L6 - Embryology 2

Question 1

Septation divides three regions, what are these?

Answer 1

Atria - interatrial septum
Ventricles - interventricular septum
Ventricular outflow Tract - pulmonary trunk and aorta

Question 2

What is the first step in initial septation?

Answer 2

Fusion of the endocardial cushions

Question 3

Formation of the interatrial septum allows a right to left shunt in the heart. Fill in the blanks in inter-atrial septation

1) endocardial cushions fuse dividing the heart into left and right AV canals
2) the _____ _______ grows towards the fused endocardial cushions
3) the septum primum fuses with the endocardial cushions and a second hole appears in the septum primum called the _____ ______
4) The initial hole the _____ _____ closes as the septum primum fuses with the endocardial cushions
5) Finally, a second crescent shaped septum, the ______ ________ grows, the hole in this is called the ______ ________

Answer 3

1) septum primum
2) ostium secundum
3) ostium primum
4) septum secundum
5) foramen ovale

Question 4

What is the remnant of the foramen ovale called in the adult?

Answer 4

Fossa ovalis

Question 5

At birth the pressure in the left atrium exceeds that of the right atrium and the foramen ovale closes, the septum primum and septum secundum are forced against one another, the fact that the osteum primum and foramen ovale are staggered means what can happen in the foetus?

Answer 5

Blood to be shunted from right to left atria

Question 6

Atrial septum defects are the result of the septum primum or the ____ ______ being too short/small

Answer 6

Septum secundum

Question 7

Hypoplastic left heart syndrome means the left heart is underdeveloped, right to left flow in the foetus is inadequate. We don’t know the exact region for this but suggest why

Answer 7

Osteum secundum is too small thus defect in the mitral/aortic valve development

Question 8

The ventricular septum has two components, one of them being membranous, whats the other?

Answer 8

Muscular

Question 9

In ventricular septation the muscular portion grows up and towards the fuses endocardial cushions leaving a small gap called the?

Answer 9

Primary intraventricular foramen

Question 10

The primary jntraventricular foramen is closed by the membranous portion of the intraventricular septum, where is this tissue derived from?

Answer 10

The endocardial cushions

Question 11

What part of the intraventricular septum most commonly is involved In ventricular septal defect and why?

Answer 11

The membranous portion because it is derived from the endocardial cushions

Question 12

septation of the outflow tracts also begins with endocardial cushions growing toward each other, here they form a spiral septum as they twist around each other as they grow. Where in the primary heart tube do these cushions exist?

Answer 12

The truncus arteriosus

Explanation - refer back to the definition of this. It describes the entry to the outflow tracts

Question 13

Congenital brith defects are normally the result of structural abnormalities or complete absence of a structure in utero. Give an example of a cause.

Answer 13

Genetic/chemical exposure/drug exposure/infectious agents

Explanation - congenital simply means from birth

Question 14

What is the worldwide incidence of congenital heart defects

Answer 14

1%

Question 15

What is a likely symptom of transposition of the great arteries?

Answer 15

Cyanosis

Question 16

Tetralogy of fallout is a ventricular septal defect. The four pathologies are

1) pulmonary stenosis
2) right ventricular hypertrophy coz the heart has to work harder
3) ———
4) ———-

Answer 16

3) overriding aorta - aorta receives blood from both ventricles
4) large ventricular septal defect

Question 17

is cyanosis a symptom of left to right or right to left shunts?

Answer 17

right to left

Question 18

how would you diagnose a PDA?

Answer 18

Patent ductus arteriosus would have a continuous machinery heart murmur as the flow is always turbulent. No problem if it small but the heart will have to work harder if it is big as extra blood will go to the lungs? Not sure I get this as it bypasses the lungs