IMED3001 Study Guide - Final Guide: Endocardial Cushions, Atrioventricular Node, Sinus Venosus
14 Dec 2020
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Although it all happens synchronously lets break it down: We need to separate or create left and right ventricles from one chamber iv septum. We need to separate primitive atrium into left and right interatrial septum. Then we need to partition the outflow system. The mitral and tricuspid valves develop from epicardial tissue near opening of av orifices. Form dense ct important part of the supporting framework of the heart (tethering valves etc) Separate the pathway from atria-ventricles (av canal into 2 openings r & l atrioventricular orifices. Comes from roof" of primitive atria floor leaves a hole" or natural. Defect" the foramen primum (acts as a natural shunt by pass lungs until birth) Mid pregnancy 30% shunted to left atrium. 70% goes to r vent pumped around the embryo. Foramen secundum forms in the septum (cranially) from cell death just as f. primum closes at endocardial cushion. Septa develop to separate atrium and ventricles.
