Anatomy and Function of the Heart

Have you ever questioned why our heart goes lub-dub, lub-dub? Well, that's exactly what we're going to be talking about today. We're going to be talking about the ATIT's version 7 human anatomy and physiology portion of the exam, more specifically, cardiovascular system. Let's get started. The cardiovascular system plays an essential role in so many body processes. First, let's discuss how blood, which serves as the vehicle for transporting glucose and gases through our body, works. There's a common misunderstanding about blood and it's important to note that human blood is always red. It's a shade that can either be a dark red or a lighter red depending on the oxygen concentration found inside it. In many educational diagrams, veins and arteries are depicted as blue and red to indicate lower and higher oxygen levels. However, this coloring is just a diagrammatic tool and does not reflect the actual colors of blood, veins, and arteries. The veins that you see peeking up underneath your skin may appear to have some blue and green vibes, but that's just a sneaky optical illusion. The human blood is quite a multitasker. It juggles between maintaining pH, temperature, and osmotic pressure, all vital for keeping the internal environment steady, also known as homeostasis. Blood is also the body's internal FedEx system, delivering hormones, nutrients, and gases wherever they are needed. So blood is made up of all kinds of really interesting stuff. Take plasma for example. Plasma is the liquid portion of our blood. It's basically a cocktail of water, proteins, salts, and lipids. Then we have our cellular heavy hitters. Our red blood cells are our transport of our gases and our white blood cells help fight off infections. But what about platelets? Platelets really are the unsung heroes because they help the blood clot out. whenever we scrape our knee. How does blood get that signature red color? We can thank hemoglobin for that, which is an iron-rich protein in red blood cells providing its stylish hue. So as we dip our toes into the circulatory system, we're going to focus on how all of these components circulate around our bodies. So arteries are the roadways that carry the blood away from our heart. Just remember A is for away. They usually transport oxygen-rich blood though there are some exceptions to that rule. Veins, on the other hand, bring that blood back to the heart. I like to remember this as using the word verb. Veins efficiently return blood. They typically carry that oxygen-poor blood back to the heart. However, what's interesting is both arteries and veins tend to flip the script when it comes to pulmonary circulation. This type of circulation is when pulmonary arteries carry oxygen-poor blood, and pulmonary veins carry oxygen-rich blood. This is the only exception to that rule. And then last up, we have capillaries. Capillaries are tiny little blood vessels where oxygen is delivered to organs and tissues and carbon dioxide hop off for their ride back to the lungs. So if we're examining a patient's heart, you're gonna notice that the right side is actually on our left side, right? But we have to really, it's important to note that we're always looking at the patient's right or the left, not from our own perspective. So when we're talking about the right side of the heart, we're talking about the deoxygenated side, the deoxygenated blood side. This is where that blood is going to get circulated into our lungs and then come back into the left side of the heart, which is the more oxygen rich side. Sometimes due to congenital heart conditions, these two different types of blood tend to mix together. We're going to explore this a little bit more later. So if we take a look at our heart, we're going to notice that we have four chambers. We have our right atrium and our right ventricle on one side, and we have our left atrium and our left ventricle on the other side. A handy mnemonic that I like to remember when it comes to the cardiovascular system is that A for atria comes before V for the ventricles in the alphabet, which helps us remember that the atria are on top and our ventricles are on the bottom. So the atria have thinner walls in comparison to the thicker walled ventricles that we see below. The heart is also equipped with valves, like we see here. These valves are like one-way doors. They not only separate the chambers, but they also prevent blood from flowing backwards. Let's take a closer look at how blood flows throughout our heart, gets into the pulmonary system, and then comes back before it gets pumped out into our body. The AT&T is going to test you on blood flow through the heart. It is imperative that you know this process and you have a good understanding of it because you're going to need to know it not only for the ATITs, but for most of the healthcare professions that you'll be going into. So let's begin with the blood that's circulating in our fingertips. This blood is deoxygenated and needs to return to the heart. so that it can be sent to the lungs to pick up oxygen. Blood is going to return to the heart via the vena cava, whether that's inferior or superior. The inferior vena cava is going to collect blood from the lower half of our body, including our legs, our back, our abdomen, and our pelvis. The superior vena cava is going to collect blood from the upper half of our body, including our head, our neck, our upper limbs, and our upper torso. The journey starts when the blood enters into our right atrium. Once it's there, that right atrium is going to contract and it's going to push blood through our tricuspid valve. Once it passes that tricuspid valve, it's going to enter into our right ventricle. And that right ventricle is going to contract, propelling that blood through that pulmonary valve, which is located right here, into our pulmonary artery, which again is our deoxygenated blood going through an artery, consequently landing into our lungs. Once that blood is in our lungs, it's going to pick up that oxygen that it got from the environment, and it's going to offload that carbon dioxide that it pulled up from the metabolic processes in our body. Once that blood is oxygenated, it's going to return back to the heart, where it's going to be pumped to nourish our entire body. Oxygen-rich blood is going to return via our pulmonary veins into our left atrium. Once it's there, that left atrium is going to contract. And it's going to push that blood through our mitral valve, which is also known as our bicuspid valve. From there, the blood is going to be pushed down into our left ventricle. And that left ventricle is then going to contract forcefully to pump that blood out through our aortic valve and then into our aorta. The aorta is a major artery that carries oxygenated blood to all parts of the body, ensuring that our tissues as well as our organs receive the oxygen that they need in order to function. Speaking of oxygenation, it's crucial not to overlook that the heart itself requires a dedicated blood supply to receive oxygen and glucose. This vital supply comes through coronary arteries which branch off from our aorta. These arteries transport blood into tiny capillaries that weave throughout the heart muscle, delivering oxygen and nutrients. After the heart cells have used up that oxygen, they are going to transport that deoxygenated blood back to the heart. through the coronary veins. This deoxygenated blood is going to return to our right atrium via the coronary sinus, allowing it to circulate back through our blood, picking back up oxygen, and delivering all of those waste products that it picked up along the way. Before we delve into the heart's electrical conduction system, it's essential to recognize that various conditions can disrupt the heart's normal function. Some of these functions anatomically alter the flow of blood within the heart. We discussed previously that sometimes we see blood is going to be mixed between deoxygenated and oxygenated blood. We call this septal defects. This is when the septum, the muscular wall that divides the heart's left and right sides, has some kind of abnormality. A septal defect involves the opening that allows oxygen-rich blood and oxygen-poor blood to mix. Depending on the defect's size, the mixing can lead to significant issues. including abnormal heart rhythms, even maybe stroke, as well as heart failure if we have severe cases. More specifically, an opening that's found in our interatrial septum is going to result in atrial septal defects, where mixing of blood occurs between the left and the right atria. Similarly, a opening between our interventricular septum is going to lead to ventricular septal defects, which involves the mixing of blood in our ventricles. Treatment options can include medications to help manage those symptoms, or we may even have to do surgical interventions. Now let's delve into the various components of the electrical conduction system of the heart. Our starting point is our sinoatrial node, and that's situated up here in the right atrium, close to where it meets with the superior vena cava. This node is essential when it comes to the heart's primary pacemaker, marking the commencement of the electrical conduction pathway. The activation of this SA node triggers a sequential contraction of atrial myocytes. It's also crucial to understand the role of the fibrous tissue found in the septum which separates the left and the right sides of our heart, including our atria as well as our ventricles. This separation is vital as it hinders direct electrical signal transmission between those heart sections. Following the SA node, we encounter a structure known as Bachmann's bundle. It is characterized by its ability to transmit high-speed signals extending from the SA node across that atrial septal wall into our left atria. The intermodal path The S-A pathway consists of three routes. We have the anterior, middle, and the posterior. These pathways are chiefly involved in conveying that electrical impulse from the S-A node all the way down to our atrioventricular node. The atrioventricular node is situated in the right atrium, but this time it's going to be near the coronary sinus and our tricuspid valve. This cluster of cells is specialized to momentarily pause that electrical signal from the SA node before it can proceed down into the ventricles. This intentional delay is crucial because it provides sufficient time for the atrium to thoroughly contract and ensure that all of that blood is going to reach the ventricles before the ventricles themselves contract. Following the AV node, we encounter the bundle of His, which is comprised of another group of high-speed transmission cells. These cells extend from the AV node, traversing partially through that right atrium and then into our interventricular septum where they're going to branch off into our left and our right ventricles. In individuals without cardiac abnormalities, these pathways represent the sole communication channel between our atrium and our ventricles. Like we discussed, the bundle of his is going to split off into two distinct pathways. We have our right bundle branch and our left bundle branch. As you can guess, the right bundle branch is going to transmit signals to the right ventricle and the left bundle branch is going to transmit signals to our left ventricle. Lastly, we turn our attention to the Purkinje fibers, which project from both the right and the left bundle branches and they directly interface with the heart's myocytes. Their primary role is to initiate depolarization within the muscle cells, triggering that contraction that we see in the cardiac muscle. Similar to the way that atrial myocytes function, the ventricular myocytes receive and further transmit those electrical signals to adjacent cells at a slower pace compared to that of the rapid transmission observed in the high-speed bundle branches. An essential characteristic to understand is that the system has its own inherent pacemaker capability of its various cells, which essentially govern the heart rate. Virtually all components of the system we've discussed possess their own intrinsic pacemaker rate. What's interesting is that this rate is going to decrease as we progressively move down the electrical pathway. You can essentially think of this as the body's contingency plan. Should a higher pacemaker fail to initiate, a lower level pacemaker eventually is going to activate, ensuring that the heart's contractions continue. An easy mnemonic to remember the order of the heart's conduction system is strong arteries benefit body's performance. Where the S in strong stands for our SC node. The A in Artery stands for our AV node, the B's in Benefit and Body stands for our bundle branches, and the P in Performance stands for our Purkinje fibers. Starting with our SA node, that is our heart's primary pacemaker. And it has a natural pace of 60 to 100 beats per minute. And it can adjust this pace depending on the body's demands. Following in sequence, we have the AV node, which is also known as our secondary pacemaker. It has its own intrinsic rate of 40-60 beats per minute. So if the SA node was to fail, then the AV node is going to be the next node to kick in, and it's going to beat at that intrinsic rate of 40-60 beats per minute. So that means when we're looking at rhythms originating from the junction, which is where the AV node sits, also known as our junctional rhythms, we're going to see rhythms that are a little bit slower. And then lastly we have our Purkinje fibers, which is our last-ditch pacemaker. and this is going to be at an intrinsic rate of 20 to 40 beats per minute. While these slower rates further down our system are not ideal and potentially life-threatening, they afford the body additional time for corrective measures. For the tease, you're going to need to know the basics when it comes to an ECG. We're going to start with our isoelectric line, and this line acts as a critical baseline, representing the moment when the heart's electrical activity shows no net movement. effectively a zero electrical potential state. This baseline is also essential for interpreting the heart's electrical signals accurately. It allows healthcare professionals just like you one day to distinguish between the various phases of heart activity, such as depolarization and repolarization. The first minor peak that we encounter on this ECG is known as our P wave. It's then preceded by this very prominent fornation known as our QRS complex. and it's ultimately going to conclude in the subsequent minor peak of our t wave this p wave signifies atrial depolarization and this is when the two atria contract following that we have our qrs complex and this signifies ventricular depolarization the period where the heart's ventricles contract. Essentially, depolarization is just a fancy way of saying contraction. How do we differentiate between these two waveforms? A helpful hint is that the QRS kind of looks like an upside-down V. So that inverted V ultimately stands for ventricles. V in ventricles, V in our QRS complex. And finally, we have our T-wave. And our T-wave represents ventricular repolarization. marking the period when the ventricles are in the process of relaxing. It's essential to remember that each depolarization phase, which leads to contraction, is invariably going to be followed by a repolarization phase allowing for relaxation. So this concept brings up an intriguing question. When does atrial repolarization occur? If the QRS complex is associated with ventricular depolarization, and the T wave is associated with ventricular repolarization, when might the atrial repolarization occur. So what happens is this atrial repolarization happens concurrently during the time frame of that QRS complex. That QRS complex being such a pronounced structure overshadows that atrial relaxation. This is because the ventricles contract more forcefully than we see with the atria, effectively concealing atrial repolarization inside that QRS complex. And lastly, we're going to talk about systolic and diastolic pressure. So blood pressure measures how forcefully blood is pushing against the walls of our arteries as the heart circulates it throughout the body. A blood pressure reading is going to consist of two numbers, our systolic and our diastolic. The systolic blood pressure is going to be that top number you see on your reading, reflecting the peak pressure in the arteries when the heart contracts and pumps blood out of the heart. This ultimately indicates how hard the heart has to work in order to circulate that blood. A high systolic reading may suggest the heart is exerting too much effort, a potential indicator of hypertension. On the flip side, our diastolic blood pressure is the bottom number that we see, and this represents the lowest pressure in the arteries when the heart is relaxed between beats. It measures the resistance to blood flow within our arteries. Elevated diastolic pressure could mean that the arteries are either narrow or they could even be too stiff, increasing the risk for heart disease. stroke, as well as other health issues. A typical blood pressure should be around 120 over 80, but ideal ranges are going to vary depending on the individual as well as age. I hope that this information was helpful in understanding the cardiovascular system. If you have any additional questions, make sure that you leave them down below. I love answering your questions. Head over to NurseChunkStar.com where there is a ton of additional resources in order to help you ace those ATITs exams. And as always, I'm going to catch you in the next video. Bye!

Let's get started. The cardiovascular system plays an essential role in so many body processes. First, let's discuss how blood, which serves as the vehicle for transporting glucose and gases through our body, works.

There's a common misunderstanding about blood and it's important to note that human blood is always red. It's a shade that can either be a dark red or a lighter red depending on the oxygen concentration found inside it. In many educational diagrams, veins and arteries are depicted as blue and red to indicate lower and higher oxygen levels.

However, this coloring is just a diagrammatic tool and does not reflect the actual colors of blood, veins, and arteries. The veins that you see peeking up underneath your skin may appear to have some blue and green vibes, but that's just a sneaky optical illusion. The human blood is quite a multitasker. It juggles between maintaining pH, temperature, and osmotic pressure, all vital for keeping the internal environment steady, also known as homeostasis. Blood is also the body's internal FedEx system, delivering hormones, nutrients, and gases wherever they are needed.

So blood is made up of all kinds of really interesting stuff. Take plasma for example. Plasma is the liquid portion of our blood. It's basically a cocktail of water, proteins, salts, and lipids.

Then we have our cellular heavy hitters. Our red blood cells are our transport of our gases and our white blood cells help fight off infections. But what about platelets? Platelets really are the unsung heroes because they help the blood clot out.

whenever we scrape our knee. How does blood get that signature red color? We can thank hemoglobin for that, which is an iron-rich protein in red blood cells providing its stylish hue. So as we dip our toes into the circulatory system, we're going to focus on how all of these components circulate around our bodies.

So arteries are the roadways that carry the blood away from our heart. Just remember A is for away. They usually transport oxygen-rich blood though there are some exceptions to that rule.

Veins, on the other hand, bring that blood back to the heart. I like to remember this as using the word verb. Veins efficiently return blood. They typically carry that oxygen-poor blood back to the heart.

However, what's interesting is both arteries and veins tend to flip the script when it comes to pulmonary circulation. This type of circulation is when pulmonary arteries carry oxygen-poor blood, and pulmonary veins carry oxygen-rich blood. This is the only exception to that rule.

And then last up, we have capillaries. Capillaries are tiny little blood vessels where oxygen is delivered to organs and tissues and carbon dioxide hop off for their ride back to the lungs. So if we're examining a patient's heart, you're gonna notice that the right side is actually on our left side, right? But we have to really, it's important to note that we're always looking at the patient's right or the left, not from our own perspective.

So when we're talking about the right side of the heart, we're talking about the deoxygenated side, the deoxygenated blood side. This is where that blood is going to get circulated into our lungs and then come back into the left side of the heart, which is the more oxygen rich side. Sometimes due to congenital heart conditions, these two different types of blood tend to mix together.

We're going to explore this a little bit more later. So if we take a look at our heart, we're going to notice that we have four chambers. We have our right atrium and our right ventricle on one side, and we have our left atrium and our left ventricle on the other side.

A handy mnemonic that I like to remember when it comes to the cardiovascular system is that A for atria comes before V for the ventricles in the alphabet, which helps us remember that the atria are on top and our ventricles are on the bottom. So the atria have thinner walls in comparison to the thicker walled ventricles that we see below. The heart is also equipped with valves, like we see here.

These valves are like one-way doors. They not only separate the chambers, but they also prevent blood from flowing backwards. Let's take a closer look at how blood flows throughout our heart, gets into the pulmonary system, and then comes back before it gets pumped out into our body.

The AT&T is going to test you on blood flow through the heart. It is imperative that you know this process and you have a good understanding of it because you're going to need to know it not only for the ATITs, but for most of the healthcare professions that you'll be going into. So let's begin with the blood that's circulating in our fingertips. This blood is deoxygenated and needs to return to the heart.

so that it can be sent to the lungs to pick up oxygen. Blood is going to return to the heart via the vena cava, whether that's inferior or superior. The inferior vena cava is going to collect blood from the lower half of our body, including our legs, our back, our abdomen, and our pelvis. The superior vena cava is going to collect blood from the upper half of our body, including our head, our neck, our upper limbs, and our upper torso. The journey starts when the blood enters into our right atrium.

Once it's there, that right atrium is going to contract and it's going to push blood through our tricuspid valve. Once it passes that tricuspid valve, it's going to enter into our right ventricle. And that right ventricle is going to contract, propelling that blood through that pulmonary valve, which is located right here, into our pulmonary artery, which again is our deoxygenated blood going through an artery, consequently landing into our lungs.

Once that blood is in our lungs, it's going to pick up that oxygen that it got from the environment, and it's going to offload that carbon dioxide that it pulled up from the metabolic processes in our body. Once that blood is oxygenated, it's going to return back to the heart, where it's going to be pumped to nourish our entire body. Oxygen-rich blood is going to return via our pulmonary veins into our left atrium. Once it's there, that left atrium is going to contract. And it's going to push that blood through our mitral valve, which is also known as our bicuspid valve.

From there, the blood is going to be pushed down into our left ventricle. And that left ventricle is then going to contract forcefully to pump that blood out through our aortic valve and then into our aorta. The aorta is a major artery that carries oxygenated blood to all parts of the body, ensuring that our tissues as well as our organs receive the oxygen that they need in order to function.

Speaking of oxygenation, it's crucial not to overlook that the heart itself requires a dedicated blood supply to receive oxygen and glucose. This vital supply comes through coronary arteries which branch off from our aorta. These arteries transport blood into tiny capillaries that weave throughout the heart muscle, delivering oxygen and nutrients. After the heart cells have used up that oxygen, they are going to transport that deoxygenated blood back to the heart. through the coronary veins.

This deoxygenated blood is going to return to our right atrium via the coronary sinus, allowing it to circulate back through our blood, picking back up oxygen, and delivering all of those waste products that it picked up along the way. Before we delve into the heart's electrical conduction system, it's essential to recognize that various conditions can disrupt the heart's normal function. Some of these functions anatomically alter the flow of blood within the heart.

We discussed previously that sometimes we see blood is going to be mixed between deoxygenated and oxygenated blood. We call this septal defects. This is when the septum, the muscular wall that divides the heart's left and right sides, has some kind of abnormality. A septal defect involves the opening that allows oxygen-rich blood and oxygen-poor blood to mix.

Depending on the defect's size, the mixing can lead to significant issues. including abnormal heart rhythms, even maybe stroke, as well as heart failure if we have severe cases. More specifically, an opening that's found in our interatrial septum is going to result in atrial septal defects, where mixing of blood occurs between the left and the right atria. Similarly, a opening between our interventricular septum is going to lead to ventricular septal defects, which involves the mixing of blood in our ventricles. Treatment options can include medications to help manage those symptoms, or we may even have to do surgical interventions.

Now let's delve into the various components of the electrical conduction system of the heart. Our starting point is our sinoatrial node, and that's situated up here in the right atrium, close to where it meets with the superior vena cava. This node is essential when it comes to the heart's primary pacemaker, marking the commencement of the electrical conduction pathway.

The activation of this SA node triggers a sequential contraction of atrial myocytes. It's also crucial to understand the role of the fibrous tissue found in the septum which separates the left and the right sides of our heart, including our atria as well as our ventricles. This separation is vital as it hinders direct electrical signal transmission between those heart sections. Following the SA node, we encounter a structure known as Bachmann's bundle.

It is characterized by its ability to transmit high-speed signals extending from the SA node across that atrial septal wall into our left atria. The intermodal path The S-A pathway consists of three routes. We have the anterior, middle, and the posterior.

These pathways are chiefly involved in conveying that electrical impulse from the S-A node all the way down to our atrioventricular node. The atrioventricular node is situated in the right atrium, but this time it's going to be near the coronary sinus and our tricuspid valve. This cluster of cells is specialized to momentarily pause that electrical signal from the SA node before it can proceed down into the ventricles. This intentional delay is crucial because it provides sufficient time for the atrium to thoroughly contract and ensure that all of that blood is going to reach the ventricles before the ventricles themselves contract.

Following the AV node, we encounter the bundle of His, which is comprised of another group of high-speed transmission cells. These cells extend from the AV node, traversing partially through that right atrium and then into our interventricular septum where they're going to branch off into our left and our right ventricles. In individuals without cardiac abnormalities, these pathways represent the sole communication channel between our atrium and our ventricles.

Like we discussed, the bundle of his is going to split off into two distinct pathways. We have our right bundle branch and our left bundle branch. As you can guess, the right bundle branch is going to transmit signals to the right ventricle and the left bundle branch is going to transmit signals to our left ventricle.

Lastly, we turn our attention to the Purkinje fibers, which project from both the right and the left bundle branches and they directly interface with the heart's myocytes. Their primary role is to initiate depolarization within the muscle cells, triggering that contraction that we see in the cardiac muscle. Similar to the way that atrial myocytes function, the ventricular myocytes receive and further transmit those electrical signals to adjacent cells at a slower pace compared to that of the rapid transmission observed in the high-speed bundle branches. An essential characteristic to understand is that the system has its own inherent pacemaker capability of its various cells, which essentially govern the heart rate.

Virtually all components of the system we've discussed possess their own intrinsic pacemaker rate. What's interesting is that this rate is going to decrease as we progressively move down the electrical pathway. You can essentially think of this as the body's contingency plan. Should a higher pacemaker fail to initiate, a lower level pacemaker eventually is going to activate, ensuring that the heart's contractions continue. An easy mnemonic to remember the order of the heart's conduction system is strong arteries benefit body's performance.

Where the S in strong stands for our SC node. The A in Artery stands for our AV node, the B's in Benefit and Body stands for our bundle branches, and the P in Performance stands for our Purkinje fibers. Starting with our SA node, that is our heart's primary pacemaker. And it has a natural pace of 60 to 100 beats per minute. And it can adjust this pace depending on the body's demands.

Following in sequence, we have the AV node, which is also known as our secondary pacemaker. It has its own intrinsic rate of 40-60 beats per minute. So if the SA node was to fail, then the AV node is going to be the next node to kick in, and it's going to beat at that intrinsic rate of 40-60 beats per minute.

So that means when we're looking at rhythms originating from the junction, which is where the AV node sits, also known as our junctional rhythms, we're going to see rhythms that are a little bit slower. And then lastly we have our Purkinje fibers, which is our last-ditch pacemaker. and this is going to be at an intrinsic rate of 20 to 40 beats per minute.

While these slower rates further down our system are not ideal and potentially life-threatening, they afford the body additional time for corrective measures. For the tease, you're going to need to know the basics when it comes to an ECG. We're going to start with our isoelectric line, and this line acts as a critical baseline, representing the moment when the heart's electrical activity shows no net movement. effectively a zero electrical potential state. This baseline is also essential for interpreting the heart's electrical signals accurately.

It allows healthcare professionals just like you one day to distinguish between the various phases of heart activity, such as depolarization and repolarization. The first minor peak that we encounter on this ECG is known as our P wave. It's then preceded by this very prominent fornation known as our QRS complex. and it's ultimately going to conclude in the subsequent minor peak of our t wave this p wave signifies atrial depolarization and this is when the two atria contract following that we have our qrs complex and this signifies ventricular depolarization the period where the heart's ventricles contract. Essentially, depolarization is just a fancy way of saying contraction.

How do we differentiate between these two waveforms? A helpful hint is that the QRS kind of looks like an upside-down V. So that inverted V ultimately stands for ventricles. V in ventricles, V in our QRS complex. And finally, we have our T-wave. And our T-wave represents ventricular repolarization.

marking the period when the ventricles are in the process of relaxing. It's essential to remember that each depolarization phase, which leads to contraction, is invariably going to be followed by a repolarization phase allowing for relaxation. So this concept brings up an intriguing question.

When does atrial repolarization occur? If the QRS complex is associated with ventricular depolarization, and the T wave is associated with ventricular repolarization, when might the atrial repolarization occur. So what happens is this atrial repolarization happens concurrently during the time frame of that QRS complex. That QRS complex being such a pronounced structure overshadows that atrial relaxation. This is because the ventricles contract more forcefully than we see with the atria, effectively concealing atrial repolarization inside that QRS complex.

And lastly, we're going to talk about systolic and diastolic pressure. So blood pressure measures how forcefully blood is pushing against the walls of our arteries as the heart circulates it throughout the body. A blood pressure reading is going to consist of two numbers, our systolic and our diastolic.

The systolic blood pressure is going to be that top number you see on your reading, reflecting the peak pressure in the arteries when the heart contracts and pumps blood out of the heart. This ultimately indicates how hard the heart has to work in order to circulate that blood. A high systolic reading may suggest the heart is exerting too much effort, a potential indicator of hypertension. On the flip side, our diastolic blood pressure is the bottom number that we see, and this represents the lowest pressure in the arteries when the heart is relaxed between beats.

It measures the resistance to blood flow within our arteries. Elevated diastolic pressure could mean that the arteries are either narrow or they could even be too stiff, increasing the risk for heart disease. stroke, as well as other health issues.

A typical blood pressure should be around 120 over 80, but ideal ranges are going to vary depending on the individual as well as age. I hope that this information was helpful in understanding the cardiovascular system. If you have any additional questions, make sure that you leave them down below.

I love answering your questions. Head over to NurseChunkStar.com where there is a ton of additional resources in order to help you ace those ATITs exams. And as always, I'm going to catch you in the next video. Bye!

Transcript for:Anatomy and Function of the Heart

Transcript for:
Anatomy and Function of the Heart