Ovarian and Menstrual Cycles

Question 1

For successful reproduction, the ovarian cycle needs to be what?

Answer 1

has to be synchronised with the menstrual cycle

Coordination between the two is brought about by hormones

Question 2

Hormones of Ovarian and Menstrual Cycles

Answer 2

GnRH (from the hypothalamus)
FSH ( from the anterior pituitary)
LH (from the anterior pituitary)
Oestrogen     (from the ovary)
Progesterone (from the ovary)

Question 3

Ovarian Cycle

Answer 3

Series of events associated with the maturation of the ovum

Question 4

Ovulation has occurred

Answer 4

Day 14

Question 5

Process of Ovarian cycle:

Answer 5

Primary follicles develop to form secondary follicles containing a fluid filled cavity, called the antrum or the follicular cavity
-Most of the secondary follicles degenerate leaving one follicle that enlarges and matures into a Graafian Follicle
AS the follicles develops it produces oestrogen and progesterone
The follicle appears on the surface of the ovary as a blister-like bulge
The bulging follicular wall weakens, and ruptures and the immature ovum is released into the peritoneal cavity, rupture results from surge in LH (caused by peak in eostrogen)

-Ruptured follicle becomes the corpus luteum

As the follicles develops it produces osterogen and progesterone

Theca Interna is the layer, which secretes androgen, which the granulosa cells convert to oestrogen.

The cells around the oocyte (egg) secrete progesterone, which also helps to attract sperm towards the ovum once it is ovulated.

Question 6

If fertilisation occurs

Answer 6

The Corpus Luteum enlarges and produces hormones needed for the maintenance of pregnancy until the placenta develops and takes over this role
The corpus luteum can continue this activity for the first 3 months of pregnancy

Question 7

If fertilisation doesn’t occur

Answer 7

~ 12 days after ovulation, the corpus luteum begins to degenerate
Eventually, fibrous connective tissue replaces it
The remnant of this is the corpus albicans (white)
When the corpus luteum degenerates, it ceases to function, and the concentrations of oestrogen and progesterone decline rapidly

Question 8

Uterine Cycle (Menstrual):

Answer 8

Series of changes in the endometrium of the uterus. Uterine wall is made up of the endometrium and the myometrium

During the menstrual phase, the functional layer of the endometrium is decreasing in thickness

During the proliferative phase it is increasing in thickness

During the secretory phase secretory glands are developing
-First signs of bleeding signal the start of a new menstrual cycle, day 1 of 3-5 day bleeding; During this time, ovarian follicles develop and secrete increasing quantities of oestrogen
This is occurring at the same time as menstruation

Question 9

endometrium is made up

Answer 9

of the stratum functionalis and the stratum basale

Question 10

Average duration of the female reproductive cycle

Answer 10

28 days, but varies from person to person

Question 11

Oestrogen acts on the uterus

Answer 11

to stimulate regeneration and growth of the endometrium from the remnants of the last cycle, the stratum basale

• 2X to 3X increase in the thickness of the functional layer of the endometrium
• The functional layer is said to be proliferating

Question 12

First 2 weeks is what phase?

Answer 12

follicular(in the ovary – follicle developing) Proliferative phase in the uterus (the functional layer of the endometrium is growing thicker – proliferating)

Question 13

What does PROGESTERONE causes the endometrial glands to do?

Answer 13

become distended with secretory products such as glycogen:Glycogen is nutrient rich mucus
-Glycogen is a storage form of glucose( important nutrient for the developing embryo)

-Endometrial blood flow increases, and the spiral arteries increase in number and become more tightly coiled and twisted

Question 14

Second half of the cycle is referred to as the?

Answer 14

LUTEAL PHASE of the OVARY because it involves the development of the corpus luteum

or

SECRETORY PHASE of the UTERUS because the glands become distended with secretory products such as glycogen

Question 15

If implantation doesn’t take place

Answer 15

• Corpus Luteum regresses
• a rapid fall in the secretion of oestrogen and progesterone
• endometrium undergoes shrinkage
• Blood leaks from the damaged vessels - Menstrual bleeding
• Stratum functionalis sloughs off
• A second phase of vasoconstriction of the spiral arteries minimises loss of blood from the arteries