Anatomy of the Menstrual Cycle

Study Notes

The menstrual cycle is a series of natural changes in the female reproductive system that make pregnancy possible.

The average menstrual cycle length is 28 days, but can range from 21 to 35 days.
During each cycle, an egg develops and is released from the ovaries.
The lining of the uterus (endometrium) builds up in preparation for a potential pregnancy.
If pregnancy doesn't occur, the endometrium is shed during menstruation.

Menstrual Phase: The first day of menstruation marks the beginning of this phase where the endometrium is shed through the vagina.
Follicular Phase: The hypothalamus signals the pituitary gland to release follicle-stimulating hormone (FSH), which stimulates follicle development in the ovaries. The maturing follicle releases estrogen, which thickens the uterine lining.
Ovulation Phase: Rising estrogen levels trigger the release of luteinizing hormone (LH), initiating ovulation. A mature egg is released from the ovary and travels down the fallopian tube.
Luteal Phase: The empty follicle transforms into the corpus luteum, which produces progesterone and estrogen. These hormones maintain the thickened endometrium. If pregnancy occurs, the corpus luteum continues to function. If not, it shrinks and the cycle restarts.

Dysmenorrhea is menstrual cramps that interfere with daily functioning. It happens due to uterine contractions during menstruation.
The pain typically starts before the period and subsides within a few days.

Primary Dysmenorrhea: Menstrual cramps occurring without an underlying medical condition. Pain usually starts one to two days before the period or with bleeding. It is the more common type.
Secondary Dysmenorrhea: Painful periods caused by a condition or infection in the reproductive organs. The pain usually begins earlier in the cycle and lasts longer than typical menstrual cramps. It is less common.

Excessive Prostaglandins: Hormones that cause uterine contractions during menstruation. The pain results from reduced blood supply to the endometrium during these contractions.
Psychological Factors: The mother's attitude may influence the daughter's response to pain.
Cervical Factors: Pain can worsen as menstrual tissue passes through the cervix, especially if the cervical canal is narrow.

Age: Most intense symptoms usually occur during adolescence and decrease with age.
Long Menstrual Periods
Heavy Menstrual Flow
Smoking
Positive Family History
Sedentary Lifestyle
Obesity
Alcohol Consumption