CV system Flashcards
Function of CV system
Provide tissues with an adequate supply of O2 and nutrients
Remove unwanted by-products of metabolism
How are materials transported
Bulk flow
What diffues faster - O2 or CO2
CO2
Benefits of pulmonary circulation
lungs do not have to compete for blood flow
pulmonary vasculature has a very low resistance to flow
What vascular beds are arranged in series
Splanchnic circulation
Renal system
What organ has a dual blood supply
Liver (blood from GIT)
Benefits of systemic circulation
Total R when arranged in parallel is much less
Blood flow to individual organs can be independently controlled
Ohm’s Law and its relevance to CV physio
V = I x R MAP = CO x TPR
What is stroke vol
vol of blood ejected by either ventricle in 1 min
HR x CO
What is Ficks Principle
Blood flow to an organ can be calculated using a marker substance if we know:
- Amt of MS taken up by organ/unit time
- Conc of MS in arterial blood entering organ
- Conc of MS in venous blood leaving organ
THEREFORE
CO is determined by:
- difference in O2 conc in blood before it enters and after it leaves the organ
- rate at which O2 is consumed => O2 = MS
CO formula
O2 absorbed/ min by the lungs DIVIDED BY arteriovenous difference in O2 conc
What happens in arteries during diastole
Elastic recoil of walls of large arteries propels blood into smaller arteries even during ventricular relaxation
What is the pressure difference driving blood flow
MAP - RAP (Right Atrial Pressure, basically 0 mmHg)
Where does blood flow correlate well with O2 consumption
Skeletal muscle
Liver/gut
Brain
Where does blood flow NOT correlate well with O2 consumption
Kidney - excretion
Skin - thermoregulation
Heart muscle - increased O2 demand due to work
