How to Draw the Diagram for Structure of Placenta Step by Step | Reproduction in Humans
115Ins this video I'm going to draw the Structure of Placenta Step by Step
This Video is a Tutorial Video to draw the Diagram for Structure of Placenta easily and Step by Step
More info :
It is a flattened, discoidal organ in the
uterus of a pregnant woman. The placenta is a
temporary structural and functional connection
between foetal and maternal circulation.
The placenta facilitate the supply of oxygen
and nutrients and also for removal of carbon
dioxide and excretory wastes produced by the
foetus. The placenta is attached to the wall of
the uterus and to the babyβs umbilical cord.
Placenta is the only organ, which is formed
of tissues from two different individuals- the
mother and the foetus. Part of the placenta
contributed by the foetus is called the foetal
placenta and it is the chorionic villi. The other rise in estrogen- progesterone ratio, increase in
oxytocin receptors in uterine muscles, .
They cause vigorous contractions of
myometrium of uterus at the end of pregnancy.
The fully developed foetus gives signals
for the uterine contractions by secreting
Adrenocorticotropic Hormone (ACTH) from
pituitary and corticosteroids from adrenal
gland. This triggers release of oxytocin from
motherβs pituitary gland, which acts on uterine
muscles of mother and causes vigourous uterine
contractions. This leads to expulsion of the
baby from the uterus. It involves the following
three steps :
1. Dilation stage : Uterine contractions begin
from top, forcing the baby towards the cervix.
Contractions are accompanied by pain caused
by compression of blood vessels. Oxytocin
induced uterine contractions become stronger
and stronger due to stimulatory reflex. As the
baby is pushed down in the uterus, its head
comes to lie against cervix. Cervix gets dilated.
The vagina also shows similar dilation.
This stage of labour can normally last upto
few hours. It ends in rupturing of amniotic
membrane of foetus.
part which is rich in blood supply shared by
the mother. It is a part of uterine wall, termed
as maternal placenta. So human placenta is
called haemochorial.
The umbilical cord is formed of three blood
vessels. Of these three blood vessels, two are
small arteries which carry blood towards the
placenta and one is a large vein which returns
blood to the foetus.
The placenta also acts as an endocrine
tissue and produces hormones like hCG,
progesterone, estrogen while relaxin is secreted
by the ovary in the later phase of pregnancy.
Level of hCG increases upto the end of first
trimester and then it declines. By the end of first
trimester progesterone is produced by placenta.
These hormones are required for foetal growth
and maintenance of pregnancy.
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