10.3 MECHANISM OF HEARTBEAT

Cardiac muscles

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The heart contracts and relaxes without receiving any impulse signals from the nervous system

• automatic

• pulsated

• myogenic

Natural pacemaker

• Purkinje fibers

• Sinoatrial node

• Atrioventricular node

• Bundle of His

Which part of the heart exerts the highest pressure during heart beat?

• Right atrium

• Right ventricle

• Left atrium

• Left ventricle

Which enables the constant high pressure of blood flow in arteries?

• Narrow lumen

• Absence of valve

• Thick muscular wall

• SA node $\rightarrow$ Purkinje fibers $\rightarrow$ AV node $\rightarrow$ Bundle of His

• Bundle of His $\rightarrow$ Purkinje fibers $\rightarrow$ AV node $\rightarrow$ SA node

• SA node $\rightarrow$ AV node $\rightarrow$ Bundle of His $\rightarrow$ Purkinje fibers

"lub" "dub"

• lub - AV valves closed

• dub - AV valves closed

• lub - semilunar valves closed

• dub - semilunar valves closed

• Electrolysis

• Electromagnet

• Electrocardiogram

What is the function of valves present in the veins?

• Ensure blood flow back to the heart

• Prevent blood clotting

• Ensure blood flow in one direction

Contraction and relaxation of _____________ muscles help the blood flow in the vein to the heart.