Heart Embryology Flashcards
What week does circulation begin during?
4th
What 3 things is the heart derived from?
- ) Splanchnic mesoderm
- ) Mesenchyme (neural crest)
- ) Angioblastic tissue
What layers do the heart fields develop between?
The endoderm and ectoderm
Where are the heart fields originally located? In what pattern?
The cranial end of the embryo in a horseshoe pattern
What layer are heart fields developed from?
Splanchnic mesoderm
Primary heart fields develop due to migration of what?
Mesoderm migrating during gastrulation
What does the primary heart field give rise to? (3 things)
- ) left atria
- ) right atria
- ) left ventricle
Secondary heart fields form from what? Where does this come from?
A second wave of mesoderm. Pharyngeal arches.
What does the secondary heart field develop into?
The right ventricle and outflow tract
The intraembryonic coelom gives rise to what?
The pericardial cavity
What is a mesentery?
A double layer of splanchnic mesoderm. It provides a route for blood vessels, nerves, and lymphatics to get to and from organs.
Is there a mesentery around the heart?
Yes
The heart is derived from what layer?
Splanchnic mesoderm
What are the three layers of the heart? What are they all derived from?
- ) Endocardium - internal epithelial layer
- ) Myocardium
- ) Epicardium (visceral pericardium)
Splanchnic mesoderm
When the dorsal mesocardium degenerates, what does it become?
The transverse pericardial sinus
What are 2 other names for heart fields?
- ) Cardiogenic cords
2. ) Heart tube
What is the dorsal mesocardium?
A mesentery that connects the heart fields
What does the newly formed transverse pericardial sinus separate?
The outflow tract from the venous flow
Where do the neural crest contributions of the heart originate?
The myelencephalon aka the medulla. So the brainstem
What pharyngeal arches do the NC cells that join up with the heart migrate through?
3, 4, and 6
Where do the NC cells end up?
The truncus arteriosus and the aorticopulmonary septa
What is the aorticopulmonary septa?
The septa that separates the aorta and the pulmonary trunk
What does too much vitamin a mess up? What can it cause?
Neural crest cell migration. It can cause cardiac defects
What genes regulate the migration of the cardiac NC cells?
Hox, NF-1, Pax 3
What are the primitive divisions of the endocardial heart tubes? (5 things)
- ) truncus arteriosus
- ) bulbus cordis
- ) Primitive ventricle
- ) Primitive atria
- ) Sinus venosus
What do the truncus arteriosus and bulbus cordis eventually become?
The aorta and the pulmonary trunk
During the formation of the bulboventriular loop, where does the primitive atria move?
It moves superiorly and posteriorly
What is dextrocardia?
Heart folding to the left instead of the right
If dextrocardia occurs in isolation is there a high likelihood of congenital heart defects?
Yes
If dextrocardia occurs with situs inversus is there a high likelihood of congenital heart defects?
No, everything should be fine
When do septation events begin? When are they complete?
They begin early 4th week and complete mid 8th week.
What is a septation event?
Separating the atria from each other, the atria from the ventricles, and ventricles from each other
What is another name for endocardial cushions?
Atrioventricular cushions
What are the endocardial cushions made of? (2 things)
They are made from mesodermal growth from the dorsal and ventral walls. Some mesenchyme invades during the 5th week.
What are the two endocardial cushions?
Dorsal and ventral
What happens to the two endocardial cushions?
They grow towards each other in the midline and eventually fuse
What do the endocardial cushions form?
The atrioventricular canals
What do the pectinate muscles come from?
The original heart tube
Anything smooth in the atria comes from what?
Sinus venosus
What are the two horns of the sinus venosus?
The left and right horns
What does the left horn become?
The coronary sinus
What does the right horn incorporate into? What does it become? (3 things)
It incorporates into the atrium and gives rise to the:
- ) Sinus venarum
- ) Opening for the coronary sinus
- Openings of the superior and inferior vena cava
How does the sinuatrial orifice come to be?
The right horn of the sinus venosus goes through process of intussusception, folds, and forms the sinuatrial orifice
On either side of the sinuatrial orifice there are what?
Left and right sinuatrial (venous) valves
Where do the left and right sinuatrial (venous) valves fuse?
Cranially and caudally
When the left and right sinuatrial (venous) valves fuse cranially, what other thing do they fuse with?
Septum spurium
The right sinuatrial valve gives rise to what cranially?
crista terminalis
The right sinuatrial valve gives rise to what caudally?
The valve of the coronary sinus and most of the valve off the inferior vena cava
Foramen Ovale becomes what?
Fossa ovale
During fetal life, does the septum secundum completely close?
No
What are the two parts of the septation of the ventricles?
Muscular portion and membranous portion
What is the muscular portion of the ventricular septum made of?
Splanchnic mesoderm
What is the path of the muscular portion of the ventricular septum?
It tries to migrate and form with the endocardial cushion, but falls short
Separation of the outflow tract involves separation of what two structures?
The bulbus cordis and truncus arteriosus
What is another name for bulbus cordis?
Conus cordis
Where do the neural crest cells migrate to? What do they form?
Truncus arteriosus. Ridges
Neural crest ridges in the truncal area are called what?
Truncal ridges
Neural crest ridges in the bulbar area are called what? Aka what?
Bulbar ridges. Conotruncal ridges
What do the neural crest cells form?
The aorticopulmonary septum
As the aorticopulmonary septum is forming, what does it do?
It rotates 180 degrees
What does the aorticopulmonary septum fuse with?
The endocardial cushions
What are the 3 players of the membranous interventricular septum?
- ) Endocardial cushion
- ) Right bulbar ridge
- ) Left bulbar ridge
What happens to form the membranous part of the interventricular septum?
The left bulbar ridge, the right bulbar ridge, and the endocardial cushion all come together. This results in the disappearance of the inter ventricular foramen and now forms the membranous part of the interventricular foramen
What does the membranous part of the interventricular septum separate? (2 things)
- ) The ventricles
2. ) The left ventricle from the right atrium
