The Female Reproductive System Narrow tube carrying eggs from the ovaries to the uterus Has ciliated cells Site of fertilisation Collects eggs released from ovary and directs them to the oviduct Produces and releases eggs Produces hormones oestrogen and progesterone Ring of muscle between vagina and uterus Allows sperm to pass into uterus from vagina and blood to pass out during menstruation and the baby during birth Before ovulation, the cervix produces a special mucus for about 3 to 9 days. This mucous is as crucial to fertility as ovulation because without it, the male’s sperm cannot survive nor be transported inside the female to fertilize the eggs. When mucous is present, it nourishes and protects sperm allowing them to live for 3 to 5 days. Located near the ovaries but not directly connected to them. When an egg cell is released, it travels through the oviduct by the action of ciliated cells that line the funnel like opening of the oviduct and the oviduct itself. If sperms are present in the oviduct, the egg may be fertilized. Produces and releases ova into the oviduct. Produces hormones Oestrogen – repairs uterine lining after menstruation Progesterone – maintains uterine lining. Site of implantation of embryo; formation of placenta Cavity in which foetus develops Muscular and elastic tube into which male penis is placed during intercourse Stretches to allow baby out at childbirth. The Ovary Production of Eggs At birth, each ovary in a female has hundreds of thousands of eggs, but they are immature and remain dormant until her first menstrual cycle, which occurs during puberty (sexual maturity). Egg development – a cyclical process of 28 days. Takes place in the ovaries. It is controlled by hormones from the hypothalamus and the pituitary gland. Every 28 days or so from puberty until menopause (when ovulation and menstruation stops), between one and three eggs, the size of the head of a pin are released from the ovaries. This whole process takes about three minutes and is known as ovulation. The eggs are then move down the fallopian tubes towards the uterus. The Menstrual Cycle The monthly ovarian and uterine cycle of the female reproductive system is called the menstrual cycle. It has an average length of about 28 days, and consists of four stages. The menstrual cycle involves interactions of the hypothalamus, pituitary gland, ovary and uterus. The cycles usually occur regularly between puberty and menopause. The cycle may be interrupted by pregnancy, illness, or other factors (example, extreme exercise or extreme dieting). 1 - Follicle stage Follicle Stimulating Hormone (FSH) is secreted by the pituitary gland (in the brain). FSH causes several follicles in the ovary to begin developing. Usually, only one matures. As the follicle develops, it secretes oestrogen, which stimulates the uterine lining to thicken with mucus and a rich supply of blood vessels. These changes prepare the uterus for a possible pregnancy. This stage lasts 10 to 14 days. 2 - Ovulation A high level of oestrogen in the blood causes the pituitary gland to decrease secretion of FSH and begin secretion of luteinizing hormone (LH). When the concentration of LH in the blood reaches a certain level, ovulation occurs - that is the follicle ruptures releasing a mature egg. Ovulation usually takes place in about the middle of the menstrual cycle. 3 - Corpus luteum stage After ovulation, LH causes the ruptured follicle to fill with cells, forming a yellow body called the corpus luteum. The corpus luteum begins to secrete the hormone progesterone, which maintains the continued growth of the uterine lining. It also prevents the development of new follicles in the ovary by inhibiting the release of FSH. This stage lasts 10 - 14 days. 4 - Menstruation • If fertilization does not occur, secretion of LH decreases, and the corpus luteum degenerates. • This results in a decrease in the level of progesterone. • As a result, the thickened lining of the uterus can no longer be maintained and it breaks down. • The extra layers of the lining, the unfertilized egg, and a small amount of blood pass out of the body through the vagina. • This is called menstruation. It lasts from about 3 to 7 days.