Detailed Analysis of Fetal Circulation, Structures, and Functions

This assignment solution provides a comprehensive overview of fetal circulation, detailing both feto-placental and materno-placental circulations. It explains the exchange of oxygenated and deoxygenated blood between the fetus and the mother, highlighting the roles of the umbilical cord, arteries, and vein, as well as the intricate arteriocapillary venous system in the chorionic villi. The solution traces the flow of blood in fetal circulation, from the placenta to the fetus, through the heart, and back to the placenta, and explains the functions of the foramen ovale and ductus arteriosus. The foramen ovale, located in the septum, allows blood flow between the atria before birth, while the ductus arteriosus shunts blood from the pulmonary artery to the aorta, bypassing the lungs. The assignment references key embryology and birth defects texts, providing a solid understanding of these crucial aspects of fetal development.

Assignment 2: Fetal Circulation
1. Describe the feto – placental and matern
(Before we are born essenti
A. Feto-placental Circulation: The feto-placental circulation refers to the exchange
oxygenated and deoxygenatedblood of the fetus. the fetus is connected to
via the umbilical cord which contains the umbilical arteries and the
umbilical vein carriesoxygenated blood to the fetus, whereas the umbilical
carry the deoxygenatedblood from the fetus to the placenta. As the um
and vein pass through the umbilical cord they form many branched ves
with the chorionic plate. After, the vessels form a complicated arteriocap
system in the chorionic villi located in the intervillous space. Th
exchange of blood takes place. The maternal and fetal blood do not mi
the vessel system in the chorionic villi, there is large surface are
of gaseous and metabolic nutrients via the capillaries.
B. Meterno-placental Circulation: refers to the transfer of oxygenated and
deoxygenatedblood from the mother via the placenta to and from the
oxygenated blood enters the intervillous space via the spiral arteries (endomet
artery) embedded in the decidua basali. The decidua basali contains
80-100 spiral arteries. It enters at a high pressure which causes the
blood in the intervillous space produced by the fetus to enter into the
via the endometrial veins. The oxygenated blood diffuses the gases and me
items into the villi, and ultimately reaches the fetus via the umbilical

2. Trace the >low of blood in the fetal circulation, and state the functio
ovale and ductus arteriosus. (pg 197-200, 215-216, 219)
a. Fetal Circulation:
i. oxygenated blood from placenta via umbilical vein to fetus
ii. 1/2 blood to IVC via ductus venosus in lives and other half to IVC
sinusoids of liver (short period)
iii. right atrium of the heart
iv. most blood enters the left atrium as the blood passes through the inferior
septum secundum (crista dividens), through the oval foramen
v. Blood from left atrium to left ventricle then out the ascending aorta sup
oxygenated blood to the heart, head, neck, and upper limbs
vi. Blood from right atrium Plows to right ventricle then leaves the heart via the
trunk
vii. It then passes through the ductus arteriosus into the aorta where it the
fetus via the umbilical arteries to the placenta

b. Foramen Ovale: is an incomplete barrier that is formed betwee
Has 2 speciPic functions:
i. Before birth: it allows for the passage of oxygenated blood from the IVC
atrium into the left atrium. Also prevents the back-Plow of blood in
direction
ii. After birth: closes due to high pressure from the left atrium and eventually
the foramen secundum creating the oval fossa.
c.DuctusArteriosus: is a blood vessel that contains the main pulmonary a
is located proximal to the descending aortic arch. 2 functions:
i. Before birth: allows for the passage of blood from the right ventricle byp
nonfunctioning Pluid-Pilled lungs.
ii. After birth: the ductus arteriosus closes and turns into ligamentum arteriosum. Oxy
plays a major role in the closure of this blood vessel. Failure to
in a condition called patent ductus arteriosus. Occursat the 12th postnatal

3. Explain wherethe foramen ovale and ductus arteriosus are located
their purpose. (pg 219)
a. Formen Ovale: is located in the septum and acts as a wal
heart. It exists as a small oval hole. Before it closes after birth’ before birt
shunt that allows for the Plow of blood from the right atrium into the left
opening is located in the passageway that contains the septum
ostiumsecundum.
b. Ductus arteriosus: is located proximal to the descending aorta con
pulmonary trunk. It acts as the second shunt in the growing fetu
allows blood to travel from the right ventricle bypassing the non-functioning
eventually supplying oxygenated blood to the rest of the fetus.

References
Blausen. (2018). Fetal Circulation: Foramen Ovale and Ductus Arteriosus. [online
Available at: https://blausen.com/en/video/fetal-circulation-foramen-ovale-and-
ductus-arteriosus/ [Accessed 10 Jan. 2018].
Moore.L, Persaud. TVN & Torchia. M. Before we are Born: Essentials o
and Birth Defects. 8th edition. Elsevier Publishing. 2013. Pg 74-75, 197-200
215-216, 219 .