0506 Flow and Pressure in Vessels Flashcards

 be cognisant of a few physical principles that relate flow, pressure and velocity; among them Ohm’s law;  realise that arteries are cardiofugal and veins cardiopetal vessels;  know the notion of blood pressure;  appreciate factors determining resistance, pressure, flow, and its characteristics;  understand the distal impact of a resistance change;  recognise why some vascular beds display different characteristics.

1
Q

Describe the relative blood pressures in each of these systems; arterial, venous, lymphatic (in terms of high or low)

A

Aterial system = high pressure. Venous system = low pressure. Lymphatic system = very low pressure

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2
Q

What is the primary role of circulation

A

The primary function is the continuous flow (and therefore transport) of blood to all tissues. This supplies O2, CO2, nutrients, metabolites, water, cells, proteins, hormones, heat, etc

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3
Q

What is the formula for Flow and Pressure

A

Flow = volume / time

Pressure = Force / area (or energy per volume)

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4
Q

What is the formula for Ohms law (in terms of circulation))

A

Mean arterial pressure = total peripheral resistance x cardiac output

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5
Q

What is the formula for total resistance of vessels in series and parallel

A

Series (R.total = sum of all resistances of the vessel). Parallel (1/R.total = 1/Ra + 1/Rb +1/Rc, etc)

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6
Q

What is the affect of increasing L (vessel length), r (vessel radius) and n (blood viscosity) on Resistance and Flow

A

Increase; L = more resistance, less flow. r = less resistance, more flow. n = (more resistance, less flow)

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7
Q

In a closed system (i.e. systemic circulation) with constant flow, what is the effect of increasing and decreasing vessel radius on velocity of fluid

A

Increasing radius = smaller velocity. Decreasing radius = larger velocity.

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8
Q

What are the two types of flow? What is the relevance of vessel size to type of flow

A

Laminar and turbulent flow. Lamina occurs < critical velocity < Turbulent flow occurs. The larger the vessels the higher the value of critical velocity.

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9
Q

Are larger vessels exposed to more or less tension than smaller vessels

A

Larger vessels are exposed to more tension

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10
Q

Which vessel(s) determine the biggest amount of resistance in the circulation

A

The arterioles

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11
Q

At which location occurs the biggest change in resistance

A

Precapillary areas

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