How the Body Works: Circulatory Changes at Birth

Circulatory Changes at Birth

During pregnancy oxygen reaches the fetus from the placenta via the umbilical vein. The fetal lungs are collapsed and inactive. Most of the oxygenated blood passes through the liver, but some flows through the ductus venosus into the general circulation. In the heart, most of the blood short-circuits the right ventricle via a hole, the foramen ovale, between the right atrium and the lift atrium. Of the blood which does reach the right ventricle, about two-thirds passes from the pulmonary artery through a special vessel called the ductus arteriosus into the aorta, and the remainder passes through the lungs. At birth the placental circulation is cut off and the carbon dioxide concentration in the baby's blood stimulates respiratory nerve cells in the brain stem to induce breathing and lung expansion. The foramen ovale, the ductus venosus and the ductus arteriosus close immediately after birth and the circulatory system becomes an independent functioning unit.

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Howto & Style

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• Circulatory
• Changes
• at
• Birth

[mojojojo928]

Is it me, or did the narrator sound like the archetype for HAL's voice?

Great schematic, much easier to absorb...

[smileofthecentury]

pretty good chum, just wish it could've gone on a bit longer to explain why - how when the lungs expand vascular resistance decreases and the pressure transmitted to the right atrium becomes much less - leading to the closure of the foramen ovale.

Then how the increased oxygen supply causes closure of the ductus arteriosus (because it decreases prostaglandin levels, if you must know :P).

was finding it a bit challenging so i had to do a bit of reading - this clarified things quite a bit,thanks!

[glitterglamour123]

simply explained and fun in understanding, thanks for the video

[Rigelcentauri58]

Very practical, congratulations!

(pay no attention to the envious)

[hipovonik]

great video help t me a lot.

Thank´s.

[skanky19]

concise and easy to understand. thanks

[gembieminx]

very concise explanation...thanks! ;o)

[bjballer3]

nice job steven!

[0trangie0]

Short and simple. I like this presentation. :) Thanks for posting! :D

[knightrydr1964]

ummmm?? Not much to do but laugh....Followed by a yawn.......and another laugh. LMAO!! Maybe you should post a vid on the facts of life.... Like the birds and the bees man.