Embryo Flashcards
Truncus Arteriosus
Ascending Aorta and pulmonary trunk
Bulbus cordis
smooth parts (outflow tract) of the left and right ventricles
Primitive atrium
trabeculated part of R and L atria
Primitive ventricle
Trabeculated part ofR and L ventricles
primary pulmonary vein
smooth part of the L atrium
Left horn of sinus venosus
coronary sinus
right horn of sinus venosus
(sinus venarum) smooth part of R atrium
Right common cardinal vein and right anterior cardinal vein
SVC
Which organ functions first?
heart
When does the heart beat?
spontaneously by week 4 of development
when is the embryonic period of development?
weeks 3 to 8
What is cardiac looping?
when the primary hear tube loops to establish left-right polarity
when does cardiac looping occur?
week 4 of gestation
in what disease do you see dextrocardia?
Kartagner syndrome
what is another name for Kartagner syndrome?
1 ciliary diskinesia
What defect do you see in dextrocardia?
defect in L-R dynein (involved in L/R asymmetry)
What are the other findings of Kartagner syndrome?
situs inversus, bronchiectasis, infertility in male and female ( immotile sperm, dysfunctional fallopian tube cilia), recurrent sinusitis, dextrocardia on xray
What is the defect of Kartagner syndrome?
immotile cilia due to defect in dynein arm
what are the steps in the separation of the atria?
- septum primum grows toward endocardial cushion ( narrowing the foramen premium)
- foramen second forms in septum premium (foramen premium disappears)
- septum secundum develops as foramen secundum maintains R to L shunt
- septum secundum expands and covers most of foramen secundum ( the residual foramen is the foramen ovale)
- remaining portion of septum premium forms the valve of the form ovale
- septum secundum and primum fuse to form atrial septum
- foramen ovale closes soon after birth because increase LA pressure
when does the foramen ovale close?
soon after birth because of an increase in LA pressure
what is it called when it stays open?
Patent foramen ovale
patent foramen ovale
caused by failure of septum premium and septum scandium to fuse after birth. most are left untreated
can lead to paradoxical emboli (venous thromboemboli that enter systemic arterial circulation), similar to those resulting from an ASD
what is a paradoxical emboli?
venous thromboemboli that enter systemic arterial circulation
what are the steps in ventricle septation?
- muscular ventricular septum forms . Opening is called inter ventricular foramen
- aorticopulmonary septum rotates and fuses with muscular ventricular septum to form membranous inter ventricular septum, closing the inter ventricular foramen
- growth of endocardial cushions separates atria from ventricles and contributes to both atrial separation and membranous portion of the interventricular septum
what contributes to both atrial separation and membranous portion of the inter ventricular septum?
endocardial cushion
what separates the atria from the ventricles?
endocardial cushion
what is the outflow tract?
smooth part of R and L ventricles
how does the outflow tract form?
truncus arteriosus rotates
neural crest + endocardial cell migration –> truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum –> ascending and pulmonary trunk
what cells cause the outflow tract to begin formation?
neural crest and endocardial cell migrations
what forms the Aorticopulmonary septum?
truncal bulbar ridges that spiral and fuse
Aorticopulmonary septum divides _____ and ______.
ascending aorta and pulmonary trunk
What abnormalities can you see with a defect in the formation of the outflow tract?
Transposition of the great vessels, Tetralogy of Fallot, and Persistent trunks arterioles
how do the A/P valves develop
they are derived from the endocardial cushion of outflow tract
how are the M/T valves developed
they are derived from fused endocardial cushion of the AV canal
list some valve anomalies
stenotic, regurgitant, atretic (tricuspid atresia) or displaced (ebstein anomaly)
which valves accelerate the normal aging process?
congenital bicuspid aortic valves
congenital bicuspid aortic valves leads to ______ in the ____ and ___ decades.
calcific aortic stenosis, 6th and 7th
in a patient without the defect, congenital bicuspid aortic valves.. what is found in the 8th and 9th decades?
senile calcific aortic stenosis
where does fetal erythropoiesis occur?
yolk sac, liver, spleen, BM
List and date where fetal erythropoiesis occurs:
Yolk sac ( 3- 8 wks)
liver (6 wks to birth)
spleen (10wks to 28wks)
BM (18 wks to adult)
embryonic globins
ζε ( 2 zeta chains and 2 epsilon chains)
fetal globins
HbF = α2γ2
Adult globins
HbA1 =α2b2
Which hemoglobin has a higher affinity for oxygen?
HbF
why does HbF have a higher affinity for O2?
due to less avid binding of 2,3 BPG, allowing HbF to extract O2 from maternal hemoglobin (HbA1 and HbA2) across the placenta
where do you see blood of a fetus with a PO2 of = 30mmHG and =80% saturation of O2
Umbilican vein
which fetal arteries/veins have a low O2 saturation?
Umbilical arteries
how many shunts do we see in fetal circulation?
three- ductus venosus,foramen ovale, pda
blood entering the fetus thru umbilical vein is conducted via:
the ductus venosus into the ivc, bypassing the hepatic circulation
fetus: the ductus venosus bypasses which circulation?
hepatic circulation
fetus: most of the highly oxygenated blood reaching the heart via the IVC is directed through the:
foramen ovale and pumped into the aorta to supply the head and body
fetus: deoxygenated blood from SVC passes through:
RA->RV->->main pulmonary artery->PDA->descending aorta; this shunt is due to high fetal pulmonary artery resistance (due partly to low O2 tension)
what happens at birth when the infant takes a breath?
decrease resistance in pulmonary vasculature–> increase left atrial pressure vs R atrial pressure; foramen ovale closure, and ductus arteriosus
what causes the closure of the ductus arteriosus?
increase in oxygen (from breath), and decrease in PG from placental separation
what helps close a PDA?
indomethacin
what is the remnant of ductus arteriosus
ligamentum arteriosum
what keeps a PDA open?
PG E1 and E2
which duct connects the bladder to the umbilicus in the fetus?
allantoic duct
urachus is part of the
allantoic duct
it is a fibrous remnant of the allantois
what is the post natal derivative of the Allantois->urachus
median umbilical ligament
what is the post natal derivative of the ductus arteriosus
ligamentum arteriosum
what is the post natal derivative of the ductus venosus
ligamentum venosum
what is the post natal derivative of the foramen ovale
fossa ovalis
what is the post natal derivative of the notochord
nucleus pulposus
what is the post natal derivative of the umbilical arteries
medial umbilical ligaments
what is the post natal derivative of the umbilical vein
ligamentum teres hepatis
the ligament trees hepatis is contained in
falciform ligament
