What Happened to 28 Days?

by

Tamar L. GouletDepartment of Biology

University of Mississippi

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A Clicker Case About the Human Menstrual Cycle

CQ#1: My knowledge of the menstrual cycle is:

A. NonexistentB. FairC. GoodD. Very goodE. Excellent

Opinion

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CQ#2: The length of a human menstrual cycle is __ days:

A. 20B. 24C. 28D. 32E. All of the above

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CQ#3: A woman has a 24-day cycle. She will ovulate on day__

A. 6B. 10C. 12D. 14E. 18

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CQ#4: The case is about Ann, who is:

A. A single mother of threeB. A high school seniorC. A married college studentD. A faculty member in the Biology DepartmentE. A waitress

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If you were Karen, what questions would you ask?

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Ann & Karen’s Conversation“So, when was the 1st day of your last period?” asked Karen.

“February 1st,” replied Ann.

“How long is your menstrual cycle?” asked Karen, her pen poised in the air.

“28 days,” Ann replied quickly.

“Is it always 28 days?” asked Karen.

“Isn’t every woman’s menstrual cycle 28 days?” asked Ann.

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CQ#5: You asked a friend about her menstrual cycle. The length of your friend’s menstrual cycle falls between ___ days.

A. 20-23B. 24-27C. 28-31D. 32 and aboveE. Other

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“Ok, let’s step back a bit. Which organs are directly involved in the menstrual cycle?” asked Karen.

List the organs that are involved.

Ann & Karen’s Conversation

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Female Reproductive Anatomy

Figure 26.4

Ovaries

Uterus

Cervix(“neck” of uterus)

Oviduct

FolliclesCorpus luteum

Wall of uterusEndometrium (lining of uterus)

Vagina

Brain - hypothalamus & anterior pituitary10

Ann & Karen’s Conversation“Are these organs physically connected?” asked Karen.

“Well, no” answered Ann incredulously. “After all, my hypothalamus is up here,” said Ann, pointing to her head, “and my ovaries are down there,” she continued as she pointed to her jeans, and then looked around consciously to see if she had been overheard.

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Ann & Karen’s Conversation“Good, good,” nodded Karen. “So, how does the hypothalamus communicate with the ovaries?”

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Hormones

• List all the hormones that are involved with the menstrual cycle.

• Specify where they are produced.

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Menstrual Cycle Hormones1. GnRH - Gonadtropin-releasing hormone.2. LH - Luteinizing hormone.3. FSH - Follicle stimulating hormone.4. Estrogen.5. Progesterone.

1 – hypothalamus.2 & 3 - anterior pituitary.4 & 5 - within ovary.

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CQ#6: How do hormones get from the anterior pituitary to the ovaries?

A. GravityB. OsmosisC. In the blood streamD. In the interstitial fluidE. Through nerve impulses

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Ann & Karen’s Conversation“Ann,” Karen asked gingerly. “Do you know what happens during a menstrual cycle?”

“Of course!” replied Ann adamantly.

Can you explain what happens?

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Hypothalamus

Anterior Pituitary

Uterus Ovary

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Hypothalamus

Anterior Pituitary

Uterus Ovary

1. FSH

a) Follicle growth

Estrogen

Thickening of lining

2. LH

a) Egg release (=ovulation) +b) Scar tissue (=corpus luteum)

Progesterone 18

CQ#7: Unless a pregnancy occurs, the corpus luteum will degenerate after ____ days.

A. 6B. 10C. 12D. 14E. 18

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CQ#8: Without the corpus luteum and progesterone, the uterine lining will:

A. Remain the same thicknessB. Increase in thicknessC. Decrease slightly in thicknessD. Shed, i.e., menstrual flow

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Ann & Karen’s Conversation“Ok, what was the first day of your last menstrual cycle?” asked Karen.

“February 2nd,” repeated Ann.

“And what was the first day of the cycle before that?” asked Karen.

“Umm, January 1st,” said Ann.

“So, how long is your personal menstrual cycle?” prodded Karen.

Ann paused to think. What was it…?22

Ann & Karen’s Conversation“So your cycle is 32 days long,” stated Karen. “Can you figure out when you ovulate?” she asked.

“I don’t feel when I ovulate,” said Ann.

“Most women do not,” stated Karen. “But, there are signs.”

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Basal body temperature changes during cycle

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CQ#9: After ovulation, for the remainder of the cycle, a woman’s basal body temperature:

A. Does not changeB. Oscillates, generating hot flashesC. Goes up slightly and stays upD. Goes down slightly and stays down

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Cycle Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45Day of week

Date

Time

99.199.098.998.898.798.698.598.498.398.298.198.097.997.897.797.697.597.497.397.297.197.096.9

CM * Intercourse Cervical Mucus textures

* CM = cervical mucus: P=period, D=dry, M=mucus, E=eggwhite Notes: (List any changes to your routine)

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Cycle Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45Day of week

Date

Time

99.199.098.998.898.798.698.598.498.398.298.198.097.997.897.797.697.597.497.397.297.197.096.9

CM * Intercourse Cervical Mucus textures

* CM = cervical mucus: P=period, D=dry, M=mucus, E=eggwhite Notes: (List any changes to your routine)

cervical secretions change throughout the cycle27

Ann & Karen’s Conversation

“I didn’t watch out for those signs!” wailed Ann.

“Even if you did not, we can still calculate when you ovulated,” said Karen.

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CQ#10: Ann has a 32-day cycle. She will ovulate on day ___.

A. 6B. 10C. 12D. 14E. 18

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Figure 3-1

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CQ#11: Within the female human body, sperm can survive up to:

A. 1 dayB. 2 daysC. 3 daysD. 4 daysE. 5 days

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Ann & Karen’s Conversation“So, I ovulated on day 18?” asked Ann.

“Yes you did,” confirmed Karen.

“Since we had sex on day 16, I have nothing to worry about,” said Ann with a sigh.

“Not necessarily,” said Karen. “A male’s sperm can stay alive in a female body for up to 5 days.”

“You have got to be kidding,” whispered Ann in an appalled voice.

“But,” Karen pointed out, “you assumed you had a 28 day cycle when in fact yours is 32. So guess what? You’re not late,” stated Karen.

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Ann & Karen - Follow UpA week later, Ann & Karen met for coffee again.

“I did not hear from you, so I assumed… Well…?” asked Karen picking up their conversation from the previous week.

“I got my period,” said Ann. “I never counted how many days were between my periods,” she admitted sheepishly. John & I are checking our options for family planning. I’m not ready yet to be a mom.”

“At least you know your own body better now,” concluded Karen. “What kind of coffee do you want today? My treat.”

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CQ#12: The length of a human menstrual cycle is __ days:

A. 20B. 24C. 28D. 32E. Any of the above

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CQ#13: A woman has a 20-day cycle. She will ovulate on day__

A. 6B. 10C. 12D. 14E. 18

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