words per minute
13
manojkumar2127224
00:00
Speed
Destruction of the endothelium and proliferation of the intima subsequently
occur, and lead to permanent closure. Diverse factors that may
promote ductal closure have been identified, and include increased
oxygen tension; increased plasma catecholamine concentrations; suppression
of prostaglandin I2 production; switching off prostaglandin E
receptors; a synergistic role of prostaglandin F2a and oxygen concentrations;
and a decrease in plasma adenosine concentration. After birth,
these interrelated events result in the closure of the ductus arteriosus.
It has been proposed that the high oxygen tension of the reversed blood
flow through the ductus initiates the synthesis of a hydroperoxy fatty
acid that suppresses prostacyclin production, thus exposing the ductus
to the contractile effects of prostaglandin endoperoxide. After closure,
the duct becomes the ligamentum arteriosum, which connects the left
pulmonary artery (near its origin) with the aortic arch.