Embryology of the CVS 1 Flashcards
What are the 4 major stages in heart development
- Primitive heart
- Heart looping
- Atrial and Ventricular Septation
- Outflow Tract Septation
What arises from the lateral plate
Somatic and Splanchnic
What does the splanchnic mesoderm form
Circulatory system and other viscera
How do the angiogenic islands form the primitive heart tubes
Angiogenic islands collect in the lateral plate splanchnic mesoderm and move towards the midline and coalesce to form the primitive heart tubes
What is the first major system to function in the embryo
The cardiovascular
When does the primordial heart start to function
At the beginning of 4th week
Why does the primordial heart start to function at week 4
The embryo is rapidly growing and nutrition by diffusion is not enough to satisfy embryo
What is the Cardiogenic Field
Primitive heart and blood vessels in the embryo
Where do blood vessels first appear
In the wall of the yolk sac, allantois, connecting stalk and chorion
When do paired endothelial strands (angioblastic cords) appear in the cardiogenic mesoderm
3rd week
What do angioblastic chords canalise to form
Heart tubes
What is the pericardium derived from
Intra-embryonic coelem
The somatic mesoderm develops into
Parietal layer of serous pericardium and fibrous pericardium
Cephalic folding of pericardial cavity
Dorsal to Ventral
Cephalic folding of cardiac tubes
Ventral to Dorsal
Venous end of primitive heart tube
Sinus Venosus
Arterial end of primitive heart tube
Truncus Arteriosus
How many horns does venous end have
2 (left and right)
Each horn of the venous end gets venous blood from
Yolk sac (vitelline)
Placenta (umbillical)
Body of the embryo (common cardinal)
Where do aortic arches terminate
Dorsal aorta
How is the bulboventricular loop formed
Bulbous cordis and ventricle grow faster than other regions forming a u shape
What is Dextrocardia and what are the consequences (4)
Abnormal cardiac looping
Heart loops to left side instead of right
Heart faces right instead of left
Associated with situs inversus
When is partitioning of the primordial heart seen
Between 27th and 37th days of embryonic development
What does the partitioning of the primordial heart involve (2)
Endocardial cushion formation
Septum formation
What is Endocardial cushion formation
Separates right atrium and ventricle from left atrium and ventricle to form the AV canal
What is septum formation
Separates right atrium from left atrium and right ventricle from left ventricle
Fused endocardial cushions (2)
Right and Left V canal
Septum intermedium
What do the AV canals temporarily separate
Primordial atrium from the ventricle
Partitioning of primitive atrium into left and right atria (3)
Septum primum forms foramen primum
Septum primum sinks down to form foramen secundum
Septum secundum travels down and forms foramen ovale and septum primum degenerates
What is the opening between septum primum and endocardial cushion called
Ostium primum
Foramen primum and Foramen secundum is opening caused by
Septum primum
Foramen ovale is opening in
Septum secundum
What is the role of the Oval Foramen at birth
Allows most of the blood to pass from the right atrium (de-oxygentaed blood) to the left atrium (oxygenated blood)
What is the role of the Oval Foramen after birth
Normally closes
What does non-closure of oval foramen cause
Atrial Septal Defect (ASD) - hole in the heart
What are the four clinically significant types of ASD (4)
A) Foramen secundum defect
B) Endocardial cushion defect with foramen primum defect
C) Sinus venosus defect
D) Common Atrium
Partitioning of Primitive Ventricle (3)
- Muscular ventricular septum forms.
- Bottom of spiral aorticopulmonary septum fuses with muscular ventricular septum
- Growth of endocardial cushions also contribute to membranous portion of IV septum
Opening created by muscular ventricular septum is called
interventricular foramen
What does the fusion of the aorticopulmonary septum and muscular ventricular septum form (2)
Membranous interventricular septum and closes interventricular foramen
What does the aorticopulmonary septum divide the bulbous cordis and truncus arteriosus into and when does this occur
Pulmonary trunk and aorta
5th week
Congenital disorder of the ventricles
Ventricular septal defect
Early pacemakers of the heart
Primitive atrium and then sinus venosus
When does the SA node (pacemaker) develop
5th week
What is the adult location of SA node
High in the right atrium near the entrance of the SVC
Where does the AV node develop from (bundle of His)
Cells of AV canals and sinus venosus
Aortic sac becomes
Aortic arch
Bulbous cordis
Right ventricle
Parts of outflow tract
Primitive ventricle
Left ventricle
Primitive atrium
Parts of right and left atria
Sinus venosus
SVC and Right atrium
Aetiology of Congenital Heart Disease (5)
Rubella infection in pregnancy (PDA) Maternal alcohol abuse (septal defects) Maternal drug treatment and radiation Genetic Chromosomal
Causes of transposition of Great Vessels (2)
Failure of aorticopulmonary septum to take a spiral course
Defective migration of neural crest cells
What is transposition of great vessels associated with
ASD and VSD
Tetralogy of Fallot
Pulomonary stenosis
Ventricular septal defect
Dextroposition of aorta
Right ventricular hypertrophy
