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: Hormone Levels During the Menstrual Cycle

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Lab Exercise 8.5.1: Hormone Levels During the Menstrual Cycle Analysis 1. Gonadotropic hormones regulate ovarian hormones. Study the feedback loop shown in Figure 4. Figure 4 Feedback loop showing the regulation of ovarian hormones by gonadotropic hormones. a) Identify as W, X, Y, or Z the two gonadotropic hormones represented in the diagram. W and X represent the hormones, which stimulate the follicle-stimulating hormone - FSH, and YZ represents the thickening of the corpus luteum, which is done by the luteinizing hormone, this in turn produces progesterone (Y). b) Identify the ovarian hormones shown in the diagram. The ovarian hormone released by W and X is estrogen and progesterone is released by Y and Z. c) Which two hormones exert negative feedback effects? The two hormones that exert negative feedback effects are progesterone and estrogen. ...read more.


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. ...read more.


Synthesis l) Figure 7, shows estrogen and progesterone levels during three menstrual cycles. Figure 7 i. 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. ii. 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. ...read more.

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