have you ever questioned why our heart goes love dub love dub well that's exactly what we're going to be talking about today we're going to be talking about the ait's version 7 human anatomy and physiology portion of the exam more specifically cardiovascular system let's get started the cardiovascular system plays an entral 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 not 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 jugles 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 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 capillar Aries 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 when we're examining a patient's heart you're going to 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 nemonic that I like to remember when it comes to the card vascular 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 oneway 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 aits 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 health care 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 venne Caba whether that's inferior or Superior the inferior venne 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 venne 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 start starts when the blood enters into to 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 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 mitro Val 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 to 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 over look 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 de de oxygenated and oxygenated blood we call this septal defects this is when the septum the muscular wall that divides the hearts left and right sides have some kind of abnormality a sepal defect involves the opening that allows oxygen rich blood and oxygen poor blood to mix depending on the defect 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 on our inter atrial septum is going to result in atrial sepal 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 venne 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 my sites 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 that essay note we encounter a structure known as Bachman's bundle it is characterized by its ability to transmit high-speed signals extending from the essay node across that atrial subtile wall into our left Atria the Nal 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 SA node all the way down to our atrial ventricular node the atrial ventricular node is situated in the right atrium but this time it's going to be near the coronary sinus and our tricuspid valve this clusters of cells is specialized to momentarily pause that electrical signal from the SA node before it can proceed SE down into the ventricles this intentional delay is crucial because it provides sufficient time for the Atria 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 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 last lastly we turn our attention to the preni 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 inherit 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 B'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 pneumonic to remember the order of the heart's conduction system is strong arteries benefit B's performance where the S and strong stands for our SE node the A and artery stands for our av node the B's and benefit in body stands for our bundle branches and the p and performance stands for our perin fibers starting with our SA node that is our heart's primary Pac maker 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 to 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 to to 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 preni 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 ISO electric 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 healthc Care 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 proceeded by this very prominent formation known as our Qs 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 and ventricles V and our CS 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 atrial repolarization happens concurrently during the time frame of that QRS complex that Qs 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 Qs 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 beets 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 880 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 nurse Chun store.com where there is a ton of additional resources in order to help you Ace those ait's exams and as always I'm going to catch you in the next video bye