2. Body temperatures of two women were monitored during their menstrual cycles. One woman ovulated; the other did not. The results are shown in Table 4.
d) Graph the data provided on a separate piece of paper. Plot changes in temperature along the y-axis (vertical axis) and the days of the menstrual cycle along the x-axis (horizontal axis).
Graph found on the next page.
e) Assuming this menstrual cycle represents the average 28-day cycle, label the ovulation day on the graph.
Graph found on the next page.
f) Describe changes in temperature before and during ovulation.
The temperature slowly decreases before ovulation and reaches a high point at ovulation then starts to decrease again.
g) Compare body temperatures with and without a functioning corpus luteum.
The corpus luteum is essential for establishing and maintaining pregnancy and it secretes hormones that are responsible for the thickening of the endometrium. Therefore when the corpus luteum is present the temperature will rise at ovulation and then return back to normal if the egg is not fertilized. Without a corpus luteum the temperature does not rise.
3. Figure 5 shows changes in the thickness of the endometrium throughout the female menstrual cycle.
Figure 5
h) Identify the events that occur at times X and Z.
The endometrium is thickening at Z because the egg has been released and the body is preparing itself to become pregnant so that if the egg get fertilized the egg can attach itself, and if its not fertilized at point X the endometrium wall will shed and the menstrual period will begin.
i) Identify by letter the time when follicle cells produce estrogen.
The letter is W, because estrogen increases the thickening of the endometrium.
j) Identify by letter the time when the corpus luteum produces estrogen and progesterone.
The letter is Z because estrogen and small amounts of progesterone are produced after ovulation.
4. Levels of gonadotropic hormones monitored throughout the female reproductive cycle are shown in Figure 6. Levels are recorded in relative units.
Figure 6
k) How does LH affect estrogen and progesterone?
LH is highest at ovulation and affects estrogen the most at ovulation when it is most needed and in order for the negative feedback to occur so that only one egg is released, progesterone is low because its not needed till after ovulation to restart the process.
Synthesis
l) Figure 7, shows estrogen and progesterone levels during three menstrual cycles.
Figure 7
- On which day (X, Y, or Z) would ovulation occur? Explain your answer.
Ovulation would occur on day X because its right in the middle of the cycle and the estrogen levels are at their highest.
- On which day (X, Y, or Z) would you expect to find a functioning corpus luteum? Explain your answer.
I would expect to find a functioning corpus luteum on day Z because this is when LH is released to secret high amounts progesterone to restart the process.
m) Explain why only one corpus luteum may be found in the ovaries of a woman who has given birth to triplets.
Only one corpus luteum would be found in the ovaries because only one egg was released and it split. Three ovum don't have to be released, only one. It can spit into 3 separate cells and develop 3 different foetuses.