embryological development of the heart

Question 1

what are the main stages in heart development

Answer 1

bilatetal heart primordua
primitive heart tibe
heart loopinh
atrial and ventriculat septatoon
outflow tract septation

Question 2

what are the 9 stages of geart development

Answer 2

formation of blood vessels
formation of pericardiu
heart tuhe
atrioventricular canals 
septatkonnof primitive atrium
sept of primitive ventricle
formation of heart valaves 
heart conducting system

Question 3

when does cardio system start fucntioning

Answer 3

4th week

as nutrion by diffusion is not sufficient to satisfy growing embryo

Question 4

what happens in the 3rd weeks

Answer 4

blood cessels forst apprar in yolk sac, allantois connecting stalk and chrouin - cardiogenic field
blood vessels in later plate mesoderm form two heart tubes
heart tibes fuse and join blood cessels in other aread to form orimerdial cardiovascular systems

Question 5

how is the pericardium formed

Answer 5

with cranial folding of embryo, heart tibe fomes to lie dorsal to pericardial cavity
parietal later of serious owricardium and fibrous form from somatic

visceral layer of serious forms from splanchnic

pericardial cavoty forms from intra embryonic coelom

Question 6

what does the heart tuhe differentiate and bulge to

Answer 6

an atterial (cranial) ans venous (caudal) ends

Question 7

what does the heart tube look like

Answer 7

Question 8

what does it mean when the heart tibe invaginates tje pericardium

Answer 8

growing tube is too large for pericardium and so needs to fold/loop - bulbovengricular loop

Question 9

how does the loopong occur

Answer 9

bulbus cordis and ventricle enlarge and loop to the right
ventricle pushes left and inferiorly
atria pushed superiorly and posteriorly

Question 10

what is abnormal loopimh

Answer 10

looping to left
heart loops to left side instead of right so centricles come to lie facibg tje right
dextrocardia

Question 11

what arw the 4 steps of partitioning the primitive heart

Answer 11

1. the single atrioventricular canal into left ans right AV canals (endocardial cushion growth)
2. the primitive atrium into left amd right atria (atrial septum formation)
3. the primitive ventricle into left and right ventricles (ventricular septim formation)
4. the atria from the centricles (heart valve formation)
   - this invilves two actuvely growing masses of tissue: endocardial cushions and heart septae

Question 12

how dp we partition the promitive intrium into left ams right attia

Answer 12

formation of septum primum
ostium secundum begins yo form by apoptosis of a part of the septum prim
formstion of the osyihm secundum completed and there is formation of the septum secundum
the foramen ovale is formed, allowing a one wat shunt allowing blood to move from right atrium to left atrium

Question 13

what happens whrn the septum premum and secundum dont shut

Answer 13

you get a patent foramen ovale which is a common form of congenital atrial septal defect

Question 14

how do we partition tje primitive ventricle

Answer 14

muscular ventricular septum forms. opening is called interventricular foramen
aprticppulmonatu septum divides bulbis cordis and trumcud arteriosus into aorta and pulmonary trunk. bottom of spiral aorticopulmonaru septum fuses eith muscular centricular septum and endocardial cushions to form membranpus interventricukwr septum, closung interventticular foramen

Question 15

what ate tje causes of transposition of great vessels

Answer 15

fsilure of aorticppulmonary septum to tale a spiral course

defective migration of neural crest cells to heart

Question 16

what does the centricular wall develop

Answer 16

the cusps, chordae tendineae and papillary muscles

Question 17

what are the semilunar valves formed from

Answer 17

subemdocardial valve tissue

Question 18

what ate early pacemakers

Answer 18

cardiomyocytes in primitive atrium and sinus venosus

Question 19

when does the SA node develop

Answer 19

durong the 5th week

Question 20

whwre is the adult location of the SA node

Answer 20

high in the right attium near tje entrance of the SVC

Question 21

where does the AV node and bundle develop from

Answer 21

cells of AV canal and sinus venosus

Question 22

what are the heart tube derivativesv

Answer 22

aortic sac - aortic arches
bulbus cordis - right ventricle and parts of outflow tracts
primitive ventricle - left ventricle
primitive atrium - parts of right and left atria
sinus venosus - superior vena cava and rught atrium

Question 23

when do tje aortic arches form

Answer 23

during the 4tg and 5th werks

Question 24

how many aortic arvh pairs are formed

Answer 24

6 from the aortic sac which unite with the dorsal aortae

they give rise to arteries of neck and head

Question 25

how do blood bessels develop

Answer 25

vasculogenesis - new formation of a promitive vascular network
anguogenesis - growth of new bessels from pre existing blood vessels

Question 26

what arw the adult derivitives of aortic arches

Answer 26

the first two disappear
the 3rd forms tje common carotid attery
the 4th right atch forms the rugjt subclavirn artery
the 4th left arch forms the aortic arch
the 5th atch disappears
6th right wtch forms the right pulmonary artery
6th left arch forms the left pulmonary artery and ductus arteriosus

Question 27

what do great artery defects arise as a result of

Answer 27

persostence of aortic atvhes that normally regress or regression of those that shouldnt

Question 28

what is a double aprtic atch

Answer 28

occurs with the non regression of the right aortic at j dorming a vascular ting around the trachea and oesophagus, which usuallt causes difficulty in breathing and swallowing

Question 29

what is oatent ductus arteriosisb

Answer 29

maternal rubella infection in early pregnancy
causes faikure id muscular wall to contract, respiratory fistress syndrome and lack of surfactant in lungs
an uncorrected PDA may lead to congestive heart faikure with increasing age
can be associauted with ASD, VSF, coat tation of aorta

Question 30

what happens to embryonic vessels as they become adukt vessels

Answer 30

vitelline vessels supply yolk sac - adult gut vessels
umbilical vessels supply placenta - internal iliac
cardinal vessels suoply rest of the bidy - SVC and IVC

Question 31

when does the lymphatix system develop

Answer 31

end of 6th week around main veins

Question 32

where does the thoracuc duct develop from

Answer 32

two cessels anterior to the aorta. these became the left and right embryonic thoracic ducts. the left one gives rise to upper third od adult thoracic duct and the lower 2/3 of adult duct are formed by embryonic thoracic duct

Question 33

what are foetal circulation shints

Answer 33

1. ductus venosus - shunts blood in left umbikical vein directly into IVC: allows oxygenated blood from tje placenta to bypss the liver
2. formane ovale - shunts clood drom right atrium to left attium:allows blood to bypass the lungs
3. ductus arteriosus - shunts blood from rught cebteicle to puomonary arteries and aorta: allows blood to bypass the lungs

Question 34

what arw the neonatal citculatoon changes after birth

Answer 34

closure of foetal shunts and umbilical arteries
ductus venosus - livamentum venosum of the liver
foramen ovale closes after birth - fossa ovalis of the heart
ductus arteriosus - ligamentum arteriosum between left pulmonary artery and aorta
umbilical arteries - medical umbilical ligaments of the anterior abdominal wall