Circulatory System at Birth

Umbilical vein constricts/prevents blood loss

Ductus arteriosus constricts blood leaving right ventricle is sent to lungs

Blood pressure in left atrium exceeds that in right atrium

Valve closes foramen ovale which fuses within atrial wall

Prevents mixing of de- and oxygenated blood

Deoxygenated blood in right ventricle is oxygenated in lungs

Replacement of foetal to adult Hb takes about 3months

Each polypeptide/globin chain is coded by a separate gene

Gene for foetal (gamma) globin is suppressed

Gene for adult (beta) globin becomes active