Formation of the Heart - Embryology: Dr. Dickson - Cedarville University

cells called cardiac ___________cells in the epiblast also migrate through the streak into the ________ layer of the lateral plate mesoderm forming the _________ _______ ______

progenitor, visceral (splanchnic), primary heart field (PHF)

The PHF lies ________ to the aspect of _______ _____

cranial, neural folds

the PHF differentiates first to form the ______ ______ _____

linear heart tube

the PHF forms the ______ _______ _____

initial heart tube

PHF cells exhibit a ___-____ patterning

Left-right

the secondary heart field is derived from ________ mesoderm

visceral (splanchnic)

laterality pathway is the same signaling pathway that establishes _________ for the entire embryo

laterality

impaired L-R patterning leads to __________ ( ________________ ) or ______ _______ of cardiac components resulting in ________ ______ ______

heterotaxy (randomization), situs inversus, congenital heart defects

during gastrulation the primitive node contains hundreds of _________

monocilia

a protein ______ is expressed from the node which causes the cilia to rotationally beat in a ___________ direction

dynein, clockwise

cilia beating clockwise causes _______________ _______ to flow toward the _____ side of the developing embryo

extraembryonic fluid, left

EB fluid flowing to the left side of the embryo causes _______ and _______ genes to be induced in the left lateral plate mesoderm along with ____________ (5-HT) or _______

Nodal, lefty2, serotonin, PITX2

this pathway specifies the ______ side of the body and it also programs heart cells in the ______ and _____

PHF, SHF

the cells of the _____ first migrate and form a ____________- shaped cardiac _______.

PHF, horseshoe, crescent

the PHF creates two distinct strands of cells called ______________ ______

angioblastic cords

the angioblastic cords hollow out to become two separate ____________ tubes

endocardial

the endocardial tubes will fuse at the ________ to create the ________ ______ ____

midline, initial heart tube

the initial heart tube gives rise to the ______ _______ and portions of the ______

left ventricle, atria

the SHF gives rise to the ______ _______ and _________ ______ ( ________ ______ and ________ ________) and the ______ tract

right ventricle, outflow tract, conus cordis, truncus ateriosus, inflow

under the influence of ________ the mesenchymal cells in the mesoderm are induced to become ______________ ________________

FGF2, bipotential hemangioblasts

the underlying endoderm secreted growth factors ( _____) that stimulate these cells to develop into ________ ______

VEGFs, blood islands

blood islands form _______ which is called __________________

vessels, vasculogenesis

hemocytoblasts are _______ ___________

blood precursors

when the embryo folds _______ the two ____ tubes fuse together

laterally, heart

the pericardial cavities will form from the ___________ cavities

intraembryonic

with ______________ folding the heart tube gets pulled into the ___________ cavity

craniocaudal, pericardial

initially the heart tube is cranial to the __________________ membrane and the _______ _____

oropharyngeal, neura plate

the heart tube is made up of what layers

endocardium, myocardium, epicardium

endocardium is made up of _________ cells developed from ________, the angioblasts are stimulated by _______

endothelial, mesoderm, VGEFs

the outer layer is the ____________

myocardium

the myoblasts in the myocardium secrete ________ _____ which separates the myocardium from the ____________

cardiac jelly, endocardium

the outside of the tube is the _________

epicardium

fusion of the paired __________ __________ tubes begins at the _______ end and progresses _________

bilateral endocardial, cranial, caudally

the developing heart tube is initially attached to the dorsal side of the pericardial cavity by the ________ ___________

dorsal mesocardium

the heart will receive its venous drainage at its _______ pole and begins to pump it out at the first ______ _______ into the dorsal aorta

caudal, aortic arch

the original paired heart tubes fuse into a single one except at the ________ ends

caudal

the caudal ends of the fused heart tubes remain separate which means they become the ________ ______

sinus horns

the caudal ends are embedded in the _______ _________

septum transversum

the outflow tract of the heart tube will lead to the _________ _____ and _______ _____

aortic sac, aortic arches

blood comes in the bottom and comes out of the top (______ _____)

dorsal aorta

the heart tube continues to elongate as cells are added from the ____ to its ________ end

SHF, cranial

the lengthening process is essential for the ________ process and proper formation of the ______ _______ and ________ ______

looping, right ventricle, outflow tracts

outflow tracts

bulbus cordis and truncus arteriosus

the cardiac tube begins to bend on day ____

23

the cardiac looping is complete by day ____

28

initially the heart created a ___ shape but then ends up ___ shaped after elongation

C, S

proper looping is essential for the correct alignment of the hearts _______ and ________ segments

inflow, outflow

the looping process depends on the presence of _______

dynein

abnormalities from poor looping process

Kartagener syndrome, dextrocardia, transposition of the great arteries

the embryonic heart typically starts beating on days ___-___

22-23

the heart tube begins to contract and pump blood at ___ weeks of gestation

5

the average heart beat at 5 weeks is _____ bpm

110

the bulbus cordis is divided into the _______ ________, _______ ______, and the trabeculated part of the _______ _________

truncus arteriosus, conus cordis, right ventricle

the proximal third of the ________ _______ forms the trabeculated part of the R ventricle

bulbus cordis

the ______ ______ forms the outflow of both ventricles

conus cordis

the _________ ________ forms the roots and proximal portions of the aorta and pulmonary artery

truncus arteriosus

the ______________________ _______ is a junction between the primitive ventricle and bulbus cordis

bulboventricular sulcus

blood enters the venous end of the heart tube ( _______ ______) from the ___________, __________, and ________ veins

sinus venosus, umbilical, vitelline, cardinal

the blood moves from the sinus inversus into the ________ ______

primitive atrium

then the blood passes through the __________________ canal into the ________ _______

atrioventricular, primitive ventricle

after blood passes through the primitive ventricle it then flows through the _______ ______ into the ________ ______

bulbus cordis, truncus arteriosus

the atrioventricular canal is the entrance of the _______ into the primitive _______ _________

atrium, left ventricle

the AV canal is separated from the bulbus cordis by the _________________ _______

bulboventricular flange

_______ is responsible for heart induction

NKX2

bone morphogenetic proteins (BPMs) 2 and 4 secreted by the ______ and lateral plate mesoderm promote ___________ ___________

cardiomyocyte differentiation

inhibition of ______ gene expression by the __________ gene in the anterior half of the embryo induce expression of NKX2

WNT, CRESENT

NKX2 gene

master gene in heart development

in the fourth week 3 pairs of _______ _______ appear

major veins

vitelline veins carry blood from the ______ ____ to the _______ _______

yolk sac, sinus venosus

umbilical veins originate in the ________ _______ and carry ______________ blood to the embryo

chorionic villi, oxygenated

cardinal veins drain the body of the ________ ______

embryo proper

initially the _________ _______ form the main venous drainage system of the embryo

cardinal veins

the _________ _________ _______ drain the cephalic part of the embryo

anterior cardinal veins

the ___________ cardinal veins drain the rest of the embryo

posterior

the anterior and posterior cardinal veins join before entering the _______ ______ to form ________ _________ veins

sinus horn, common cardinal

the _______ vitelline system will become the dominant one

right

the sinus venosus drains into the __________ ______

primitive atrium

in the middle of the 4th week the sinus venosus receives blood from the R and L _____ _______

sinus horns

the anterior _________ ________ drain the cranial region

cardinal veins

the ___________ _________ ______ drain the caudal

posterior cardinal veins

each horn receives blood from these veins

vitelline, umbilical, common cardinal

vitelline (VIT) receives blood from the

yolk sac

umbilical veins (UV) receives blood from

O2 blood from placenta

in the 4-5th weeks the L-R shunting of blood in the venous system shifts the entrance to the ______

right

ALL this circulation is going to be _______-______ dominant

right-side

the right _________ ______ becomes dominant

vitelline vein

around 7th-8th week the anterior cardinal veins will be connected by an ____________

anastomosis

an anastomosis shunts blood from the ______ to the _____ cardinal veins which will become the ____ ______________ _____

left, right, left brachiocephalic vein

all that will remain of the left sinus horn is the ________ _____ of the ______ _______ and the ________ ______

oblique vein, left atrium, coronary sinus

the superior vena cava is formed from the right _______ __________ _______ and the right ________ _______ _____

anterior cardinal vein, common cardinal vein

the right vitelline vein becomes the terminal part of the ________ ______ _______

inferior vena cava

before entering the sinus venosus the vitelline veins form a ______ around the _______ and pass through the ______ ________

plexus, duodenum, septum transversum

liver buds grow into the septum and interrupt the course of the veins forming the ________ ________

hepatic sinusoids

left to right shunting results in enlargement of the _____ ______ _______

right vitelline vein

the left vitelline vein between the ________ and the _______ ( the left ____________ _________) will disappear completely

liver, heart, hepatocardiac channel

the rest of the left vitelline vein contributes to the what

sinusoids, left hepatic vein, part of the portal vein

the right vitelline vein becomes the what

superior mesenteric vein, right hepatic vein, part of portal vein

initially the umbilical veins pass on each side of the ______

liver

the proximal part of the L __________ vein and all the R __________ veins disappear

umbilical, umbilical

the posterior cardinal veins largely ________

regress