Lub Dub | Circulatory system physiology | NCLEX-RN | Khan Academy

Summary

This script delves into the heart's sounds, 'lub dub,' by explaining the role of its four valves in blood flow. It illustrates how the tricuspid and mitral valves open to fill the ventricles, while the pulmonary and aortic valves close to prevent backflow. The 'lub' sound corresponds to the closure of the former valves, and 'dub' to the latter, marking the transition from systole, when blood is pumped out, to diastole, the filling phase. The explanation simplifies the complex mechanics of the heart into an engaging rhythmic pattern.

Takeaways

• 👂 The heart makes sounds that are typically described as 'lub dub, lub dub, lub dub'.
• 🔍 The 'lub dub' sound can be spelled out as L-U-B, D-U-B, which repeats in a cycle.
• 📚 A diagram of the heart with exaggerated valves helps explain the origin of these sounds.
• 🔑 The heart has four valves: tricuspid (T), pulmonary (P), mitral, and aortic, which play a key role in the heart sounds.
• 💧 Blood flow through the heart is continuous, with simultaneous filling of the right and left ventricles.
• 🚫 Valves prevent backflow of blood by closing when blood tries to move in the wrong direction.
• 📉 The 'lub' sound corresponds to the closure of the tricuspid and mitral valves, also known as the first heart sound (S1).
• 📈 The 'dub' sound is associated with the closure of the pulmonary and aortic valves, known as the second heart sound (S2).
• 🔄 The opening and closing of these valves create a rhythmic cycle of sounds that can be heard and timed.
• 🕒 The time between 'lub' and 'dub' represents systole, when blood is being pumped out of the heart.
• ⏸ The period between 'dub' and the next 'lub' is diastole, when the heart is refilling with blood from the atriums.

Q & A

What are the typical sounds produced by the heart?

The typical sounds produced by the heart are 'lub dub, lub dub, lub dub', which is often represented by the letters L-U-B, D-U-B.

What is the purpose of the heart valves?

The heart valves, including the tricuspid, pulmonary, mitral, and aortic valves, regulate the flow of blood through the heart, ensuring it moves in the correct direction and preventing backflow.

How does the heart's anatomy relate to the 'lub dub' sounds?

The 'lub dub' sounds are associated with the opening and closing of the heart valves. 'Lub' corresponds to the closure of the tricuspid and mitral valves, while 'dub' is the sound made by the closure of the pulmonary and aortic valves.

What is the term for the first heart sound?

The first heart sound is also known as 'S1' and is produced by the closure of the tricuspid and mitral valves.

What is the term for the second heart sound?

The second heart sound is referred to as 'S2' and is produced by the closure of the pulmonary and aortic valves.

What happens during the period between 'lub' and 'dub'?

During the period between 'lub' and 'dub', the ventricles are ejecting blood into the arteries, a phase known as systole.

What is the phase called when blood is refilling from the atriums into the ventricles?

The phase when blood is refilling from the atriums into the ventricles is called diastole.

How can one differentiate between systole and diastole by listening to the heart sounds?

By listening to the heart sounds, systole can be identified by the period when blood is being squeezed out between 'lub' and 'dub', while diastole is the period of refilling, occurring between 'dub' and the next 'lub'.

Why do the heart valves close with a sound?

The heart valves close with a sound because of the sudden stop of blood flow when the valves snap shut to prevent backflow, creating the audible 'lub' and 'dub' sounds.

What is the significance of the black and white arrows in the explanation?

The black arrows represent incorrect or backward flow of blood, which the valves prevent. The white arrows indicate the correct flow of blood through the heart.