The Female Reproductive System How it works!

FEMALE REPRODUCTIVE SYSTEM

The Basic Function of the Female Reproductive System : Sexual Reproduction is the union of the female (ovum) and male (sperm) sex cells, to create a new individual. Each sex cell, also called Gametes, contain half the number of chromosomes that a normal body cell contains. When the nuclei of the two gametes unite (known as fertilization), the cells receive half of the genetic material from each parent cell.

ANATOMY: Female Reproductive System The Ovaries are the primary female reproductive organ. The sex organs are called Gonads and It contains the female ova(egg) also called gametes. It secretes female sex hormones called estrogen and progesterone. The accessory structures or organs include: the uterine or fallopian tubes, the uterus, and the vagina.

The Female Reproductive System

Anatomy: The ovaries Each ovary is about the size of a large walnut and shaped like an almond. In young women the ovaries are about 1½ - 2 inches long, 1 inch wide and 1/3 of an inch thick. Once a woman reaches menopause, they shrink in size. The ovaries produce eggs or ova. All females are born with a lifetime supply of eggs. When all the eggs have been expelled a woman is said to be in menopause. The ovaries also produce hormones called: estrogen and progesterone function of estrogens is development of female secondary sexual characteristics. These includes breasts, endometrium, and regulation of the menstrual cycle. prepare your body for conception and pregnancy and regulates the monthly menstrual cycle. It also plays a role in sexual desire.

Anatomy: The fallopian Tubes (also called the oviducts or uterine tubes): The fallopian tubes stretch from the uterus to the ovaries and measure about 8 to 13 cm in length. They range in width from about one inch at the end next to the ovary, to the diameter of a strand of thin spaghetti at the end connected to the uterus. Millions of tiny hair-like cilia, line the fimbria (which are finger-like projections) and the interior of the fallopian tubes. The cilia beat in waves, hundreds of times a second in order to catch the egg at ovulation and move it through the tube to the uterus. Fertilization typically occurs in the fallopian tube.

Anatomy: The Uterus: The uterus is a pear-shaped muscular organ. The fundus is the upper portion of the uterus where pregnancy generally occurs (or the developing fetus grows). The cervix is the lower portion of the uterus that connects with the vagina and serves as a sphincter to keep the uterus closed during pregnancy until it is time to deliver a baby. the uterus can expand considerably, during the reproductive process. It can grow10-20 times its normal size during pregnancy.

Location: of the Uterus

Location: Ovaries and the Fallopian/Uterine tubes Figure 28.14a, b

Oogenesis: Oogenesis is the creation of an ovum. When a female reaches puberty or sexual maturity (also called Menarche), the primary oocytes recommence their development. This means that the ovaries begin to grow and mature such that they begin to produce ova or eggs. The ova are usually produced one at a time and only once a month (or approx. every 28 days).

How is Ovulation Regulated ? The HYPOTHALAMUS of the brain releases Gonadotropin-releasing Hormone (GnRH), which stimulates the release of Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH) from the Anterior Pituitary gland of the brain. The menstrual cycle begins with menstrual bleeding (menstruation), which marks the first day of the follicular phase. About this time, the FSH level increases slightly, stimulating the development of several ovarian follicles. Each follicle contains an egg. As these follicles mature (graafian follicles), they produce estrogen. The follicles eventually rupture releasing an ova and leaving an empty follicle called the corpus luteum (the yellow body). As the FSH levels decrease, the corpus luteum secretes estrogen and progesterone that stimulates the building up of the lining of the uterus in anticipation of fertilization of an ova.

How is Ovulation Regulated ? Cont… The moment that an ovum leaves the ovary is called ovulation. The egg erupts from the ovary on the 14th to 16th day of an approximate 28-day menstrual cycle. If the ova is not fertilized, the corpus luteum degenerates, and the egg is passed from the reproductive tract during menstrual bleeding or flow. At this point a new menstrual cycle begins, which is approx. two weeks after ovulation. If the egg is fertilized, the cells around the developing embryo begin to produce a hormone called Human Chorionic Gonadotropin (HcG). This hormone maintains the corpus luteum, which continues to produce progesterone, until the growing fetus can produce its own hormones. Pregnancy tests are based on detecting an increase in the HcG level.

When does ovulation occur?   The timing of ovulation varies with the length of a woman's menstrual cycle. In the average 28 day menstrual cycle, the Leutinizing Hormone (LH) surge usually occurs between the cycle days 11-13 and ovulation follows about 36-48 hours later, on or close to cycle day 14. Women with shorter menstrual cycle lengths tend to ovulate earlier and women with longer cycle lengths tend to ovulate later than cycle day 14. Despite the variations in menstrual cycle length, the time from ovulation to the onset of the next menstrual period is usually constant (about 2 weeks). This principle is the basis for the use of ovulation calendars that take into account an individual's shortest and longest cycle lengths.

Ovulation

FEMALE REPRODUCTIVE SYSTEM  HORMONAL REGULATION OF OOGENSIS AND OVULATION OVULATION FOLLICULAR PHASE LUTEAL PHASE ovary undergoes cyclic changes that include the follicular and luteal phase; with ovulation between the two phases increased levels of estrogens and progesterone make follicle independent of FSH

How fertilization occurs: Fertilization occurs in the fallopian tubes (also called oviducts or uterine tubes) and takes place within hours of the sperm being released during sexual intercourse to a few (approx.3) days after the day of ovulation. Only one of the approximately 300 million sperm released into a female's vagina during intercourse can fertilize the single female egg cell. The successful sperm cell must enter the uterus and swim up the fallopian tube to meet the egg cell, where it passes through the thick coating surrounding the egg. The tip of the head of the sperm cell contains enzymes which break through the coating and aid the penetration of the sperm into the egg. Once the head of the sperm is inside the egg, the tail of the sperm falls off, and the perimeter of the egg thickens to prevent another sperm from entering. Sometimes two ova are released, and if fertilized, become what is called fraternal twins. These twins can be of the opposite sex. Identical twins are formed when one sperm fertilizes one egg, and as the egg cell divides and is forming many new cells, it splits and each part continues separately to undergo further division, each producing an embryo.

Picture: How fertilization Occurs

Implantation: Once the embryo (newly fertilized ovum/egg) begins to divide it will reach the blastocyst stage (approximately 5 to 6 days after fertilization); It then begins the process of implantation. The fertilized egg travels to the uterus and implantation takes place when the egg attaches or implants in the endometrium (or inner lining) of the uterus. At this point, the egg (or ova) and the developing placenta, begin to release Human Chorionic Gonadotropin (hCG) hormone. The presence of hCG will help facilitate the continued production of progesterone – which is essential for a fertile, hospitable environment for the implanted egg until the third month of pregnancy; in which the placenta (the outer sac that surrounds the developing embryo) begins to produce estrogen and progesterone (of which until this point, the corpus luteum was producing). http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000045&ptid=17

Pregnancy: The embryo undergoes a 40 week (approx. 9 month) period of development or gestation in the uterus until the delivery of the fetus. During pregnancy (at approx. 6 months of gestation), the hormones from the ovaries and the placenta stimulate glandular tissues in the breasts to develop fully. After parturition (giving birth), hormones from the pituitary glad stimulate the production of milk (lactation). An embryo is called a fetus after the 2nd month of gestation or pregnancy.

Mammary Glands: Are present in both sexes - normally only functional in females Developmentally they are derived from sweat glands They are contained within a rounded skin-covered breast anterior to the pectoral muscles of the thorax At the center of each breast is a ring of pigmented skin, called the areola - this surrounds a centrally protruding nipple. Internally - they consist of 15 to 25 lobes that radiate around the breast and open at the nipple Each lobe is composed of smaller lobules; these contain alveoli that produce milk when a women is lactating during pregnancy. non-pregnant women - glandular structure is undeveloped; thus the breast size is largely due to genes and the amount of fat deposits

The Mammary Glands Figure 28.23a-c

Things to Remember!!! Gynecology is the study of the female reproductive system. Obstetrics is a specialty concerned with pregnancy and the delivery of a fetus. Sexual intercourse is also called Coitus, copulation, or pareunia. Puberty/menarche is the beginning of the fertile period and development of secondary sex characteristics Menopause is also called: change of life and climacteric. The bartholin glands are two small glands on each side of the vaginal orifice (opening) that produce a mucous secretion to lubricate the vagina. To avoid a tear of the tissue between the anus and vagina (perineum) the obstetrician cuts this section during child birth; called an episiotomy. The external genitalia of the female are collectively called the vulva The hymen is a mucous membrane that (normally) partially covers the entrance to the vagina. Afterbirth is the expelled placenta; minute after the delivery of the fetus.

Pathology and Procedures of the Female Reproductive System Endometriosis: is when the endometrial tissue is abnormally located outside the uterus. Fibroids: are benign tumors in the uterus. Pelvic inflammatory disease(PID): an infection of the female reproductive system and the leading causes are gonorrhea and chlamydial infections. Ectopic pregnancy: implantation of the fertilized egg outside of the uterus Tubal ligation: sterilization by blocking of the fallopian tubes by burning or cutting and tying them off. Abortion: premature termination of a pregnancy before it is able to exist on its own. Cesarean section: removal of the fetus by abdominal incision into the uterus. Pap Smear: The physician inserts a vaginal speculum and wooden spatula; along with a cotton swab to take secretions and cells from the vagina and cervix for microscopic examination.