Unit 2 - Structure & Function of the heart Key Area 6 Flashcards
What is the role of Atria-ventricular (AV) valves.
Atrio- ventricular (AV) valves prevent back flow of blood from ventricles to atria.
What is the role of Semi-lunar (SL) valves.
Semi-lunar (SL) valves prevent back flow of blood at the entrance of the aorta and pulmonary arteries.
What happens when these valves open and close?
These valves open during contraction allowing blood to pass through, and close to prevent back flow of blood.
What is cardiac output?
The volume of blood pumped through each ventricle per minute is the cardiac output.
Equation to calculate cardiac output
Cardiac output is determined by heart rate and stroke volume.
CO = HR x SV
State the relationship between the volume of blood pumped through the arteries on either side of the heart.
The left and right ventricle pump the same volume of blood through the aorta and pulmonary artery.
What is heart rate?
Heart rate (pulse) is the number of heartbeats that occurs per minute.
What is Stroke Volume?
Stroke volume is the volume of blood expelled by each ventricle on contraction, the greater the stoke volume.
Define the term Cardiac Cycle
The cardiac cycle refers to the patternof contraction (systole) and relaxtion (diastole)
Describe what happens during diastole?
During diastole, blood returning to the atria
flows into the ventricles. In diastole, the higher pressure in the arteries closes the SL valves.
Describe what happens during atrial systole?
Atrial systole transfers the remainder of the blood through the atrio-ventricular (AV) valves to the
ventricles.
Describe what happens during ventricular systole?
Ventricular systole closes the AV valves and pumps the blood out through the semi lunar (SL) valves to the aorta and pulmonary artery.
What is responsible for the heart sounds heard with a stethoscope?
The opening and closing of the AV and SL valves are responsible for the heart sounds heard with a stethoscope.
Where does the heartbeat originate?
The heartbeat originates in the heart itself
What sets the rate at which the heart contracts?
The auto-rhythmic cells of the sino-atrial node (SAN) or pacemaker, located in the wall of the right atrium, set the rate at which the heart contracts.
