1.2.5 The cardiac cycle and pathway of blood

• What is the cardiac cycle?

  Sequence of events in one heartbeat
• During systole, the heart chambers contract to pump blood out
• Describe the path of blood through the heart in the correct sequence.

  1️⃣ Deoxygenated blood enters the right atrium from the vena cava

  2️⃣ Blood passes through the tricuspid valve into the right ventricle

  3️⃣ Blood is pumped through the pulmonary valve into the pulmonary artery

  4️⃣ Oxygenated blood returns to the left atrium via the pulmonary veins

  5️⃣ Blood passes through the mitral valve into the left ventricle

  6️⃣ Blood is pumped through the aortic valve into the aorta
• What are the two phases of the cardiac cycle?

  Systole and diastole
• Oxygenated blood returns to the left atrium via the pulmonary veins
• The SA node initiates the electrical impulse in the heart.

  True
• The Purkinje fibers distribute the electrical impulse throughout the ventricles
• What happens during the diastole phase of the cardiac cycle?

  Heart chambers relax and fill with blood
• During diastole, blood pressure decreases in the heart.

  True
• Match the heart valve with its function.

  Tricuspid valve ↔️ Prevents backflow into right atrium

  Mitral valve ↔️ Prevents backflow into left atrium

  Pulmonary valve ↔️ Prevents backflow into right ventricle

  Aortic valve ↔️ Prevents backflow into left ventricle
• Where does deoxygenated blood enter the heart first?

  Right atrium
• What is the function of the AV node in the heart's electrical pathway?

  Delays the impulse
• The cardiac cycle consists of two main phases: diastole and systole.


  True
• What is the purpose of the cardiac cycle?

  Pumps blood through the heart
• How many major valves are in the heart?

  Four
• During diastole, the heart chambers fill with blood.

  True
• Which valve does blood pass through from the right atrium to the right ventricle?

  Tricuspid valve
• Describe the electrical pathway of the heart in the correct sequence.

  1️⃣ SA node initiates electrical impulse

  2️⃣ Impulse travels to AV node

  3️⃣ Impulse is delayed briefly

  4️⃣ Impulse travels down the Bundle of His

  5️⃣ Purkinje fibers distribute impulse in ventricles

  6️⃣ Ventricles contract