Intrinsic and extrinsic regulation of the heart and vascular system

Question 1

describe the Frank-Starling law of the heart in intrinsic regulation

Answer 1

1. relationship between EDV, contraction strength and SV
2. intrinsic mechanism:
   - varying degree of stretching of myocardium by EDV
   - as EDV increases: myocardium is increasingly stretched, and contracts more forcefully
3. as ventricles fill, the myocardium stretches
   - increases the number of interactions between actin and myosin
4. allows more force to develop
5. explains how the heart can adjust to rise in TPR

Question 2

what is increased contractility caused by

Answer 2

caused by sympathetic nerve stimulation

Question 3

what affects regulation of venous return

Answer 3

1. increases in sympathetic activity
2. compression from skeletal muscles
3. ventilation