anatomy cardiac embryology II Flashcards
What are the two major mechanisms by which blood vessels are formed
1.) Vasculogenesis (large vessels) 2.) Angiogenesis (small vessels)
Vasculogenesis
Formation of new blood vessels through the differentiation of angioblasts which join together to form vascular structures. Larger blood vessels are formed this way
Angiogenesis
formation of new blood vessels through budding and sprouting from existing vessels. This is usually how smaller blood vessels are formed.
What forms the first aortic arch
Dorsal aortae (formed from primary outflow vessels- develop in dorsal mesenchyme on the dorsal side of the notal cord) that get pulled ventrally
Describe the development of arches 2,3,4,and 6
Develop between days 26 and 29. Ventrally the aortic arches arise from the aortic sac (anterior expansion of the conus arteriosus) As these areches are fromed the first and second arches begin to regress.
First aortic arch gives rise to
External carotid and maxillary arteries
Second aortic arch gives rise to
Stapedial artery
Thrid aortic arch gives rise to
left and right common carotid arteries and part of the internal carotid arteries
Fourth aortic arch gives rise to
Right fourth arch: Right subclavian artery (proximal part) Left fourth arch: ascending part of the aorta (aortic arch)
Six aortic arch gives rise to
Right sixth arch: pulmonary arteries Left sixth arch: ductus arteriosus
Ductus arteriosus
Arises from the left sixth arch. Connects to the aorta and allows shunting blood to the pulmonary trunk to the decending aorta
What forms the ligamentum arteriosum after birth
Ductus arteriosus
Vitelline arteries arise from…
plexuses in the yolk sac
Vitelline arteries give rise to what
1.) Celiac Trunk 2.) Superior Mesenteric Artery 3.) Inferior Mesenteric Artery
Lateral Branches of the descending aorta give rise to
1.) Suprarenal arteries 2.) Gonadal arteries 3.) Renal arteries
Gonadal arteries
Gonads descend and the vasculature follows - becomes fixed at the 3rd or 4th lumbar level
Renal arteries
Kidneys ascend- vasculature is degenerated and reformed at each level until the final pair forms in the upper lumbar region
Intersegmental branches of the aorta
arise from the posterolateral surface of the aorta and supply somite derivatives ( MUSCLES)
What do dorsal branches of intersegmental arteries supply
1.) Developing neural tube 2.) Developing deep muscles of the back and neck (epimeri muscles) 3.) Cutaneous braches supply the dorsal skin
What do ventral branches of intersegmental arteries supply
developing hypomeric muscles and associated skin
intercostal arteries arise frm what
ventral branches of intersegmental arteries in the throacic region
lumbar and lateral sacral arteries arise from what
ventral branches of intersegmental arteries in the lumbar and sacral region
Name the vessels that arise due to anastamosis of intersegmental branches
1.) Vertebral artery 2.) Deep Cranial 3.) Ascending cervical 4.) internal throacic 5.) Superior epigastric 6.) Inferior Epigastric
How are arteries of the limbs fromed
remodeling of intersegmental arteries
Umbilical arteries
return DEOXYGENATED blood to the placenta. Initailly brances of the dorsal aorta but during the 4th week they shift their origin to internal iliac arteries (th pair of lumbar intersegmental arteries)
Fate of umbilical arteries after birth
Proximal parts persist as internal iliac and superior vesicular arteries, distal parts become obliterated
Vitelline veins
arise from the capillary plexuses in theyolk sac and carry blood from the yolk sac to the sinus venosus
Hepatic sinusoids arise from
right and left vitelline plexuses
Hepatocardiac portion of the inferior vena cava arises from? How?
Right vitelline vein. As the left sinus horn is reduced, blood from the left side of the liver is redirected to the right causing enlargement of the right vitelline vein
Portal vein arises from
venous anstomosis around the liver develops into a single portal vein
Superior Mesenteric vein arises from
right vitelline vein caudal to the liver
In general, the portal system arises from?
Vitelline Plexuses
Where do umbilical veins originate
chorionic villa - carry OXYGENATED blood to the embyro
Fate of umbilical veins
initially two umbilical veins pass on either side of the liver. During the second moth the RIGHT becomes obliterated and the LEFT forms a connection with the right vitelline vein = ductus venosus
how is the ductus venosus formed? What is its function?
Formed by the connection between the left umbilical vein and the right vitelline vein. Crutial during fetal life as it shunts oxygenated blood from the umbilical system to the IVC and right atrium allowing it to BYPASS THE PORTAL SYSTEM (prevents hepatic capillaries from sucking out all the oxygen)
What forms the ligamentum teres hepatis after birth
left umbilical vein
what forms the left brachiocephalic vein
anastamosis of the anterior cardinal veins
The Superior Vena Cava arises from
the right anterior cardinal vein and the right common cardial vein
What veins supplement the posterior cardinal veins
1.) Subcardinal veins 2.) Supracardinal veins
Subcardinal veins
drain the kidneys and develop into the posterior cardinals
Supracardinal veins
replace posterior cardinals in draining the posterior part of the body wall through series of intercostal veins
what forms the azygous vein
right supracardinal vein
what froms the hemiazygous vein
left supracardinal vein - loses its connection to the left sinus horn and drains into the right supracardinal system
Hepatic segment of the IVC is derived from
right vitelline vein
Renal segment of the IVC is derived from
right subcardial vein
Postrenal segment of IVC is derived from
right supracardinal vein
Sacral segement of IVC is dervied from
right and left posterior cardinal veins
Describe fetal circulation
Oxygenated blood is carried by the umbilical vein- most of it goes through the ductus venosus (some goes through the hepatic sinusoids) to the right atrium where it is joined by deoxygenated blood from the superior vena cava. Due to high pressure on the right side of the heart (due to pulmonary resistance) a majority of the blood passes through the foramen ovale to the left atrium (some goes to the right ventricle and is pumped to the pulmonary trunk where it meets pulmonary resistance- some goes to the lungs, most is shunted through the ductus arteriosus to the descending aorta) from the left atrium it goes into the left ventricle and is pumped into the aorta where it goes through systemic circulation. Deoxygenated blood flows through the iliac arteries to the umbilical artery. FLows to the placenta due to low resistance where it gets reoxygenated.
Describe circulatory changes at brth
1.) Closure of umbilical arteries 2.) Closure of umbilical vein and ductus venousus 3.) Closure of ductus arteriosus 4.) closure of foramen ovale
what causes closure of the ductus arteriosus
initial inflation of the lung releases bradykinin causes closure. Complete obliteration takes 1-3 months
What causes closure of the foramen ovale
occurs by increased presure in the left atrium (carrying blood from the lungs) and a decreased pressure in the right atrium (no more pulmonary vascular resistance). These pressures press the septum primum against the septum secundum closing the foramen ovale
Patent ductus arteriosus(PDA)
failure of the ductus arteriosus to cloase completely. Generates a machine like murmur in the heart. Major risk factor is maternal rubella infection during pregnancy.
Coarctation of the Aorta
lumen distal to the left subclavian is narrowed. May be proximal (preductal) or distal (postductal) to the ductus arteriosus
Infnats with Turner sydrome are at a higher risk of what type of coarctation of the aorta
preductal coarctation
What type of coarctation of the aorta is most common in adults
postductal coarctation
Abnormal right subclavian artery
aries from the aorta distal to the left subclavian artery then crosses behind the esophagus to reach the right art
Double aortic arch
right dorsal aorta persists and the two arches form a vascular ring around the trachea and esophagus
Double inferior vena cava
due to failure of the left supracardinal vein to lose its connection with the left subcardinal vein
Absence of inferior vena cava
blood from the lower body reaches the heart via the azygous vein (and superior vena cava) Due to failure of the right subcardinal vein to connect to the liver
Left superior vena cava
blood from the irght is channeled to the left via the right brachiocephalic vein. The left superior vena cava drains into the coronary sinus (then right atrium) Due to the presistance of left anterior cardinal vein and obliteration of right common cardinal vein
Double Superior Vena cava
due to persistance of the left anterior cardinal vein and failure of the formation of the left brachiocephalic vein
