heart development Flashcards
the cardiovascular system is the _____ major organ system to function in the embryo at the _____
-first
-end of week 3
what is the origin of blood vessels
blood islands: mesodermal mesenchyme cells, gives rise to blood cells, vessels and the heart
-collect at the cranial end
middle end of W3:
-day 20:
the embryonic heart reaches the thorax and isa pair of endothelial tubes in the body midline
-the tubes fuse together and pushes blood out of both ends.
-all four chambers arise from tubes
day 22:
heart starts pumping
-4 buldges have dev along the heart tube: sinus venosus, atrium, ventricle, bulbus cordis
sinus venosus
initially receives all blood from the veins of the embryo
-becomes: smooth walled part of the right atrium, coronary sinus, and the SA node, also the posterior wall of left atrium
-collects deox blood
atrium
gives rise to pectinate muscles of right and left atria
ventricle:
strongest pumping chamber
-becomes the left ventricle
bulbus cordis and truncus arteriosis (cranial extension)
gives rise to the right ventricle, pulmonary trunk, and first part of the aorta
when does bending of the heart occur and why
days 23-28
-rapid growth of ventricle and bulbus cordis cause bending
bending
what direction do the ventricle and atrium move
-s shape
-ventricle: caudally
-atrium
-cranially
result of cardiac looping
the heart fold on itself and assumes its normal position of the left part of the thorax with atria: posteriorly and ventricles: anterior
by month 2
the heart divides into a series of chambers by formation of midline atrial and ventricular septa and valves
month 2
endocardial cushions
help form the hearts midline septum and valves
month 2
interatrial septum
forms by growing caudally from the hearts roof
month 2
interventricular septum
grows cranially from the hearts apex
month 2
neural crest cells
migrate where the atrium meets ventricle and make valves, base of pulmonary trunk, and descending aorta
what are the 3 vascular systems during fetal development
- intra-embryonic
- vitelline
- placental
intra-embryonic function and 2 vessels that belong to it
vessels supply blood to and drain blood from embryonic tissues
-dorsal aorta: supplies blood to embryonic tissues
-cardinal veins: return deoxy blood from the body of embryo to the heart tube
vitelline function and two vessels
vessels supply blood to and drain blood from the yolk sac, which contributes to blood supply in the GI tract in adults
-paired vitelline arteries
-veins to yolk sac
placental vasc system function and 2 vessels
-includes paired umbilical arteries that deliver deoxy blood and fetal wastes to the placenta and umbilical vein that transports highly oxygenated, nutrient rich blood from the placenta.
-umbilical arteries: carries deoxy blood from the heart to the placenta
-veins to placenta: carries oxygenated blood from the placenta to the heart.
placental and pulmonary vein
only veins that carry oxygenated blood
placental artery and pulmonary artery
only arteries that carry deoxy blood
all blood vessels are in place by
month 3
during pregnancy the placenta
provides both O2 and nutrients to fetus
-fetal circulation bypass the liver and lungs
where does blood filter through in fetal circulation
liver of the mother via the placenta
vessels to and from the placenta
-umbilical vein
-ductus venosus
-IVC and SVC
vessels to and from the placenta
-umbilical vein
provides oxyg blood from the placenta
vessels to and from the placenta
-ductus venosus
a shunt that bypasses the liver and enters the IVC, drains to IVC where oxygen rich blood mizes with deox blood returning to heart from caudal region of the body
vessels to and from the placenta
IVC and SVC
drain moderately oxygenated blood into the right atrium
shunts away from the pulmonary circuit
-foramen ovale
-ductus artiosis
shunts away from the pulmonary circuit
-foramen ovale
hole in the interatrial septum; blood can travel from the right atrium- to the left atrium- to left ventricle-aorta- then body
shunts away from the pulmonary circuit
-ductus arteriosis
between the pulmonary trunk and the aorta, any blood that passes the right atrium follows to the right ventricle- pulmonary trunk- diverts to the aorta-then to the body
after birth
alveolar pressure in the lungs causes physiological changes in pulmonary arteries and veins
pressure increases in both of the atria and cause the foramen ovale to
close and become the fossa ovalis
after birth
-ductus arteriosis
degrades and becomes ligamentum arteriosum: CT
clamping of the umbilical cord:
-umbilical cord
umbilical cord constricts and becomes ligamentum teres that anchors liver to body wall
clamping of umbilical cord:
-ductus venosus
closes and becomes ligamentum venosum on the inferior surface of the liver
clamping of umbilical cord:
-umbilical arteries
no longer functions, persist as medial umbilical ligaments
the embryo has _____ oxygen levels
lower
-due to mixing
ventricular septal defect
superior part of interventricular septum fails to form
-blood mixes between ventricles
transposition of the great vessels
bulbus cordis does not divide properly, aorta comes from right ventricle and pulmonary trunk comes from left ventricle
-pumps deox blood to the body
tetralogy fallot
-multiple defects
-pulmonary infundibulum stenosis: septum with a hole
-large IV septal defect: narrow opening
-overriding aorta arising directly above the septal defect: misplaced
-R ventricular wall hypertrophy due to high R side pressure
