WEBVTT 00:00:07.513 --> 00:00:09.666 The heart is a vital organ. 00:00:10.333 --> 00:00:13.000 It is located roughly in the center of the chest. 00:00:13.726 --> 00:00:17.000 The tip of the heart points towards the left. 00:00:17.633 --> 00:00:21.273 This is why the heartbeat is felt more strongly in the left side of the chest. 00:00:22.599 --> 00:00:24.732 The heart is roughly the size of a fist. 00:00:25.426 --> 00:00:29.112 It consists of several layers of tissue with a hollow center. 00:00:29.906 --> 00:00:34.105 The outermost layer is the heart sac, also known as the pericardium. 00:00:35.000 --> 00:00:37.300 The next layer is the epicardium, 00:00:37.300 --> 00:00:40.220 consisting largely of fat and connective tissue 00:00:41.073 --> 00:00:44.806 Next comes the actual muscle tissue, known as the myocardium. 00:00:45.679 --> 00:00:48.159 The innermost layer is the endocardium, 00:00:48.159 --> 00:00:50.759 which lines the interior of the heart. 00:00:50.759 --> 00:00:53.572 It is therefore also known as the lining of the heart. 00:00:54.719 --> 00:00:56.599 The layers of tissue in the heart 00:00:56.599 --> 00:00:59.165 may become inflamed for various reasons. 00:00:59.925 --> 00:01:05.384 Doctors then use terms such as myocarditis or endocarditis. 00:01:06.618 --> 00:01:10.651 Bacteria or viruses are potential triggers of this inflammation. 00:01:12.431 --> 00:01:14.544 The role of the heart is to 00:01:14.544 --> 00:01:16.670 supply all organs and tissues with blood 00:01:16.670 --> 00:01:19.450 and thus also with oxygen and nutrients. 00:01:20.530 --> 00:01:24.000 The heart pumps oxygen-rich blood from the lungs into the body 00:01:24.000 --> 00:01:27.393 and pumps oxygen-poor blood from the body back into the lungs. 00:01:30.073 --> 00:01:32.600 This is why the heart is divided into two halves, 00:01:32.600 --> 00:01:35.286 which are separated by the heart wall. 00:01:36.073 --> 00:01:39.000 It is therefore more accurate to describe the heart as two pumps. 00:01:39.746 --> 00:01:43.686 Our circulatory system actually consists of two parts – 00:01:43.686 --> 00:01:47.199 the smaller pulmonary system and the larger systemic system, 00:01:47.199 --> 00:01:49.485 with the heart located between the two. 00:01:50.378 --> 00:01:54.652 The left half of the heart pumps blood through the body to the right half, 00:01:54.652 --> 00:01:58.418 which pumps the blood back into the left half through the lungs. 00:01:58.418 --> 00:02:01.338 Each half of the heart consists of a small upper chamber, the atrium, 00:02:01.338 --> 00:02:03.452 and a larger lower chamber, the ventricle. 00:02:05.111 --> 00:02:08.000 Let's take a look at how the heart works in more detail: 00:02:08.000 --> 00:02:10.584 • Oxygen-rich blood from the lungs 00:02:10.584 --> 00:02:13.986 travels via the pulmonary veins to the left atrium. 00:02:14.560 --> 00:02:18.166 There, it passes through a heart valve (the mitral valve) 00:02:18.166 --> 00:02:21.160 into the left ventricle, where it is pumped through a valve 00:02:21.160 --> 00:02:24.226 into the body through the aorta. 00:02:25.293 --> 00:02:29.213 • The oxygen in the blood is used for various metabolic processes in the body. 00:02:30.073 --> 00:02:32.766 • The oxygen-poor blood from the body travels 00:02:32.766 --> 00:02:35.359 through the vena cava into the right atrium, 00:02:35.359 --> 00:02:42.132 where it passes through a value known as the tricuspid valve and enters the right ventricle. 00:02:42.132 --> 00:02:44.445 Here, it is pumped through another heart valve 00:02:44.445 --> 00:02:48.000 back into the lungs via the pulmonary artery. 00:02:48.000 --> 00:02:51.084 In the lungs, it can be enriched with oxygen once more. 00:02:52.765 --> 00:02:56.046 The heart valves act like one-way doors to ensure that the blood 00:02:56.046 --> 00:02:59.231 flows in one direction only and cannot flow backwards. 00:03:00.398 --> 00:03:03.000 If the heart valves are not working correctly, 00:03:03.000 --> 00:03:05.361 either due to a condition that was present at birth 00:03:05.361 --> 00:03:07.966 or because they were damaged over the course of a person's life, 00:03:07.966 --> 00:03:11.817 the strength and performance of the heart and the entire body are weakened. 00:03:12.671 --> 00:03:17.000 The heartbeat is produced by the rhythmic contractions of the heart’s muscle cells, 00:03:17.000 --> 00:03:18.997 which can be felt as throbbing. 00:03:19.891 --> 00:03:25.171 When at rest, an adult’s heart beats approximately 60 to 80 times a minute. 00:03:26.297 --> 00:03:29.878 The heartbeat is regulated by electrical signals, 00:03:29.878 --> 00:03:32.677 generated by the sinus node, 00:03:32.677 --> 00:03:35.310 which is located in the wall of the right atrium. 00:03:36.466 --> 00:03:39.000 Even if a heart is completely healthy, 00:03:39.000 --> 00:03:41.607 its rhythm is never entirely regular – so there’s no need to worry 00:03:41.607 --> 00:03:45.233 if your heartbeat briefly falls out of its usual rhythm. 00:03:46.000 --> 00:03:49.266 However, if the rhythm of the heartbeat is significantly disrupted, 00:03:49.266 --> 00:03:53.721 causing palpitations (racing heartbeat) or a slowing of the heartbeat, 00:03:53.721 --> 00:03:56.553 this is known as a cardiac arrhythmia, i.e., an abnormal heart rhythm. 00:03:57.000 --> 00:03:59.553 There are a range of possible causes, such as 00:03:59.553 --> 00:04:03.333 inflammation of the heart muscle, heart failure, 00:04:03.333 --> 00:04:07.873 an overactive thyroid or certain medications. 00:04:09.659 --> 00:04:11.003 To recap: 00:04:11.003 --> 00:04:13.506 • The heart is a hollow organ, comprising 00:04:13.506 --> 00:04:16.953 four different layers of tissue: 00:04:16.953 --> 00:04:21.592 the pericardium, epicardium, myocardium and endocardium. 00:04:22.486 --> 00:04:23.979 • It has two halves, 00:04:23.979 --> 00:04:28.000 each comprising an atrium and a ventricle, 00:04:28.000 --> 00:04:31.000 which are separated from one another by a heart valve. 00:04:32.192 --> 00:04:35.000 • Blood enriched with oxygen from the lungs 00:04:35.000 --> 00:04:37.000 flows into the left half of the heart, 00:04:37.000 --> 00:04:39.178 and is pumped from there around the body. 00:04:40.000 --> 00:04:44.346 Oxygen-poor blood from the body flows into the right half of the heart, 00:04:44.346 --> 00:04:46.560 from which it is pumped back to the the lungs. 00:04:47.926 --> 00:04:51.000 • The heartbeat is produced by the contracting heart muscle cells 00:04:51.000 --> 00:04:54.000 and is triggered by electrical signals.