Loading....
Coupon Accepted Successfully!

Paediatric

Open Flashcards

CVS

Question
18 out of 63
 

Anatomical closure of ductus arteriosus occurs at- (LQ)



A Birth
B 3-4 day

C 10'h day
D 30th day

Ans. C

lOth day

Circulatory adjustments at birth

o These are brought about because of a shift from placental dependance for gas exchange in the fetus to pulmonary gas exchange in neonate.

a. Pulmonary circulation

i. Immediatly after birth lungs expand due to first few breaths of neonate.

ii. This causes a fall in pulmonary vascular resistance (O2 causes pulmonary vasodilatation).

iii. This results in increased flow into pulmonary trunk and arteries.

iv. The pulmonary artery pressure falls due to lowering of pulmonary vascular resistance.

v. The pressure relations between aorta and pulmonary trunk are reversed so that the blood flow through the ductus arteriosus is reversed + Instead ,rf blood flowing from the pulmonary artery to aorta, the direction of flow through ductus, is from aorta to pulmonary trunk.

vi. Increasing oxygen sahration causes the muscte of ductus to constrict + In full term neonates the ductus arteriosus closes within 10 to 25 days.

b. System circulation and circulation through heart

i. Loss of placental circulation and clamping of the cord after birth results in increase in systemic vascular resistance.

ii. This tends to increase the aortic blood pressure and the left ventricular systolic pressure.

iii. The loss of placental circulation results in sudden reduction of flow through ductus venosus which closes off

iv. Flow through ductus yenosus disappears by the 7n day of posnatal life.

v. The loss of placental flow results in a decrease in the volume of blood returning to right atrium -+ Right atrial pressure decreases

vi. The left atrial pressure becomes higher than right atrial pressure and the septum primum rnhich ats as a valve of fossa ovalis, approximates with the septum secundnm to close off formen ovale.

vii. Functional ctrosure of foramen ovale occurs very quickly.

viii. Over a period of months, the septum primum and septum secundum become firmly adherent resulting in anatomical closure of the foramen ovale.

ix. After closure of ductus arteriosus, there is establishment of postnatal circulation : -

x. The blood reaching the right atriutn through IVC and SVC is emptied into the right ventricle from where it is pumped into pulmonary trunk.

xi. After coursing through lungs for gas exchange. it reaches the ieft atrium and ventricle.

xii. The left ventricle pumps it out for distribution in the body for oxygenation of the tissues.

xiii. The venous return again comes back to right atrium through IVC and SVC.

All of the blood leaving the right ventricle, after coursing through lungs, reaches the left ventricle -+ The two ventricles are connected in series and therefore, the output of right and left ventricles are same (in contrast to fetal circulation, where rigtrt ventricular output is more).

CVS Flashcard List

63 flashcards
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
26)
27)
28)
29)
30)
31)
32)
33)
34)
35)
36)
37)
38)
39)
40)
41)
42)
43)
44)
45)
46)
47)
48)
49)
50)
51)
52)
53)
54)
55)
56)
57)
58)
59)
60)
61)
62)
63)