Lecture 9-CV Physiology

Question 1

indicator dilution method is a way to find ____

Answer 1

CO

Question 2

Fick’s principle

Answer 2

• A = Q x [a-v]

- CO = O2 cons/[a-v] (of O2) where a = systemic O2 and v = PA O2

Question 3

Plethysmography

Answer 3

• rate of change of an appendage volume when venous circulation is cut off
• measures blood flow

Question 4

Doppler flow meter

Answer 4

• measures difference in transit time of ultrasonic signals (remember MCAT doppler effect equation) sent in and against the flow direction
• based on the calculation of velocity and flow
• based on the velocity of fluid across a cross sectional area
• *if dimensions of the vessel are known then this can be determined

Question 5

Electromagnetic flow meter

Answer 5

• measures (voltage-induced) potential difference when the electrolyte fluid passes through a magnetic field (Faraday’s law)
• voltage is proportional to velocity
• velocity and cross sectional area are the basis for calculating the flow

Question 6

Electrocardiography

Answer 6

• measures through sound waves the interfaces between tissue and fluid and thus can measure how the heart moves
• used to measure CO
• dimensions gathered approximate SV and therefore CO and HR