development of the cvs

Question 1

the heart starts developing in which week

Answer 1

it develops in week 3

Question 2

where does angioblastic cells get derived form and what doe sit form into

Answer 2

the angioblastic cells are derived from the intraembryonic mesoderm and the Fetal membranes: including the chorion, connecting stalk and wall of yolk sac.

and the angioblastic cells form islands and the central cells form the blood cells and the peripheral ones for the blood vessels

Question 3

explain the blood flow during the fetal life

Answer 3

o2nated blood comes form the umbilical vein and goes to the liver via the left branch of the portal vein (and some of the blood goes directly in to the ivc via the ductus venosus) so from the left branch of the portal vein the blood enters the vein and leaves via the hepatic vein and enters the IVC and enters the heart but remember that IVC is bringing deo2nated blood from the tissues and thus the blood entering the right side of the heart is mixed blood.
and when the blood reaches the right atrium it goes via 2 pathwyas
1)via foramen ovale to the left atrium
2) to the right ventricle —> pulmonary artery –>ductus arteriosus–> aorta.

Question 4

changes in the fetal circulation at birth:

1) the umbilical vein:
2) ductus venosis:
3) umbilical arteries:
4) ductus arteriosus
5) foramen ovale

Answer 4

1) ligamentum teres
2) ligamentum venosum
3) distal part =medial umbilical ligaments & proximal part = superior vesical arteries
4) ligamentum arteriosum
5) fossa ovalis (septum primum) and the annulus ovalis (septum secondum)

Question 5

where does the heart arise from and from which day does it start to beat

Answer 5

it arises from the splanchinic mesoderm in the cardiogenic area and stats beating form day 22

Question 6

briefly explain the development of the heart

Answer 6

the heart is starts developing by the 3rd week and it developes from the cardiogenic area in the splanchinic mesoderm and when the embryo starts folding the heart moves to the ventral and the thoracic region.
and from there we have the heart tubes and so on

Question 7

the heart begins as

Answer 7

as 2 endothelial heart tube .The two heart-tubes fuse with each other giving single heart tube.

Question 8

septum transversum gives rise to

Answer 8

it gives rise to the diaphragm

Question 9

what is the dorsal mesocardium and what happens to it when it breaks down

Answer 9

the heart attaches to the esophagus via the dorsal mesocardium
when the dorsal mesocardium breaks down it forms the transverse pericardial sinus.

Question 10

imagine we are in the single tube stage but then later on the heart starts bending how does the heart bend

Answer 10

The cephalic portion of the tube bends ventrally, caudally, and to the right and the atrial (caudal) portion shifts dorsocranially

Question 11

what structures remain unbend during the bending of the heart

Answer 11

The Atrioventricular canal (AVC) between the primitive common atrium and the primitive ventricle; and the outflow tract (OFT) is continuous cranially.

Question 12

explain the structure of sinus venosus in the beginning

Answer 12

we have a body and 2 horns and each horn has
Vitelline vein: carries unoxygenated blood from the yolk sac.
Umbilical vein: carries oxygenated blood from the placenta
Common cardinal vein: carries unoxygenated blood from the body wall. It is formed by the union of anterior and posterior cardinal veins

Question 13

why does the right horn become more than the left horn

Answer 13

The development of the liver on the right side.
The presence of transverse anastomoses between the left and right cardinal veins, shifting the blood from left to right side.

Question 14

what is the fate of the body of the sinus venosus, right horn and left horn

Answer 14

The body: becomes reduced in size to form the coronary sinus.
The right horn: is enlarged and absorbed into the right atrium to form the smooth posterior part of the right atrium.
The left horn: is reduced in size to form the oblique vein of left atrium.

Question 15

what forms the septum intermedium and what does it share in the formation of

Answer 15

the dorsal and the ventral endocardial cushions form the septum intermedium

shares in the formation of interatrial septum and the membranous part of the interventricular septum

Question 16

explain the formation of the foramen ovale

Answer 16

Okay so fisrt we have the septuem intermedium then the SP with FP and then SP with FS and then the SS comes in as well and thus now we get a pathway called as the foramen ovale (remember The foramen ovale is not a simple orifice, but an oblique passage )

Question 17

what stimulates breathing in a newborn

Answer 17

according to our lecture change in the temp is one of the factors that stimulate breathing

but according to NCBI a rise in the arterial PCO2 is the reason for the initial breathing.

Question 18

the fossa ovalis is formed from _________

and the annulus ovalis is formed of _______

Answer 18

septum primum

septum secondum

Question 19

what is the development of the interventricular septum

Answer 19

it has 2 parts the muscular part and the membranous part
the muscular part is a muscular ridge that arises from the endocardium of the ventricle
and the membranous part
Dorsal & ventral atrioventricular endocardial cushions (septum intermedium).
Right and left bulbar ridges.

Question 20

what does the caudal part of the bulbus cordis form into

Answer 20

the bulbus cordis forms into the outflow track after the division by the right and the left bulbar ridges the ant part forms into infundibulum which is the outflow tract of the right ventricle and the aortic vestibule which is the outflow tract of the left ventricle.

Question 21

how does the aortic and pulmonary valve develop and how do they have the valves arranged

Answer 21

the valves develop from cushions and in the pulmonary trunk there was one anterior and 2 post but due to the 45 degree rotation the cusps in the pulmonary valve becomes one post and 2 anterior and vise versa.

Question 22

explain the spiral aortico-pulmonary septum

Answer 22

Two bulbar ridges appear in the cephalic part of the truncus arteriosus. These ridges are located on the right superior wall (right ridge) and on the left inferior wall (left bulbar ridge). The right ridge grows distally and to the left, while the left bulbar ridge grows distally and to the right.

Question 23

At the caudal part of truncus arteriosus, the spiral septum lies ______ & divides it into:
___________
At the middle part of truncus arteriosus, the spiral septum lies _________ & divides it into:
_____________
At the cranial part of truncus arteriosus, the spiral septum lies ___________& divides it into:
__________________

Answer 23

At the caudal part of truncus arteriosus, the spiral septum lies transversely & divides it into:
Anterior part (pulmonary trunk) 
Posterior part (ascending aorta)
At the middle part of truncus arteriosus, the spiral septum lies antero‑posterior & divides it into:
Left part (pulmonary trunk)
Right part (ascending aorta)
At the cranial part of truncus arteriosus, the spiral septum lies transversely & divides it into: 
Anterior part (ascending aorta)
A posterior part (pulmonary trunk)