The Human Menstrual Cycle! Consists of 3 distinct phases The cycle is typically 28 days It is not always 28 days for all women all the time For.

The Human Menstrual Cycle!

Consists of 3 distinct phases The cycle is typically 28 days It is not always 28 days for all women all the time For example Athletics/stress/malnutrition may

cause a cycle to STOP Or some women may based on stress/age/

health have longer or shorter cycles

I – Menstrual Phase:

Occurs between Day 28/1 to Day 3-4

Most hormones are low (FSH, LH, Progesterone & Estrogen), but Oxytocin is HIGH.

The endometrium lining breaks down to be SHED 1st day of bleeding is the 1st day of the NEW CYCLE 2-8 day loss period, where 20-80ml of blood is SHED

II – Follicular Phase:

Named for the developing FOLLICLE (Day 4-14) Release of FSH & LH increases The ovary is stimulated to release ESTROGEN ENDOMETRIUM thickens to support the

IMPLANTATION of the ZYGOTE! Ovulation occurs at the peak of FSH & LH release

(Day 14) Body temperature increases at the time of ovulation Fertility remains high for 3-5 days!

III – Luteal Phase:

Named for the CORPUS LUTEUM (forms after Ovulation) (Day 14-25)

The envelop of the Follicle becomes the CORPUS LUTEUM

Corpus Luteum produces PROGESTERONEa)   maintains the endometriumb)   –ve feedback to APG to stop FSH release

Why is this important?

III – Luteal Phase…

Corpus Luteum maintains progesterone throughout pregnancy or until Day 25 if no fertilization has occurred!

PLACENTA eventually takes over PROGESTERONE production to maintain the PREGNANCY! see green line above, it

may continue for 9 months!

A simple view of Pro & Estro & Endometrium

See your handout &

write

Note the peaks of

each hormone & when they

occur!

How Menstrual Feedback works!

*** write on your handout***

Hypothalamus contains the chemoreceptors that respond to increasing Progesterone & Estrogen levels (Pro & Estro)

As Pro & Estro increase the hypothalamus stops release of GnRH (Gonadotropin Releasing Hormone Puberty initiator)

As GnRH decreases the APG ceases FSH & LH release RU Ready!

How Menstrual Feedback works…

After Day 14 no more eggs will be stimulated to grow! WHY?

This is the basis of the PILL mimic an existing –ve feedback system by introducing Pro & Estro during the Follicular Phase!

Pill is also medicinal regulate cycles, treats menstrual disorders (like endometriosis) etc

Our Catholic Faith calls for us to examine our reasons for this artificial treatment to the body & the decisions we make!

It is not meant to cheat our biological nature & abdicate our responsibilities for the creation of life!

See your handout & write

Note the targets of estrogen & progesterone!

Also note the event before & after ovulation!

What Now!

Menstrual Cycle Review Worksheet 1, 4, & 5

STS assignments on CLONING

Dolly the 1st mammal clone A sheep

Now Pigs for various reasons

What next Humans for various reasons!