NBME CBSE TERMS AND EXPLANATIONS 2022 A+ MATERIAL

NBME CBSE TERMS AND EXPLANATIONS 2022 A+ MATERIAL Bulbus cordis - Gives rise to Smooth parts (outflow tract) of left and right ventricles Endocardial cushion - Gives rise to atrial septum, membranous interventricular septum; AV and semilunar valves Left horn of sinus venosus - gives rise to coronary sinus Posterior, subcardinal, and supracardinal veins - Gives rise to Inferior Vena cava Primitive atrium - gives rise to trabeculated part of left and right atria Primitive ventricle - Gives rise to trabeculated parts of LV and RV Primitive pulmonary vein - Gives Rise to Smooth part of left atrium Right common cardinal vein and right anterior cardinal vein - Gives rise to Superior vena cava (SVC) Right horn of sinus venosus - Gives rise to Smooth part of right atrium (sinus venarum) Truncus arteriosus - Gives rise to ascending aorta and pulmonary trunk Heart - First functional organ in vertebrate embryos; beats spontaneously by week 4 of development. Cardiac looping - Primary heart tube loops to establish left-right polarity; begins in week 4 of gestation Defect in left-right Dynein - involved in L/R asymmetry can lead to Dextrocardia, as seen in Kartagener syndrome(1°ciliary Dyskinesia). Patent foramen ovale - caused by failure of septum primum and septum secundumto fuse after birth; most are left untreated. Can lead to paradoxical emboli (venous thromboemboli that enter systemic arterial circulation), similar to those resulting from an ASD Ventricular septal defect - most common congenital cardiac anomaly, usually occurs in membranous septum. Septation of atria (7 Steps) - 1. Septum primum grows toward endocardial cushions, narrowing foramen primum. 2. Foramen secundum forms in septum primum (foramen primum disappears). 3. Septum secundum develops as foramen secundum maintains right-to-left shunt. 4. Septum secundum expands and covers most of the foramen secundum. The residual foramen is the foramen ovale. 5. Remaining portion of septum primum forms valve of foramen ovale. 6. (Not shown) Septum secundum and septum primum fuse to form the atrial septum. 7. (Not shown) Foramen ovale usually closes soon after birth because ofLA pressure. Septation of Ventricle - 1. Muscular interventricular septum forms. Opening is called interventricular foramen 2. Aorticopulmonary septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum, closing interventricular foramen. 3. Growth of endocardial cushions separates atria from ventricles and contributes to both atrial septation and membranous portion of the interventricular septum Aorticopulmonary septum - rotates and fuses with muscular ventricular septum to form membranous interventricular septum, closing interventricular foramen Septum primum - grows toward endocardial cushions, narrowing foramen primum Foramen secundum - forms in septum primum (foramen primum disappears). Septum secundum - develops as foramen secundum maintains right-to-left shunt expands and covers most of the foramen secundum foramen ovale - connects the two atria in the fetal heart usually closes soon after birth because of inceased LA pressure and decreased RA pressure. Conotruncal abnormalities - associated with failure of neural crest cells to migrate 1.Transposition of great vessels 2.Tetralogy of Fallot. 3.Persistent truncusarteriosus. Neural crest and endocardial cell migrations - - truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum - ascending aorta and pulmonary trunk Aortic/pulmonary Valve Development - derived from endocardial cushions of outflow tract Mitral/tricuspid Valve Development - derived from fused endocardial cushions of the AV canal Valvular anomalies - may be stenotic, regurgitant, atretic (eg, tricuspid atresia), or displaced (eg, Ebstein anomaly). umbilical vein - blood has a Po2 of 30 mm hg and is 80% saturated w/ O2 Umbilical arteries - have lower O2 saturation than veins in fetus ductus venosus - Blood entering fetus the rough the umbilical vein is conducted into the IVC, by passing hepatic circulation. foramen Ovale - Most of the highly Oxygenated blood reaching the heart via the IVC is directed through and pumped into the aorta to supply the head and body Ductus arteriosus - a blood vessel in a fetus that bypasses pulmonary circulation by connecting the pulmonary artery directly to the Descending aorta aorta shunt is due to high fetal pulmonary artery resistance At birth - infant takes a breath - decreases resistance in pulmonary vasculature - increases left atrial pressure vs right atrial pressure- foramen ovale doses ; increase in 02 (from respiration) and I in prostaglandins (from placental separation) - closure of ductus arteriosus. Indomethacin - helps close PDA - ligamentum arteriosum (remnant of ductus arteriosus) ligamentum arteriosum - remnant of ductus arteriosus Prostaglandins E1/2 - keep PDA open Allantois - urachus - Postnatal Derivative: Median umbilical ligament Urachus - part of allantoic duct between bladder and umbilicus Ductus arteriosus - Postnatal Derivative: Ligamentum arteriosum Near the left recurrent laryngeal nerve. Ductus venosus - Postnatal Derivative: Ligamentum venosum Foramen Ovale - Post Natal Derivative: Fossa ovalis Notochord - Postnatal Derivative: Nucleus pulposus