Menstrual Cycle

Menstrual Cycle Definition – series of events controlled by hormones preparing the uterus for reception of the fertilized egg cell

Menstruation (Days 1-5) – lining of uterus is discharged a. Corpus luteum dies – the uterine lining is discharged (becomes scar on ovary or corpus albicans) b. Progesterone – when corpus luteum dies, amount of this hormone decreases in quantity due to failure of egg fertilization c. Follicle-stimulating hormone – begins to increase

Follicle Stage (proliferative phase) [DAYS 6-14] a.  FSH levels continue to rise b.  Several follicles develop, only one will ovulate c.   Follicle secretes estrogen d.  Estrogen  more LH being made e.  Uterus lining thickens f.    LH peaking triggers ovulation

Corpus Luteum Stage (secretory phase) [DAYS 14-28] a.  Ruptured follicle  corpus luteum b.  Corpus luteum makes progesterone  thicker endometrium c.   High levels of progesterone inhibits FSH production

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

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

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

Animals having a menstrual cycle (humans, apes, monkeys) 6. Estrous cycle - Mammalian Females become receptive to mating a. Caused by Sex hormones b. Reabsorb endometrium layer, does not shed like humans c. Males sense the phermones D. Some animals may display bloody vaginal discharge, often mistaken for menstruation e. Typically continues until death

Birth Control Pills = High levels of progesterone (or a related hormone) trick body into thinking it is pregnant  NO OVULATION Some also thicken the mucus around the cervix to prevent sperm into the uterus as well as making it difficult to implant on the uterine wall. How do you still menstruate? 7 placebo pills a month