Page 74 - كتاب تمريض نسا الاكتروني

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Functions of placenta

1-Nutritive: nutrients (glucose, amino acids and vitamins) are transmitted from the

maternal to fetal blood by active diffusion.

2-Respiratory: placenta acts as fetal lung. o2 and co2 pass by simple diffusion.

3-Excretory: placenta acts as fetal kidney excreting waste products as urea into

maternal blood.

4-Hormonal: the placenta secretes many hormones HCG, HPL, Estrogen, Progesterone,

Relaxing.

5-Hemopoietic: it forms fetal hemoglobin

6-Barrier action: placenta prevents passage of undesirable substances such as some

toxins and organisms

• The term embryo is used during the first 8 weeks of development. It is important to

know the events that occur in the beginnings of life, when all the blueprints of the

human body are laid down in the embryo. The embryonic period is followed by the

fetal period (months 3-9) when there is extensive growth and differentiation and

when the embryo acquires a more human form

 The Zygote—Month 1

• Fertilized egg reaches the uterus and attaches itself to the uterus.

• Cell multiplication begins.

• Internal organs and circulatory system begins to form.

• Cell Division takes place and at the end of two weeks the zygote is the size of a

pinhead

• Heart begins to beat

• Small bumps show the beginnings of arms and legs

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