Physiology Exam 2
Terms
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- Plasma Constituents
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Electrolytes (Na, K, Ca, Mg...)
Proteins (Albumins, Globulins, Fibrinogen)
Gases - CO2, O2, N2
Glucose, Cholesterol, Urea - Flow Rate
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Amount of Vol flowing in a time interval
Controlled by pressure difference at beginning and end of vessel
Also depends on diameter of the vessel (lg=more flow)
Inversely proportional to resistance (flow=1/R)
Determined by MAP (depends on TPR and CO)
Length of Vessel inversely influences Flow
Viscosity inversely influences flow
****Take home - A very little amount of constriction on a vessel causes HUGE decreases in Flow - Pressure
- Driving force that is applied to make a fluid flow (pressure difference) High to low
- Resistance
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Property of a fluid to resist the impostition of flow (caused by fluid's viscosity)
Resistance = 1/radius to the fourth power
Resistance is summative if in a serial arrangement, although if R1+R2+R3, R2 is the greatest resistance, then Rtotal = R2 - Principle 1
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Blood flows according to its pressure gradient
MAP=TPR X CO - Conductance
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Conductances are additive in a parallel arrangement
Capillary beds have little flow resistance b/c of the great # of capillaries which sum their conductance and therefore decrease/limit resistance - Longitudinal Pressure Profile
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The segment with the highest resistance experiences the greatest percent pressure change
ie. Carries 80% of resistance, then sees 80% of pressure change - Arterioles
- Dominant Resistance vessels
- Transmural Pressure is influenced by:
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1. Pumping pressure of the heart (pressure gradient from left to right heart)
2. Compliance of Blood Vessels (elasticity) The more compliant, the more blood storage
3. Hydrostatic Pressure - Velocity and Capillaries
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Blood flow and velocity is slowest here b/c of the greater combined cross section of all capillaries
Good for Diffustion - Laminar vs. Turbulent Flow
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Laminar - smooth parallel (energetically most favorable)
(most blood flow)
Turbulent - Non-parallel movements; FAST, heart beat; determined by velocity, diameter and viscosity - Heart circulation
- Corotid Artery
- Equation for Flow
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Flow = 1/R x Delta P
1/R= Conductance
P = pressure - Flow Resistance Equation
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R ~ nL/r to the 4 fourth
R=resistance
n = viscosity
L = Length
r = radius - Combined Resistance in Parallel Arrangement
- is reversely addiditive; hence it decreases in organs/capillary beds
- Serial Arrangements
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Resistance is additive
Conductance is inversely additive (hence it decreases)
If you constrict just one vessel, you greatly reduce overall flow - Serial vs Parallel arrangement
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Each class of vessels (arteries, capillaries, and veins) are arranged serially
Within each serial, the venules are arranged in parallel - Resistance of Dominant segment
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If the resistance in the dominant high resistance segment changes, this will change the overall pressure profile in a serial arrangement
ie. vasodilation - does not effect upstream artery but does increase P in downstream capillaries (hose)
ie. vasoconstriction - decreases P in downstream cappilaries and increases P in upstream Artery