THE MENSTRUAL CYCLE

Define the term eumenorrhea

the start of bleeding in the menstrual cycle, usually lasts 3-4 days

What are the stages of the female menstrual cycle in order

menstrual, follicular, ovulation, and secretory phase.

Explain the menstrual phase of the menstrual cycle

The menstrual phase refers to the beginning of the menstrual cycle. This is where the functional layer of the uterus lining sheds and bleeding occurs. In this phase the spiral artery of the endometrium go into spasms. There is necrosis of the endometrium and the breakdown of its tissue, leading to menstrual flow. Some women may experience dysmenorrhea which is pain or discomfort during menstruation.

What happens to the levels of estrogen and progesterone during the menstrual phase of the cycle.

oestrogen and progesterone levels re low during the menstrual phase due to the disintegration of the corpus luteum and the shedding of the uterine lining.

Explain the follicular phase of the menstrual cycle

The follicular phase beings after the bleeding/shedding of uterus lining. The pituitary gland releases follicle stimulating hormone (FSH) which stimulates the follicles in the ovaries to mature. This causes the egg to grow thus stimulating oestrogen release which promotes thickening of uterine lining in preparation for implatation

Describe the ovulation phase of the menstrual cycle

There is a surge of leutenising hormone (LH) which causes the release of an egg. This happens at around day 14. This causes the corpus luteum to from and release progesterone which supports uterine lining in preparation for pregnancy.

Describe the secretory phase of the menstrual cycle

During this phase, if no fertilisation occurs the corpus luteum breaks down, oestrogen and progesterone levels drop leading to a menstruation.

Where is Luteinising Hormone and Follicle Stimulating Hormone released from?

LH and FSH are both released from the anterior pituitary gland. It triggers ovulation and progesterone to be released from the corpus luteum which maintains thickness of uterus in preparation for implantation.

Describe the role of inhibin in the menstrual cycle

Inhibin is secreted by the corpus luteum and it inhibits secretion of follicle stimulating hormone (FSH). this limits maturation of more follicles.

Describe the role of oestrogen and progesterone in the menstrual cycle

Oestrogen released from ovaries stimulates development of the endometrium in first half of menstrual cycle. Progesterone maintains the thick vascular lining of the uterus in second half of the menstrual cycle

What is the NAEGELE’S rule?

It is a way to calculate gestation. It assumes pregnancy is 280 days. To calculate, add 9 months and 7 days to first day of last menstrual cycle