FETAL CIRCULATION

 

⦁ Source of oxygenated Blood  - Placenta  ( not lungs )

⦁ Oxygenated blood forms the placenta comes to the the fetus through the umbilical vein. Which joins the left branch of the portal vein.

⦁ A small portion  of this blood passes through the substance of the liver  to inferior vena cava ( IVC) but but the greater part passes directly to the IVC through the ductus venosus.

⦁ The  IVC carries the oxygen rich blood from the liver to the right atrium .

⦁ Mastly blood form right atrium goes in to left atrium through foramen ovale,But remaining blood goes to right ventricle.

⦁ From right ventricle to pulmonary trunk.

⦁ From p. trunk , mastly blood goes  to the left atrium through ductus arteriosus and the remaining goes to the lungs

⦁ Much of the blood of the aorta is carries to the umbilical arteries to the placenta where it is again oxygenated and reurened to the heart.

⦁ Oxygen satration of umbilical vein blood – 80%

And o2 saturation arterial blood -50-60%

Mean cardiac ,out put in fetus  - 350ml/ kg/ m

                   Vessel                                                             Remnant 

⦁ Umbilical artery                                                   Mediacl Umbilical

                                Ligament

Closes soon after birth                                                         or 

                                                                                 Lateral umbilical ligament 

⦁ Umbilical vein                           -----                     ligamentum teres of the liver 

Dasure                                                                ( Round ligament of liver )

⦁ Ductus venosus                        ----                     ligamentum venosum

⦁ Ductus arterious                      -----                    ligamentum of arteriosum

Mean cardiac out put             -----                     1 -2 after birth 500ml/ minute

Heart rate ------                                                140 beats /minute, 

                                                                                 120-160 b/ minute

CLOSUSE OF OPENINGS -:

Foramen ovale -: functional closuse soon after birth but anatomical closuse in about 1 yrs.

Ductus arterosus -: functional closuse soon after the establishment  of pulmonary circulation, but anatomical about 1-3 months. 

Embryo develops separate fetal circulation afterf 16 dayof fertilization after 21 days fetal heart start beating.

            Umbilical vein

Fetal umbilical & branches

                                                Liver 

⦁ One large branch                    (b) one small branch 

⦁ Large branch ( vein to vein by pass ) – called 1st by pass ,large branch--- by pass ---liver ---enter --- IVC --- RT atrium --- small branch --- unit of c  partal vein --- liver --- hepatic vein--- IVC .

⦁ 75% blood in RT atrium goes to LA. atrium through foramen oval this is called 2ed by pass. 

                                        LT.atrium --- LT. ventrical 

⦁ Caronary aryeries

⦁ Aorta

⦁ Head neck & supper extrimities

⦁ 25%  blood in  RT. Atrium mixes with blood form SVC &  brain ,head,nack &upper extrmite – RT.ventricle --- pul. Artery –lungs –pulmonary vein .

⦁ Large part is stunted to desconding aorta by ductus asteriosus      ( this is 3rd by pass ) – it connect pulmonary artery with desending aorta --- 60 % --

Ab. Aorta

                         (a) main organs                                   (b) legs 

Abd. Aorta

2 hypogastric arteies           (b) 2 internal illisc arteries 

                                               Runs to umbilical enter

                                                        cord 

     Carry  umblical arteries blood to placenta for puritfication (a 2 umbilical arteries )