Embryology - Cardiovascular system

Question 1

describe the formation of primary heart field

Answer 1

1. cardiac progenitor cells (epiblast layer) migrate through the primitive streak into SPLANCHNIC MESODERM, cranial-lateral direction
2. at the cranial region, arranges in horse-shoe cluster of cells, on either side of neural plate = cardiogenic area

Question 2

describe the formation of heart tubes (endocardial tubes), and the movement of blood flow

Answer 2

1. angioblastic cords arise in the cardiogenic area, canalise and forms bilateral tubes
2. blood from caudal end in, out via cranial end

Question 3

with regards to lateral body fold and cephalic folding, explain how hear is positioned

Answer 3

Day 21: fusion of the bilateral tube by lateral folding. Primitive heart tube at the midline. attached to the dorsal peritoneal cavity by dorsal mesocardium

cephalic folding: brings CNS over the heart tube and pericardial cavity, its folding brings the structures to the cervical region, finally to thorax

Question 4

describe the process of heart tube looping, when is it completed

Answer 4

1. ventricle (cranial end of heart tube): VCR (ventral, caudal and right bending)
2. Atrium (caudal end of tube): opposite - dorsal, cranial and left bending

day 28 completion

Question 5

what is dextrocardia and what is the cause of it

Answer 5

1. early on in development: problem with laterality
2. problem with cardiac looping: ventricles bend to the left instead

= heart found in the right side of chest

Question 6

describe formation of secondary heart field and structures arising

Answer 6

1. by cells in the splanchnic mesoderm, ventral of the pharynx
2. Right ventricle and right ventricle outflow tract, parts of the atrium

Question 7

what is cardiac jelly and its significance

Answer 7

• gelatinous connective tissue
• role in septation of the chambers
• contributes to thickness of heart wall
• regresses as differentiate