Lecture 10- Cardiac output

Question 1

time period of AS, VS and relaxation period?

Answer 1

AS- 0.1s
VS- 0.3s
Relaxation-0.4s

Question 2

5 parst of cardiac cycle?

Answer 2

Atrial Contraction
Isovolumetric contraction
ventricular ejection
isovlometric relaxation
ventricular filling

Question 3

EDV and ESV

SV

Answer 3

EDV- 120-130
ESV- 60
SV-70

Question 4

ejection fraction?

Answer 4

the fraction of EDv that is ejected during an average heart beat. Equal to the SV/EDV

Question 5

Cardiac Reserve

Answer 5

the difference between MAX CO and RESTING CO

average is 4-5x but athletes 7-8x

Question 6

Preload

Answer 6

the degree of stretch on the heart before it contracts

Question 7

contractility

Answer 7

the forcefulness of contraction of individual ventricular muscle fibers. SV increases when a positive intropic agent is present. They promote Ca2+ inflow which strengthens subsequent muscle fibre contraction.

Question 8

Afterload

Answer 8

the pressure that must be exceeded before ejection of blood from the ventricles can occur.

Question 9

Venous Return

Answer 9

the volume of blood returning to the heart from the vasculature every min and is linked to CO

Question 10

Frank-Starling Law

Answer 10

the energy of contraction of the ventricles(and cardiac myocyte) is a function of the initial length of the muscle fibers comprising its walls. DETERMINED BYT THE PRELOAD

Question 11

4 phases of the pressure-volume loop?

Answer 11

1. Mitral valve opening, and filling
   (SUCTION EFFECTS of muscle cause an initial pressure dip)
2. mitral valve closes at slightly higher pressure
3. increase in pressure till aortic valve opens
4. ejection phase till aortic valve closes

Question 12

Stroke volume regulation

Answer 12

1. Instrinsic regulation- force of contraction governed by the pre-load.
2. Extrinsic regulation- determined by the activity of the ANS and circulation of various hormones