Physiological Changes in the Reproductive System

7/22/2019 Physiological Changes in the Reproductive System

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Physiological changes in the reproductive system

The uterus

The uterus is an essential role in pregnancy by protecting and

supporting the fetus,placenta and amniotic fluid.in 40 weeks of

pregnancy,it expands to accommodate the growing fetus and remain

relatively quiescent,at time labour it is able to contract regularly and

forcibly to expel the fetus due unique properties of contractility and

elasticity.Uterine wall consists of three muscle.

Perimetrium: is a thin layer of peritoneum that protect theuterus.During pregnancy,the peritoneal sac is greatly distorted

as the uterus enlarged and rises out of the pelvis.The increasing

tension on the broad ligament causes to become longer and

wider.The round ligament undergo considerable hypertrophy and

increase in length and diameter.spasm of the round ligaments

causing sharp groin pain when movement.

Myometrium: enlargement of the uterus duringpregnancy,involved in contraction during labour.human

myometrium is not composed of well defined circular and

longitudinal layer.Myometrium lying under the serosal

perimetrium,very thin muscle.increase in elastin will resulting

increase in elasticity to allows the uterus grow and stretch to

accommodate the growing fetus.


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DECIDUA

Can be seen as early day 23 of the normal menstrual

cycle.Decidualization prepares the uterine lining for the invading

trophblast.Decidua in the cervix and isthmus are less welldeveloped.1sttrimester,deciduas basalis approximately 5mm thick at 6

week to 1mm thick at 14 week.The gland within the deciduas provide

a nutrients,growth factor and cytokines for the fetoplacental

unit.Relaxin produced by the deciduas.The deciduas also produces

large amount of prostaglandin which enhance uterine quiescence or

initiated labour.

BLOOD SUPPLY

Uterine blood flow supplies the myometrium,endometrium and

placenta.receiving 90% of total uterine blood flow.diameter of uterine

arteries dilate to 1.5 times in noon pregnant state.The arcuate artery

supply the placental bed 10 times larger.Coiled spiral arteries of the

deciduas and myometrium marked physiological changes that disrupt

their muscular and elastic element.Increased blood volume needed

within the intervillous spaces of the placenta leding to a large pool of

blood.

The first 10-12 week blood supply into the intervillous space is

limited.The action of the invasive trophoblasts on the maternal spiral

arteries lead to very low resistance..Increase in maternal cardiac

output and decline in uterine vascular resistance.Uterine blood flow

increases during gestation approximately 50ml/min at 10 week

gestation,increasing to 200ml/min by 28 week and 750ml/min at

term.The passage of blood through the dilated uterine vesselsproduces a soft blowing sound.

CHANGES IN UTERINE SIZE


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The uterus and fruit has become a fairly reliable.

5 weeks gestation-like a small unripe pear 8week -feel like a large orange 12 week -size of grapefruit.Increase in uterine size

is limited principally to the anteroposterior diameter and the

uterus maintains its original pear shape.Physical

movement,allowing the uterus to move relatively

16 week -Fundus become dome shaped,with theascent of the uterus from pelvis.Internal os relaxes and the lower

uterine segment develops from the greatly expended and thinned

out muscular isthmus.

20 weeek -Uterine rises in the abdomen,assumes anovoid shape.Isthmus has fully develop into the lower uterine

segment and the cervical canal expands from above downwards

in wedge shapes fashion

30 week -Displacing intestines laterally andsuperiorly and continue to rise.In supine position the uterus fall

back to rest on vertebral column

36 week -Insersation of the uterine tubes and broadand round ligament is located slightly above the

middle of uterus.Decent of the fetal head into the pelvic brim.

CERVIX

The cervix becomes softer and cyanosed dur to oedema and increased

vascularity 1 month of conception.The elastin cologne ratio is greatest

at the internal os.The glands of the cervix marked hyperthrophy andhyperplasia.The cervical canal shorten from above downwards from

about 2cm long.Effacement can be compared with a funneling

process.In this formulation the weakest point of the sphere.bulges,thin

and dilate.Nitric oxide production increases in the cervix at the end of

pregnancy.


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VAGINA

Increased in vascularity and hyperaemia develop in the skin and

muscle of perineum and vulva with softening of the underlying

connective tissue.Increased volume of vaginal secretion due to hightoestrogen result in thick white discharge.Glycogen is metabolized to

lactic acid by lactobacillus acidophilus a normal commensal of the

vagina.This leads to increased vaginal acidity.

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Physiological Changes in the Reproductive System