Obs & Gynae Flashcards
Explain the role of the Hypothalamic-Pituitary-Gonadal Axis and the roles of LH and FSH
The hypothalamus releases GnRH. GnRH stimulates the anterior pituitary to produce LH and FSH
LH and FSh stimulate the development of follicles in the ovaries. The theca granulosa cells around the follicles secrete oestrogen. Oestrogen has a negative feedback on the anterior pituitary and hypothalamus to suppress the release GnRH, LH and FSH
Explain the role of Oestrogen
It stimulates: Breast tissue development, Growth and development of the female sex organs at puberty, Blood vessel development in the uterus and development of the endometrium
Explain the role of progesterone
Prodcued by the corpus luteum after ovulation. It acts to: Thicken and maintain the endometrium, Thicken the cervical mucus, Increase the body temperature
Why do overweight children start puberty earlier
Aromatase, an enzyme foudn in adipose tissue, has an important role in making oestrogen. Therefore the more adipose tissue the higher the quantity of the enzyme that produces oestrogen.
What is the first episode of menstruation called?
Menarche
What are the five stages of puberty according to Tanner staging?
1 - Under 10 - No pubic hair, no breast development
2 - 10-11 - Light and thin pubic hair - Breast buds develop from behind areola
3 - 11-13 - Coarse and curly - Breasts begin to elevate
4 - 13-14 - Adult like but no reaching thigh - Areolar mound forms and projects
5 - Above 14 - Hair extending to medial thigh - Areolar mounds reduce, and adult breasts form
What are the two phases of the menstrual cycle
Follicular and luteal phase
Follicular - from menstruation to ovulation (at day 14)
Luteal - From day 14 to 28
What are immature ovums called
oocytes
What cells surround oocytes to from follicles
granulosa cells
What are the four keys stages in follicle development in the ovaries
Primordial follicles, Primary follicles, Secondary follicles, Antral follicles (aka Graafian follicles)
What is required for further developemnt after the secondary follicle stage
FSH
What does oestrogen do during the follicular phase of the menstrual cycle
Oestrogen has a -ve feedback effect on the pituitary gland, reducing the quantity of LH and FSH produced. It also causes the cervical mucus to become more permeable so that sperm can penetrate during ovulation
Role of LH in the follicular phase
Spikes during ovulation causing the dominant follicle to release the ovum from the ovary.
What does the corpus luteum do
It forms from the follicle once the ovum is released. It releases high levels of progesterone which maintains the endometrial lining. It also secretes a small amount of oestrogen
Role of progesterone in the luteal phase
Causes the cervical mucus to thicken and no longer penetrable
After fertilisation occurs what is secreted from the embryo
HCG from the synctiotrophblast
What does HCG do
Maintains the corpus luteum
What happens when no fertilisation occurs
The corpus luteum degenerates and stops producing oestrogen and progesterone. This causes the endometrium to break down and for menstruation to occur. Also the stromal cells of the endometrium release prostaglandins which encourage the endometrium to break down and the uterus to contract. Menstruation is on the first day of menstrual cycle
Explain the three stages of labour
First stage: From onset of labour (true contractions) until 10cm cervical dilatation
Second stage: From 10cm to delivery
Third stage: From delivery of the baby to delivery of the placenta
Role of prostaglandins
Local hormones. Play a crucial role in menstruation and labour by stimulating contraction of uterine muscles, role in ripening of the cervix before delivery
Key prostaglandin to be aware of
Prostaglandin E2 - used in pessaries to induce labour
What is a Braxton-Hicks contraction
Occasional irregular contractions of the uterus. Felt during second and third trimester. Temporary and irregular tightening or mild cramping. They don’t progress or become regular. Stay hydrated and relax
What is cervical effacement
The cervix gets thinner from back to front
What is the cervical ‘show’?
Refers to the mucus plug falling out and creating space for the baby to pass through