name ________
The Human Menstrual Cycle
Pre-Lab Discussion
The menstrual cycle is the hormone-controlled reproductive cycle of human females. It involves the periodic development and release of an egg and the periodic shedding of the uterine lining. The menstrual cycle involves interactions of the hypothalamus, pituitary, ovary, and uterus. The cycle usually occur between puberty and menopause. The cycle may be interrupted by pregnancy, illness, or other factors. The menstrual cycle is about 28 days long, but it varies from one female to another.
Each egg produced by the female matures inside a follicle, or egg sac, near the surface of the ovary. When the egg is fully mature, the follicle bursts an the egg is released into a fallopian tube, which leads to the uterus( day 13-14). An unfertilized egg will pass from the female body within a short time. If this occurs, the lining of the uterus, which has been prepared for the implantation of a fertilized egg, deteriorates and also passes out of the body. The process by which blood and uterine cells are shed through the vagina is called menstruation. Menstruation is one(first) phase of the four-phase menstrual cycle
In this investigation, you will examine the changes that occur during the different phases of the menstrual cycle.
Problem
What changes occur within the body of a human female during the menstrual cycle?
Materials (per student)
Metric ruler Colored pencils
Procedure
Follicular Phase (days 1-14)
1. Many egg cells are located within the ovary of a human female. Each egg is contained within a structure called a follicle. Under the influence of follicle-stimulating hormone, or FSH, the
follicle matures within the ovary. The amount of FSH is the bloodstream influences the growth and development of the maturing follicle. Figure 1 shows the various stages of a follicle's
maturation. Notice that an immature follicle is much smaller than a mature follicle. Note what happens to the egg as LH increases?
2. Figure 2 (table 2) shows the concentration of FSH and LH in the bloodstream of an average human female throughout the 28-day menstrual cycle. On graph prepare a line graph of the data in Figure 2 Follicle maturation only lasts about 14 days.
The actual units used to measure FSH levels in the blood are called milli-international units/milliliter of blood. This is Figure #2-table2 :-put on first graph.
days LH FSH days LH FSH
1 9 9 15 30 13
2 12 11 16 14 8
3 16 13 17 10 8
4 18 14 18 9 8
5 19 15 19 7 8
6 16 14 20 5 7
7 12 14 21 3 7
8 19 15 22 3 6
9 15 13 23 2 5
10 16 15 24 2 5
11 20 16 25 3 5
12 30 30 26 4 6
13 75 35 27 4 7
14 58 20 28 4 8
15 30 13 29 9 9
3.
Answer questions 1 through 4 –last page!!!.
Part B. The Luteal Phase (the second half- days 15-28)
4.
Once a follicle is mature, it bursts open and the egg is released (due to
FSH). This process is called ovulation. The egg passes into the Fallopian tube
where it may or my not be fertilized. Once the mature follicle loses its egg, it
forms a body within the ovary called the corpus luteum. Figure 3 shows the
changes that occur within the corpus luteum
during the menstrual cycle
(corpus luteum
lasts about 10 days
). After maturation, the
corpus luteum begins to break apart (day 24)
and disappear. During this time, the corpus
luteum is producing progesterone. The
5. Figure 2/Table 1 shows the concentration of LH in the bloodstream of an average human female during the 28-day menstrual cycle. On a Graph ,
prepare a line graph of the data shown in Figure 2. Corpus luteum maturation occurs during day 15-24.
Estrogen
is measured in picograms/milliliter of blood. Progesterone is measured in nanograms/milliliter of blood. The actual units used to measure LH levels in the blood are called milli-internationalunits/milliliter of blood. This is figure #4.
days Progesterone Estrogen days Progesterone Estrogen
1 6 20 15 23 180
2 8 20 16 37 150
3 10 25 17 48 120
4 10 25 18 68 100
5 10 30 19 90 50
6 10 80 20 102 30
7 12 130 21 104 25
8 12 140 22 101 25
9 13 180 23 95 25
10 15 200 24 72 25
11 15 220 25 40 30
12 16 230 26 30 30
13 18 220 27 20 25
14 20 200 28 18 25
29 6 20
6.
Answer questions 5 through 10
Part C. Uterine Changes During the Menstrual Cycle
7.
As the follicle and luteal phases of the menstrual cycle occur, a series of
changes occurs in the uterus. Through rapid cell division, the lining of the
uterine walls becomes very thick. At one point in the menstrual cycle
(around day 27-28), the uterus lining ceases to thicken and begins to break
apart. This loss of the uterine lining through the vagina is called
8. Two hormones that are responsible for the building up of the uterine lining are estrogen and
LH and FSH-from Figure 2-table 2
Name______________________
The Human Menstrual Cycle Questions
1. Between days 1and 14 of the menstrual cycle, what happens to the amount of FSH produced by the body of an average human female?
And what part is it acting on?
2. During which days of the menstrual cycle is the level of FSH at its lowest in the bloodstream?
3. About how long is the follicle phase of the menstrual cycle?
4. On which day of the menstrual cycle is the production of LH the greatest?
5. What event occurs immediately after this increased production of LH? (think part/picture)
6. What happens to the corpus luteum during days 15 through 24 of the menstrual cycle? And why is this significant or important?
7. What is happening to the corpus luteum around days 24-28
8. What happens to the amount of estrogen produced by the body during days 6 to 12 of the menstrual cycle?
9. What happens to the amount of progesterone produced by the body during days 13 to 23 of the menstrual cycle?
Why is this hormone needed?
10.During which days of the menstrual cycle are the levels of both estrogen and progesterone at their lowest?
What event is occurring at this time?
Analysis and Conclusions
11.How is the name follicle-stimulating hormone appropriate for its function?
12.How is the name luteinizing hormone appropriate for its function?
13.Based on your observations, do you think estrogen and progesterone both cause similar changes in the uterus? Explain your answer.
14.What events occur during the follicle phase of the menstrual cycle?
