Flashcards in Menstruation Deck (26)
What are the two processes that make up the menstrual cycle?
the development of the egg and the development of the endometrium
What coordinates the two processes?
What is the goal of the cycle?
To develop an egg and to prepare for pregnancy
What are the three cycles?
Ovarian, Endometrial and Hormonal
What does menarche mean?
The first period a girl gets
When does the development of an egg starts?
During the fetal stage when a branch of stem cells will specialise and become primary oocytes.
How many chromosomes do primary oocytes have?
What process do the primary oocytes have to go through to become a mature egg?
The double division of meiosis
How long will the double division take?
What will the primary oocyte do before finishing the first division?
It will freeze. At birth a baby girl is born with all of her potential eggs frozen in this state. They will remain like this for years?
What happens at the menarche?
The hypothalamus will start releasing GnRh that will start the menstrual cycle, making the first division continue and complete, generating a secondary oocyte.
When is the egg finally mature?
At the point of fertilisation. The mature egg is also called the ovum
What is the process of maturation?
It is what happens to a single cell inside the ovary. This small cell develops inside a ball of cells called a follicle
What part is released during ovulation?
The inside while the follicle will remain in the ovary
How long does the maturation of the follicle take?
Around 3 months
How many follicles start the maturation process?
Several but only one will fully develop into a mature egg in response to hormonal changes
What happens in the first stage of the ovarian cycle?
Activated by the hypothalamus, the pituitary gland starts the cycle by releasing a hormone called FSH. This stimulates the follicle to grow.
What is the second stage of ovulation?
Once the follicles have developed enough they start producing more and more oestrogen which signals they are ready for ovulation. FSH is no longer needed and the levels start to fall.
What happens 12 hours after the peak of oestrogen?
The pituitary gland sends the order of ovulation by releasing a big peak of LH.
What happens after 24 hours?
Ovulation will happen and the levels of LH will fall. The oocyte will start its travel through the uterine tube, while the follicle will remain in the ovary, maintaining oestrogen to stimulate the growth of the endometrium to prepare for implantation.
What is stage 5 of the ovulation cycle?
It is now transformed into the corpus luteum. This corpus luteum starts producing progesterone to maintain the endometrium and protect the fertilised egg until it's able to produce its own hormones in the primitive placenta.
What happens if there is not pregnancy?
The corpus luteum will degenerate in corpus albicums (white body), and the levels of oestrogen and progesterone will fall, finishing the cycle and signalling the pituitary gland to start the next cycle again with FSH.
What happens during mensturation?
The levels of oestrogen and progesterone have fallen which leads to menstrual bleeding.
What happens in the proliferative phase?
When the endometrium grows. The endometrium remains at its basal level until the oestrogen level starts to grow again with the follicle development.
What happens if there is a pregnancy?
The corpus luteum continues developing, progesterone levels are maintained and develop the endometrium further to nourish and develop the future placenta. the blastocyte releases human chorionic gonadotrophic (hcG) which stimulates the continuation of progesterone production.