Does anyone know any good website that explains what happens in the body when a baby takes its first breath?
If not, can someone briefly explain the main steps that take place?
Also, What was produced by Miller-Urey experiment? (wondering if proteins, lipids, and carbs were seen)
*Help will be appreciated
Cause of Breathing at Birth.
After normal delivery from a
mother who has not been depressed by anesthetics, the
child ordinarily begins to breathe within seconds and
has a normal respiratory rhythm within less than 1
minute after birth.The promptness with which the fetus
begins to breathe indicates that breathing is initiated by
sudden exposure to the exterior world, probably resulting
from (1) a slightly asphyxiated state incident to the
birth process, but also from (2) sensory impulses that
originate in the suddenly cooled skin. In an infant who
does not breathe immediately, the body becomes
progressively more hypoxic and hypercapnic, which
provides additional stimulus to the respiratory center
and usually causes breathing within an additional
minute after birth.
Closure of the Ductus Arteriosus After Birth. As soon as a
baby is born and begins to breathe, the lungs inflate;
not only do the alveoli fill with air, but also the resistance
to blood flow through the pulmonary vascular
tree decreases tremendously, allowing the pulmonary
arterial pressure to fall. Simultaneously, the aortic
pressure rises because of sudden cessation of blood
flow from the aorta through the placenta. Thus, the
pressure in the pulmonary artery falls, while that in
the aorta rises. As a result, forward blood flow through
the ductus arteriosus ceases suddenly at birth, and in
fact, blood begins to flow backward through the ductus
from the aorta into the pulmonary artery. This new
state of backward blood flow causes the ductus arteriosus
to become occluded within a few hours to a few
days in most babies, so that blood flow through the
ductus does not persist.The ductus is believed to close
because the oxygen concentration of the aortic blood
now flowing through it is about twice as high as that
of the blood flowing from the pulmonary artery into
the ductus during fetal life. The oxygen presumably
constricts the muscle in the ductus wall
