Chapter 13 Flashcards
Clinical Correlates only
The vascular system appears in the middle of the what week?
a. 2nd
b. 3rd
c. 4th
d. 5th
B
The vascular system appears in the middle of the third week, when the embryo is no longer able to satisfy its nutritional requirements by diffusion alone
These cells lie in the epiblast, immediately adjacent to the cranial end of the primitive streak
Progenitor heart cells
A horseshoe-shaped cluster of cells cranial to the neural folds forming portions of the atria and the entire left ventricle
Primary heart field (PHF)
The right ventricle and outflow tract (conus cordis and truncus arteriosus) are derived from the
Secondary heart field (SHF)
also contributes cells to formation of the atria at the caudal end of the heart
These cells resides in the visceral (splanchnic) mesoderm ventral
to the pharynx
Progenitor heart cells migrate through the primitive streak on approximately day
Day 16 of gestation
True or False
The laterality of SHF is determined by the same signaling pathway that establishes laterality for the entire embryo
True
This explains the spiraling nature of the pulmonary artery and aorta and ensures that the aorta exits from the left ventricle and the pulmonary artery from the right ventricle.
The process of formation of blood cells and vessels
Vasculogenesis
Blood islands unite and form a horseshoe-shaped endothelial-lined tube surrounded by myoblasts. This region is known as
Cardiogenic region
intraembryonic (primitive body) cavity
over the cardiogenic region later develops into the
pericardial cavity
Refers to the pair of longitudinal vessels
Dorsal aortae
a key molecule in initiating the pathway of laterality. This is concentrated on the left side of the embryo
Serotonin [5-HT]
Serotonin signals this transcription factor that restricts the Nodal expression to the left
MAD3
The master gene for the left sidedness
PITX2
This period is critical for heart development and individuals with laterality defects
Days 16 to 18
A laterality defect where the both the aorta and pulmonary artery exit the right ventricle
Double outlet right ventricle
Refers to a right sided heart
Dextocardia
A laterality defect wherein both atria or both
ventricles have similar characteristics instead
of the normal left—right differences
Atrial and ventricular isomerisms
A laterality defect wherein the characteristics of the atria or ventricles are reversed
atrial and ventricular inversions
These are antidepressants that have been linked by epidemiology studies to an increase in heart defects
Selective Serotonin Reuptake Inhibitor
Mechanism: SSRI disrupts 5-HT signaling
A fold of mesodermal tissue derived from the SHF
dorsal mesocardium
With further development, the middle section of the dorsal mesocardium disappears, creating the
transverse pericardial sinus (connects
both sides of the pericardial cavity)
A layer of extracellular matrix rich in hyaluronic acidsecreted by the thickened myocardium
Cardiac jelly
Cells from this structure proliferate and migrate over the surface of the myocardium to form the epicardial layer (epicardium) of the heart
Proepicardial organ
The formation of this organ occurs in the mesenchymal cells located at the caudal border of the dorsal mesocardium
The three layers of the heart
endocardium
myocardium
epicardium or visceral pericardium
The layer of the heart forming its internal endothelial lining
Endocardium
which layer forms the muscular wall of the heart
Myocardium
It covers the outside of the heart tube
epicardium or visceral pericardium
This outer layer of the heart is responsible for the formation of the coronary arteries, including their endothelial lining and smooth muscle
epicardium or visceral pericardium
True or False.
The lengthening process of the heart tube is essential for normal formation of the left ventricle and the outflow tract region (conus cordis and truncus arteriosus that form part of the aorta and pulmonary artery and for the looping process.
False.
The lengthening process of the heart tube is essential for normal formation of the right ventricle
As the outflow tract lengthens, the cardiac
tube begins to bend on day
23
The cephalic portion of the tube bends ventrally, caudally, and to the right and the atrial (caudal) portion shifts dorsocranially and to the left.
This bending, which may be due to cell shape changes, creates the cardiac loop
Cardiac tube bending is completed by day
28
What portion forms the common atrium and is incorporated into the pericardial cavity
Atrial portion
This junction remains narrow and forms the atrioventricular canal
Atrioventricular junction
This canal connects the common atrium and the early embryonic ventricle
Atrioventricular canal
The bulbus cordis is narrow except for its
a. proximal third
b. proximal half
c. distal third
d. distal half
A
The proximal third of the bulbus cordis will form the trabeculated part of which ventricle
a. left
b. right
Right
The midportion of bulbus cordis that form the outflow tracts of both ventricles
conus cordis
The distal part of the bulbus that form the roots and proximal portion of the aorta and pulmonary artery
truncus arteriosus
The junction between the ventricle and the bulbus cordis is externally indicated by
bulboventricular sulcus
The junction between the ventricle and the bulbus cordis is called
primary interventricular foramen
Which of the following best describes the organization of the cardiac loops by region
a. the cardiac tube is organized by regions
along its craniocaudal axis from the conotruncus to the left ventricle to the right ventricle to the atrial region respectively
b. the cardiac tube is organized by regions
along its craniocaudal axis from the conotruncus to the right ventricle to the left ventricle to the atrial region respectively
B
When looping is completed, the primitive ventricle, which is now trabeculated, is called the
primitive left ventricle
The trabeculated proximal third of the bulbus cordis is called
primitive right ventricle
