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.
Describe the relative blood pressures in each of these systems; arterial, venous, lymphatic (in terms of high or low)
Aterial system = high pressure. Venous system = low pressure. Lymphatic system = very low pressure
What is the primary role of circulation
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
What is the formula for Flow and Pressure
Flow = volume / time
Pressure = Force / area (or energy per volume)
What is the formula for Ohms law (in terms of circulation))
Mean arterial pressure = total peripheral resistance x cardiac output
What is the formula for total resistance of vessels in series and parallel
Series (R.total = sum of all resistances of the vessel). Parallel (1/R.total = 1/Ra + 1/Rb +1/Rc, etc)
What is the affect of increasing L (vessel length), r (vessel radius) and n (blood viscosity) on Resistance and Flow
Increase; L = more resistance, less flow. r = less resistance, more flow. n = (more resistance, less flow)
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
Increasing radius = smaller velocity. Decreasing radius = larger velocity.
What are the two types of flow? What is the relevance of vessel size to type of flow
Laminar and turbulent flow. Lamina occurs < critical velocity < Turbulent flow occurs. The larger the vessels the higher the value of critical velocity.
Are larger vessels exposed to more or less tension than smaller vessels
Larger vessels are exposed to more tension
Which vessel(s) determine the biggest amount of resistance in the circulation
The arterioles
At which location occurs the biggest change in resistance
Precapillary areas
