Embryology 1

Question 1

The CVS is created from which germ layer?

Answer 1

mesoderm

Question 2

What is created in the first 2 weeks of embryonic development?

Answer 2

tissues for future embryo and placenta

Question 3

What is created in the third week of embryonic development?

Answer 3

3 germ layers- ectoderm, mesoderm, endoderm

Question 4

What occurs in the 4th week of development?

Answer 4

Recognisable body form develops and mesoderm begins to organise

Question 5

What impact does lateral and cephalocaudal folding have on the cardiac field?

Answer 5

lateral –> creates a heart tube

cephalocaudal –> creates a tube into the thoracic region

Question 6

Why does the embryo need a primitive heart tube?

Answer 6

To push blood/ nutrients around

Question 7

Name the different sections of the primitive heart tube

Answer 7

Aortic roots, truncus arteriosus, bulbus cordis ventricle, atrium, sinus venosus

Question 8

Which sections of the primitive heart tube are surrounded by the pericardial sac (before folding)?

Answer 8

Truncus arteriosus, bulbus cordis, ventricle

Question 9

What does looping achieve in the primitive heart tube?

Answer 9

places inflow/ outflow in correct orientation

Question 10

What vessels are inferior/superior in the transverse pericardial sinus?

Answer 10

arteries (outflow) are on top, veins (inflow) are behind

Question 11

Describe the development of the sinus venousus

Answer 11

• R & L horn equal size
• as baby grows inflow requirements of baby change
• venous return shifts to right hand side and left horn recedes
• Right sinus horn is absorbed by enlarging right atrium

Question 12

From which tissues does the right atrium develop?

Answer 12

Most of the primitive atrium, swallow s the sinus venosus

-recevies venous drainage from venae cava and the heart

Question 13

From which tissues does the left atrium develop?

Answer 13

Small part of primitive atrium
absorbs proximal parts of pulmonary veins
receives oxygenated blood from lungs

Question 14

Why is most of the left atrium smooth?

Answer 14

Absorbs pulmonary vessels

Question 15

The section of the left atrium derived from the primitive atrium is called?

Answer 15

The left auricle

Question 16

How is the oblique sinus formed?

Answer 16

As the left atrium expands, absorbing the pulmonary veins

Question 17

Where do oxygenation and removal of CO2 occur in the embryo?

Answer 17

At the placenta

Question 18

Where does oxygenated blood from the placenta enter the embryonic heart?

Answer 18

Right side (wrong side)

Question 19

What direction does the shunt in the foetal heart move blood?

Answer 19

Right to left (as the right side receives oxygenated blood via the inferior vena cava from the placenta and this needs to be moved to the left atria via foramen ovale to be pumped around the body)

Question 20

Through which vessel does oxygenated blood from the placenta move to the right atrium?

Answer 20

Inferior vena cava

Question 21

Why do the lungs receive a small amount of blood in the embryo?

Answer 21

Not being used but need blood supply to help grow! Does this via a blood vessel called the ductus arteriosus

Question 22

What vessel connects the placenta to the inferior vena cava?

Answer 22

Ductus venosus

Question 23

What happens at birth when respiration begins?

Answer 23

Birth
-Placental support removed
ductus venous closes
-Respiration begins
LA pressure increases and this causes the foramen ovalle to close
The ductus arteriosus contracts (sensitive to 02 and this has increased)

Question 24

What happens with PDA (persistent ductus arteriosus?)

Answer 24

After birth:

• persistent communication between descending aorta and pulmonary artery (if ductus arteriosus does not contract)
• failure of closure
• Blood shunts left to right (when should have no shunt)
• common in immature babies