Cardiac output: volume of blood pumped by one ventricle in heart in 1 MIN
heart rate x stroke volume
What are valves used for?
Blood always flows from a region of high blood pressure to a lower blood pressure. Valves are used when situations within circulatory system when pressure differences result in blood flowing in opposite direction, they shut to prevent backflow
how do valves prevent back flow?
Valves open whenever difference in blood pressure either side favours movement in required direction.
When pressure difference is reversed, flowing in opposite direction, valves close
Atrio ventricular valves
Between left atrium/ventricle and right atrium/ventricle. They prevent back flow of blood during contraction of ventricles (ventricular pressure exceeds atrial pressure) closing these valves, blood flows to aorta and pulmonary artery NOT atria
Semi lunar valves
In aorta and pulmonary artery. These prevent back flow into ventricles. This arises when elastic walls of vessels recoil increasing pressure and when walls relax, reducing pressure in ventricles.
Pocket valves
In veins, apart of venous system ensuring veins fully squeezed.
