bio menstrual cycle - About midway through the menstruation...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Brian Resnick The menstrual cycle is the cycle in which in the female body eggs are prepared to receive sperms and where the uterus is prepared to hold the developing fetus. In most women the menstrual cycle is twenty-eight days long. It runs under great hormonal control. The cycle is broken in several stages. During the follicle stage, the hypothalamus releases GnRH which acts on the pituitary gland in the brain to stimulate the release of follicle stimulating hormone (FSH) and Luteinizing Hormone (LH). FSH causes a follicle in the woman’s ovaries to develop. As the follicle develops it releases the hormone estrogen which stimulates the creation of the inner membrane of the uterus, otherwise known as the vascularization of the uterus. Rising levels of estrogen also provide negative feedback and slows the hypothalamus’s production of GnRH. Estrogen itself controls its own levels through negative feedback. LH causes the egg within the follicle to complete the first meiotic division.
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: About midway through the menstruation cycle, ovulation occurs. The egg is released from the follicle into the fallopian tube. A surge of LH causes this to occur. Once the egg is released it has about 24 hours to be fertilized. After the follicle releases the egg it becomes a gland releasing the hormone progesterone. Progesterone inhibits new follicle formation, keeps blood lining of uterus in place, and inhibits uterine contractions. If no fertilization occurs the corpus leutem will break down and progesterone levels will drop. Without progesterone uterine cramps occurs and the blood lining of the uterus begins to break down. A new follicle will begin to form and the cycle will start again. If fertilization does occur, the corpus leutem will remain and progesterone levels will remain high for the entire gestation period. Chart of Uterine Lining:...
View Full Document

This note was uploaded on 04/20/2008 for the course BIO bio101 taught by Professor Dest during the Spring '08 term at University of Delaware.

Ask a homework question - tutors are online