CVS embryology 1 and 2

Question 1

the CVS is the first major system that functions in the embryo, when does it begin to work?

Answer 1

week 4

Question 2

what is the importance of the early functioning of the CVS in embryology?

Answer 2

the embryo is rapidly growing and nutrition by diffusion alone is not sufficient to satisfy the growing embryo

Question 3

describe what happens in CVS development in the 3rd week?

Answer 3

blood vessels ‘islands’ begin to appear in the yolk sac, allantois, connecting stalk, and chorion (these are called the cardiogenic field)

two heart tubes are formed from blood vessels in lateral plate splanchnic mesoderm

heart tubes fuse and join blood vessels in other areas to form primordial CVS

Question 4

what does the parietal and fibrous pericardium from from?

Answer 4

somatic mesoderm

Question 5

what does the visceral layer form from?

Answer 5

splanchnic mesoderm

Question 6

what is the function of the foramen ovale?

Answer 6

to allow blood in the foetal heart to pass from right to left atrium so it does not pass the lung as it is non-functioning at this stage.

Question 7

what is the fossa ovalis

Answer 7

a depression in the interatrial septum in the ADULT heart and is the remnant of the foramen ovale

Question 8

where do the cusps, chordae tendineae and papillary muscles of the ATRIOVENTRICULAR valves develop from?

Answer 8

ventricular wall

Question 9

why does the bulboventricular loop form?

Answer 9

growing tube becomes too large for the pericardium, this is caused by bulbous cordis and primitive ventricle becoming larger than the rest of primitive heart tube

Question 10

in formation of the bulboventricular loop, which direction do the atria and ventricles move?

Answer 10

atria, posteriorly and superiorly

ventricles, left and inferiorly

Question 11

what is the most common positional abnormality of the heart?

Answer 11

dextrocardia

Heart tube loops to left side (instead of right side), so ventricles come to lie facing the right (= dextro)

Question 12

what does the aorticopulmonary septum split and cause the formation of?

Answer 12

divides bulbous cordis and truncus arteriosus into aorta and pulmonary trunk

Question 13

what causes the partitioning of the primitive ventricle?

Answer 13

membranous ventricular septum which closes the interventricular foramen

formed when aorticopulmonary septum comes down and forms with ventricular septum and endocardial cusions

Question 14

what are the first arteries to appear in the embryo?

Answer 14

right and left primitive aortae

Question 15

what are the two methods by which blood vessels develop?

Answer 15

vasculogenesis - defined as the new formation of a primitive vascular network

angiogenesis - defined as the growth of new vessels from pre-existing blood vessels

Question 16

how do most aortic arch abnormalities occur?

Answer 16

Most defects of the great arteries arise as a result of persistence of aortic arches that either normally should regress or regression of arches that normally shouldn’t.

eg. right subclavian artery
sometimes has abnormal origin on
the left may constrict trachea and oesophagus

Question 17

what is double aortic arch abnormality?

Answer 17

occurs with the non-regression of the right aortic arch forming a vascular ring around the trachea and oesophagus, which usually causes difficulty in breathing and swallowing.

Question 18

what is patent ductus arteriosus?

Answer 18

Common anomaly associated with maternal rubella infection in early pregnancy

caused by failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs

Question 19

what is a consequence of patent ductus arteriosus?

Answer 19

An uncorrected PDA may lead to congestiveheart failurewith increasing age

Question 20

what do the 3 embryonic vessels supply and what do they become in adulthood?

Answer 20

Vitelline vessels supply yolk sac, become adult gut vessels

Umbilical vessels supply placenta, become internal iliac

Cardinal vessels supply rest of body, become SVC & IVC

Question 21

what are the 3 types of foetal shunt?

Answer 21

Ductus venosus - shunts blood in left umbilical vein into IVC: allows oxygenated blood from the placenta to bypass the liver.

Foramen ovale - shunts blood from rightatriumto left atrium: allows blood to bypass the lungs.

Ductus arteriosus - shunts blood from right ventricle and pulmonary arteries to aorta: allows blood to bypass the lungs.

Question 22

what happens to the foetal shunts and umbilical arteries after birth?

Answer 22

Ductus venosus - ligamentum venosum of the liver

Foramen ovale closes after birth - fossa ovalis of the heart

Ductus arteriosus - ligamentum arteriosum between left pulmonary artery and aorta

Umbilical arteries - medial umbilical ligaments of the anterior abdominal wall