09 Starling

  • preload can be either pressure or volume
  • the more you load the ventricle with fluid, the more it'll pump
  • allows heart to pump with higher venous return, otherwise blood would pool in venous system

  • shifting to left: at same preload, more stroke volume

  • TPR = SVR = peripheral resistance

Venous Return

  • venous return = CO: blood returned to heart = blood pumped out of heart
  • X axis could be either venous return or CO
  • as CO increases, RAP falls

  • RAP equal to venous pressure from SVC/IVC
  • Increased CO: pulls more blood out of RV/RA, lowers RA pressure

  • how actually drawn

  • MSFP defined by volume in venous system and tone of veins in body
  • MSFP = pressure when CO is 0

  • green: right shift

  • increased TPR: same CO leads to lower venous pressure and lower RAP

Combined Curves

HF

  • lower contractility: shift to right of starling curve
  • fluid retention: increased fluid volume, shift venous return curve right
  • increased TPR: changes slope of venous return curve

  • lower CO and higher RAP

Hemorrhage

  • blood loss: shift venous return left
  • TPR up: slope left
  • contractility: starling curve up

  • lower CO, lower RAP

Exercise

  • venous contraction from sympathetic activation
  • venous contraction: move to right
  • decreased TPR: slope right
  • higher CO in exercise

Fistula

  • same as exercise
  • high output heart failure

  • nl: arteriole connectes arteries and veins. Arteries have high resistance
  • AV: bypass from A to V with low resistance
  • result: TPR down

Vasopressors