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Integrated ScienceGrades 101&2
Shifts 1 &2Lesson Topic:The Menstrual Cycle
Instructions: Read the information below and write as notes in your notebooks. Record and complete the activities that follow in your notebook as well. Send answers and questions to YOUR teacher via email.
Miss Green [email protected]
Miss Campbell [email protected]
Mrs. Smith-Morgan [email protected]
Specific Objectives: Students should be able to:
i) Give a quick overview of the changes that happen during puberty
ii) Describe the menstrual cycle
iii) Describe what happens in the ovary uterus during the menstrual cycle
iv) List the four hormones that influence the menstrual cycle.
v) State site of production of the four hormones utilized in the menstrual cycle
vi) Explain the roles of FSH, LH, oestrogen and progesterone in the menstrual cycle.
vii)Explain the terms ovulation, fertilization, implantation and menopause.
Content
The Menstrual Cycle
Menstruation is the monthly breakdown of the uterine lining, which results in a discharge of blood.
The menstrual cycle is the monthly cycle of egg production and bleeding in females, which takes place approximately every 4 weeks throughout the life of a fertile woman.
Stages in the menstrual cycle
1. Days 1-5: period- bleeding occurs as the lining of the uterus breaks down.
2. Days 5-14: uterus lining builds up again with vast number of blood vessels3. Day 14: Ovulation- egg is released4. Days 14-28: uterus wall is maintained. If no fertilization occurs, the cycle begins again
with the next period.
In the menstrual cycle there are simultaneous events occurring, as there are changes in the ovary, uterus and hormone levels of the blood.
At menopause the hormone levels drop, the ovaries and uterus shrink and the woman stops having periods.
Menstrual Cycle Hormones
Follicle stimulating hormone (FSH) – secreted by the pituitary, it causes the development of a follicle in the ovary, and causes an egg to mature and ripens. It also stimulates the ovaries to produce oestrogen.
Luteinising hormone (LH) – secreted by the pituitary, it triggers the release of the egg from the ovary (controls ovulation) and forms the corpus luteum (stimulates the ovaries to produce progesterone). Stops the production of FSH
Oestrogen – secreted by the ovarian follicles, it stimulates the uterine wall to build up in preparation for pregnancy and it controls menstruation.
Progesterone – secreted by the corpus luteum in the ovary, it maintains the thickened lining of the uterus, stimulates the growth of blood vessels in the lining to prepare for a pregnancy and it stops ovulation.
Events in the Ovary during the menstrual cycle
1. The egg cell begins to mature inside an ovarian follicle (Graafian follicle)2. The follicle secretes oestrogen.3. Oestrogen allows ovulation to occur. (Ovulation- the release of a mature egg cell (ovum)
from the ovary.4. The remainder of the follicle is the corpus luteum, which produces progesterone.5. Corpus luteum degenerates
Events in the blood concerning hormones LH, FSH, oestrogen and progesterone.
FSH- rises between days 1-5, which stimulate the growth of the follicle.
LH- peaks around days 13-14 to stimulate ovulation
Oestrogen – peaks around day 12
Progesterone- peaks around day 22
Thickness of the uterus lining
1. Breaks down days 1-5, menstruation.2. Oestrogen stimulates uterus lining to thicken3. Progesterone causes lining to remain thick4. Decrease in progesterone causes uterus lining to begin to break down- if no fertilization
(If fertilization does occur, then progesterone continues to be secreted and the uterus wall develops as the placenta).
Menopause
At menopause the hormone levels drop, the ovaries and uterus shrink and the woman stops having periods.
Worksheet
1. The diagrams below show the human female and male reproductive organs.
a. Label on the female system the VAGINA AND CERVIX. On the male system label the
TESTES, EPIDIDYMIS AND VAS DEFERENS
b. Complete the following table by writing the name and reproductive function of the
labelled structures on the diagrams above.
Name of Structure Function of structure
A
B
C
c. Structures A and B are similar in function. Explain how they are similar
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d. On the diagram, draw arrows to show the movement of sperm through the male
reproductive system from where it made to where it leaves the body.