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Fetal circulationBy:
Asmaa mashhour eidSupervised:
Dr Aida abd-alrazk
Objective:1-summarize anatomuy cardiovascular fetus2-explian what heart rate fetus affected3-define different aspects in fetal circulation 4-explain fetal circulation intrauterine
5-explain fetal circulation extrauterine6-describ fetal hemoglobin and differs from adult 7-summary8-referans
Cardiovascular system-first systems become functional in intrauterine life-simple blood cell joined to the walls of the yolk sac progress to become a network of blood vessels and single heart tube which forms as early as the 16th of day of life
-heart beats as early as the 24th day -heart divides four chambers 6th or 7th week (two atrium and two ventricle )-heart begin to develop in the 7th week
Cont
Fetal circulation intrauterine-umbilical vein transports blood
rich in O2 and nutrients from the placenta to the fetal body
-This divides into two inside the body of the fetus
1-one branch goes to the liver2- other called ductus venosus-ductus venosus joins inferior
vena cava, which carries deoxygenated blood to the right
atrium
-As the blood from the inferior vena cava enters the right
atrium, a large proportion of it is shunted directly into the left atrium through an opening
called the foramen ovale .
-the foramen ovale helps prevent blood from moving in
the reverse direction
-The right atrium also receives deoxygenated blood from the
upper parts of the body through the superior vena cava
-enters the right ventricle and then pumped into the pulmonary
artery .
.-In the fetus the pulmonary artery is connected to the descending aorta by a blood vessel called ductus arteriosus -Most of the blood in the pulmonary artery bypasses the lungs by entering a fetal vessel the ductus arteriosus
-Because there is no point in pumping blood into the lungs most of the blood in the pulmonary artery
in shunted across the ductus arteriosus into the aorta
-This blood contains less oxygen than that pumped by the left
ventricle and supplies the lower parts of the body
-The umbilical cord also contains two umbilical arteries.
These arteries contain deoxygenated blood from the
fetus into the placenta completing the cycle.
Fetal circulation extrauterine
-after birth the umbilical cord is clamped and cut
-Inflation of the lungs reduces the resistance to blood flow through the lungs resulting in increases blood flow from the pulmonary arteries
-an increased amount of blood flows from the right atrium to
the right ventricle and into the pulmonary arteries and less
blood flows through the foramen ovale to the left atrium
-increased volume of blood returns from the lungs through
the pulmonary veins to the left atrium, which increases the
pressure in the left atrium .
-ductus arteriosus starts shrinking and functionally closes
by about 72 hours of life and anatomically closes within a few
weeks
Heart rate fetal affected:1-fetal oxygen level 2-body activity 3-circulation blood volume
Fetal hemoglobin-The concentration of hemoglobin in fetal blood is about 50 % greater than in maternal blood.
-Fetal hemoglobin is slightly different chemically and has a
greater affinity for O2 than maternal hemoglobin.
-fetal hemoglobin can carry 20-30% more O2 than maternal
hemoglobin
Difference between fetal and adult hemoglobin
* fetal hemoglobin composition (two alpha and two gamma
chains)
Cont*adult hemoglobin composition
(two alpha and beta)* hemoglobin form at birth that newborn about (17g/100 ml)
* adult hemoglobin normal level (11g/100ml)
Cont *fetal hematocrit is about 53%* adult hematocrit about 45%
Summary:- fetal circulation difference about
adult circulation- fetal circulation intrauterine
depend on mother- fetal circulation extrauterine
develop gradually - fetal hemoglobin difference adult
hemoglobin
Reference:1- Book (maternal and child health
nursing)fifth edition
(Adele pillitteri)pages (190 ,191,191)
2- internet
www.homebusinessandfamilylife.com
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