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Cardiovascular System (ESA 2) > Revision: Embryology > Flashcards

Flashcards in Revision: Embryology Deck (11)
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1
Q

formation of primitive heart tube

A

cardiogenic field, where heart, blood vessels and cells arise from, is created in gastrulation and begins in the cranial end of the embryo before folding starts

as development of CVS starts, a pair of endocardial tubes develop in the 3rd week

Folding: lateral folding brings these two together to form the heart tube (diagram)

-cephalocaudal folding brings the tube into thethoracic region

2
Q

regions of primitive heart tube

A

originally recieves blood at sinus venosus (caudal) before pumping blood out of the aortic roots (cephalic)

consists of: sinus venosus, primitive atrium, primitve ventricle, bulbus cordis, truncus arteriosus, aortic roots

3
Q

looping of heart tube and result

A

continued elongation leads to bending between days 23-28

Cephalic/cranial part: caudally, ventrally, to the right

Caudal part: cranially, dorsally, to the left

Afterwards, the atrium communicates w/ vent.s via a/v canal, a constriction between the two, the first division between the chambers

Forms tranverse pericardial sinus, a space behind the outflow and in front of the inflow, where a finger can be inserted

4
Q

describe fate of sinus venosus

A

receives blood from yolk sac, placenta and body

at first the r and l horns are equal in size -> venous return then shifts to the RHS -> l/horn recedes -> enlarging RA absorbs r/ sinus horn

5
Q

describe development of atria

A

RA: from most of the prim. atrium and r/horn of sin. ven.

LA: from small amount of prim. atrium, absorbs prox. part of pulmonary veins

-as the LA expands and absorbs the pulmonary veins, the oblique pericardial sinus is formed - with the heart in the palm of your hand, your fingers are in a cul-de-sac - the OPS

6
Q

development of the aortic arches

A

early system is a bilateral symmetrical system of arched vessels -> undergo extensive remodelling -> major arteries

-NB no. 5 has no derivative in humans and either incompletely forms or never forms at all

4th arch: l -> arch of aorta, r -> prox. part of r/ subclavian

6th arch: the recurrent laryngeal nerve forks underneath here, l -> l/pulmonary artery and ductus arteriosus, r -> r/pulmonary artery

7
Q

first stage in septation

A

development of endocardial cushions on back and front of a/v canal -> grow towards each other -> divides heart to r/ and l/ sides

8
Q

atrial septation

A

formation of 2 septa w/ 3 holes:

Septa: Septum primum: grows down towards endocardial cushions

-Septum secundum: crescent shaped 2nd septum

Holes: ostium primum: hole beofre SP fuses w/ endocardial cushions

  • ostium secundum: before ost. prim. closes, 2nd hole appears in sep. prim. by apoptosis
  • foramen ovale: hole inside septum secundum
9
Q

ventricular septation

A

formed of a muscular and membranous portion:

  • muscular: forms most of septum, grows upwards towards fused endocardial cushions leaving a hole at the top, the primary interventricular foramen
  • membranous: fills gap of primary interventricular foramen, derived from spiral septum that grows to separate the truncus arteriosus into outflow valves
10
Q

foetal circulation principles, outline, fate

A

Lungs are obv. non functional in a foetus and it is important that they do not receive too much blood as they can be damaged

Foetus: receives blood from mother via placenta -> umbilical veins, which bypasses the lungs, blood returns to the placenta via umbilical arteries

-changes in circulation must occur immediately at birth, shunts are required to make this happen

Diagram: IVC=inf. ven cava

ignore written part about DA

after birth: baby takes breath -> massively dec. press in lungs -> more blood enters lungs -> more blood enters LA -> press. in LA>RA -> foramen ovale shuts, DA contracts, placental support removed so DV shuts

11
Q

fates of foetal shunts

A

forman ovale -> fossa ovales

ductus arteriosus -> ligamentum arteriosum (mediated by bradykinin)

ductus venosus -> ligamentum venosum

umbilical vein -> ligamentum teres hepatitis