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In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow. [4] The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium. [8]
One of the simplest methods of assessing the heart's condition is to listen to it using a stethoscope. [1] In a healthy heart, there are only two audible heart sounds, called S1 and S2. The first heart sound S1, is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as "lub".
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
The section shows: 1) the opened ventricles contracting once per heartbeat—that is, once per each cardiac cycle; 2) the (partly obscured) mitral valve of the left heart; 3) the tricuspid and pulmonary valves of the right heart—note these paired valves open and close oppositely. + (The aortic valve of the left heart is located below the ...
The mitral valve is typically 4 to 6 square centimetres (0.62 to 0.93 sq in) in area and sits in the left heart between the left atrium and the left ventricle. [5] It has two cusps: an anterior one, and a posterior one. [6] The opening of the mitral valve is surrounded by a fibrous ring known as the mitral annulus. The anterior cusp attaches to ...
The cardiac skeleton binds several bands of dense connective tissue, as collagen, that encircle the bases of the pulmonary trunk, aorta, and all four heart valves. [2] While not a traditionally or "true" or rigid skeleton, it does provide structure and support for the heart, as well as isolate the atria from the ventricles. This is why atrial ...
The UK's NHS was using around 130,000 pagers in 2019, more than one in 10 of the world's pagers, according to the government. ... It said North America and Europe are the two biggest pager markets ...
A heart valve is a biological one-way valve that allows blood to flow in one direction through the chambers of the heart. A mammalian heart usually has four valves. Together, the valves determine the direction of blood flow through the heart. Heart valves are opened or closed by a difference in blood pressure on each side. [1] [2] [3]