ICL 4.6: Development of the Vascular System Flashcards
what are the 3 venal systems in the body?
- Cardinal System of Veins
- Umbilical System of Veins
- Vitelline System of Veins
what is vasculogenesis?
formation of primitive vessel by fusion of locally formed endothelia vesicles by the process of vasculogenesis
formation of the blood cells in the embryo consists of several phases: the first is the specification of the angioblasts (vascular precursors) –> the second is organization in primary capillary plexus. (vasculogenesis)
what is angiogenesis?
outgrowth or branching of preformed vessels
to keep pace with rapid growth of the embryo this capillaries must undergo reorganization thru resorption and sprouting of new vessels a process called angiogenesis
this process occurs not only in development but also in adult during life to adapt to changes conditions of life in normal and pathological process
do embryos have blood vessels?
no, early embryo devoid of blood vessels because all the nutrients were receives by diffusion
as the embryo grows, you need a vascular channel to deliver nutrients
the first to develop is the extraembryonic vascular channel which has origins in different organs
vascular channels then become large vessels or capillaries or some disappear altogether; it’s all based on necessity and what the body needs at the time and in a certain location!
what does the circulatory system look like at 4 weeks of development?
the first intraembryonic circulatory arc is organized in a similar manner as the fish
the ventral aortic outflow tract from the heart splits into aortic arch arteries passing around the pharynx though the pharyngeal arches and then collecting into a cephalic paired dorsal aorta that distribute blood throughout the body –> a system of cardinal veins collects the blood and returns it to the heart via a common inflow tract
the second arc (vitelline arc or omphalomesenteric arc) extraembryonic circulatory loop supplies the yolk sac
the third arc extraembryonic (umbilical) consist of vessels associated with the allantois ( in humans this is associated with the umbilical vessels) which extend into the placenta and chorionic tissues
slide 8
what are the 3 venal systems in the body during embryogenesis?
- Cardinal System of Veins
- Umbilical System of Veins
- Vitelline System of Veins (omphalomesenteric)
slide 8
what are the 2 arterial systems in the body during embryogenesis?
- dorsal aorta
2. aortic arches
what is the cardinal system of veins? what are the 2 parts?
the cardinal veins form the basis for the intraembryonic venous circulatory system
several sets of cardinal veins appears at different times and in different locations; some will regress and other persist either as independent channels or as components of composite veins that also include veins of other cardinal veins
the anterior cardinal veins (superior) bring the blood from the head region via the left and right common cardinal vein
the posterior cardinal veins (inferior) drain the blood from the lower half of the body into the two common cardinal veins
slide 12
what is the cardinal system of veins? what are the 2 parts?
the cardinal veins form the basis for the intraembryonic venous circulatory system
the anterior cardinal veins (superior) bring the blood from the head region via the left and right common cardinal vein
the posterior cardinal veins (inferior) drain the blood from the lower half of the body into the two common cardinal veins
from there, the blood is emptied into the sinus venosus and into the atrium via the sinus horns
slide 12
what is the umbilical system?
the umbilical veins bring the nutrient- and oxygen-rich blood from the placental villi via the umbilical cord to the embryo
they are unpaired umbilical veins –> the right umbilical vein disappears while the left umbilical vein gets enlarged and starts forming a big channel in the liver called the ductus venosus which is very important in heart development since during embryonic development it controls the amount of blood that reaches the heart
then the umbilical veins become included in the developing liver –> the ductus venosus will become the ligamentum venosum in the liver
what is the vitelline system?
aka the omphalomesenteric system
it’s closely associated with the development of:
- duodenum
- liver
- drain blood of umbilical vesicle
with the development of the liver the omphalomesenteric veins form a thick hepatic plexus and they also anastomose with the umbilical veins
through various transformative and degenerative processes the vena portae arises which brings the blood from the intestines into the liver – by this means the absorbed nutrients from the intestines can be taken up later through the liver and metabolized
on the other hand, a short-cut, the ductus venosus, is engendered from the thick network of anastomoses of vitelline veins; up to the time of birth, it takes the blood from the umbilical vein and the omphalomesenteric veins and directs it directly into the sinus venosus of the heart
during the course of the early cardiac development the left sinus horn atrophies and with it the posthepatic part of the left omphalomesenteric vein – so now all of the blood from the liver is conveyed via the right omphalomesenteric vein to the sinus venosus
which venal system are the pulmonary veins part of?
they are not assigned to any of the 3 venal systems! they develop independently and there’s no consensus about their development
some think that they branch from the left atrium while others thing they form as a a solitary vessel
what does the arterial system look like?
The system of aortic arches in early human embryo is organized along the same principles as the system of arteries supplying blood to the gills of many aquatic lower vertebrates. Blood exits from a common ventricle into a ventral aortic root, from which it is distributed through the branchial arches by pairs of aortic arches. In gilled vertebrates the aortic arch arteries branch into capillary beds, where the blood become oxygenated as it passes thru the gills. In mammalians the aortic arches remains as a unit because the oxygenation is done in the placenta. The aortic arches empty into a paired dorsal aorta where the blood enters the systemic circulation.
slide 24-6
what are the adult derivatives of the arches?**
arch 1: regresses, and part of the arch becomes part of the maxillary artery
arch 2: regresses and becomes steapedial artery
arch 3: forms the common and internal carotid arteries; doesn’t regress!
1,2,3 go to the head
_____________
R. arch 4: forms the proximal right subclavian artery
L. arch 4: forms arch of the aorta
R. arch 6: forms part of the right pulmonary artery
L. arch 6: forms part of left pulmonary artery and ductus arteriosus
R. arch 7: forms part of the right subclavian artery
L. arch 7: forms entire left subclavian artery
R. dorsal aorta: regress and forms middle of the right subclavian artery
L. dorsal aorta: forms descending thoracic aorta
aortic sac: forms ascending aorta and brachiocephalic artery
what is the role of the neural crest cells?
they give signals to the endothelial vessels so that the aortic arch is preserved after the neural crest is gone
why are the recurrent laryngeal nerves located where they are?
the vagus nerve wraps around the 4th arch
but the 4th arch turns into the aortic arch and subclavian artery on the left and right side, respectively
what are some of the aortic arch anomalies?
- right aortic arch
- double aortic arch
- aberrant subclavian artery
- interrupted aortic arch
what is the right aortic arch anomaly?
the right aortic arch results from developmental obliteration of the left fourth branchial arch artery and the regression of the left dorsal aorta
in the anomaly, the aortic arch is constructed from the equivalent vessels on the right side
to reach the arch, the ductus arteriosus must traverse the midline and in doing so, it may produce constriction of the esophagus
what is the double aortic arch anomaly?
a double aortic arch is an anomaly of the arch resulting in two arches that surround the esophagus and trachea in the superior mediastinum to form a vascular ring
dysphagia and respiratory distress may follow
it results from a failure of regression of the section of the right dorsal aorta between the seventh intersegmental artery and the junction with the left dorsal aorta
slide 38
what is the interrupt aortic arch anomaly?
it is caused by obliteration of the left fourth branchial arch artery which is related to the aortic arch
so the proximal part of the aortic arch artery divides to form the brachiocephalic trunk and left common carotid arteries and there is no continuity of the arch beyond these branches
the descending aorta doesn’t form! so instead the ductus arteriosus becomes very large and functions as the aorta
slide 39
what is the right subclavian artery anomaly?
rarely, the right subclavian artery arises from the aortic arch distal to the left subclavian artery
to reach the right side of the thorax, it passes behind the esophagus and trachea to produce a vascular ring
developmentally, this condition results from regression of the right fourth branchial arch artery
slide 40
what’s the adult derivative of the 1st aortic arch?
it regresses and forms part of the maxillary artery
what’s the adult derivative of the 2nd aortic arch?
it regresses and forms part of the stapedial artery
what’s the adult derivative of the 3rd aortic arch?
forms the common and internal carotid arteries
what’s the adult derivative of the 4th aortic arch?
R = proximal right subclavian artery
L = arch of the aorta
what’s the adult derivative of the 5th aortic arch?
trick question, there is no 5th aortic arch! it never developed
what’s the adult derivative of the 6th aortic arch?
R = forms part of the right pulmonary artery
L = forms part of the left pulmonary artery and ductus arteriosus
what’s the adult derivative of the 7th aortic arch?
R = forms part of the right subclavian artery
L = forms the entire left subclavian artery
what’s the adult derivative of the dorsal aorta?
R = it regresses and forms the middle of the right subclavian artery
L = forms the descending thoracic aorta
what’s the adult derivative of the aortic sac?
it forms the ascending aorta and brachiocephalic artery
