16. Great Vessels Flashcards
What is the difference between splanchnic mesoderm and mesenchyme?
Mesenchyme is embryonic connective tissue which is mainly mesoderm and has some neural crest
Lung is made up of splanchnic mesoderm while heart is made of mesenchyme: splanchnic mesoderm and neural crest which help make bulbar ridges and the aorticopulmonary septum
Undifferentiated mesoderm differentiates into angioblasts/hemangioblasts which give rise to which two cells?
Hematopoetic Stem Cells and endothelial precursor cells (EPC)
Hemangioblasts aggregate and form blood islands which have the EPCs forming the vessels and channels, and inside the EPCs youll find the?
Hematopoietic Stem cells, BLOOD ISLANDS
Where do the blood islands form? (HPCs)
The extraembryonic mesoderm that surrounds the umbilical vessel/ yoke sack and in the region of the aortic gonad mesenephrose (AGM)
Once the blood islands form, they accumulate and form plexuses. Channels within the plexus enlarge to form?
The arteries and the veins
What is the definition of vasculargensis (starts end of 3rd week)?
Formation of new vascular channels by assembly of individual cell precursors called angioblasts (mesoderm)
What is the difference between agiogenesis and arteriogenesis?
Angio: development of blood vessels from preexisting vessels
Arterio: Remodeling of existing arteries in response to changes
Angiomas can form is something went wrong. Capillary hemangioma is excessive growth of small capillary networks. What occurs during cavernous hemangioma/ hemangioma of infancy?
Proliferation of large dilated vascular channels, benign tumor that get bigger betweenbirth and first year of life and then regress, 10% white bbs **endothelial cells by vasculogenesis (EPCs)
Paired dorsal aorta, there are two d/t there being two heart tubes that come together. What is the flow of blood during the fourth week?
Bulbus cordis to trucus arteriosus to aortic sac to pharyngeal arch arteries (1-2-3-4-6) all have own arches, then finishes in dorsal aorta
The paired dorsal aorta fuse in the region of the abdomen, and in the region of the thorax they?
remained paired so they can be remodeled to form blood vessels
What are the three branches off of the fused abdominal aorta?
- Ventral segemental arteries
- Lateral segmental arteries
- Dorsal segmental arteries
Ventral segmental arties supply structures that came from the splanchnic layer of the lateral plate mesoderm and endoderm, such as?
Celiac Trunk, Superior mesenteric artery and inferior mesenteric artery (IMA)
Lateral segmental segmental supply structures that came from the intermediate mesoderm, such as?
Gonads and Kidneys- Renal arteries and gonadal arteies
Dorsal segmental arteries supply derivatives of the somites, such as?
Intersegmental arteries, such as intercostal arteries and lumbar arteries
As aortic arches form during days 26-32, 1 forms first, then second and third, and as third forms, one degrades, and as fourth formss?
second degrades, as 6 forms, third degrades, done by days 32-37 sending branches to the developing head
The 1st aortic arch/ pharyngeal arch gives rise to?
External carotid and maxillary arteries
The 2nd aortic arch gives rise to?
stems of the stapedial arteries in the ear
The Aortic sac gives rise to?
brachiocephalic artery and base of arch of aorta
The 3rd pharygeal arch/aortic arches gives rise to?
common carotid and internal carotid arteries
The 4th pharyngeal arch/aortic arch gives rise to?
Left: medial portion of arch of aorta
right: proximal right subclavian
The 6th arch gives rise to?
LUNGS AND LARYNX
pulmonary arteries
left: ductus arteriosus
right: distal part degenerates
What does the 7th intersegemental artery give rise to?
distal right subcalvian
entire left subclavian
The two dorsal aorta remodel and give right to?
Right: right subclavian
Left: descending aorta
Left recurrent laryngeal N wraps around ligamentum arteriosus and goes back up. What happens on the right side?
It did wrap around 6th aortic arch, however the distal part of the 6th arch degenerates, and the right recurrent migrates up to go under the right subclavian A
Fetal circulation: from placenta, travels in left umbilical vein, to the liver, where there is a sphincter, if the pressure from the placenta is high, the sphincter constricts and sends blood into sinusoids of the liver. What is the rest of the path to the heart?
The rest of the blood from the sphincter bypasses liver by ductus spinosus***. Which then travels to inferior vena cava, (usually will go through liver but moms blood is already cleaned), to right atrium, majority goes to formane ovale and foramen secundum to left atrium, to left ventricle, to aorta.
In the right atrium, some blood goes down to the right ventricle can mix with rich and poor o2 blood getting mixed blood, which will then take what path?
Pulomonary trunk into lungs, blood in lungs is solely for the development of them, pulmonary constriction can constrict to make sure there isnt too much blood in lungs, rest of blood goes through the ductus arteriosus.
Neonatal circulation: Fluid interface to air interface. At birth you get aeration of the lungs which includes? (3)
Decrease in pulmonary vascular resistance
Increase in pulmonary blood flow
Thinning of walls of pulmonary arteries
In neonatal circulation, we do not need blood supply from mom, left umbilical vein turns into?
ligamentum teres (round ligament of the liver)
What does the ductus venosus turn into once the baby is born?
Ligamentum venosum GI
What occurs due to the high pressure in the left atrium?
the septum primum fuses with foramen ovale, forming the fossa ovale (ductus arteriosus forms into ligamentum arteriosum within 72 hours)
Increased O2 leads to decreased prostaglandinE2 and increased?
Bradykinin, which causes smooth muscles to constrict allowing ductus arteriosus to close with PGE2, to form ligamentum arteriosus
Coarctation of the aorta is aortic constriction, which has two variations known as?
Preductal and postductal (meaning before and after ductus arteriosus)
If postductal coarctation, fetus develops a collateral circulation so blood goes to lower extremeties. What happesn with preductal coarctation?
Fetal life is okay because bypassed by ductus arteriosus. Neonatal, it closes and then there are problems. There will be normal/high pulses in upper limb d/t brachiocepahlic, subclavian and carotid being before the constriction, and pulses in the lower limbs would be decreased or absent. CYANOTIC
What would you give to baby is the baby is sweating and blue post birth? How does this occur embryologically?
PGE2 to keep ductus arteriosus open so we can fix it by surgery.
Smooth muscle abnormally goes into aorta, constricts
When aortic arches are remodeling, there was a narrowing of the artery
Double aortic arch: persistence of the distal portion of the right dorsal aorta (which wouldve disinegrated), what occurs during remodeling?
Formation of a vascular ring around the trachea and esophagus.
Stridor, respiratory infections/distress, weezing, cough
Interupted aortic arch, both right and left 4th aortic arch arteries are obliterated/degenerated, what is retained?
distal right aorta is retained
What usually occurs with interupted aortic arch?
VSD/PDA to keep the baby alive.
Within first two days, weakness, fatigue, tachypnea
Right is always getting oxygen, left side is not sometimes, d/t PDA/VSD O2 blood can still get to places. Most severe form of coarctation
What is the suspected causes of interupted aortic arch?
DIGEORGE SYNDROME
Low calcium
Development delay
NC cell migration abnormalities
Abnormal orgin of the right subclavian artery arises from the distal part of the right dorsal aorta and the 7th intersegmental artery. What happens with the right 4th aortic arch and right subclavian?
r 4th aortic arch and proximal part of the right dorsal aorta obliterate, right subclavian passes behind the esophagus and trachea
What can be caused be abnormal origin of the r subclavian passing behind the trachea and esophagus?
Constricts esophagus, dysphasia, can’t swallow
pressure on vertebra, lower pulse/BP on right upper extremity
Right aortic arch is caused by the left fourth arch and left dorsal aorta being obliterated and replaced by the vessels on the right side. What happens if the ligamentum arteriosum is on the left side?
Passes behind the esophagus and swallowing can be affected, most of cases form with ligamentum arteriosum anterior
Sinus venosus (where venous imput is coming in) is incorporated into the atria and left horn gives rise to? How about the right horn?
Left horn gives rise to smooth wall and coronary sinus
Right horn gives rise to crista terminalis, orificies of inferior vena cava, coronary sinus
There are three sets of veins, each have 2 sets: cardinal vessels (anterior, posterior, common), vitelline veins are around the yoke sac and liver, umbilical veins. What do they all do?
Cardinal: oxygen poor blood from body back to heart
Vitelline: oxygen poor blood from yoke sac and liver to heart
Umbilical: oxygen rich blood from the placenta to the heart
The vitelline are in the yoke sac and liver, Proixmal to the heart and within the liver, what occurs?
Proximal: left vein degenerates, right vein persists
Liver: right forms hepatic vein (inferior vena cava part)
right/left merge to form portal vein (from gut)
The umbilical veins do what? Right/left side
Right degenerates entirely
Left persists, proximal part degenerates, distal umbilical artery anastamoses with ductus venosus, bringing O2 rich blood to heart, bypassing liver via ductus venosus
Anterior cardinals drain from the cranial head, right forms the internal jugular and superior vena cava, what does the left form?
Left brachiocephalic vein
Posterior cardinal vein drain from body wall, how is it remodeled?
Posterior system degenerates except for root of azygous and common iliac, REPLACED by subcardinal and supracardinal veins
Veins are made in week four to give blood supply to many places due to growth occuring rapidly during this period. What does she want us to realize?
VEINS DONT FOLLOW THE BEWK
subcardinal veins become supracardinal veins which is replaced by IVC and more
What occurs when there is a persistence of the left anterior cardinal vein and obliteration of the common cardinal and proximal part of the anterior cardinal veins on the right?
Left superior vena cava: blood needs to go into coronary sinus in order to get into right atrium
What occurs when there is persistence of the left anterior cardinal vein and failure of the left brachiocephalic vein to form?
Double superior vena cava: right superior VC goes into right atrium while left superior VC goes into coronary sinus and then right atrium
Inferior Vena Cava- what is each segmental made from? Hepatic segment: Prerenal: Renal: Postrenal:
Hepatic: Right vitelline/hepatic veins and sinuses
Prerenal: right subcardinals
Renal: subcardinal-supracardinal anastamosis
Postrenal: Right supracardinal
Malformation of the IVC: double inferior vena cava due to?
Persistence of the left sacrocardinal vein, resulting in two LVCs dumping into the renal vein (GI)
