Flashcards in Cardio - Physio (Resistance, pressure, flow, & Cardiac/vascular function curves) Deck (23)

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1

## What is the equation that relates resistance, pressure, and flow in the cardiovascular system? On what is this equation based?

### Pressure gradient or driving pressure (deltaP) = Flow (Q) x Resistance (R); Ohm's law (V = I*R or I = V/R)

2

## What is/are the equation(s) that defines/characterizes resistance? To what factors does resistance relate, and how so?

### Resistance = driving pressure (deltaP) / flow (Q) =( (8(eta)(viscosity) x length) / (pi)(radius)^4 ; See FA p. 255 for equation ; Based on equation, resistance is directly proportional to viscosity and vessel length & inversely proportional to radius to the 4th power

3

## How do you calculate the total resistance of vessels in series? What about in parallel?

### TOTAL RESISTANCE OF VESSELS IN SERIES = R1 + R2 + R3...; 1/TOTAL RESISTANCE OF VESSELS IN PARALLEL = 1/R1 + 1/R2 + 1/R3...

4

## On what does viscosity mostly depend? What are 3 conditions in which viscosity is increased?

### Hematocrit; (1) Polycythemia (2) Hyperproteinemic states (3) Hereditary spherocytosis

5

## Again, on what does viscosity mostly depend? What is a condition in which viscosity is decreased?

### Hematocrit; Anemia

6

## Again, what is the Ohm's law based equation that applies to the cardiovascular system? What role does pressure gradient play?

### Q = deltaP / R; delta P = Pressure gradient, which drives flow from high pressure to low pressure

7

## What accounts for most of the total peripheral resistance? In turn, what does/do this/these regulate?

### Arterioles; Capillary flow

8

## What effect does inotropy have on cardiac/vascular function curves?

### Changes in contractibility --> altered CO for a given RA pressure (preload)

9

## What are 2 examples of positive inotropy?

### (1) Catecholamines (2) Digoxin

10

## What are 2 examples of negative inotropy?

### (1) Uncompensated heart failure (2) Narcotic overdose

11

## What effect does venous return have on cardiac/vascular function curves?

### Changes in circulating volume or venous tone --> altered RA pressure for a given CO. Mean systemic pressure (x-intercept) changes with volume/venous tone

12

## What are 2 examples of increased venous return?

### (1) Fluid infusion (2) Sympathetic activity

13

## What are 2 example of decreased venous return?

### (1) Acute hemorrhage (2) Spinal anesthesia

14

## What effect does total peripheral resistance have on cardiac/vascular function curves?

### Changes in TPR --> altered CO at a given RA pressure; however, mean systemic pressure (x-intercept) is unchanged

15

## What is an example of increased TPR?

### Vasopressers

16

## What are 2 examples of decreased TPR?

### (1) Exercise (2) AV shunt

17

## What represents mean systemic pressure on cardiac/vascular function curves? How does venous return versus TPR affect mean systemic pressure?

### Mean systemic pressure (x-intercept) changes with volume/venous tone; Mean systemic pressure (x-intercept) is unchanged with TPR

18

## What does the intersection of cardiac and vascular function curves represent?

### Intersection of curves = operating point of heart (i.e., venous return and CO are equal)

19

## What are the axes for cardiac and vascular function curves?

### x-axis: RA pressure or EDV; y-axis: Cardiac output/Venous return

20

## Draw cardiac and vascular function curves in the following contexts: (1) operating point of heart (2) positive inotropy (3) negative inotropy.

### See p. 269 in First Aid 2014 for graph on left

21

## Draw cardiac and vascular function curves in the following contexts: (1) operating point of heart (2) increased volume/venous tone (3) decreased volume/venous tone.

### See p. 269 in First Aid 2014 for graph in middle

22

## Draw cardiac and vascular function curves in the following contexts: (1) operating point of heart (2) increased TPR (3) decreased TPR.

### See p. 269 in First Aid 2014 for graph on right

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