RECAP!
Parts of the Reproductive System
3D model of the female
reproductive system
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Identify each part with the
correct labeled terms.
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FACT OR BLUFF
A woman can
get pregnant
any time of
the month.
FACT!
FACT OR BLUFF
Your period must come every 28 days.
FACT!
FACT OR BLUFF
Exercise is good for
women having their
period.
FACT!
FACT OR BLUFF
Your period stops
when you get in the
water
BLUFF!
FACT OR BLUFF
BLUFF!
FACT OR BLUFF
BLUFF!
The Menstrual
Cycle
UNIT III: Living Things & Their Environment
At the end of the lesson, the students should be
able to:
1.describe the feedback mechanisms involved in
regulating process in the female reproductive system;
2.explain the roles of different hormones in the control
of the menstrual cycle; and
3.explain feedback mechanism and how it works in our
body.
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READ ALTOGETHER
•The menstrual cycle is complex and
controlled by many different glands and
the hormones that these glands
produce.
•The four phases of the menstrual cycle
are menstruation, the follicular
phase, ovulation and the luteal phase.
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READ ALTOGETHER
•Common menstrual problems
include heavy or painful periods and
premenstrual syndrome (PMS).
•Knowing when in the menstrual
cycle a woman is most likely to
conceive can increase the chance of
pregnancy.
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Menstruation
a sign that a girl is capable of producing offspring
The Menstrual Cycle
Main organs involved:
• Fallopian tubes
• Ovaries
• Uterus
• Cervix
• Vagina
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Functions
• Fallopian tube - transports the ova from the ovaries
to the uterus each month
• Ovaries - produce oocytes(eggs) for fertilization and
produce the reproductive hormones, estrogen and
progesterone.
• Uterus - nurtures the fertilized ovum that develops
into the fetus and holding it till the baby is mature.
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Functions
•Cervix – allows flow of menstrual blood from
the uterus into the vagina
•Vagina - receives the penis during intercourse
and also serves as a canal for menstrual fluid
and the exit of the baby.
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Menstrual Cycle Process
(overview)
• Menstruation: The period—
the shedding of the uterine
lining. Levels of estrogen
and progesterone are low.
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Menstrual Cycle Process
(overview)
• The follicular phase: The
time between the first day
of the period and ovulation.
Estrogen rises as an egg
prepares to be released.
• The proliferative phase:
After the period, the uterine
lining builds back up again.
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Menstrual Cycle Process
(overview)
• Ovulation: The release of
the egg from the ovary, midcycle. Estrogen peaks just
beforehand, and then drops
shortly afterwards.
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Menstrual Cycle Process
(overview)
• Luteal phase or Secretory
Phase: If the mature egg is
fertilized, the body will
produce Human Chorionic
Gonadotropin (HCG) that
will help keep the uterine
lining thick for the fertilized
egg to develop into an
embryo.
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Hormones… again
Yes, they are involved in menstruation
Hormones involved:
• Luteinizing Hormone (LH) - LH
stimulates estrogen and
progesterone production from
the ovary.
• Follicle-stimulating hormone
(FSH) - is produced by the
pituitary gland during the first
half of the menstrual cycle. It
stimulates development of the
maturing ovarian follicle and
controls ovum production in the
female
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Hormones involved:
• Estrogen - develops female secondary sexual
characteristics. These includes breasts, endometrium,
regulation of the menstrual cycle etc.
• Progesterone - hormone secreted by the female
reproductive system that functions mainly to
regulate the condition of the inner lining
(endometrium) of the uterus.
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Feedback mechanism in menstrual cycle
• FSH - stimulates the ovaries to release estrogen. High
levels of estrogen then prevent the further
production of FSH. (↑Estrogen, ↓FSH)
• Estrogen - stimulates the release of luteinizing
hormone (LH). Controls the production of
progesterone. High levels of progesterone inhibits
release of LH. (↑Progesterone, ↓LH)
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Feedback mechanism in menstrual cycle
• GnRH - stimulates the pituitary gland to produce
follicle stimulating hormone (FSH), the hormone
responsible for starting follicle (egg) development
• causes the level of estrogen, the primary female
hormone, to rise.
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GIVE EXAMPLES OF A FEEDBACK MECHANISM
THAT CAN BE OBSERVED IN EVERYDAY LIFE
• 2 Examples each for positive & negative feedback
mechanisms.
• Identify the variables and whether they are
increasing or decreasing.
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GIVE EXAMPLES OF A FEEDBACK MECHANISM
THAT CAN BE OBSERVED IN EVERYDAY LIFE
1.
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POSITIVE
Boiling water in a kettle
NEGATIVE
Hot summer day and Airconditioned room
Increasing: Temperature
Increasing: Temperature
Increasing: Number of bubbles
Decreasing: Thermostat level in the aircon
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What if the body produced more FSH or LH?
• ↑FSH, ↓production of good quality eggs and
embryos for fertilization.
• A common reason for this is your age. As you age,
your fertility starts to decline and fewer eggs
mature in your ovaries. The quality of the eggs that
remain is lower than during earlier years
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What if the body produced more FSH or LH?
• an abnormally high levels of LH
during nonovulatory times in
your menstrual cycle may mean
you are in menopause.
• It may also mean that you have
a pituitary disorder or
“polycystic ovary syndrome”.
Step 1
Menstrual
Phase
Step 4
Post
ovulatory
Phase
Step 2
Pre
ovulatory
phase
Step 3
Ovulation
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Check your
understanding
Let’s see what you have learned
JUMBLED WORDS:
Short quiz on hormones
involved in menstrual
cycle:
1. Which controls the production of progesterone?
2. This hormone stimulates the ovaries to release estrogen.
3. High levels of this hormone prevent further production of
FSH.
4. Estrogen stimulates the release of what hormone?
5. High levels of progesterone inhibit the further release of?
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