BIOLOGY - 10TH - circulatory system

The healthy heart beats normally ___ per minute.

• 85-90 times
• 80-85 times
• 70-80 times
• 60-70 times

The back flow of blood during the pumping of blood by heart is prevented by:

• Walls of ventricles
• Walls of atrium
• Valves in heart
• Walls between atria and ventricles

The circulatory system consists of

• Heart, blood, lungs
• blood vessels, blood, oxygen
• Heart, blood, blood vessels
• Heart, blood vessels, lungs

Blood vessels entering the heart are

• Anterior vena cava, posterior vena cava
• Anterior vena cava, pulmonary vein
• Aorta, pulmonary artery
• Right coronary artery, aorta

The impulse of heartbeat originates from

• SA node
• AV node
• vagus nerve
• cardiac nerve