2. CV Function Flashcards
What happens to the blood that is leftover from net filtration and reabsorption?
Goes to the lymph system
How does plasma volume shift w/ weight training?
Plasma volume drops by 20% at onset of lifting, then fluid moves back into circulatory system after about an hour
Equation for blood flow to an organ
Q(organ) = ΔP/R(organ)
- ΔP = pressure driving it in vs. pressure at the end of the organ
- R(organ) = summed resistance of all vasculature
Flow rate in a parallel resistance network
Can tailor flow to specific tissues and organs b/c of different resistances
Flow rate in a series resistance network
- Flow rate is dictated by highest resistance (narrowest tubes)
- Pressure diminishes further down series –> organs later in series unhappy b/c less pressure = less flow to organ
What is total peripheral resistance?
Summed resistance to forward flow in systemic circulation
Equation for MAP
MAP = 2/3 DBP + 1/3 SBP
What is the highest blood pressure heard? Lowest?
- Highest = systolic
- Lowest = diastolic
Equation for cardiac output of the CV system
Qsystem = MAP/TPR -MAP = ΔP(a-v)
What causes cardiogenic shock?
Myocardial failure
What causes hypovolemic shock?
Fluid loss
What causes anaphylactic/septic shock?
Vasodilator release
What causes neurogenic shock?
Decrease in sympathetic nerve activity
Is there a diff in flow rate though the left vs. right sides of the heart?
No, they are equal
What is the relative pressure and resistance in systemic circulation?
- High pressure (avg ~100 mmHg)
- High resistance to flow
What is the relative pressure and resistance in pulmonary circulation?
- Low pressure (avg ~20 mmHg)
- Low resistance to flow
What is the driving force for blood flow?
Pressure gradient created by the heart
What primarily regulates the blood flow to each organ?
Resistance properties of its arterioles
What is the primary cause of cardiac output?
Venous return
What are the physiological determinants of cardiac output?
Stroke volume and heart rate
What determines heart rate?
Depolarization properties of the pacemaker cells
What factors affect preload?
Frank-Starling law, venous return
What determines afterload?
Arterial pressure
On a pressure-volume loop, what denotes preload?
End-diastolic volume
On a pressure-volume loop, what denotes afterload?
Aortic diastolic pressure
