Female Reproductive System Flashcards
What is the uterus?
The uterus is a hollow, pear-shaped organ responsible for various functions, such as gestation (pregnancy), menstruation, and labour and delivery.
What is the endometrium?
The endometrium is made up of two layers: The first layer, the stratum basalis, attaches to the layer of smooth muscle tissue of the uterus called the myometrium.
The second layer changes in response to the monthly flux of hormones that guide the menstrual cycle. For this reason, it’s called the stratum functionalis, or functional layer.
What are the fallopian tubes?
The primary function of the uterine tubes is to transport sperm toward the egg, which is released by the ovary, and to then allow passage of the fertilized egg back to the uterus for implantation
What are ovaries?
The ovaries arepaired, oval organs attached to theposterior surface of the broad ligamentof the uterus
The main functions of the ovaries are:
To produceoocytes(eggs) in preparation for fertilisation.
To produce the hormonesoestrogenandprogesterone, in response to pituitary gonadotrophins (LH and FSH).
What is the Menstruation Cycle?
ThehypothalamussecretesGnRH.
GnRHtravels down to the anteriorpituitary glandand bindsto receptors on thegland.
This promotes the release ofLH(luteinizing hormone) andFSH(follicle-stimulating hormone).
LHandFSHtravel in the bloodstream to theovaries.
WhenLHandFSHbind to theovariestheystimulatethe production ofoestrogenandinhibin:
FSH stimulates the development of ovarian follicles, with the follicle most sensitive to FSH becoming the dominant Graafian follicle
LH causes the Graafian follicle to change into the corpus luteum, which begins to produce progesterone
Progesterone stimulates the endometrium to become receptive to the implantation of a fertilised ovum
Increasing levels ofoestrogen,progesteroneandinhibinhave anegative feedbackeffect on thepituitaryandhypothalamus.
This leads to thedecreased productionofGnRH,LHandFSH.
This, in turn, results indecreased productionofoestrogenandinhibin.
If a woman becomes pregnant, GnRH, FSH and LH remain inhibited, causing menstruation to cease.
Phases of the Menstruation cycle: Proliferative phase
Phases of the uterine cycle
The uterine cycle hasthreephasesknown as theproliferative,secretoryandmenstrualphases.
Proliferative phase
During the proliferative phase, the endometrium is exposed toincreasing levels of oestrogenas a result of FSH and LH stimulating its production.
Phases of the Menstruation cycle: Secretory phase
The secretory phase beginsonce ovulation hasoccurred.
This phase is driven byprogesteroneproduced by thecorpus luteumand results in the secretion of varioussubstancesby theendometrial glands, making the uterus a morewelcoming environmentfor anembryo to implant.
Phases of the Menstruation Cycle: Menstrual phase
At theend of the luteal phase, thecorpusluteumdegenerates(if no implantation occurs).
The loss of the corpus luteum results indecreased progesterone production.
loss of blood supplycauses the functional endometrium to becomeischemicandnecrotic.
As a result, the functional endometrium shedsand exits through the vagina asmenstruation.
Key Points to Consider
The Uterus and Ovaries are complex organs, which are sensitive to hormone changes.
The uterus’s primary function is to carry a gestation.
Implantation of the embryo occurs within the endometrium, which is reliant on oestrogen to thicken it in preparation.
FSH stimulates the ovaries to produce oestrogen, the antral follicle most susceptible to FSH and will mature to produce a dominant follicle.
LH surges and the dominant follicle matures to produce an egg, what is left of the follicle becomes a corpus luteum.
Corpus luteum produces progesterone which maintains the pregnancy
Fertility can be impacted by both structural abnormalities and hormonal imbalances.
