Session 3-Development Of Heart And Great Vessels

Question 1

What is the cardiogenic field?

Answer 1

Zone within mesoderm that can differentiate into the CVS

Question 2

True or false: congenital birth defects can be either structural abnormalities or complete absence of a structure

Answer 2

TRUE

Question 3

What are the potential causes congenital birth defects? (2)

Answer 3

1) genetic

2) exposure to chemicals/drugs/infectious agents

Question 4

When can a congenital heart defect occur? (3)

Answer 4

When there is:

1) a structural defect of the chambers or vasculature
2) obstruction
3) communication between pulmonary and systemic circulations

Question 5

What is the primitive heart tube?

Answer 5

Essentially a modified blood vessel with no chambers or valves

Question 6

What are the different zones of the primitive heart tube, from inlet to outlet tubes? (6)

Answer 6

1) sinus venosus
2) atrium
3) ventricle
4) bulbus cordis
5) truncus arteriosus
6) aortic roots

Question 7

What does cardiac looping allow?

Answer 7

Septation

Question 8

What happens in cardiac looping?

Answer 8

Heart tube elongates, runs out of room and twists and folds up

Question 9

Why is the RA rougher than the LA?

Answer 9

RA has more primitive atrium (trabeculated tissue) than LA

Question 10

What does the RA develop from? (2)

Answer 10

1) most of the primitive atrium

2) sinus venosus

Question 11

What dos the LA develop from? (2)

Answer 11

1) small portion of primitive atrium

2) absorbs proximal parts of pulmonary veins

Question 12

True or false: lungs don’t work in the foetus

Answer 12

TRUE

Question 13

What is required to allow oxygenation and removal of CO2 at the placenta in a foetus?

Answer 13

Shunts

Question 14

In foetal circulation, where does blood with the highest PO2 arrive and where does it travel to?

Answer 14

At the umbilicus, travels through the umbilical vein and up to the liver

Question 15

Why is a shunt created around the liver?

Answer 15

To pump blood into the inferior vena cava because the liver is highly metabolically active during foetal life and would otherwise use up most of the O2 supply

Question 16

Why does a small amount of blood flow from the RA to RV?

Answer 16

To allow the muscle in the RV to contract and to ensure normal development of the ventricle

Question 17

What is the name of the shunt between RA and LA?

Answer 17

Foramen ovale

Question 18

What is the name of the shunt between the pulmonary trunk and aorta?

Answer 18

Ductus arteriosus

Question 19

What is the name of the shunt between the placenta and the inferior vena cava?

Answer 19

Ductus venosus

Question 20

What does the early arterial system begin as?

Answer 20

Bilaterally symmetrical system of arched vessels

Question 21

Which nerve becomes hooked around the shunt between the pulmonary trunk and aorta?

Answer 21

Left recurrent laryngeal nerve

Question 22

What is patent ductus arteriosus? (PDA)

Answer 22

Persistent communication between descending aorta and pulmonary artery and the failure of physiological closure

Question 23

What does ostium primum mean?

Answer 23

First hole

Question 24

What leads to the formation of the ostium secundum?

Answer 24

Apoptosis

Question 25

True or false: blood flows through the foramen ovale when pressure in LA > pressure in RA

Answer 25

FALSE - flows when pressure in LA < pressure in RA

Question 26

After birth, why can blood not flow through the foramen ovale?

Answer 26

Pressure in LA > pressure in RA and septum primum is pushed against septum secundum and as the holes aren’t aligned, no blood can flow through

Question 27

What is atrial septal defect?

Answer 27

Ostium secundum defect-

Septum primum is resorbed and is too short and the septum secundum is too small

Question 28

What is hypoplastic left heart syndrome?

Answer 28

Left heart is underdeveloped

Question 29

What are the potential causes of hypoplastic left heart syndrome? (2)

Answer 29

1) defect in development of mitral and aortic valves resulting in atresia and limited flow
2) ostium secundum is too small therefore R to L flow is inadequate in utero

Question 30

What are the two components of the ventricular septum?

Answer 30

Muscular

Membranous

Question 31

True or false: membranous portion of the ventricular septum forms most of the septum and grows upwards towards the fused endocardial cushions

Answer 31

FALSE - muscular, not membranous

Question 32

Complete the sentence:

The ____________ portion of the ventricular septum grows upwards towards the endocardial cushions leaving a small gap called the primary ________________ __________

Answer 32

Muscular

Interventricular foramen

Question 33

How is the membranous part of the interventricular septum formed?

Answer 33

By connective tissue derived from endocardial cushions to fill the gap

Question 34

Which portion of the interventricular septum is most commonly affected by ventricular septal defect?

Answer 34

Membranous

Question 35

Complete the sentences:

Endocardial cushions also appear in the truncus ___________. As they grow towards each other they twist around each other, forming a ________ _______

Answer 35

Arteriosus

Spiral septum

Question 36

Which operation may be carried out to treat cyanosis?

Answer 36

Arterial switch operation

Question 37

What happens in tetralogy of Fallot? (5)

Answer 37

1) Large ventricular septal defect
2) Aorta straddles both ventricles
3) RV outflow tract obstruction
4) RV hypertrophy
5) Conotruncal septum formation is defective

Question 38

What does the 4th aortic arch develop into?

Answer 38

R=Proximal part of right subclavian artery

L=arch of aorta

Question 39

What does the 6th aortic arch develop into?

Answer 39

R=right pulmonary artery

L=left pulmonary artery and ductus arteriosus