Female Reproductive System & Pregnancy

I. Early Female Reproductive System• A. During the 7th week of

development ovaries begin to form and produce estrogen.

• B. During puberty female’s pituitary gland starts to release FSH & LH stimulating cells in the ovaries to produce estrogen.

II. The Female Reproductive System

• A. The main function of the female reproductive system is to produce ova & prepare the female body to nourish a developing embryo.

• B. Unlike the male reproductive system that produces millions of sperm, female ovaries produce only one mature ovum (egg) a month(~400 eggs).

III. The Organs of the Female Reproductive System

• A. The female reproductive system includes:– 1. Ovaries– 2. Fallopian Tubes– 3. Uterus– 4. Vagina

IV. The Ovaries• A. Slightly below your waist are a females ovaries,

which are the structures that produce eggs. Each egg has follicles which are clusters of cells that surround a single egg.

• B. The ovaries also trigger the release of estrogen which allows the development of adult female characteristics including – widen hips and breast development.

V. The Fallopian Tube• A. Fallopian tube is a passageway an egg travels

from an ovary to the uterus. Fertilization (egg + sperm) usually occurs along this tube.

VI. Uterus • A. The uterus is a hollow, muscular organ which

develops a thick lining from the endometrium during the month so it is prepared to receive the fertilized egg. Implantation occurs, gastrulation follows

• B. The bottom end of the uterus is called the cervix which an unfertilized egg and wall lining will leave.

VII. Vagina

• A. Beyond the cervix is a canal – the vagina – (birth canal) that leads to the outside of the body.

IIX. Menstrual Cycle

• A. At the start of a teenage girls life each month an egg is developed & is released.

• B. During the same time, the lining of the uterus thickens in a way that prepares the uterus for a fertilized egg.

IX. Pregnancy• A. If an egg is fertilized in the fallopian tube, the

now zygote begins to divide on its way to the uterus. When this cell dividing ball attaches to the uterus it is called an embryo.

• B. From the 8th week until birth, a developing human is called a fetus, where all the internal & external organs begin to form & start to function.

X. Nourishment of the Embryo• A. Membranes & structures that form in the uterus

during pregnancy protect & nourish the developing baby.

• B. The Membranes include:– 1. Amniotic sac – filled with fluid that cushions &

protects the embryo/fetus– 2. Placenta – links the mother & embryo together, it is

across this membrane where oxygen/nutrients & waste/carbon dioxide diffuse between the mother & embryo’s blood vessels (umbilical cord)

XI. Human Development • A. Occurs through 3 stages:– 1. First trimester (implantation, gastrulation, neurulation

& placenta)• 4 wks – Brain, heart & spinal cord begin to form• 8 wks – heart beats, all major organs form as well as sex

organs• 12 wks – nerves & muscles begin to work (neurulation)

– 2. Second trimester – more complete skeleton, fetus is more active, lungs form (not functional)

– 3. Third trimester – organs are ready to function on their own, fetuses begin to move in the head down position

XII. Child Birth• A. After about 9 months the birth of a baby takes

place in 3 steps:– 1. Labor – strong muscle contractions, cervix widens– 2. Delivery – baby is pushed out of the uterus head first,

umbilical cord is cut– 3. Afterbirth – muscle contracts in the uterus pushing

out the empty amniotic sac & placenta.