Embryology of the Heart Flashcards
draw the primary heart tube
what happens to the primary tube?
looping
- caudal end loopsposteriorly cranially left
- cranial end loops anteriorly caudally right
is blood flow always from caudal end?
no b looping caudal becomes crainal
where do you hear heart sounds from? and why?
- all prosititues take money (2nd intercostal space /5th intercostal space) mid clavicular line sternal edge
- because sound radiates elsewhere
development of the sinus venosus
- 2 sunus horns L R with 3 veins coming off them (vitelline, umbilical, common cardinal vein)
- due to L-R shunt in 4/5week increased pressure in the R horn so centre moveto the right and the R horn enlarges due to more blood flow, also theres the loss ofthe LVV LUV and RUV
- the R horn contiunes to grow and the RCCV abosrbs intp Ratrium forming the smooth part of the inner Ratrium wall and opening of the superior vena cava, whilst the R viteline vein forms the inferior vena cava
- the diminished body of the left forms the coronary sinus and the LCCV forms the oblique vein of the LA
how does folding affect the heart?
- lateral folding creates the heart tube
- cephalocaudal folding brings the tube into the thoracic region
how are gap formed inbetween the main b vessels and what arethey called
- due tofolding
transerve pericardial sinus
sicne a fetus lung doenst work whats important in maintaining its life and whats must it do?
- L - R shunts
- must be reversible at birth
describe from where each atria develops and what it transports
R = from primtiive atrium
L = little bit from the primitive atrium but mainly abosrbs proximal parts of pumonary veins
whatare the types of septations there are?
interarterial
interventricular
septation of the ventricular outflow tract (PULMONARY TRUNK ADN AORTA)
describe the interartial septation
- endocardial cushions which are from neural crest cells from R L sides of artioventricular canal and move towards eachother deviidn the heart inot r l channels
describe atrial septation
- septum primum grows down from the atrial wall towrds the fused endocardial cushion, but before theres a gap is formed before it fused known as ostium primum
- just before ostium primum closes a second hoelforms in the septum oprimum called ostium secundum
- another cresent shape grows from the atrial wall known as the septum secundum and theres a hole in it forming the foramen ovale
- this shunt is now R-L and allows b f from the Ra t La by passing the lungs since the lungs arent developed yet, but once the baby first breathes pressure will be pushed against the septum secndum against the septum primum closeing it shut
describe interventricular septation
muscular portion growing upwards and then intremembranous tissue is formed by endocardial cushions to fuse this endocardial cushion to the axial one of the interventriuclar septation
septation of the outflow tract
endocardial cushions appear in the truncus arterisosus and they form membranous tissue that twists around each other forming spiral septum, this gives arise to the Pulomary trunch and aorta
describe the aortic arches
at first its bilateral. theres a 1-6th arch no 5th but present in some animals, the R4th = R subcalvian vein L4th = aorta
R6th = R pulonary artery L =Lpulomnary artery adn ductus arteriosus
why is damage around the left 6th branch more dangerous thatthe 6th right
and what do patients present with
because the left laryngeal nerve extends and tucks beneath the ductus artetioes whilst the right travels a shorter distance is higher upclser to te right subclavian artery
hoarse voice
describe the shunts/ducts?
ductus arteriosus - by pass liver since the liver requires alot of blood for it metabolic reactions and by the timeit reached the heart not enoguht blood
ductus arterious - by pass lungs because not formed
- foraemen ovale - shutn allow blod from from R - L to by pass the lungs but alsolet b flow into L atrium and ventricle for musclular development
