Women's: Menstrual Cycle

Lutenizing Hormone (LH)

Causes final maturation of follicles & lutenization of ruptured follicle.

Estrogen

From ovaries. Causes growth of endometrium & maturation of follicle. Most prevalent during follicular phase.

Prostaglandins

Produced by endometrium and most other cells of body. Frees ovum from graafian follicle. Large quantities can be found in menstrual blood.

Gonadotropin-releasing hormone (GnRH)

Promotes secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). GnRH is constantly released & is high during luteal phase as it causes release of LH.

Follicle-stimulating hormone (FSH)

Responsible for maturation of a follicle. Highest during follicular phase (shedding of lining).

hypthalamus

Secretes GnRH to anterior pituitary

Follicular Phase

The first phase of the ovarian cycle during which a follicle (an oocyte and its surrounding cells) enlarges and matures. This phase is under the control of FSH from the anterior pituitary, and typically lasts from day 1 to day 14 of the menstrual cycle. The follicle secretes estrogen during this time period. -Day 1 through ovulation -Initiated by the hypothalamus -Follicles grow & form a mature egg -Anterior Pituitary gland releases FSH (follicle-stimulating hormone) which stimulates ovary to produces 5-20 immature follicles. -Anterior Pituitary releases a surge of LH (luteinizing hormone) which stimulates final maturity & rupture of a mature follicle. -Release of a mature egg (ovulation)

Ovulation

The second phase of the ovarian cycle. -Surge of LH causes rupture of a mature follicle releasing a mature oocyte (egg / ovum) -Usually occurs on day 14 in a 28d cycle -Drop in estrogen occurs -Fallopian tubes develop currents to carry ovum to uterus -Ovum life span = 24 hours (unfertilized) -Cervical mucus becomes thin, clear, stretchy, and slippery to facilitate sperm traveling through the cervix to meet & fertilize the ovum

Luteal Phase

The third phase of the ovarian cycle. From ovulation until the menstrual phase of the next cycle (typically days 15-28) -Corpus luteum releases progesterone to prepare the endometrium for implantation. It also raises body temperature .5 to 1 degrees Fahrenheit -Without fertilization: --Estrogen & progesterone levels decrease --Endometrium involutes --Menstruation then begins approximately 14 days after ovulation -FSH & LH are at the lowest levels during the luteal phase

During the first week of menstrual cycle (during bleeding)

When is FSH the highest?

Progesterone

hormone produced by the corpus luteum in the ovary and the placenta of pregnant women. Peaks 5-7 days after ovulation. "Hormone of Pregnancy" because it sustains embryo until placenta takes over.