Menstrual CycleMenstrual Cycle

Menstrual CycleMenstrual CycleDefinitionDefinition – series of events controlled by – series of events controlled by

hormones preparing the uterus for reception hormones preparing the uterus for reception of the fertilized egg cellof the fertilized egg cell

MenstruationMenstruation (Days 1-5) – lining of (Days 1-5) – lining of uterus is dischargeduterus is discharged

a. a. Corpus luteum diesCorpus luteum dies – then lining – then lining is is dischargeddischarged

b. b. ProgesteroneProgesterone – when corpus – when corpus luteum dies, amount of this hormone luteum dies, amount of this hormone decreases in quantity due to failure decreases in quantity due to failure of egg fertilizationof egg fertilization

c. c. FollicleFollicle-stimulating hormone – -stimulating hormone – begins to begins to increaseincrease

Follicle Stage Follicle Stage (proliferative phase) (proliferative phase)

[[DAYS 6-14DAYS 6-14] ] a.a.    FSH levels continue to riseFSH levels continue to riseb.b.    Several follicles develop, Several follicles develop,

only one will ovulate only one will ovulatec.c.      Follicle secretes estrogenFollicle secretes estrogend.d.    Estrogen Estrogen more LH being made more LH being madee.e.    Uterus lining thickensUterus lining thickensf.f.        LH peaking triggers ovulation LH peaking triggers ovulation

Corpus Luteum Stage Corpus Luteum Stage (secretory phase) (secretory phase)

[[DAYS 14-28DAYS 14-28] ]

a.a.    Ruptured follicle Ruptured follicle corpus luteum corpus luteum

b.b.    Corpus luteum makes Corpus luteum makes progesterone progesterone thicker endometrium thicker endometrium

c.c.      High levels of progesterone inhibits High levels of progesterone inhibits FSH production FSH production

Menstrual CycleMenstrual Cycle

http://anatomy.iupui.edu/courses/histo_D502/D502f04/lecture.f04/Female04/cycle.jpghttp://anatomy.iupui.edu/courses/histo_D502/D502f04/lecture.f04/Female04/cycle.jpg

http://health.howstuffworks.com/humhttp://health.howstuffworks.com/human-reproduction8.htman-reproduction8.htm

During pregnancy, estrogen and During pregnancy, estrogen and progesterone levels rise dramatically progesterone levels rise dramatically (about 300x). At birth, they drop (about 300x). At birth, they drop drastically and prolactin production drastically and prolactin production increases to begin milk productionincreases to begin milk production

Animals having a menstrual cycle Animals having a menstrual cycle (humans, apes, monkeys)(humans, apes, monkeys)

6. 6. Estrous cycleEstrous cycle

a. Females become receptive to a. Females become receptive to matingmating

b. Sex hormonesb. Sex hormones

c. Males sensec. Males sense

d. Eggsd. Eggs

Birth Control Pills = Birth Control Pills = High levels of progesterone High levels of progesterone (or a related hormone) trick body into (or a related hormone) trick body into thinking it is pregnantthinking it is pregnant NO OVULATION NO OVULATION

Some also thicken the mucus around Some also thicken the mucus around the cervix to prevent sperm into the the cervix to prevent sperm into the uterus as well as making it difficult to uterus as well as making it difficult to implant on the uterine wall.implant on the uterine wall.

How do you still menstruate?How do you still menstruate? 7 placebo pills a month7 placebo pills a month