Blood Flow Pressure/Resistance Flashcards

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1
Q

What major factors affect Blood flow and pressure?

A
  • Cardiac Output
  • Compliance
  • Volume
  • Resistance
  • Vessel Length
  • Vessel Diameter
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2
Q

Define Perfusion.

A

∆P along a vessel access.
Pressure difference upstream to
downstream. Pressure loss.

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3
Q

Compare Laminar and Turbulent flow?

A

Laminar Flow: Fluid elements in any given lamina remain in that lamina as fluid moves longitudinally along the tube.

Turbulent: Fluid elements in any given lamina remain in that lamina as fluid moves longitudinally along the tube.

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4
Q

What is Reynolds numb Er, and how is it calculated?

A
  • Ratio of inertial to viscous forces for a fluid flowing through a cylinder
  • Determines laminar vs Turbulent flow
  • N = pDv/n
  • > 3000 turbulent
  • <2000 laminar
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5
Q

Murmur

A

when turbulence occurs in the heart

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6
Q

Bruit

A

when turbulence occurs in the vessel.

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7
Q

What is Shear Stress?

A

As blood flows through a vessel, it exerts a force on the vessel wall
parallel to the wall.

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8
Q

What is the Two plates model of Viscosity?

A

provides there are two
plates with fluid in-between.
• Two criteria: 1. fluid does not glide along but is in contact. An
adhesive force operates between fluid + plates. 2. flow is laminar. Thin layers + no turbulence
• Lower plate does not move + upper plate drifts aside

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9
Q

How are Velocity and Flow of a fluid related in a rigid tube?

A

V = Q/A (A = SA)

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10
Q

What is the determining factor for how erythrocytes flow in vessels?

A
  • Flexibility of RBCs
  • At low flow rates like in microcirculation rigid particles do not migrate toward the central axis of a tube and flexible
    particles do.
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11
Q

How are viscosity and shear rate related?

A

apparent viscosity of blood diminishes as the

shear rate is increased

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12
Q

How does Fibrinogen affect flow?

A
  • Large plasma protein

- High fibrinogen causes aggregation —> more viscous blood —> change in flow

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13
Q

What law is used to determine flow of a fluid through cylindrical tube?

A
  • Poiseulle’s law

- Q = piPr^4 / 8nl

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14
Q

What are the two categories of superficial stress to blood vessels?

A

Circumferential: due to pulse pressure variation inside the vessel. Intravascular hydrostatic pressure produces not only
circumferential but also normal tensions

Shear Stress: Due to blood flow

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15
Q

What are major vasodilators and vasoconstrictors?

A

Vasodilators:

  • Low O2, High CO2, INC metabolic acids, High NO, High L, High H+
  • Inflammation
  • INC blood flow
  • relaxed precapilary sphincters

Vasoconstrictors:

  • Prostaglandins; Activated platelets; Leukocytes, endothelium
  • Cinricted precapilary sphincters
  • DEC blood flow
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16
Q

What are the endocrine regulators of Blood pressure?

A

Renal: Erythropoeitin; RAS
Adrenal: Catecholamines
Brain: Antidiuretics
Heart: ANP

17
Q

How is blood pressure estimated?

A

CO x TPR

18
Q

What is the action of Spironolactone?

A

Blocks Aldosterone receptors in kidney

19
Q

What is the main function of Alpha 1 receptors?

A

Smooth muscle contraction

20
Q

What is the main function of Alpha 2 receptors?

A

Inhibits secretory activity

21
Q

What is the main function of Beta 1 receptors?

A

Increases HR, Conduction, and contractility

22
Q

What is the main function of Beta 2 receptors?

A

Inhibits smooth muscle contraction, stimulates GNG, Glycgenolysis, lipolysis, secretion of glucagon, and RAAS

23
Q

What are the two controls for arterial blood pressure?

A

Neural: Baroreceptor reflex

Hormonal: RAAS

24
Q

What are the two primary effects of Angiotensin II?

A
  • Stimulates Adrenal cortex to synthesize and secrete Aldosterone
  • Causes Vasoconstriction of arterioles