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