chronic/acute conditions because they take time to form)
What type of flow waveform coincides with venous circulation?
Phasic Flow
(Accelerates/Decelerates with respiration)
What are the "negative" components of the Pouisille's equation?
(What is in the denominator?)
8, 𝜂, 𝐿
(Full Equation: 𝑄 = Δ𝑃𝜋𝑟^4/8𝜂𝐿)
(An increase in viscocity and length would decrease the flow rate)
What is the type of flow that occurs when blood flow is no longer parallel to the vessel walls but remains in the correct direction?
Disturbed flow
(Disturbed flow is a subcategory of laminar flow)
What is the term for the pressure difference across the inside and outside of veins?
Transmural Pressure
What is the minimum percentage decrease of the cross sectional area or percentage decrease of the vessel diameter to be considered a critical stenosis?
75% decrease of cross sectional area
50% decrease in diameter
What type of "phasic" flow has high resistance and has low diastolic flow with some flow reversal?
Multiphasic Flow
(Triphasic and Biphasic)