Embryology Flashcards
Where does the heart arise from (2)
From visceral mesoderm
Cranial to the developing neural tube
How does the heart reach its final position
By lateral and cranio-caudal folding inferiorly towards thoracic cavity
Heart tube regions and adult derivatives (5)
Truncus arteriosus - Aorta and Pulmonary Trunk
Bulbus cordis - Right ventricle and outflow part of both ventricles
Ventricle - Left ventricle
Atrium - Both atria
Sinus venosus (Right and left horns) - Smooth part of right atrium and coronary sinus
Looping and folding (4)
Occurs on day 23
Atrium moves dorsal and cranial
Ventricle is displaced left
Bulbus cordis moves inferiorly then ventrally to the right
Aortic Arches development (5)
6 pairs associated with pharyngeal arches
Pair 3: Common carotid aortic arches and first part of inferior cerebral artery
Pair 4: Right subclavian artery - Part of aortic arch
Pair 6: Sprout branches forming pulmonary aortic arches with ducuts arteriosus on left
Other pairs are absent or obliterated
Viteline veins function and parts (4)
Drains yolk sac
Portal venous system draining gut
Hepatic sinusoids and veins
Hepatic portion of IVC
Umbilical veins function and parts (3)
Carries oxygenated blood from Placenta
Right degenerates
Left remains as Definitive Umbilical vein
Cardinal veins function
Give systemic venous system
Systemic veins types (2)
Anterior Cardinal Veins
Posterior Cardinal Veins
Anterior Cardinal Veins (3)
Drains head and neck
Jugular system and left branchiocephalic vein
SVC
Posterior Cardinal Veins (5)
Drain trunk Azygous and Hemiazygous systems Gonadal and Renal veins Iliac veins IVC
Placenta function (8)
Fetal homeostasis Gas exchange Acid base balance Nutrient transport to fetus Waste product transport from fetus Hormone production Transport of IgG Prostaglandin E2
Placenta in circulation (2)
Foetal heart pumps blood to placenta via umbilical arteries
Blood from the placenta returns to foetus via umbilical vein
Ductus Venosus (2)
Connects umbilical vein to IVC bypassing portal circulation
nutrients come form placenta that doesn’t need further processing in liver
Foramen Ovale (3)
Opening in atrial septum connecting RA to LA
allows best oxygenated blood to enter LA then on to LV, ascending aorta and carotids
Membrane flap on LA side
Ductus Arteriosus (3)
Connects pulmonary bifurcation to descending aorta
Only 7% of RV output goes to lungs
Patency maintained by circulating prostaglandin E2 produced by placenta
Circulatory changes upon birth (3)
Pulmonary Vascular Resistance decreases and reaches adult levels by 2-3 months
Systemic Vascular Resistance increases
More cardiac output to lungs
Physical changes upon birth (2)
Foramen Ovale closes - Remains open in 25% with implicated stroke or migraine
Ductus Arteriosus constriction - Increases pO2, decreases flow and prostaglandins and closes within 7-10 days
Failure of duct closure (3)
High incidence in preterm infants
Contributes to complications
Treatments are NSAIDs or surgery
Maintaining duct patency
IV prostaglandin E2 is used to keep open duct until an alternative shunt established or surgery carried out
Effects of failed adaptation (2)
Persistent pulmonary hypertension
Sick babies - Sepsis, Hypoxic ischaemic insult, Meconium aspiration syndrome, cold stress
Persistent Pulmonary Hypertension (PPHN) (4)
Lung vascular resistance fails to fall
Shunts remain
Right to left flow at Patent Foramen Ovale and Patent Ductus Arteriosus
Large difference between pre and post ductal oxygen saturation
PPHN treatments (9)
Reduce pulmonary vascular resistance and increase systemic vascular
Ventilation, oxygenation, high systemic blood pressure via inotropes, inhaled nitric oxide, Extracorporeal life support resistance, acidosis correction, thermoregulation, sepsis treatment
