Lesson 11 Partitioning of the Heart (Fetal Development) MacNeil 1. What does the entire heart tube raise from? a. Splanchnic mesoderm of the lateral plate mesoderm b. Somatic mesoderm of the lateral plate mesoderm c. Intermediate mesoderm d. Endoderm 1. A: The entire heart tube arises from the splanchnic mesoderm layer of the trilaminar disc 2. Which of these is incorrect? a. Blood islands form in the splanchnic layer of the lateral plate mesoderm (above the developing brain) b. A U-shaped endothelial primitive heart tube develops as the blood islands merge c. A single heart tube is created by the fusion of the two sides of the U-shaped endothelial primitive heart tube d. The fusion of the two sides occurs everywhere except the rostral aspect of the tube 2: D: The fusion of the two sides occurs except in the caudal aspect of the tube. 3. What occurs in the caudal and cranial ends of the developing heart? I. Cranial: Arterial portion, blood flows from truncus arteriosus->aortic sac->aortic arches II. Caudal: Poles remain separated and form venous inflow region of heart (SVC/IVC->Right Atrium) a. I b. II c. I & II d. None of the above 3.C: Cranial is the arterial portion, blood flows from truncus arteriosus->aortic sac->aortic arches & in the caudal section the poles remain separated and form venous inflow region of heart (SVC/IVC which flow to the Right Atrium) 4. Which of these are heart dilations? I. sinus venosus (coronary sinus) II. primitive atria (trabeculated left and right atria) III. primitive ventricle (left ventricle; trabeculated left ventricles) IV. bulbus cordis (right ventricle; smooth part of the left and right ventricle) V. truncus arteriosus (outflow tract; ascending aorta and the pulmonary trunk). a. I, II, III, IV, V b. I, II, IV, V c. I, II, III d. All of the above 4. D: All of them are heart dilations