Lecture 19: Embryonic Cardiovascular System Flashcards Preview

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Flashcards in Lecture 19: Embryonic Cardiovascular System Deck (47):

cardiogenic mesoderm of heart primordium

epiblast cells ahead of precordal plate that migrate through primitive groove as mesoderm forms, and will become heart


angioblastic cords

pairs of vessels that will make pair of aorta and then fuse to become single aorta


where does heart begin in fetus?

above chest


what comes down to chest during folding

cardiogenic mesoderm, pericardial sac, septum transversum


why no circulation through lungs in fetus

because lungs haven't formed and no air/oxygen in the lungs, so don't need blood circulation

therefore blood pumps out of aortic arches, oxygenated blood is used by fetus's tissues, and then carried back to heart by vein


cranial to caudal, parts of embryonic single heart tube

aortic sac, truncus arteriosis, bulbus cordis, primitive ventricle, primitive atrium, sinus venosus


where veins entering into heart tube go through

from ylk sac, through sinus venosus, to embryonic heart


why single heart tube folding occurs

genes tell heart to fold, and cells proliferate more rapidly on 1 side causing cranial fold


fetal heart circulation

blood goes into sinus spinosis - ventricle - bulbus cordis - aortic sac - 1st pharyngeal arch artery


endocardial cushions

2 mounds of tissue that separate primordial atria from ventricle and divide heart into R and L atrio-ventricular canals

also play role in AV valve formation (mitral, tricuspid)


papillary muscles

hold tissue strands growing from walls of ventricles to endocardial cushion in places

will become the AV valves


interventricular septum

separates R and L ventricles

muscular, membranous parts


muscular part of interventricular septum

ingrowth of cardiac mesoderm that grows toward cardiac cushions


membranous interventricular septum

tissue that grows from endocardial cushions and meets up with muscular part of septum


ventriculo septal defect

in membranous portion of interventricular septum most likely

when thin tissue there doesn't grow closed properly and so child needs surgery to close it


leaflets that partition right and left primitive atrium

septum primum, septum secundum


septum primum

starts from posterior wall of primitive atrium, grows toward endocardial cushion; as grows, little fenestrations within so blood can get from R to L atria

includes foramen primum and foramen secundum


foramen primum

little space that remains in septum primum so blood can pass from R to L atria; eventually is fused/obligerated


foramen secundum

growth of fenestrations in septum primum causes this opening

it remains into development of heart, doesn't get obliterated - becomes the foramen ovale


foramen ovale

remnant of the septum secundum

passage between 2 atrial cavities through which blood flows from right to left atrium


septum secundum

second septum in atria

is anterior to septum primum

leaves opening in development of heart so blood can flow from R to L atria through foramen ovale


structures associated with primitive atria

septum primum, foramen primum, septum secundum, foramen ovale


where a stroke in a young person could go across

foramen ovale


foramen ovale function

right to left shunt
allows blood to bypass fetal lungs
closes after birth when pulmonary vascular resistance decreases and left atrial pressure increases


conotruncal ridges (bulbar, truncal)

form in truncus arteirosis and part of bulbus cordis


aorticopulmonary septum

formed by ridges of right superior truncus and left inferior truncus growing toward the aortic sac, swelling and twisting around each other

meets interventricular septum

divides truncus into aorta and pulmonary artery


aorta v pulmonary artery re: outflow

aorta- L ventricular outflow tract

pulmonary artery- R ventricular outflow tract


order of aorta/pulmonary trunk and why

pulmonary trunk- more ventral, aorta- more dorsal, because of spiraling


2 types of valves

semilunar, atrioventricular


semilunar valves

aortic and pulmonic

aortic: separates aorta from left ventricle

pulmonic: separates arteries from right ventricle


derivation of semilunar valves

swellings in subendocardial region

usually 3 cusps/seminlunar portions, although have a bicuspid aortic valve


types of AV valves

tricuspid: right atria to right ventricle

mitral: left atria to left ventricle


derivation of atrioventricular valves

proliferation of tissue around endocardial cushions/A-V canals


dorsal aorta

initially, pair of tubes; fuses to form single dorsal aorta; connects w/ aortic arches; aortic arches connect to aortic sac in primitive heart tube


paired dorsal aortae

each paired arch is assocaited with a pharyngeal arch; they connect to aortic sac


how many aortic arches develop

6; do not all develop at the same time


what is descending aorta result of

fused dorsal aorta


pharyngeal arches

pair to form aortic arch


left 4th pharyngeal arch

becomes much of aortic arch


left 6th pharyngeal arch

becomes left pulmonary artery and ductus ateriosis


ductus arteriosis

derivative of left 6th pharyngeal arch

shunt in fetal pulmonary artery that shunts blood through to aorta instead of going to lungs


3 pairs of primitive veins

all empty into sinus vinosus; will contribute to vena cava and primitive blood return to heart

vitelline veins- drain yolk sac (low O2)

umbilical veins- form placenta (high O2)

common cardinal veins- from body of embryo (low O2)


what happens to R umbilical vein?

it disappears


what carries blood from mom to fetus?

L umbilical vein

only vein in umbilical cord

has ductus venosus shunt to shunt blood back to heart, doesn't go through liver like normally does


derivatives of superior vena cava

right anterior cardinal vein, right common cardinal vein


tetrology of fallot components

frequent abnormality

due to unequal partitioning of truncus arteriosis from spinous arteriosis

4 cardiovascular alterations:
1. pulmonary stenosis (narrow right ventricular outflow region)
2. ventricular septal defect
3. overriding aorta
4. right ventricular hypertrophy


do embryonic umbilical arteries have high or low O2 content?

they have the highest O2 content of the embryonic veins