Eduqas A Level The Cardiac Cycle

Which is correct?

• The cardiac cycle is a coordinated sequence of contractions and relaxations by the heart muscle which causes blood to move from the atria, into the ventricles and then the arteries.
• The cardiac cycle is a coordinated sequence of contractions and relaxations by the heart muscle which causes blood to move from the ventricles, into the atria and then the veins.

Muscle contractions are referred to as systole and relaxation is referred to as diastole.

• TRUE
• FALSE

Which is correct?

• The movement of blood through the different compartments of the heart rely on changes in volume and pressure as a result of the contraction of the heart muscle walls.
• The movement of blood through the different compartments of the heart rely on changes in volume and pressure as a result of the pacemaker.

Study this first, and then select yes to proceed: Atrial systole: The atria contract while the ventricles relax. This decreases the volume inside the atria which increases the pressure. This increased pressure forces the atrioventricular valves open and pushes blood into the ventricles.

• Yes
• No

What happens during atrial systole?

• The atria contract while the ventricles relax.
• The atria relax while the ventricles contracts.

Atrial systole - This (fill in the blank) the volume inside the atria which (fill in the blank) the pressure.

• decreases, increases
• increases, decreases

Atrial systole This increases the volume inside the atria which decreases the pressure.

• True
• False

Atrial systole - This increased (fill in the blank) forces the atrioventricular valves open and pushes blood into the ventricles.

• pressure
• volume

Study this first, and then select yes to proceed: Ventricular systole The ventricles contract while the atria are relaxed. This decreases the volume inside the ventricles which increases the pressure. The pressure is higher in the ventricles compared to the atria, which forces the atrioventricular valves closed and causes the semi-lunar valves to open. The closure of the AV valve is important because it prevents the back-flow of blood into the atria. Blood is forced out of the ventricles and into the arteries (the aorta and the pulmonary artery).

• Yes
• No

Ventricular systole The ventricles contract while the atria are relaxed. This increases the volume inside the ventricles which decreases the pressure.

• True
• False