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IMF-086-01-0001-en	How does the primitive heart tube form from cardiogenic mesoderm, and what separates its layers?	Embryonic folding brings the paired heart-forming regions ventrally and together, where endothelial tubes fuse; surrounding splanchnic mesoderm forms myocardium, separated from endocardium by cardiac jelly.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0002-en	Why must a congenital heart be described by tracing its connections rather than by chamber position alone?	Looping sets spatial relationships but does not complete chamber identity, and abnormal looping can give discordant atrioventricular or ventriculoarterial connections, so venous return and each connection must be traced.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0003-en	Why does the right horn of the sinus venosus become part of the right atrium while the left horn becomes the coronary sinus?	Shunting of venous return toward the right enlarges the right horn into the smooth sinus venarum, while the left horn becomes the coronary sinus and oblique vein; the crista terminalis marks the smooth-trabeculated junction.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0004-en	Why is the posterior wall of the left atrium smooth, and what happens when this process goes wrong?	Pulmonary veins are progressively incorporated into the posterior left atrium, forming its smooth wall; abnormal connection leaves them draining partly or entirely into systemic veins, with presentation set by obstruction and mixing.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0005-en	How does the fetal atrial septum permit right-to-left flow while restricting reverse flow?	Septum secundum forms to the right, leaving the foramen ovale, and septum primum acts as a flap valve that permits fetal right-to-left flow but restricts flow in the opposite direction.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0006-en	Why does the foramen ovale close functionally after birth?	Increased pulmonary blood flow raises left-atrial pressure, which presses septum primum against septum secundum and closes the foramen; anatomical fusion may follow later.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0007-en	What distinguishes a probe-patent foramen ovale from a true atrial septal defect?	A probe-patent foramen ovale reflects incomplete anatomical fusion after functional closure, whereas a true atrial septal defect reflects deficient tissue and permits sustained shunting.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0008-en	Why can an endocardial cushion defect combine atrial and ventricular septal defects with abnormal atrioventricular valves?	The cushions divide the atrioventricular canal and contribute valve leaflets, the membranous ventricular septum and atrial septal closure, so a failure of cushion formation affects all of these together.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0009-en	Where do ventricular septal defects most often occur, and why can a large one eventually reverse its shunt?	Most involve the membranous region, derived from cushions and outflow ridges; prolonged large left-to-right shunting causes pulmonary vascular disease that can eventually reverse the shunt.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0010-en	Why do defects of neural-crest migration produce conotruncal anomalies?	Neural crest populates the outflow ridges that spiral and fuse into the aorticopulmonary septum, so migration or rotation defects leave great arteries unseparated or misaligned, as in persistent truncus or tetralogy of Fallot.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0011-en	How does a single developmental error produce all four features of tetralogy of Fallot?	Anterior displacement of the outflow septum creates right-ventricular outflow obstruction, a ventricular septal defect and an overriding aorta, with secondary right-ventricular hypertrophy; severity depends mainly on obstruction and shunt.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0012-en	Why does survival in complete transposition of the great arteries depend on an atrial, ventricular or ductal communication?	Failure of normal outflow spiralling creates parallel systemic and pulmonary circuits, so the two circulations meet only where blood can mix through such a communication.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0013-en	Why may a congenital valve abnormality become clinically important only years after birth?	Abnormal cusp number, fusion or matrix is structurally present at birth, but the resulting stenosis or regurgitation may become clinically important only after years of altered stress.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0014-en	How does asymmetric aortic arch remodelling account for the carotid, aortic arch, right subclavian, pulmonary arteries and ductus arteriosus?	Third arches form common and proximal internal carotids; left fourth forms part of the aortic arch and right fourth the proximal right subclavian; sixth arches form proximal pulmonary arteries, the left distal sixth persisting as the ductus.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0015-en	How can abnormal persistence of aortic arch segments compress the airway and oesophagus?	A double aortic arch, or a right arch with ligamentous components, can form a vascular ring around the trachea and oesophagus; an aberrant subclavian artery passing behind the oesophagus may occasionally impair swallowing.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0016-en	How does embryonic venous remodelling explain variants such as a left-sided superior vena cava or anomalous renal veins?	Cardinal systems form the major systemic veins through selective anastomosis and regression, so variations in this complex remodelling leave a left superior vena cava, anomalous renal veins or collateral pathways.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0017-en	Which anomalous coronary origins or courses particularly compromise perfusion, and what developmental step do they reflect?	An artery passing between the great vessels or arising from the pulmonary artery; they reflect failure of the proximal coronary stems to enter the appropriate aortic root sinuses.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0018-en	How does incomplete tracheoesophageal partition present before and after birth?	Incomplete separation by the tracheoesophageal folds commonly gives oesophageal atresia with distal fistula, causing polyhydramnios prenatally and choking, respiratory distress or gastric distension after birth.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0019-en	Why are the laryngeal muscles supplied by branches of the vagus nerve?	Laryngeal cartilages and muscles derive largely from fourth- and sixth-arch mesenchyme and retain vagal innervation through the superior and recurrent laryngeal branches.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0020-en	Which lung tissues derive from endoderm and which from splanchnic mesoderm, and what drives repeated branching?	Epithelium and glands are endodermal, while smooth muscle, cartilage, connective tissue and vessels are splanchnic mesoderm; reciprocal epithelial-mesenchymal signalling guides repeated branching.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0021-en	What distinguishes the pseudoglandular stage from the canalicular stage of lung development?	In the pseudoglandular stage conducting airways branch but gas-exchange structures are absent; the canalicular stage enlarges lumina, increases vascularisation and begins respiratory bronchioles.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0022-en	Why does surfactant deficiency in prematurity cause respiratory distress, and how can maturation be accelerated?	Inadequate surfactant from type two pneumocytes raises surface tension, causing atelectasis and low compliance; antenatal glucocorticoids accelerate maturation when preterm birth is likely.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0023-en	Why can severe oligohydramnios or absent fetal urine cause pulmonary hypoplasia?	Fetal lung fluid maintains expansion and supports growth, so conditions that impair expansion, including oligohydramnios, prolonged membrane rupture or absent fetal urine, limit lung growth.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending
IMF-086-01-0024-en	In congenital diaphragmatic hernia, why does clinical severity reflect lung development more than the defect itself?	Abdominal viscera herniating through the posterolateral defect compress the developing lung, causing hypoplasia and pulmonary hypertension, and these, not the hole, determine severity.	Integrated Medical Foundations; chapter 86, TTS module 1; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 9ca814733ca5a2512b145fbaca156694132985022cc9035fd6e0035cbb850763; editorial review pending	imf lang::en chapter::086 module::086-01 review::pending