Female Reprodutive System Flashcards
(52 cards)
Why does the uterus change
Provide support for the growing fetus
Expel fetus and placenta in labour
Contract after birth to prevent maternal haemorrhage
Remodel by involution to the non pregnant Tagus within 4 eels of birth
What does the uterus grow due to
Increased calculation and fluid retention in the mayo metric M under influence of progesterone nd oestrogen an mechanical stretching
What does the uterus change to and from
Pelvic organ to abnormal organ almost reaching the border of the liver by full term
What are the layers of the uterus
Inner. Endometrium - ciliates epithelium
Middle - myometrium- thick muscle cells
Outer - perimetrium - loose connective tissue protecting uterus room friction with other organs
What does the endometrium become
Decidua
What is the process of decidualization
Cells differentiate to prepare for implantation, protect from the trophoblast and repae to provide nutrition to th blastocyst
Endometrial thickness of 8mm or more is necessary for successful implantation
What are the three layers of the myometrium
Longitudinal
Oblique
Circular
Hyperplasia - myometrium
10x increase in number of myocytes in first half of pregnancy
Hypertrophy
Increase in size of myocytes in second half of pregnancy
What does hyperplasia and hypertrophy result in
Myometrium growth during pregnancy
Uterine contractions - myometrium
High levels of progesterone in pregnancy promotes relaxation of myometrium and inhibit production of prostaglandins and oxytocin receptors (inhibits contractions)
T the end of the pregnancy, rise in oestrogen and CCRH trigger activation of xytocin receptors and prostaglandins needed for regular contractions
In established labour, oestrogen, oxytocin and prostaglandins increase the density and permeability of the gap junctions between the myometrial cells so contraction beck more coordinated and forceful.
Cessation of bleeding
In the middle oblique muscle layer, each myocytes is a figure or 8 to enable it to constrict around a blood vessel t stop bleeding post birth.
What is the perimetrium
B-road ligaments or med by the perimetrium open out to accommodate massive increase in size of uterine and ovarian blood vessels, lymphatics and nerves
Enlarge uterine nerves act as a reservoir for blood during uterine contractions
What is the ishmus
The lower uterine segment is formed from the isthmus which does not undergo such hyertrophy and becomes increasily thin and distensible. The muscle fibre are mostly transverse
Lowe segment caesarean section where the uterine in ion follows the direction of the muscle fibres - less vascular- reduce blood loss
How does the blood flow to the uterus change
There is.Ten fold increase from 2% cardia output in the non pregnant state to 17% at term
Uterine and ovarian arteries hypertrophy muscle cells increase in size) greatly in pregnancy.
The blood is redistributed within the uterus and a pregnancy progresses 80-0% goes to the placenta and the remainder is equally distributed between the myometrium and the endometrium
What is uterine vascular remodelling
Blood vessels within the uterus change significantly during pregnancy
What are arteries like pre preganancy
Spiral arteries supply bloood to the endometrium in the menstrual cycle and are narrow in diameter
What are the spiral arteries like in pregnancy
Trophoblast causes them to dilate 5-10 x and lose muscle from their walls
The arteries straighten out and increase in diameter so by 2nd trimester maternal blood pools into the intervillous space - pool of maternal blood used for gases exchange between fetus and woman.
The intervillous space will contain 400-500ml oxygen rich blood
How ones the uterus chang postnatally
Following birth, the uterus returns to its normal size, tone and position through the process of involutin
Through this process the uterus reverts back to being a pelvic organ from occupying te abdomen
At the end of the first week postnatally the uterus has lost 50% of its muscle bulk
By the end of the sixth week, the uterus should be at me pre pregnant position of anteversion nd anteflexion - normal/.
What ae the three processes that enable myometrium to return to normal thickness
Ischaemia
Autolysis
Phagocytosis
Ichaemia
Muscle of the uterus retract at te end of 3rd stage of labour to constrict blood vessels at the placental site
Resulting in haemostasis
Uterine blood supply is greatly reduced
Autolysis
Th process of removal of the redundant actin and myosin muscl fibres and cytoplasm by proteolytic and macrophages. The size of the individual myometrial cells is reduced
Phagocytosis
Removes the excess fibrous and elastic tissue
process is incomplete and some elastic tissue emails so that a uterus never quite returns to the nulliparous state
On what days do the lochia change
The superficial layers of the Dudu are shed as bleeding per vaginum with regeneration off the endometrium
Lochia
Rubra - 1-3 days
Serosa - 4-10 days
Alba - 11-21 days
