lecture 12: cardiac output

Question 1

normal heart rate

Answer 1

60-100bpm

Question 1

normal stroke volume

Answer 1

50-100mls

Question 2

cardiac output equatio

Answer 2

CO = HR X SV

Question 3

stroke volume equation

Answer 3

SV = End Diastolic Volume (EDV) - End Systolic Volume (ESV)

Question 4

preload

Answer 4

force that stretches the cardiac muscle prior to contraction. before contraction, more blood returns to heart, which increase pressure causing ventricles to stretch to accomodate. increase in preload increases stroke volume

Question 5

frank starling law

Answer 5

“the energy of contraction of the ventricle is a function of the
initial length of the muscle fibres comprising its walls.”
*meaning, increasing the stretch of the ventricles will increase the force of contraction”

Question 6

factors affecting preload

Answer 6

∆ Venous return
∆ Blood volume
∆ Filing time
∆ Respiratory pump
∆ Compliance eg MI damage

Question 7

contractility

Answer 7

the force of contraction of the heart. its peroformans at a given preload and afterload. more contractility means more calcium for contraction means increase in stoke volume. norepinephrine through sympathetic increases stroke volume

Question 8

afterload

Answer 8

The amount of pressure that the heart needs to exert to eject the blood during ventricular contraction. pressure in the aorta that the pressure in ventricle needs to overcome. increase in afterload increases ESV and deceases SV