irst Aid USMLE Step 1 Cardiovascular Questions And Answers 2023 (A+)

First Aid USMLE Step 1 Cardiovascular Questions And Answers 2023 (A+) Truncus arteriosus gives rise to __________. - ANS-Ascending aorta and pulmonary trunk Bulbus cordis gives rise to __________. - ANS-Smooth parts (outflow tract) of left and right ventricles Endocardial cushion gives rise to? - ANS-Atrial septum ,membraneous interventricular septum; AV & semilunar valves Primitive atrium gives rise to __________. - ANS-Trabeculated (muscular) portions of the left and right atria Primitive ventricle gives rise to __________. - ANS-Trabeculated (muscular) portions of the left and right ventricles Primitive pulmonary vein gives rise to __________. - ANS-Smooth part of the right atrium Left horn of sinus venosus gives rise to __________. - ANS-Coronary sinus Right horn of sinus venosus gives rise to __________. - ANS-Smooth part of the right atrium (sinus venarum) Right common cardinal vein and right anterior cardinal vein gives rise to __________. - ANS-Superior vena cava (SVC) When does the heart beat begin to beat spontaneously? - ANS--4 weeks of development -First functional organ in vertebrate embryos What is cardiac looping? - ANS--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___________, as seen in Kartagener syndrome (primary ciliary dyskinesia). - ANS-Dextrocardia What is a foramen/ostium? - ANS-opening What is a septum? - ANS-wall Septation of atria (7 Steps) - ANS-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 of increased LA pressure. Patent foramen ovale is caused by a failure of __________ and ___________ to fuse after birth. What can this lead to? - ANS--Caused by failure of septum primum and septum secundum to 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. Septation of the ventricles (3 steps) - ANS-1. Muscular ventricular 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. What is the most common congenital cardinal anomaly? - ANS-VSD Most common location of VSD? - ANS-The membranous septum Outflow tract formation - ANS-Truncus arteriosus rotates; neural crest and endocardial cell migrations cause truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum to form ascending aorta and pulmonary trunk. What are the conotruncal abnormalities associated w/ failure of neural crest cells to migrate? - ANS-Transposition of the greta vessels Tetralogy of Fallot Persistent truncus arteriosus Aortic/pulmonary valves are derived from ____________. - ANS-The endocardial cushions of outflow tract. Mitral/tricuspid valves are derived from __________. - ANS-Fused endocardial cushions of the AV canal. Fetal erythropoiesis occurs in ___________? - ANS--Yolk sac (3-8 weeks) -Liver (6 weeks-birth) -Spleen (10-28 weeks) -Bone marrow (18 weeks to adult) Hemoglobin development - ANS--Embryonic globins: ζ and ε. -Fetal hemoglobin (HbF) = α2γ2. -Adult hemoglobin (HbA1) = α2β2. -HbF has higher affinity for O2 due to less avid binding of 2,3-BPG, allowing HbF to extract O2 from maternal hemoglobin (HbA1 and HbA2) across the placenta. Fetal circulation diagram - ANSBlood in umbilical vein has a Po2 of _________ and is ________ saturated with O2. - ANS-≈ 30 mmHg, ≈ 80% Umbilical arteries have _____ O2 saturation. - ANS-Low 3 important shunts - ANS-1. Ductus venosus 2. Foramen ovale 3. Ductus arteriosus Ductus venosus - ANS-Blood entering fetus via placenta through the umbilical vein is conducted via the ductus venosus into the IVC, bypassing hepatic circulation. Foramen ovale - ANS-Most of the highly oxygenated blood reaching the heart via the IVC is directed through the foramen ovale and pumped into the aorta to supply the head and body. Ductus arteriosus - ANS-Deoxygenated blood from the SVC passes through the RA - RV - main pulmonary artery through patent ductus arterioles - patent descending aorta; shunt is due to high fetal pulmonary artery resistance (due partly to low O2 tension). Closure of foramen ovale - ANS-At birth, infant takes a breath; decreased resistance in pulmonary vasculature (d/t a decrease in intra-thoracic pressure from the baby taking a breath) - increased left atrial pressure vs. right atrial pressure (d/t increase in blood entering the pulmonary artery & more blood returning to the LA); foramen ovale closes (now called fossa ovalis); Closure of ductus arteriosus - ANS-Increase in O2 (from respiration) and decreaese in prostaglandins (from placental separation) causes closure of ductus arteriosus. ________ helps close a PDA - ANS-Indomethacin __________ keeps the PDA open. - ANS-PGE1 and PGE2 **Prostaglandins dilate vessels "E1 & E2 kEEp PDA open" What is the remnant of the ductus arteriosus called - ANS-ligamentum arteriosum What becomes of the allaNtois- urachus - ANS-MediaN umbilical ligament Urachus is part of what? - ANS-Urachus is part of allantoic duct between bladder and umbilicus What is the adult remnant of the ductus arteriosus? - ANS-Ligamentum arteriosum What is the adult remnant of the ductus venosus? - ANS-Ligamentum venosum What is the adult remnant of the foramen ovale? - ANS-Fossa ovale What is the adult remnant of the Notochord? - ANS-Nucleus pulposus What is the adult remnant of the umbiLical arteries? - ANS-MediaL umbilical ligaments What is the adult remnant of the umbilical vein? - ANS-Ligamentum teres hepatis Tunica intima - ANS--Innermost layer of the wall of a blood vessel -In contact with blood -Composed of endothelium (simple squamous epithelium), subendothelium (loose connective tissue), and (maybe) an internal elastic lamina (IEL) -Endothelium provides very smooth surface -Subendothelium is the "glue" -Where the fat/cholesterol deposits in atherosclerosis Tunica media - ANS--Middle layer of blood vessel wall -Primarily contains circularly arranged smooth muscle cells (*except in elastic artery where elastic lamina/fibers dominates) -Contraction of smooth muscle cells changes the diameter of the vessel and affect the blood pressure Tunica adventitia - ANS--Outer layer of blood vessel wall -A layer of c.t. containing collagen and elastic fibers -In large and medium veins it contains longitudinal smooth muscle fibers -Small blood vessels called vasa vasorum may be present Internal elastic lamina - ANS--A layer of elastic tissue that forms the outermost part of the tunica intima of blood vessels. It separates tunica intima from tunica media External elastic lamina - ANS-A layer of elastic connective tissue lying immediately outside the smooth muscle of the tunica media of an artery Coronary Artery Anatomy (Pic!) - ANSSA and AV nodes are usually supplied by _____. - ANS-RCA Infarct of blood supply to SA and AV nodes may cause _____________. - ANS-Nodal dysfunction (bradycardia or heart block). The coronary arteries arise from _________. - ANS-The aorta 3 main branches of the left main coronary artery (LCA) - ANS-Left circumflex artery (LCX), left anterior descending artery (LAD), & Left (obtuse) marginal artery The left circumflex artery (LCX) supplies what? - ANS-Lateral and posterior walls of left ventricle, anterolateral papillary muscle The left anterior descending artery (LAD) supplies what? - ANS-The anterior 2/3 of the interventricular septum, anterolateral papillary muscle, and anterior surface of the left ventricle "Widow-Maker" Branches of the Right Coronary Artery (RCA)? - ANS-Right (acute) marginal artery and the posterior descending/interventricular artery (PDA) What does the right (acute) marginal artery supply? - ANS-Right ventricle What does the posterior descending/interventricular (PDA) artery supply? - ANS-The posterior 1/3 of the IV septum, posterior walls of the ventricles, and the posteromedial papillary muscle What is right-dominant circulation? - ANS-PDA arises from RCA (occurs 85% of the time) "most people are right-handed" What is left-dominant circulation? - ANS-PDA arises from LCX (occurs 8% of the time) What is co-dominant circulation? - ANS-PDA arises from both RCA & LCX (occurs 7% of the time) Coronary artery occlusion most commonly occurs in the ____. - ANS-LAD Coronary blood flow peaks in ________. - ANS-Early diastole What is the most posterior part of the heart? - ANS-Left atrium CONTINUES....