CVS 4 Flashcards

1
Q

What does the Bernoulli principle state?

A

Bernoulli’s Equation states that the work done on a fluid as it moves from one place to another is equal to the change in its mechanical energy.
∆𝑊= ∆𝑃𝐸+ ∆𝐾𝐸
(work energy relation)

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2
Q

When a liquid flowing through a pipe of two regions of different diameters, the velocity of the liquid will ____.

A

change.

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3
Q

The change in velocity involves an acceleration, a, which means there is a…

A

net force acting upon the liquid (F = ma).

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4
Q

𝑃+1/2 𝜌𝑣^2+𝜌𝑔ℎ=𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
What does each represent?

A

Where P is the external pressure, 1/2 𝜌𝑣^2 is the kinetic energy and 𝜌𝑔ℎ is the fluid pressure (potential energy).

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5
Q

Bernoulli’s Equation can only be used given the following assumptions:

A
  1. Fluid is incompressible (i.e. its density does not change).
  2. Fluid is non-viscous (i.e. no appreciable frictional effects).
  3. Fluid flow is streamline
    .
  4. Flow velocity at a fixed point does not change rapidly (i.e. steady state conditions apply).
    i.e. Bernoulli’s Equation is only an approximation
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6
Q

If Velocity Increases –>
If Velocity Decreases –>

A

Pressure Decreases
Pressure Increases

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7
Q

P + 𝜌gh is the _______ term.

A

pressure

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8
Q

½ 𝜌v2 is the ______ term.

A

velocity

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9
Q

An aneurysm is a

A

swelling in a blood vessel which may rupture – can be fatal.

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10
Q

Aneurysms usually occur due to a…

A

weakness in the wall of the vessel which ‘bubbles’ due to the fluid pressure within the vessel.

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11
Q

Once an aneurysm starts, it will continue to grow until:

A
  1. It cannot grow anymore because of an obstruction (bone or tissue obstruction or stent),
  2. The elastic tension in the vessel wall is large enough to contain it,
  3. It bursts.
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12
Q

The fact that the aneurysm continues to grow is a direct consequence of the Continuity Principle and the Bernoulli Principle, why?

A
  1. Since the fluid pressure acts perpendicular to the surface, it will cause the vessel wall to swell in the region of weakness
  2. As the cross-sectional area gets bigger, the velocity decreases (Continuity Equation).

As the velocity decreases, the fluid pressure increases (Bernoulli Principle).

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13
Q

Detected aneurysms may be treated by clamping the blood vessel or using a…

A

stent.

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14
Q

A stent is a…

A

cylindrical ‘tube’ which can be placed within the lumen of the blood vessel at the location of the aneurysm.

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15
Q

A stent will contain the blood (allowing it to flow through it), but stop…

A

the fluid pressure from acting directly on the vessel wall where the aneurism exists.

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16
Q

High blood velocity past the constriction causes low BP in left vertebral artery. A reverse (downward) blood flow can then result in…

A

Subclavian Steal Syndrome which in turn results in Transient Ischaemic Attack.

17
Q

Vessels in circulatory system suffers one of two fates:

A

1- Aneurysm
2- Obstruction due to clot

18
Q

The value of g is critical, and if the body is exposed to external accelerations, then the pressure…

A

in each of the arteries will change [by r(g +/- a)h if the acceleration is in the up or down direction] – this is directly analogous to Effective Weight.

19
Q

One-way valves in blood vessels passing through muscle help in…

A

venous return.

20
Q

One-way valves keep blood from…

A

flowing backwards.

21
Q

Defective valves means…

A

pooling of blood in leg veins (Varicose )

22
Q

The use of the Bernoulli Principle to draw a second fluid into the initial fluid is called…

A

entrainment.

23
Q

As the main fluid flows from the wider tube into the constricted tube, its flow speed…

A

increases because the cross-sectional area has decreased (Continuity Principle). Consequently, the fluid pressure in the constricted region decreases.

24
Q

If the vertical tube is connected to a reservoir of other fluid, then this will be ‘entrained’ into the main fluid provided the…

A

pressure in the constricted region is lower than that in the fluid reservoir.

25
Q

In aspirators, if the pressure decreases below normal atmospheric pressure, then…

A

air will be ‘sucked in’ through the vertical open tube.

26
Q

A vacuum aspirator pump is essentially a…

A

pipe with a narrowing in it.
As air flows through that narrowing, it speeds up and its pressure drops, A tiny opening in the side of the narrowing allows water or air to enter the high-speed flow.