Cardiovascular Part 3

Question 1

Stroke Volume

Answer 1

Volume of blood ejected per cardiac cycle.

Difference between end diastolic
volume (EDV) and end systolic volume (ESV)

SV = EDV - ESV

SV = 135 – 65 = 70 ml

Question 2

SV influenced by

Answer 2

1. Preload = EDV
2. Sympathetic nervous system
3. Afterload: Ventricular force required to open the semilunar valves during systole

Question 3

CO

Answer 3

HR x SV

Question 4

Frank-Starling Mechanism

Answer 4

Ability of the heart to change its force of contraction and therefore stroke
volume in response to changes in venous return (myocardial stretch)

Venous return affects EDV
– ↑ venous return = ↑ EDV
– ↑ EDV = ↑ ventricular
myocardial fiber stretch
– Slow heart rate = ↑ EDV
– Exercise = ↑ EDV

↑ EDV = ↑ ventricular myocardial fiber stretch = ↑ x-bridges = ↑ force = ↑ SV (optimal alignment of the actin and myosin)

Question 5

Three things contribute to the resistance:

Answer 5

1. Blood viscosity
   * Volume
   * # of RBC
2. Total blood vessel length
   * how much tubing is needed
   * body mass
3. Blood vessel diameter
   * relaxed vessels decrease resistance
   * constricted vessels increase resistance
   * biggest contributor to minute-to-minute control of
   resistance 22

Question 6

pulmonary arteries

Answer 6

carry deoxygenated blood to
the lungs to get oxygenated

Question 7

Plasma

Answer 7

carries blood cells, proteins, nutrients, metabolic wastes, and other molecules being transported around the body

Question 8

Blood

Answer 8

• Cells
• Cell fragments
• Plasma (mostly water)

Question 9

Ejection Fraction

Answer 9

EF = SV / EDV

The ejection fraction (EF) formula equals the amount of blood pumped out of the ventricle with each contraction (stroke volume or SV) divided by the end-diastolic volume (EDV), the total amount of blood in the ventricle.