Pregnancy and parturition Flashcards
what is the purpose of the menstrual cycle?
promote growth of the lining of the womb so the lining of the womb proliferates and becomes receptive at the right time of ovulation, release of the egg to accept the egg whether or not it’s worth accepting or rejecting
what is the menstrual cycle ?
feedback system between hormone released from brain and lining of the womb so there is appropriate release of the egg. Through gonadotrophin luteinizing hormone-follicle stimulating hormone and surge in oestrogen-drives proliferation of lining for the womb.
once the egg is released what does the ovary become
corpus luteum
what hormone does the corpus luteum produce
progesterone
what happens after ovary becomes corpus luteum?
egg is released and fertilised over next few days it forms into a blastocyst-arrive in time for implantation so lining of the womb is prepared
After the blastocyst is formed where does it implant?
side of uterus and outer cell layer called syncytiotrophoblasts
what are syncytiotrophoblasts?
specialised layer of epithelial cells
function of syncytiotrophoblasts
This produces hormone called human chorionic gonadotrophin-copy of follicle stimulating hormone and luteinising hormone -tells ovary to keep producing progesterone and oestrogen for first 12 weeks
how can the womb collapse?
signal does not arrive -corpus luteum will cease, progesterone falls
what does progesterone do?
suppress mitral contractions through pregnancy
2 functions of progesterone
-essential for maintenance of pregnancy in all mammals.
-promotes formation of mucus plug in cervical canal-block the lower chamber ensuring it stays insulated from infection
what does oestrogen do?
responsible for growth of uterus, proliferation of uterine cells and increase in size and increase size of breasts
2 functions of oestrogen
making ductal structures-releasing milks once babies born
-preparing uterus, and cervix for labour by induction of pro-labour genes.
what hormone does the placenta directly make?
progesterone can be made directly in here by taking cholesterol and manufacture progesterone
how does the placenta make oestrogen?
for oestrogen it needs to take a substance which is coming from foetal adrenal cortex -produces precursor called dehydrated epi androstenedione sulphate(DHEA). It is then converted across placenta into maternal liver where it is de sulphated into DHEA which the placenta uses to make estrogen
foetal hypothalamic pituitary adrenal axis
brain is growing, adrenal is growing
what hormone does the foetal hypothalamic pituitary adrenal axis produce? (happens in feedback loop)
produce stress hormone-cortisol and drives change in body and gives important feedback and growth of baby.
stimulation of foetal pituitary releases what?
corticotrophin-which feeds back to adrenal to produce more cortisol- this is the feedback loop.
what are the 3 differences between maternal circulation and foetal circulation lead to ?
ability to exchange gases
-ability to exchange nutrients
-ability to enter into an endocrine dialogue between mother and baby- 2 organisms are connected.
what is the function of umbilical cord?
baby gets oxygen and all of its nutrients.
when would there not be gas exchange leading the baby to not breathe?
lungs when in amniotic fluid -when filled with fluid there is no gas exchange
Amniotic sac
important for creating a sterile environment
Onset of labour
is water breaking -the rupture of amniotic sac
what can cause pre term births
if amniotic sac breaks to soon
Corian
a membrane that surrounds a developing fetus in conjunction with the amnion
function of corian
exchange of blood and gases between mother and fetus and develops into the fetal aspect of the placenta
Decidua
maternal uterine tissue
function of decidua
direct connection between residual which is maternal component- stroma cells of endometrium changing throughout menstrual cycle and then underlying muscle or myometrium -direct connection of mother and baby.
Gestation
quite environment where baby is growing
Anterior pituitary
produce CRH which acts on adrenal gland to produce cortisol and DHEA this cross to maternal circulation where it’s converted into estrogen which then drives into uterus which are required to initiate onset of labour
3 ways on how is onset of labour initiated?
uterus which are required to initiate onset of labour. This is done by:
-proteins and hormone receptors in wall of uterus
-oxytocin receptors
-gap junction- connect smooth muscle cells together so electrical potentials can fire down
what increasing concentrations does the placenta start to produce?
CRH- corticotrophin releasing hormone
What 3 things does the CRH being increased in the placenta lead to?
-more cortisol produced
-more DHS produced organ preparation
-maturation of the brain
what does cortisol cause within foetal membrane and what does it produce
inflammation and prostaglandins
Prostaglandins
act upon receptors that are changing within uterus and cause contractions and inflammation to happen and start to mature cervix. This ripens -allow baby to descend into birth canal then be expelled through process of active parturition.
Parturition
expolsian of products of conception before 24 weeks
spontaneous abortion
24 weeks
term labour gestation
37-43-
post labour gestation
42 weeks and more
Phase 1-activation
feedback from estrogen drops driving changes in uterine wall which cause prostaglandin receptors, gap junctions, oxytocin receptors whilst starting to stimulate inflammatory reaction within lower pole of uterus bringing about the changes needed to go into active labour itself
Phase 2-stimulation
uterus is stimulated by oxytocin and prostaglandins -causing changes in structure and behaviour of woman
Phase 3- evolution
after baby is delivered placenta has to be delivered
placenta is size of a hand wound on side of uterus
what will happen if the placenta is not delivered?
if not closed down blood stops from coming out -obstetric haemorrhage is cause -leads to loss of blood volume in 8 minutes
what does mechanism do in phase 3
head engages into the cervix and baby turns during delivery process itself such as the anterior posterior the baby comes out through birth canal.
Alternatives of pregnancy
caesarean section if baby is breech- head is wrong way round
what happens during rapid labour?
cervix goes through dilation- where it’s completely thinned and its moved upwards + lower segment of womb-becomes passive segment and upper segment of uterus the fundus pushing and contracting to push baby down
what are 3 things rapid labour ensures?
Baby’s head can engage properly
-head needs to descend into vaginal canal and engage properly so it can be pushed out
-ripening: big inflammatory reaction in cervix massive collagen analysis -breaking down structure of cervix
what are 3 things that happens after rapid labour?
-change in external matric of foetal membranes-start to weaken -rupture then water breaks -failure of tissue integrity.
-labour is initiated by prostaglandins and inflammation down at the lower pole- baby is now large within the uterus.
Placenta previa
placenta is down at the bottom
what happens when the baby is ready to come out?
Inflammatory reaction down in lower pole of the uterus -starts to initiate cervical ripening- baby puts increasing tension and stretch on bottom lower pole of uterus.
when the baby is ready to come out uterus causes increases in oxytocin receptors and prostaglandin receptors.What does prostaglandins receptors do?
allow contractions to happen forcefully and get the baby out
if baby is ready to come out and everything is normal what does it initiate
Ferguson reflex- classic positive feedback loop
process of feedback loop- sensory receptors in the cervix function
send signals back to part of the brain called nucleus structure solitary saying uterus is lower , uterus and cervix is being stretched, causes neurones to fire and release oxytocin into general circulation
what does oxytocin do during labour?
contracts the uterus further -pushes baby in its birth canal which gives it an extra push to get it through the cervix.
anterior shoulder
function of oxytocin concentration – increase in amount of oxytocin present in the plasma of these woman- this gives baby the extra kick to come out + prevents postpartum haemorrhage.
how does oxytocin work to cause contractions?
Big increase in oxytocin receptors which are depicted and membrane in those smooth muscle cells and present in membrane of the mammary gland
what does oxytocin release during breastfeeding?
release of milk
what does oxytocin cause in uterus?
release inositol from plasma membrane via phospholipids
IP3
second messenger in smooth muscle – releases calcium into cytosol – release of calcium stimulates a further calcium influx from outside and electrical potential fires it way across uterus cause more calcium entry and calcium into cytosol.
what enzyme does calcium bind to?
calcium myosin light chain and myosin light chain kinase
calcium myosin light chain and myosin light chain kinase function
causes muscle to contract – phosphorylated the myosin heads at the same time.
In parallel pathway: stimulates rhoa kinases-inhibit myosin light chain phosphortase. Both give forceful contraction to push the baby out.
at 28-32 weeks baby’s physiology not ready for outside world babies need care from special baby uni, what 3 factors would this lead to?
increased risk of moderate severe long-term disability – breathing
-increased risk of stroke
-increased risk of gut problems
3 examples of complications of preterm delivery
-bronchopulmonary dysplasia-lungs not ready
-pneumothorax-lungs collapsed
-necrotising enterocolitis- gut is not ready for the outside the world-for example not ready to provide any kind of sustenance(food or drink which a person needs to remain healthy) or taking in even milk.
