The Reproductive System, unlike other systems we have studied, is not essential to the survival of an individual. Organisms can survive and lead healthy lives without reproducing. What the reproductive system is important to is the survival of the species. Reproduction is absolutely essential to the continuation of the species…some of us must reproduce. Reproductive System
Yeah..it a real word with real meaning Gonads…are actually testes and ovaries. They are endocrine glands that secrete sex hormones. The primary function of gonads is not to produce hormones but to produce and store gametes—sperm and egg. Gonads???
In humans the reproductive system produces, stores, nourishes, and releases specialized sex cell known as Gametes. The ways in which the Gametes are released make possible the fusion of Sperm (Male Gametes) and Egg (Female Gametes) in the process of Fertilization. From a fertilized egg, or Zygote, come all the cells in a human body Reproduction
Reproduction • 1. For the first six weeks after fertilization, human male and female embryos are identical in appearance. • 2. During the seventh week of development, major changes occur:
Reproduction • A. The Testes, which are the primary reproductive organs of a male, begin to produce Steroid Hormones (Sex) known as Androgens. The tissue of the embryo responds to these hormones by developing into the Male reproductive organs. • B. The Ovaries, or the primary reproductive organs of a female. They produce steroid hormones (Sex) known as Estrogens. The tissue of the embryo responds developing female reproductive organs.
Reproduction • The male and female reproductive organs develop from exactly the same tissue in the embryo. • After birth the Testes and the Ovaries continue to produce small amounts of Sex Hormones. These Sex Hormones continue to influence the development of the reproductive organs. • Neither Testes or Ovaries are capable of producing active reproductive cells (Gametes) until Puberty.
Puberty- is a period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. At the completion of puberty, the male and female gonads, or reproductive organs, are fully developed. The onset of puberty varies among individuals. It may occur anytime between the ages of 9-15 Generally begins a year early in females. Puberty
Puberty • Puberty begins with a change in the hypothalamus, the part of the brain that regulates the secretions of the pituitary gland • This changes causes the pituitary gland to produce increased levels of two hormones that affect the gonads: • A. Follicle Stimulating Hormone (FSH) • B. Luteinizing Hormone (LH)
The male gonads help in production and storage of sperm and the to prepare sperm for the possible fertilization of an egg Males begin to produce Sperm during Puberty, the adolescent stage of development when changes in the body make reproduction possible. At this time, the concentration of the hormone Testosterone is high enough to stimulate sperm production. Testosterone is the Main Androgen (Male Sex Hormone) produced by the Testes Male Reproductive System
Male Reproductive System • The Testes develop within the abdominal cavity, just before birth the testes descend through a canal into an external sac called the Scotum.
The Testes (two egg-shaped structures) remain in the Scrotum, outside the body. The temperature is about 3 degrees C Cooler than the body internal temperature (27 degrees C). Sperm development in the testes requires the lower temperature. Male Reproductive System
The Testes are clusters of hundreds of tiny tubules called Seminiferous (sehm-uh-NIHF-er-uhs) Tubules, which means "Seed Bearing". In total over 200 meter of seminiferous tubules. Sperm form through meiosis in the specialized lining of this extensive network of tubules. Male Reproductive System
As the pituitary gland begins to release FSH and LH, these hormones stimulate the testes to make the principal male sex hormone Testosterone. Testosterone produces a number of secondary sex characteristics that appear in males at puberty Voice Deepens Beard Grows Body Hair. Male Reproductive System
FSH and Testosterone stimulate the development of Sperm. When large numbers of sperm have been produced in the Testes, the development process of Puberty is completed - The male reproductive system is now functional. . Male Reproductive System
Sperm Development • Sperm are derived from Special Cells within the Testes that go through the process of Meiosis to form haploid nuclei found in Mature Sperm. • The Chromosome number drops from 46 to 23. • Four sperm cells result from each cell that begins meiosis. • This process is called spermatogenesis
A Mature Sperm consists of three Regions: (Figure 52-1) HEAD - which contains the Nucleus (The 23 Chromosomes) and enzymes that help the sperm penetrate the protective layers that surround and Egg Cell. MID PIECE - packed with energy releasing Mitochondria (Energy Source). The Mitochondria supply the energy that is required for sperm to reach an Egg. TAIL – Consists of a Single, Powerful flagellum that propels the Sperm. Sperm Development
Sperm Development • Developed Sperm travel from the Seminiferous Tubules ( in the testes) into the Epididymis. • The Epididymis function is to nourish immature sperm cells, promote their growth, and gain their ability to swim as it flagellum completes development.
Although most sperm remain stored in each epididymis, some leave the epididymis and pass into through the Vas Deferens. Vas Deferens, a duct that extends from the epididymis into the abdominal cavity, where it loops around the urinary bladder and merges with the urethra. In a male, both urine and sperm exit the body through the urethra Sperm Development
In the urethra, sperm mix with Fluids that are secreted by 3 other glands- (Seminal Vesicles, Bulbourethral Glands, and the Prostate Gland) to produce Seminal fluid -which protects and nourishes the sperm. The combination of sperm and seminal fluid is known Semen Sperm Development
Sperm Development • Between 100 and 200 million sperm are present in 1 milliliter of semen or about 5 million sperm per drop.
Sperm Development • The Vas Deferens merges with the Urethra, the tube that leads to the outside of the body through the penis. • Sperm are ejected from the penis by contractions of smooth muscles lining the Vas Deferens. This process is called ejaculation. • The function of the penis is to convey urine and semen.
300 - 400 million Sperm are released in the reproductive tract of a female during a single ejaculation; The chances of a single sperm fertilizing and egg, if one is available, are quit Good. Most sperm are killed by the Acidic environment of the female reproductive track. Only a few sperm reach the site of fertilization. Sperm
Sperm Development • Remember….Sperm make up only 10 Percent of Semen, 90 percent is the fluid secreted by the Three Glands.
Female Reproduction • The female gonads-ovaries-are endocrine glands that produce gametes. • The female reproductive system prepares the female gametes-eggs-for possible fertilization. • It also contains structures that enable fertilization to occur and that house and nourish a developing baby.
The primary reproductive organs of the the female are the OVARIES. The Ovaries are located in the lower abdominal cavity The Ovaries usually produce only one egg or ovum per month. The production of egg through meiosis is called Oogenesis. In addition to producing eggs, the female reproductive system has another important job to perform … Each time an egg is released the body must be prepared to nourish a developing embryo. Female Reproduction
Puberty in females starts with changes in the hypothalamus that causes the release of FSH and LH from the pituitary gland. FSH (follicle stimulating hormone) stimulates cells within the ovaries to produce the hormone Estrogen. Estrogen causes the reproductive system to complete its development Also produce secondary sex characteristics – Enlargement of Breast and Reproductive Organs. Widening of the Hips Growth of Body Hair. Female Reproduction
Each ovary contains about 400,000 primary follicles, which are clusters of cells surrounding a single ovum (egg). During her lifetime fewer than 500 Ova (Eggs) will actually be released, averaging one egg about every 28 days. A female is actually born with ALL of her immature eggs. They don’t become active until puberty. The function of a follicle is to prepare a single ovum for release into the part of reproductive system where it can be fertilized. Ova mature within their follicles. The maturing eggs become large, highly complex cells, growing nearly 75,000 times Larger than Sperm. Egg Development
When a follicle has completely matured, the Ovum (Egg) is released. This process is called Ovulation. If two eggs mature, fraternal, or non identical twins may result. Ovulation begins at puberty and usually continues until a female is in her late forties, when menopause occurs. After menopause, follicle development no longer occurs and a female is no longer capable of bearing children. (Biological Clock) Egg Development
OOgenesis • Gamete production in males begins at puberty and continues throughout life, but the situation is quite different in females. • It has been assumed that a female’s total supply of eggs is already determined by the time she is born, and the time span during which she releases them extends from puberty to menopause. • Approximately 250,000 eggs are available at the beginning stage of puberty but only about 400-500 are used between puberty and menopause.
OOgenesis • Meiosis occurs in testes in the males and the ovaries in females. • Female sex cells are produced and the process is called oogenesis. • The process can be very complicated so I have tried to simplify it. • The process of meiosis actually begins prior to birth but is stalled in Prophase I (called a primary oocyte) until puberty. • In puberty it will begin again one each month, Meiosis I will be complete forming what is called a (first) polar body and secondary oocyte.
OOgenesis • The (first) polar body is not functioning. It may or may NOT undergo Meiosis II producing two polar bodies that will degenerate. • In humans the secondary oocyte will begin Meiosis II continue through to Metaphase II and then pause. • This is where fertilization will occur. If it is NOT penetrated by a sperm it simply degenerates. • If fertilization does occur it quickly completes meiosis II yielding one large ovum and a tiny secondary polar body.
OOgenesis • The end products of oogenesis are three tiny polar bodies, nearly devoid of cytoplasm, and one large ovum. • Key difference in males…all 4 gametes are functional. • The unequal cytoplasmic division that occur during oogenesis ensure that a fertilized egg has ample nutrients for its six to seven day journey to the uterus. • Without the cytoplasm the polar bodies degenerate and die.
The follicle literally ruptures, and the ovum is swept from the ovary into one of the two Fallopian tubes. The Fallopian Tubes provide a way for an egg to travel from the ovary to the uterus. The Ovum (egg) is moved through the fluid filled Fallopian tubes by cilia attached to the cells that line the walls of the tube. The fallopian tubes are approximately 4 inches long. Female Reproduction
Female Reproduction • It is during its journey through the fallopian tube that an egg can be fertilized. • An egg must be fertilized within 48 hours of its release - after that, the egg begins to break down. • Unfertilized eggs dissolve in the Uterus.
Female Reproduction • The fact that the uterine tubes (fallopian) are not continuous with the ovaries places women at risk for ectopic pregnancy. • This is where the zygote or fertilized egg actually begins to develop in the uterine tube. • Because of the obvious lack of adequate mass and vascularization to support a full term pregnancy, such pregnancies naturally abort and usually with substantial bleeding.
After a few days, the ovum passes from the fallopian tube into the Uterus. The lining of the uterus is specially designed to receive a fertilized ovum. The uterus (Latin for womb)- is located in the pelvis, it is a hollow, thick-walled, muscular organ that functions to receive, retain, and nourish a fertilized ovum. Here the blastocytes is finding a place to attach on the cervix wall. Female Reproduction
Female Reproduction • In a never before pregnant woman the uterus is about the shape of a pear…usually grows larger with each additional pregnancy. • The major portion of the uterus is called the body, the rounded superior region is called the fundus, and the region between the body and the cervix is called the isthmus. • After delivery nurses will do what is called a “fundus check”, they will press on your stomach (which is painful) to help you uterus return to its original shape.
Female Reproduction • The wall of the uterus is made of three layers. • Perimetrium (outer most layer) • Myometrium (middle layer) • Endometrium (inner most layer)
Female Reproduction • If fertilization occurs the young embryo burrows into the endometrium (implants) and resides there for the rest of its development. • The enodmetrium is highly vascular and supplies the embryo with nutrients throughout pregnancy. • If fertilization fails to occur the egg is discarded along with the lining (which is shed monthly) of the endomentrium.
Female Reproduction • The lower entrance to the uterus is called the Cervix. A sphincter muscle in the cervix controls the opening to the uterus. • The cervix contains cervical glands that secrete a mucus that fills the cervical canal. • The mucus blocks bacteria from the vagina into the cervix as well as blocking the entry of sperm except during mid-cycle where it becomes less viscous and allows sperm to pass through.
Female Reproduction • Cancer of the cervix strikes a bout 450,000 women worldwide each year, killing about half. • Affects women between the ages of 30-50 • The cancer cells arise from the epithelium covering the cervical tip. • Risk that increase the chances of cervical cancer are frequent cervical inflammation, sexually transmitted diseases and partners, and multiple pregnancies. • How do you find out if you have cervical cancer??
Pap Smear • Papanicolaou (pap) smear- (cervical smear) is a test in which a speculum is inserted in the vagina and a tiny sample of cervical tissue is scraped off. • This sample is smeared on a glass slide and send to a lab where a cytotechnologists stains and examines it for the presence of abnormal cells which may indicated cervical cancer. • Pap smears should be begin as soon as the female becomes sexual active and should last until the age of 70. • Pap Smears are the most effective way to determine cervical cancer.