Hemorrhage and Exercise Flashcards
Systemic Circulation
each segment of the vascular system has a specific purpose
Plotting arterial pressure (Pa or MAP) versus flow (CO) –> slope
= resistance (TPR)
Ca
= deltaVolume/deltaPressure
Voa
= unstressed arterial volume (amount of blood in vessels before pressure starts to increase)
Plotting arterial pressure (Pa or MAP) versus Arterial volume (Va) –> slope
= 1/Ca
Vov
= unstressed venous volume (amount of blood in vessels before pressure starts to increase)
Va =
Voa + CaPa
Vv =
Vov + CvPv
Plotting venous pressure (Pv) versus Venous volume (Vv) –> slope
= 1/Cv
Assume constant blood volume, Vt
= Va + Vv
Venous return curve
The slopes (and unstressed volumes) change due to the ANS (alpha1-receptors on blood vessels) TPR, Cv (and to lesser extent Ca), and Vtotal are all important
Where is equilibrium?
CO = Venous Return, in quadrant 1, the intersection of the heart (Starling Curve) and vessels (Venous Return Curve)
What happens during hemorrhage
loos of volume, venous curve shifts downward with no change in slope (decrease in MSFP), baroreceptors respond with increased contractility (increase in contractility and decrease in Cv venous constriction)
During hemorrhage
Decrease in capillary pressure
Stroke volume increases almost to maximal levels immediately upon exercising
EDV increase due to increase venous return, ESV decrease due to increased contractility, SV increase due to increase EDV and decrease ESV, Ejection fraction increase due to increase in SV/EDV
HR increases
linearly with work
SV increases
small amount early on
CO increases
HR * SV (linear)
MAP increases
CO increases * decreased TPR
TPR decreases
due to vasodilatio
Aerobic training
increases SV, heart gets stronger
What happens during exercise
decreases in systemic circulation (decreased TPR, Cv) and increases i the heart (increased HR and contractility)
Hemorrhage short term
baroreflex activates ANS
Hemorrhage long term
fluid shifts into capillaries, replace volume (day), make new RBC (weeks)
Exercise short term
Increase HR, contractility, and venous return (decreased Cv), increased baroreceptor set point
Exercise long term
Increase stroke volume, decreased HR –> stronger, healthier heart
