The Cardiac Cycle 2 Flashcards
What is the function of valves in the cardiovascular system?
To prevent backflow of blood and ensure blood flows in one direction, from higher to lower pressure
When do valves open and close?
Valves open when the pressure difference favours blood flow int he required direction
Valves close when the pressure difference would cause backflow
Where are atrioventricular valves located, and what is their function?
Atrioventricular valves are located between the atria and ventricles (left and right sides)
They prevent backflow into the atria when the ventricles contract (when ventricular pressure exceeds atrial pressure)
Where are semi - lunar valves, and what is their function?
Semi - lunar valves are located within the aorta and pulmonary artery
They prevent backflow into the ventricles when pressure in these vessels exceeds ventricular pressure
Why does blood pressure in the aorta and pulmonary artery sometimes exceed ventricular pressure?
The elastic recoil of the artery walls increases pressure so the ventricles relax, lowering their internal pressure
Where are pocket valves found, and what is their funtion?
Pocket valves are found in veins throughout the body, ensuring blood flows towards the heat when veins are squeezed by muscle contractions
What is the structure of valves in the circulatory system?
Valves are made up of tough, flexible, fibrous tissue with a cusp - shaped
How do valves close to prevent backflow?
When pressure is higher on the concave (hollow) side, blood collects in the cusps. This causes the cusps to push together, forming a tight seal
What is cardiac output?
The volume of blood pumped by one ventricle of the heart in one minute
What is the unit of measurement for cardiac output?
cubic decimetere per minute (-1)
What two factors determine cardiac output?
Heart rate - the number of beats per minute
Stroke volume - the volume of blood pumped out per beat
How is cardiac output calculated?
Cardiac output = heart x stroke volume
What happens to cardiac output during exercise?
Heart rate increases to pump more blood and the stroke volume increases as more blood is released per beat. Overall making the cardiac output increase to supply the muscles with more oxygen and nutrients
