System Overview

Question 1

Fetal circulatory modifications increase/minimize: pulmonary blood flow

Answer 1

minimize

Question 2

What blood is preferentially vented to the left atrium via the foramen ovale in fetal circulation?

Answer 2

umbilical vein blood (more oxygenated and goes to the brain) vs. svc blood which goes through the rv, pulmonary artery, ductus arteriosus to the descending aorta

Question 3

4 circulatory changes at birth

Answer 3

1. decrease in pulmonary vascular resistance
2. increased venous return from lungs
3. closure of ductus arteriosus
4. increased RV compliance

Question 4

What stimulates closure of the ductus arteriosus?

Answer 4

increased o2 concentration and withdrawal of pge2

Question 5

What is the importance of increased venous return from lungs in the days after birth?

Answer 5

left heart filling opposes flow across foramen ovale

Question 6

Which cardiac parameter? volume of blood/unit time

Answer 6

cardiac output

Question 7

Which cardiac parameter? cardiac output normalized to body size by dividing by body surface area

Answer 7

cardiac index (2.5-3.5 is normal)

Question 8

Which cardiac parameter? volume of blood ejected during each heart beat

Answer 8

stroke volume (100 ml/beat is normal)

Question 9

Which cardiac parameter? pressure in arterial system

Answer 9

systemic arterial pressure

Question 10

Which cardiac parameter? resistance to flow through vascular system

Answer 10

vascular resistance

Question 11

Which cardiac parameter? percent of blood volume in left ventricle at end diastole that is ejected during systole

Answer 11

left ventricular ejection fraction/LVEF = crude measure of left ventricle contractile performance (normal = 55-70%)

Question 12

Which cardiac parameter? axial pressure difference in a vessel or series of vessels

Answer 12

driving pressure

Question 13

Which cardiac parameter? radial pressure difference

Answer 13

transmural pressure

Question 14

Which cardiac parameter? pressure due to gravitational effect

Answer 14

hydrostatic pressure

Question 15

2 parameters that affect flow resistance

Answer 15

1. vessel radius

2. blood viscosity

Question 16

Which cardiac parameter? relationship between pressure distending a structure and its volume

Answer 16

compliance (dV/dP)

Question 17

Rigid structures have high/low compliance

Answer 17

low

Question 18

Highly/non compliant structures distend easily

Answer 18

highly

Question 19

What physical phenomenon describes the change in force required to maintain constant compliance as vessel size increases?

Answer 19

laplace relationship

Question 20

Which physical principle? relationship between pressure gradient/driving pressure and flow velocity

Answer 20

bernoulli –> change in pressure is quadratically related to velocity (c = p +.5pv^2) –> enables you to determine severity of obstruction caused by diseased valve or severity of stenosis

Question 21

Which physical principle? relationship between transmural pressure, radius, and wall force

Answer 21

laplace –> larger radius chambers require greater wall force to generate a given pressure (t = p * radius) –> risk of rupture for aneurysms and determines contractile performance of pathologically enlarged hearts

Question 22

Which physical principle? relationship between pressure drop/driving pressure and flow of fluid in a tube in relation to viscosity and tube diameter/length

Answer 22

poiseulle –> pressure regulated by changing flow resistance via modulation of arteriolar diameter (flow = change in pressure * pi * r^4/9nl) –> increased blood viscosity impairs circulatory performance

Question 23

Which physical principle? relationship between flow velocity, blood viscosity, vessel diameter, and flow turbulence

Answer 23

reynolds (v=Kn/pr) –> determines laminarity/turbulence in generation of cardiac murmurs and bruits

Question 24

Which physical principle? relationship between voltage, resistance, and current flow in a DC circuit

Answer 24

current = voltage/resistance –> flow (q) = pressure/resistance