CHAPTER 10.3 (F4): THE MECHANISM OF HEARTBEAT

What is the function of the arrangement of cardiac muscles in the heart?

• To slow down the heartbeat

• To allow electric impulses to spread rapidly

• To prevent the heart from contracting

• To store energy for the heart

What does it mean when cardiac muscles are described as myogenic?

• They require signals from the nervous system to contract.

• They contract and relax without any external signals.

• They are controlled by voluntary actions.

• They need constant oxygen supply to function.

What is the primary function of the sinoatrial node (SA node) in the heart?

• It pumps blood throughout the body.

• It generates electrical impulses.

• It filters blood.

• It stores oxygen.

What is the role of electrical impulses in the atria of the heart?

• They cause the atria to relax.

• They cause the atria to contract simultaneously.

• They cause the ventricles to contract.

• They stop blood flow to the ventricles.

What is the role of Purkinje fibers in the heart?

• They initiate the heartbeat.

• They spread electrical impulses from the apex to the ventricles.

• They pump blood into the atria.

• They regulate blood pressure.

Reorder the mechanism of the heartbeat.

• Electrical impulse is transfered into the AV nodes and then, bundle of His

• Reaches Purkinje fibers and causes the contraction of the ventricles

• Atria contracts (Tricuspid/bicuspid valves open)

• The electrical impulse spreads to both atria

• SA node acts a pacemaker generates electrical impulse

What happens during cardiac diastole?

• Ventricular chambers are relaxed, and blood flows into the heart.

• Atria contract, pushing blood into the ventricles.

• Ventricles contract, pushing blood out of the heart.

• The heart stops beating.

What is the sequence of events during ventricular systole?

• Atria contract, pushing blood into the ventricles.

• Ventricles contract, pushing blood out of the heart.

• All chambers are relaxed, and blood flows into the heart.

• The heart stops beating.

What sound is heard during heart pumping?

• Lub-dub

• Tick-tock

• Beep-beep

• Ring-ring

What causes the lub-dub sound in the heart?

• Opening of the heart valves

• Closing of the heart valves

• Blood flowing through veins

• Heart muscle contraction