Скачать с ютуб Why does the right heart has tricuspid valve and the left has bicuspid? - 3D ANIMATED Lecture в хорошем качестве

Why does the right heart has tricuspid valve and the left has bicuspid? - 3D ANIMATED Lecture

Right heart has the Tricspid valve while the left heart has the bicuspid valve. Why is that so? The reason is explained in this visual lecture by Dr. Aizaz from MedicoVisual 00:00 Intro 01:19 Mnemonic 02:24 Right AV orifie is larger than the left AV Orifice 04:26 Why is Right AV orifie bigger than the left AV Orifice 06:12 Why the right ventricle is triangular shaped while the left is tube shaped 07:20 Difference in Cardiac Dynamics of Right and Left ventricles Whether or not you are a medical student, if you have even a little background in human biology you must be knowing that the right heart consists of a tricuspid valve, meaning that it has three flaps or cusps. Opposite to that, the left heart has a bicuspid valve i.e., a valve with two flaps. Your intriguing mind might have compelled you to question that why the right heart has a valve with three cusps while the left has valve with two cusps. Actually, it is easy to remember Right side has tRicuspid valve. But I don’t want you to just cram this up. I want to build the basic concepts in your mind. The cusps of these valves are attached at periphery to the rim of an orifice called atrioventricular orifice. The right AV orifice is larger than he left av orifice. According to Grays anatomy the mean circumference of the right av orifice is 11.4cm in males and 10.8cm in females while the mean circumference of the left av orifice is 9.0cm in males and 7.2cm females. So, it means more cusps are needed on the right side. That is the most plausible reason for the presence of three cusps on the right side. Now this explanation breeds another question in our mind. Why the hell, the right av orifice has a greater diameter than the left? There must be some reason behind it. Well, as it turns out, there actually is. If you look carefully, the base of the right ventricle is much wider as compared to the left ventricular. The right ventricle is kinda triangular shaped while the left ventricle is shaped much like a tube or bullet. Also, because the left ventricle has to pump the blood to whole of the body against much greater resistance, its walls are much thicker, and lumen is relatively narrower. Overall, the surface area of the right ventricle is great than that of left ventricle, even though both chambers pump approximately the same volume of blood. You see, everything in our body is purpose-built and the heart is epitome of such intelligent design. To understand the rationale of such shape and design of ventricles, let’s dive a bit into the sea of physiology. The right ventricle has to pump the blood to the lungs which are very near to the heart. So not much resistance is offered to the pulmonary blood flow. It means, much lesser pressure is needed to open up the pulmonary valve and push the blood through the pulmonary trunk. Opposite to that, the left ventricle has to pump the blood throughout the body, so much greater pressure is required for this task. As a result, the left ventricle generates a much greater pressure compared to the right ventricle with the same volume of blood. Imagine we have two balloons. One is smaller and has of course, smaller surface area. The other one is bigger and has a larger surface area. If we pour an equal volume of water in both of these balloons and measure the pressure within their lumen, which balloon will have greater pressure? The smaller one. Because here the surface area to volume ratio is lower. Now imagine that the left ventricle is the balloon with smaller surface area while the right ventricle is the balloon with larger surface area. I hope you got the point here. Now what is the reason for the triangular shape of right ventricle and bullet like shape of left ventricle. The answer lies in their dynamics of working. This concept has been brilliantly explained by “Walter F. Boron” in the book “Medical Physiology” on Pg no. 539 The right ventricle has a free wall that moves against the relatively fixed interventricular septum in a bellows like motion. This effectively pushes a good volume of blood without causing an excessive buildup of intraluminal pressure. The contraction dynamics of left ventricles are quite different. The left ventricle is squeezed in a circular motion, thus decreasing the diameter of the tube-like left ventricle. Its mechanism of contraction mimics squeezing the toothpaste out of the tube. This builds up a greater pressure. ____________________ Heart 3D Model from "BodyParts3D, © The Database Center for Life Science licensed under CC Attribution-Share Alike 2.1 Japan" -modified and completed by "Z-Anatomy.com - The open source atlas of human anatomy" -Textures modified by Dr. Aizaz on Blender