Cardio Physio

Question 1

2 circuits of Vascular system

Answer 1

1. Systemic circuit (skin, skeletal, splanchnic, renal, coronary, cerebral)
2. Pulmonic circuit (Lungs) = Low pressure

Question 2

The Heart as a pump

Answer 2

• Generator of pressure
• Distributes blood @ steady flow to whole body DUE to constant pressure across variety of pressures
• Delta P is constant

Question 3

Hemodynamics

Answer 3

• In an ideal system–>Delta P=FxR
• Delta P = Change in pressure across 2 points
• F = Flow
• R = Resistance between 2 points
• Used in Vessel performance

Question 4

Ohm’s law

Answer 4

• Delta V=IxR
• Is applicable at any time makes NO assumptions on vessels being rigid/compliant
• R has to be constant

Question 5

Resistance in Circulation

Answer 5

• Resistance & flow can fluctuate
• Resistance is calculated in parallel or series
• Parallel= more added total resistance decreases
• Series=proportional to each individual vessel (artery, arteriole, capillaries, etc..)

Question 6

Flow in Circulation

Answer 6

• F = Q = Delta P/R
• F = Q = Cardiac output
• DIRECTLY proportional to change in pressure (with a constant R)
• INDIRECTLY proportional to change in resistance

Question 7

Poiseulle’s Law

Answer 7

• Flow DIRECTLY proportional to axial pressure difference
• Flow DIRECTLY proportional to 4th power of vessel radius
• Flow is INVERSELY proportional to vessel length & viscosity of fluid
• This law makes the assumptions that: Flow is laminar, Nonpulsatile, Viscosity is constant

Question 8

Blood flow in Realtime

Answer 8

• Ohm’s law: Flow (Q) increases linearly with increasing driving pressure
• High flow rates = Turbulent flow not energetically favorable
• Flow increases along with Delta P, DUE to R increasing with flow
• Blood flows from high pressure to low pressure

Question 9

Reynolds Number

Answer 9

• Turbulent flow = Greater than 3000 (Bruits)
• Laminar flow = less than 2000
• Viscosity is variable and effects overall flow (anemia lowers hematocrit = low blood vis.)
• Reduction in vessel diameter=turbulent flow
• V=Q/pieR2: radius decreases & velocity increases by power of 2

Question 10

Vessels, branching and circuits

Answer 10

-At each lvl of branching parameters change:
># of vessels at each lvl
>Radius
>cross sectional area (daughter vessel always exceeds cross sectional area of parent)
>Mean linear velocity of flow
>Blood volume
>Structure of vascular wall (elastic)