Female Reproductive System

How eggs are formed: Oogenesis

1. Ovary Eggs are produced by meiosis Estrogen and progesterone are released (secondary sex characteristics) During ovulation an egg is released

Where does the egg travel once it is released from the ovaries?

2. Oviduct (Fallopian Tubes) Where fertilization occurs Oviducts are lined with cilia Fertilization = union of egg and sperm (nucleus of each) Fertilized egg = zygote

Internal vs. External Fertilization Internal – occurs inside the body. Example: Humans External – fertilization and development occur outside the body. Example: Fish

Tubal Ligation – procedure done if woman does not want any kids Fallopian tubes are cut, burned, or blocked with rings, clips or bands. Prevents sperm from reaching the fallopian tubes and prevents an egg to travel out of the ovary into the uterus

3. Uterus Where implantation (zygote attaches to wall of uterus) and development of an embryo occurs

7. Cervix Base of the Uterus that holds the baby in after implantation.

Diagram 1. Ovary 2. Oviduct 3. Uterus 4. Bladder 5. Urethra 6. Vagina 7. Cervix 8. Rectum

Life’s greatest Miracle http://www.youtube.com/watch?v=CbxQg1VeXc8  Bangaii Cardinal fish female egg transfer http://www.pbs.org/wgbh/nova/miracle/program_adv.html

Hormones…..it’s not our fault!

Menstrual Cycle A) 28 day cycle B) Series of changes in the ovary and uterus which prepares the female for pregnancy C) Controlled by hormones D) Hormones are secreted from the pituitary and ovaries E) Begins at puberty

Hormones Pituitary gland (brain)- secretes LH and FSH (follicle stimulation hormone) Ovary – secretes Estrogen and Progesterone Note: A follicle holds the eggs in an ovary

Follicle Stage (10 – 14 days) FSH and Estrogen levels increase in the body Uterus lining thickens

Ovulation (day 14) LH (Luteinizing Hormone) increases to promote ovulation Release of the egg into the oviduct This is the most likely time an egg can be fertile

Corpus Luteum (10 days) Progesterone levels increases and creates a thicker uterine lining to prevent another egg from ovulating

Menstruation (3 – 5 days) Blood, muccus and uterine lining shed.

How do Hormones Regulate the Menstrual Cycle FSH – growth of follicle LH – ovulation Estrogen and Progesterone – thick uterine lining and prevents ovulation

Menopause Cessation (stopping) of the menstrual cycle (all of a woman’s eggs have been used) Usually occurs after the age of 50

Twins Fraternal – 2 eggs are released from the ovaries and fertilized by two different sperm. Identical – one egg is released and fertilized by one sperm. The egg splits which results in identical twins.

Growth of a Zygote Cleavage – stages of growth of a zygote by mitosis

Growth and Implantation of a Zygote Blastocyst – hollow ball of cells that implants into the uterus (day 5) Differentiation – the process by which cells become specialized. Example – kidneys, heart, skin, etc.

Fallopian Tubes (4) Where fertilization happens

Uterus (6) Where embryo implants and grows

*Placenta (3) Structure that attaches embryo to uterine wall Exchange of substances (oxygen, nutrients, and wastes) occurs here by diffusion

Umbilical Cord (2) Attaches embryo to placenta Transfers nutrients to growing embryo

Blood Blood does not mix between mother and fetus

Amniotic Sac (5) Sac that is filled with fluid to protect the embryo Amniocentesis – fluid is extracted to determine if the fetus has any genetic abnormalities

Cervix and Birth Canal (1) Cervix – opening between the uterus and birth canal. Closed during pregnancy Birth Canal – where fetus exits the mother head first during labor