Heart Structure and Circulation

Cardiacs structure and basic circulation I'm going to show you the parts of the heart in the order that blood passes through them so let's start with the right atrium blood returns to the right atrium from two big vessels called the vena cava so this one is the superior vena cava this one is the inferior and it's draining the lower body the superior vena cava is draining the head and the thorax and upper limbs so we're using blue because this blood is deoxygenated so it enters into the right atrium of the heart and then the heart gives a little bit of a pump and pushes blood down into the right ventricle sorry about that this is the right ventricle with the right ventricle pumps it pushes up the blood out we're use a purple highlighter here up and out through the pulmonary trunk and arteries and that sends the blood to the lungs this would be the left lung and also to the right lung so you've got deoxygenated blood coming in and then it goes down into the right ventricle and then when the right ventricle pumps that blood goes up the pulmonary trunk into the right and left lungs now you there are two important valves to know about here so I'll use green or this valve right here it's called the tricuspid valve or and also known as the right atrioventricular valve or the tricuspid those two different names and when the right ventricle contracts the papillary muscles down here papillary can mean like carrot and so we'll make them orange for fun the papillary muscles hold the AV valve closed so that blood doesn't go backwards back up to the right atrium and it holds them closed with these collagen fibers called the Corday's and didier and then the blood goes up and through semilunar valve and this is the pulmonary semilunar valve pulmonary semilunar and this valve shuts after the right ventricle is finished pushing blood out and pressure starts to decrease in the right ventricle and then this valve fall shut so the AV valve is closed during ventricular contraction and the semilunar valve closes at the end of ventricular contraction and the semilunar valve closes at the end of ventricular contraction for sometimes it's called systole okay so then reset retracing our steps deoxygenated blood comes into the right atrium from the body it's pumped down into the right ventricle when the right ventricle contracts the papillary muscles hold the AV valve closed and push blood up and out through the semilunar valve into the lungs where it gets oxygenated so now we're going to switch over to a pink pen and actually a pink highlighter now that oxygenated blood returns the pulmonary veins from the right and left lung it's coming in on the right and left lung and now this is oxygenated blood and then when that right atrium which is this and the right atrium contracts it pushes blood down into oh sorry left when the left atrium contracts it pushes blood down into the left ventricle and then those papillary muscles are also found in the bottom of the left ventricle and they're also held meant to hold shut an AV valve and so we use green again for the valve so this is the left AV valve sometimes it's known as the by cuspid because it only has two flaps compared to the three flaps of the tricuspid and it looks a little bit like a Pope's hat for something so sometimes it's called a mitral valve three different names for the same valve and this just like the right AV valve closes during ventricular contraction and then during ventricular contraction blood is pumped up from the left ventricle up and out the aorta so get our pink kyle later and okay so goes up and out this blood vessel is called the aorta when it's going up right here it's called the a sending aorta and then it goes across what's called the aortic arch you can see three big arteries coming off there and then when it goes down it's called the descending aorta and then as it continues to go down behind the heart it's called the thoracic aorta and then where it pierces the diaphragm and enters the abdominal cavity it's called the abdominal aorta and meanwhile many blood vessels are coming off along the way so in order for it to be able to be pumped into the aorta though it has to go through one last valve and this is also semilunar valve but this one is the aortic semilunar valve so this one's going to close at the end of ventricular contraction just like the pulmonary semilunar valve so the blood is pouring into both sides of the heart at the same time and then it's going down into both ventricles at the same time and then it's going up and out the exiting vessels exiting arteries at the same time so it's coming in veins at the same time going into ventricles at the same time going out arteries at the same time the difference is is that the right side of the heart is sending its blood to the lungs to get oxygenated and the left side of the heart will be sending its blood to the head the neck the arms the thorax the abdominal cavity the lower legs to send oxygenated blood around there are three bullets that you see these little guys right here these are the coronary arteries the right and left coronary arteries come off first so a lot of times when someone has a thorough sclerosis and heart disease this right coronary artery will be filled with fatty plaques and it can include the ability of the right side of the heart to get enough oxygen to be able to pump effectively that's essentially what a heart attack is the left coronary artery divides and breaks into something called the left anterior descending artery and that goes down to feed the left ventricle so if this is clogged then the left ventricle is not going to get enough oxygen and be able to pump as effectively as it needs to so that would be a heart attack so these coronary arteries are the first to come off of the aorta so that the muscle of the heart gets its oxygen first and why don't we just what color am I not used very much maybe I'll use the orange again so this is muscles this is myocardium you can see that the right ventricle doesn't have as thick of a muscle as the left ventricle and that's because the right ventricle just has to pump the blood a few inches away to the lungs but the left ventricle has to plump pump the blood all the way up to your brain and all the way down to your toes so it's bigger and stronger and the atria have thin walls and walls of muscle too so everything in orange along the sides there this is all a myocardium and Myo means muscle cardio means heart and then this part in the middle is the interventricular septum of the but it's muscle - and it gets its name because it divides so it's between inter means between the ventricles and a septum is a wall so it's the wall between the two ventricles okay then the three large branching arteries that first come off of the aorta which we usually include in a discussion of the heart because you can see them so clearly the first one is the brachiocephalic and it sends oxygenated blood to the arm that's what brachio means and to the head that's what cephalic means and then the next one is called the left common carotid and it says blood up to the left side of the head of the neck and then this one is the left subclavian just like it sounds it goes underneath the clavicle and so this artery sends blood to the left arm so the brachiocephalic sends oxygenated blood to the right arm and the right side of head and neck and up to the brain the left common carotid sends blood to the left side of the brain the left subclavian artery sends blood to the left arm so one artery here splits to go to the arm and to the head whereas in these to come off separately okay I'm gonna go through the pathway one more time deoxygenated blood enters the right atrium via the superior in inferior vena cavas it passes through the right a V valve and enters the right ventricle when the ventricle pumps it pushes blood up and out through the semilunar valve and to the lungs oxygenated blood returns to the left side of the heart via pulmonary veins that oxygenated blood passes down through the right earth left atrium down into the left ventricle when the left ventricle pumps it presses blood up and out through the aortic semilunar valve and out the aorta the coronary arteries are the first little branches to come off to ensure that myocardium gets plenty of oxygen the next branch is the brachiocephalic which sends blood to the right arm and to the right side of the head the left common carotid sends blood to the left side of the head in the left subclavian artery sends blood to the left arm and then as the aorta descends branches come off that give to other parts of the thorax and then the abdominal aorta branches to serve all the internal organs and the lower legs

Channel: Science with Susanna

Views: 832,555

Keywords: heart structure, blood flow through heart, pulmonary trunk, aorta, mitral valve, bicuspid valve, circulation through heart

Id: gkIDX_zlccI

Length: 15min 20sec (920 seconds)

Published: Wed Jan 15 2014