Describe the cardiac cycle, using the terms systole and diastole. What are the roles of the SA n

Describe the cardiac cycle, using the terms systole and...

Key Concepts

Atrioventricular (AV) Node

The atrioventricular node acts as an electrical relay station between the atria and the ventricles. It receives the impulse from the SA node and introduces a slight delay, which is critical for maintaining proper timing; this delay allows the atria to contract and complete the filling of the ventricles before they contract during systole. The AV node is a crucial component of the conduction system that ensures efficient coordination between the atrial and ventricular contractions.

Sinoatrial (SA) Node

The sinoatrial node is known as the natural pacemaker of the heart. It initiates the electrical impulse that triggers the contraction of the atria. Located in the right atrium, the SA node sets the pace for heart rate and plays a key role in controlling the timing of the cardiac cycle by ensuring that the heart beats in a coordinated and rhythmic manner.

Cardiac Cycle

The cardiac cycle is the complete sequence of mechanical and electrical events that repeats with every heartbeat. It encompasses the contraction and relaxation phases of the heart (systole and diastole) that ensure blood is received, pumped throughout the body, and then refilled. This cycle is fundamental to cardiovascular physiology and is critical for maintaining effective circulation.

Systole

Systole is the phase of the cardiac cycle during which the heart muscles contract, leading to the ejection of blood from the chambers. In ventricular systole, blood is pumped into the aorta and pulmonary artery, while atrial systole aids in topping up the ventricular volume. This phase is central to generating the pressure needed to circulate blood throughout the body.

Diastole

Diastole is the relaxation phase of the cardiac cycle when the heart muscles relax and the chambers fill with blood. During diastole, the heart’s chambers expand, allowing the atria and ventricles to fill with blood, which is essential for an effective ensuing contraction. This period of relaxation is crucial for maintaining optimal cardiac filling and efficient subsequent pumping.

Transcript

00:02 Hello everyone so here we need to discuss about the cardiac cycle in terms of systole diastole and we also have to discuss what is the role of s -a node and ev node in the cardiac cycle right? so let us discuss it one by one so first we will see what is cardiac cycle cardiac cycle we will discuss this about discuss about this cardiac cycle in terms of sistol and diastole right? so one cardiac cycle basically includes it includes the electrical events okay electrical events that occurs in the inside the heart along with this it also includes the mechanical mechanical events okay mechanical events of heart and also includes the heart sound okay and heart sound these all are included under the cardiac cycle what happens in this cardiac cycle the atria and the ventricle in the cardiac cycle the atria and the ventricle they basically will contract alternatively okay they contract alternatively okay in each cardiac cycle this happens the atria contracts after that the ventricle contracts and this process goes on during the cardiac cycle the pressure inside the chambers it keeps on changing okay chambers it basically keeps on changing because of this alternative contraction and relaxation the pressure keep on changing inside the chambers of art now if you see one cardiac cycle we can split them into two parts okay if we'll take the cardiac cycle over here cardiac cycle basically it can be splitted into two parts one part will become the systole okay one is the systole now what do you mean by systole? cisstool is the contraction phase.

02:05 Contraction that occurs in the heart that comes under the systole.

02:10 Now we will see another phase that we can broke the cardiac cycle into that is the diastole.

02:16 And what do you mean by diastole? diastole is the relaxation phase.

02:19 Okay? it is the relaxation phase of the heart that is called as diastole.

02:24 And both this occurs in the atrium as well as ventricle.

02:28 Now we will see the cardiac cycle therefore because of this.

02:32 Sistole and diastole.

02:34 There are four phases we can see or four phases or we can say four stages we can see in a cardiac cycle.

02:40 What are the four stages we'll discuss now? first one will be the atrial.

02:45 The atrial systole.

02:48 Okay.

02:48 Now we will see what do you mean by atrial systole? so it is nothing but as we discussed what do you mean by cystole contraction? so it is the contraction of it is the contraction of the atrium.

03:02 Okay.

03:03 Atrium will contract in this part.

03:05 Now because of this contraction what happens? the blood from the atria, the blood from atrium, it will basically atrium, it will move into the ventricles.

03:17 Okay.

03:18 So it what happens? the blood will force into the or move into the ventricles in this process, ventricles.

03:26 Now if we'll talk about the duration of this atrial system, so it takes about 0 .1 second.

03:33 Okay.

03:33 It lasts about 0 .1 second.

03:36 Now we'll move to the another phase.

03:39 That is the second one is your ventricular systole.

03:42 Okay, that is ventricular systole.

03:45 Now, what do you mean by ventricular cystole? it is nothing but the contraction of the ventricles.

03:50 Okay...