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Flashcards in Embryology Deck (14)
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1
Q

Descirbe the development of the sinus venosus

A
  1. Right and left sinus horns are equal in size, receiving veins from the yolk sac, placenta and umbilical cord.
  2. Venous return then shifts to the RHS, the left sinus horn recedes.
  3. Right sinus horns is absorbed by the enlarging atrium. The left horn becomes a vestigial structure.
2
Q

Describe the differences in the formation of the right and left atria

A

Right atrium develops form

  • Most of primitive atrium
  • Sinus venosus

Left atrium develops from

  • Small portion of the primitive atrium
  • Absorbs proximal part of the pulmonary veins
3
Q

Name the foetal circulatory shunts

A

Ductus venosus

Foramen ovale

Ductus arteriosus

4
Q

Why is some blood allowed to pass from the RA to the RV and what shunt is used to prevent blood going to the lungs

A

This is to allow the RV to develop normally as for the muscles of the RV to be normal, they must be in use.

Ductus arteriosus

5
Q

What are the functions of the foetal circulatory shunts

A

Ductus venosus - allows blood to enter the inferior vena cava from the unbilical vein

Foramen ovale - stops blood going into the RV, is a passageway between the RA and LA

Ductus arteriosus - stops blood from the RL going to the lungs, this ensures the lungs are protected from the high pressures of the blood supply

6
Q

What do the circulatory shunts become after birth

A

Ductus venosus - ligamentum venosum

Foramen ovale - fossa ovalis

Ductus arteriosus - ligamentum arteriosum

7
Q

What does the 4th arch of the early atrial system become

A

Right side becomes the proximal part of the right subclavian artery

Left side becomes the arch of the aorta

8
Q

What does the 6th arch of the early arterial system become?

A

Forms the pulmonary arch

Right side becomes the right pulmonary artery

Left side becomes the left pulmonary artery

9
Q

What is PDA, what is it caused by and how does it present

A

Patent ductus arteriosus

Casued by failure of physiological closure of the ductus arteriosus

Presents in children as sweating, rapid and heavy breathing, fatigue, little interest in feeding and poor weight gain

Mechinery murmur heard on auscultation

10
Q

What is septation and what does it form in the heart

A

Septation is the formation of the septum

Forms the interatrial and interventricular septums and forms the pulmonary trunk and aorta

11
Q

What septa ard holes are formed in the process of atrial septation

A

Septum primum which has the ostium primum before septum primum fuses with endocardial cushions, and the ostium secundum which forms in the septum primum

Septum secundum has the foramen ovale

12
Q

How does the interventricular septum form

A

Muscular portion grows upwards towards endocardial cushions, leaving primary interventricular foramen

Membranous portion is then formed by connective tissue from the endocardial cushions fills the primary interventricular foramen

13
Q

What is ventricular septal defect

A

A defect in formation of interventricular septum, most commonly defect in formation of the membranous portion of the septum

14
Q

Label

A