Embryology III- Shane Flashcards
(103 cards)
What part of mesoderm is responsible for cardiac development?
cardiogenic mesoderm(cranial to the neural tube and the future mouth.)
What happens to the cardiogenic mesoderm at the end of week 3?
the splanchnic(?) mesoderm begins to condense into a more solid arrangement of cells that form a horse‐shoe shaped cord. The cord will hollow out, forming a horse‐shoe shaped tube that will eventually form left and right heart tubes.
The right and left cardiogenic tubes arise how?
Lateral body folding occur when the lateral margins of the disc fold ventrally, eventually meeting and fusing in the ventral midline axisthese tubes eventually fuse into a single heart tube with a common chamber
Fusion of the right and left primordial heart tubes is complete by when?
end of 4th week of development
Fusion of the right and left primordial heart tubes occurs in what manner? Caudal to cranial?
cranial to caudal (gives rise to a single embryonic heart tube in the midline with a common inner chamber)
When does head to tail folding begin?
end of 3rd week
What induces head folding?
occurs as a consequence of the rapid development of the nervous systemAs the anterior end of the neural tube develops and grows in mass, it induces the head to begin tucking in. This initiates a migration of the cardiogenic tissue, first through the cervical region and then ultimately into the thorax.
When is autonomic innervation to the developing heart tube established?
During migration of cariogenic tissue through the cervical region
What are the autonomic innervation to the heart?
parasympathetic- vagussympathetic- T1-T5
When does the heart reach its definitive position in the thorax?
end of week 4
What are the five divisions of the embryonic heart tube?
truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and sinus venosus (from cranial to caudal)
When does the heart gain contractability?
day 23. moving blood in a caudal to cranial direction in the still vertical heartThe cranial part of the tube represents the arterial outflow, while the caudal end of the tube represents the venous inflow.
How does the caudal (atrial) end of the vertical heart tube move during folding and looping?
superior, posterior, and to the right. The arterial (truncal) end of the tube will move anteriorly, inferiorly, and to the left (see image on far right). This will be complete by the end of the 4th week.
What structures does the truncus arteriosus form?
aorta & pulmonary trunk and their semilunar valves.
What structures does the bulbus cordis form?
t gives rise to the smooth walled areas (outflow tract) of the right and left ventricles (conus arteriosus & aortic vestible).
What structures does the primitive ventricle form?
the trabeculated parts of the right and left ventricles.
What structures does the primitive atrium form?
trabeculated parts of the right and left atria (i.e. the auricles)- pectinate muscles
What is the only part of the embryonic tube that consists of right and left parts?
sinus venosus
The right horn of sinus venous forms what?
the majority of the right atrium (sinus venarum).
The left horn of sinus venous forms what?
cardiac veins on the surface of the heart (coronary sinus and the oblique vein of the left atrium).
In pre‐natal development, blood from mom is being provided through the placental circulation to the fetus via what?
umbilical vein. Deoxygenated blood is returned to the placenta via a pair of umbilical arteries.The umbilical vein contains the blood with the highest oxygen content (~80 %) as it is coming directly from mom via the placenta and through the umbilical cord.
During development, what visceral structures are not doing much work?
the liver (because mom has already processed the blood) and the fetal lungs (because blood has already been oxygenated)
What is the ductus venosus?
It allows most of the blood in the umbilical vein to bypass the liver by re‐directing it into the IVCThe blood in the ductus venosus is still ~ 80% oxygenated. Notice that a small volume of blood flows through the liver, supplying those tissues with adequate oxygenation.
Is blood in the IVC more or less oxygenated than in the umbilical vein? Why?
Less. In the IVC, the high oxygen saturated blood from the ductus venosus is mixed with low oxygen saturated blood (~ 20%) returning from the fetal periphery. Nevertheless, blood flow from the IVC into the right atrium still has reasonable oxygen saturation of ~60‐70%.