Fetal circulation By: Asmaa mashhour eid Supervised: Dr Aida abd-alrazk

Objective: 1-summarize anatomuy cardiovascular fetus 2-explian what heart rate fetus affected 3-define different aspects in fetal circulation 4-explain fetal circulation intrauterine

5-explain fetal circulation extrauterine 6-describ fetal hemoglobin and differs from adult 7-summary 8-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 16 th of day of life

-heart beats as early as the 24 th day -heart divides four chambers 6 th or 7 th week (two atrium and two ventricle ) -heart begin to develop in the 7 th 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 liver 2- 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 % 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 m