:

THE CARDIOVASCULAR SYSTEM The picture shows the tranverse section of the embryo demonstrating the formation of the angioblastic cords

. In which region do these cords develop? The picture shows the lateral folding of the embryo and the fusion of the endocardial tubes

. What is the significance of this folding? This picture shows the formation of cardiac loop

. What are the five dilatations which form on the primordial heart tube? . What results in the bending of the heart tube? The picture shows the structure of a primordial heart

. Give the three pairs of veins which are received by the sinus nenosus. The picture shows blood circulation through a primordial heart

. Describe the circulation of blood through the primordial heart. The picture shows the formation of

. What are endocardial cushions and what is their significance? The picture shows the septation of the in the primordial heart

. Give the two septa which are responsible for the formation of the interatrial septa. . What results in the perforations denoted by the red arrows? . What results in the formation of foramen primum and ? . What is its significance? . What result in the formation of ? What is the significance of this foramen? . What structure does formen ovale forms in the adult? The diagram shows the division of the into the left and right horns

. Which structure is responsible for this division? . What are the derivatives/remnants of the left horn of the sinus venosus? . What is the fate of the right horn of the sinus venosus? The picture shows the absorption of the pulmonary vein into the left atrium

. What is the significance of this absorption? The diagram shows the septation of the

. What forms the pars muscularis of the ? The diagram shows the septation of the ventricle

. What forms the pars membrenacea of the interventricular septum? The picture shows the development of the and the

. What are bulbar and truncal ridges? The picture shows the formation of the

. What results in the formation of this septum? This diagram illustrates the spiral form of the aorticopulmonary septum

. What is the significance of this septum? The diagram shows the great arteries twisting around each other as they leave the heart

. How does the aortocopulmonary septum contribute towards this twisting? Short essay questions

. Describe the formation of the . (10 marks)

. Describe the formation of the interventricular septum. (8 marks)

. Describe the septation of the atrio-ventricular canal. (3 marks)

Multiple choice questions

. The umbilical arteries form the following structures in the adult

a) Medial umbilical ligament. b) Ligamentum arteriosum. c) Ligamentum venosum. d) Superior vesical arteries. e) Ligamentum teres.

. The interatrial septum is formed by

a) Pars muscularis. b) and . c) Septum secundum and foramen secundum. d) Septum primum and foramen primum. e) Pars membranacea.