REPRODUCTIVE SYSTEM

Amniotic Sac

A thin membrane called the amniotic sac is formed. The amniotic sac is filled with fluid that protects the embryo and regulates the temperature.

Hormones

Another important function of the reproductive system is to produce male and female hormones. Hormones are a regulatory substance produced in the body and transported through the bloodstream.

Fetus

At the end of the first 8 weeks, the embryo develops into a fetus. The fetus grows within the female for approximately 9 months.

Menstrual Cycle

Both the ovarian and uterine cycles work together to prepare the female for pregnancy. When discussing both their effects together we refer to this process as the menstrual cycle. The first menstrual cycle signals that the female has reached puberty.

Seminal Fluid

During ejaculation, the following secretions combine to form seminal fluid: • A sticky, yellowish secretion from the seminal vesicle • A thin, milky-colored secretion from the prostate gland Seminal fluid functions to: • Provide a fluid medium for the sperm to travel through. • Provide carbohydrates so that sperm can produce ATP to power their flagella. • Create a slightly alkaline (basic) environment to protect the sperm from the acidity of the female vagina. • Cause the female's uterus to contract to propel sperm forward.

Ovulation

Each follicle is composed of one egg, or ova, and its surrounding cells. No new follicles are produced during the female's life. Only a few of the ova (about 400) will reach maturity. • The follicle, with enclosed ovum, continues to grow larger and larger. • Eventually the mature follicle bursts open and releases the ovum. This is known as ovulation. • The release of a mature ovum occurs once each month. Usually one ovary releases a mature ovum one month, and the other ovary releases a mature ovum the next month. • The walls of the uterus thicken in preparation for receiving a fertilized ovum. If the ovum is not fertilized, it is discharged along with the uterine lining.

Endometriosis

Endometriosis is a potentially painful disorder where tissue that lines the inside of the uterus grows outside the uterus. This condition typically involves the ovaries, bowels, or pelvis. This endometrial tissue thickens, breaks down, and bleeds during the menstrual cycle but has no way to exit the body as it should. Symptoms can include: • Internal irritation, scarring, and cysts • Pelvic pain, especially during menstruation, intercourse, or while going to the bathroom • Heavy periods or bleeding between periods • Infertility • Other symptoms (fatigue, diarrhea, constipation, bloating, nausea, etc.) Endometriosis: Risk Factors Risk factors for endometriosis include: • Family history of endometriosis • Medical conditions that impair blood flow during menstruation • Previous pelvic infection • Abnormal uterus • Never giving birth Endometriosis: Treatment Treatment options for endometriosis might include: • Pain relievers • Hormone therapy • Surgery to remove tissue outside of the uterus • Hysterectomy (removing the uterus, ovaries, and cervix) • Assisted reproductive technologies to get pregnant Endometriosis: Prevention Endometriosis cannot be prevented.

Zygote

Fertilization, the union of a sperm cell and an egg, takes place in the fallopian tubes. Although millions of sperm are present, only one sperm is permitted to fertilize the egg. Once the egg is fertilized, it is then called a zygote.

Embryo

Following implantation, the zygote develops into an embryo. The embryo is about the size of a dot over the letter i. The embryo continues to divide, thereby forming the layers of cells that will eventually become the systems within the human body.

Menstrual Cycle

For pregnancy to occur, the female must be ovulating, which is the release of a mature egg. An average menstrual cycle is 28 days, marked by the beginning of the menstrual flow. This menstrual flow lasts for about 5 days. Ovulation occurs approximately on day 14. Therefore, for the greatest chance of fertilization, sexual intercourse would need to take place between day 12 and day 16.

Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common hormonal disorder where a woman has ovaries that are enlarged and lined with several small cysts. Symptoms can include: • Unusual menstrual periods • High levels of androgens • Polycystic ovaries (must exist along with one of the above to be PCOS) Polycystic Ovary Syndrome: Risk Factors The exact causes of PCOS are unknown but may involve: • High levels of insulin • Low-grade inflammation • Genetics • High exposure to male hormones (androgens) as a fetus Polycystic Ovary Syndrome: Treatment Treatment options for PCOS might include: • Medications for menstruation and ovulation • Medication to reduce hair growth • Surgery to induce ovulation Polycystic Ovary Syndrome: Prevention PCOS cannot be prevented.

Steroids

Testosterone is classified as a steroid. It, and other hormones that build up protein, are known as anabolic steroids. Anabolic steroids are commercially made and are used by body builders and athletes. There are many serious and dangerous side-effects of doing this, such as: • Liver and kidney disorders • High blood pressure • Decreased sperm count • Aggressive behavior

If not Implanted

If a fertilized egg is not implanted on the endometrium, then the sex hormones drop, and the uterine cycle begins again.

Nocturnal Emission

If the sperm is not released during sexual activity, it will be released automatically approximately monthly while the male is asleep. This is known as nocturnal emission, commonly called a wet dream. The first nocturnal emission signals that the male has reached puberty

The Miracle of Life

In order for a child to be born, a complex process must take place. The process begins with sexual intercourse. Sexual intercourse is when the penis of a male enters of the vagina of a female. Ejaculation, muscular contractions that occur at the height of sexual arousal, propels semen into the female's body. In this semen, there are between 300 million and 400 million sperm that travel through the vagina, uterus, and fallopian tubes in order to find an egg.

Infertility

Infertility is a condition where someone is unable to become pregnant or contribute to pregnancy after having frequent, unprotected sex for at least one year. Women should talk to a doctor about infertility if they: • Having been trying to conceive unsuccessfully for a year or more • Are over the age of 35 • Menstruate irregularly or not at all • Have very painful menstruation • Have had more than one miscarriage • Have endometriosis or pelvic inflammatory disease • Have been treated for cancer Men should talk to a doctor about infertility if they: • Having been trying unsuccessfully to conceive with a woman for a year or more • Have sperm issues such as low sperm count • Have had testicular, prostate, or sexual problems • Have been treated for cancer Infertility: Risk Factors Risk factors for infertility include: • Age: over 35 for women, over 40 for men • Smoking • Drinking alcohol • Being overweight or underweight • Not enough or excessive amounts of exercise Infertility: Treatment Infertility treatment can be financially, physically, and psychologically difficult. Treatment options for the couple might include: • Medications, hormones, or behavioral treatments • Surgery • Sperm retrieval • Intrauterine insemination (placing concentrated sperm in the uterus around ovulation) • In vitro fertilization (taking multiple eggs out of the ovaries to fertilize in a lab with the man's sperm, then implanting the embryos into the woman's uterus) • Other assisted reproductive technology Treatment complications can include: • Getting pregnant with multiple babies • Bleeding or infection • Birth defects • Early delivery or lightweight babies • Ovarian hyperstimulation syndrome (causes swollen and painful ovaries) Infertility: Prevention Infertility is not always preventable. However, some strategies for prevention include: • Having intercourse several times around ovulation • Waiting 2-3 days between ejaculations to boost semen quality • Not smoking • Avoiding alcohol and drug use • Avoiding medications that affect fertility • Men avoiding high temperatures and exposure to toxins • Women limiting caffeine, maintaining a healthy weight, and exercising moderately

Labor

Labor begins, and the baby is then delivered out the vagina or by a Caesarean section. Caesarean section, or C section, is when a cut is made through the abdominal wall and the uterus, and the baby is pulled out.

Menstruation

Menstruation is the discharge of the uterine lining. Menstrual flow usually lasts about 3-5 days. Once menstruation ends, the uterine lining begins to thicken again and prepare for the possibility of receiving a fertilized egg. The menstrual cycle is the time from the beginning of one menstrual period to the onset of the next. Although there is great variation, the menstrual cycle is approximately 28 days.

Female Secondary Sex Organs

The female secondary sex organs include: • The fallopian tubes • The uterus • The cervix • The vagina • Mammary glands Secondary sex organs help: • To nourish and protect each fertilized ovum from the beginning of pregnancy through birth. • Provide nourishment for the baby through the secretion of milk.

Gonads

The male and female hormones are produced in the primary sex organs, gonads: • Males- testes • Females- ovaries

Three Characteristics

The male and female reproductive systems are unique because of three characteristics: 1. The reproductive system is not designed to support the individual. Instead, its focus is to continue the species. 2. The anatomy and physiology of the reproductive organs are the major difference between males and females. 3. The reproductive system is latent, and then develops during puberty. Whereas, the other body systems are completely functional at birth or shortly thereafter.

Male Sex Hormones

The male sex hormones are produced in the seminiferous tubules in the testes; which is also where sperm are produced. Male sex hormones are called androgens. The most important androgen is testosterone In addition to developing the secondary sex characteristics of a male, testosterone: • Controls the development and function of the male secondary sexual organs (ie- penis & accessory glands) • Is necessary for spermatogenesis • Contributes to the sexual drive • Stimulates protein production After puberty, testosterone is produced and secreted at a fairly constant rate.

Semen

The mixture of seminal fluid and sperm is called semen. • About ½ tsp of semen is released during ejaculation. • Semen usually contains 300-400 million sperm.

Ovarian Cycle

The ovarian cycle is divided into two phases: 1. Follicular phase 2. Luteal phase Follicular Phase The follicular phase occurs approximately during days 1-13. This process is known as oogenesis; which is the production of a mature egg. • Follicle stimulating hormone (FSH) is secreted from the anterior pituitary gland to begin generating a mature follicle and egg. • As the follicle matures and develops, it secretes estrogen. • Just before the follicle is completely mature, accumulated estrogen in the bloodstream, triggers the anterior pituitary gland to stop secreting FSH. Once the follicle is mature, it bursts open and releases the mature egg. This is known as ovulation. Ovulation occurs on about day 14 of the monthly cycle. It marks the end of the follicular phase. Luteal Phase The luteal phase begins after ovulation and occurs approximately during days 15- 28. • The anterior pituitary gland now secretes the luteinizing hormone (LH). Luteinizing hormone modifies the empty follicle to become a gland like structure known as the corpus luteum. • Corpus luteum secretes progesterone for about 13 days. This keeps the uterine lining thick preparatory to receiving a fertilized egg. • If the released ovum is fertilized, the corpus luteum lingers longer to maintain uterine lining until the placenta begins to secrete progesterone. • If the released ovum is not fertilized, the corpus luteum disintegrates and progesterone levels drop. • The drop in progesterone, results in the uterine lining to shed.

Ova

The ovaries in the female produce the gametes, ova, in a process known as oogenesis. At birth, the ovaries contain approximately 400,000 follicles.

Female Sex Hormones

The primary female sex hormones are: • Estrogen • Progesterone Both are produced in the ovaries. However, they are not secreted constantly, the amounts secreted vary throughout a monthly 28-day cycle.

Reproductive Functions

The primary reproductive organs for the male and female are known as the gonads: • Male gonads- testes • Female gonads- ovaries

Reproductive Issues

The reproductive system allows sexually mature human beings to create children. Reproductive issues can interfere with this ability. Specific issues can affect both sexes or may only affect a single gender. A few reproductive issues include: • Infertility • Endometriosis • Polycystic ovary syndrome (PCOS)

Male Secondary Sex Organs

The secondary sex organs of the male protect and transport sperm. In males, the secondary sex organs are: • Epididymis • Ductus deferens (vas deferens) • Ejaculatory ducts • Seminal vesicles • Prostate gland • Cowper's glands • Penis • Scrotum

Secondary Sex Characteristics

The sex hormones develop the secondary sex characteristics of males and females. For example, in males: • Broad shoulders • Muscular physique • Body and facial hair • Deep voice For example, in females: • Feminine shape • Pubic hair • Breasts

Ejaculation

The sperm are stored in the epididymis and ductus deferens (vas deferens) until released during sexual activity. This is known as ejaculation.

Sperm

The testes in the male produce the gametes, sperm, in a process known as spermatogenesis. Within the testes, are tightly coiled tubules called the seminiferous tubules. This is where spermatogenesis takes place. Mature sperm begins to be produced at puberty. They produce sperm at a rate of 100 million per day. The sperm resemble tadpoles and are so tiny that if you were to line up 500 of them it would only measure 1 inch.

Uterine Cycle

The uterine cycle also occurs as a monthly 28-day cycle. The uterine cycle focuses on the changes that occur to the endometrium; which is the walls of the uterus. The uterine cycle is divided into three phases: • Menstrual phase • Proliferative phase • Secretory phase Menstrual Phase The menstrual phase, also known as the bleeding phase, begins on day 1 and lasts about 3-5 days. • There is a marked decrease in both estrogen and progesterone. • Because of this drop in hormones, the thick, vascular uterine wall undergoes vasoconstriction. • This decrease in blood flow, results in the uterine wall disintegrating and sloughing off. • The smooth muscles of the uterus also begin to constrict generating menstrual cramps. • After the initial vasoconstriction, the arterioles that serve the endometrium undergo vasodilatation; which results in bleeding. • Therefore, blood combines with the endometrial debris and creates the menstrual flow. Possible Symptoms Decreased estrogen and progesterone levels during the menstrual phase may also create the following symptoms: • Bloating, also known as water retention • Headaches • Nausea • Vomiting Proliferative Phase Proliferative phase lasts from approximately days 6-14. During this phase, estrogen begins to increase. • This causes the bleeding to stop. • The uterine walls begin to thicken. • Cervical mucus increases. During this phase, cervical mucus is clear and stretchy. It helps to channel sperm to the cervical opening. Ovulation, which usually occurs on about day 14 marks the end of the proliferative phase. Secretory Phase The secretory phase occurs during days 15-28. The uterus is generating an optimal environment for implantation of a fertilized egg. • Progesterone secreted from the corpus luteum increases. • This results in the uterine lining thickening and become more vascular. • Cervical mucus decreases. During this phase, cervical mucus becomes cloudy and thick. It helps protect the cervical opening from sperm and bacteria.

Implantation

The zygote then travels from the fallopian tubes to the uterus. In the uterus, the zygote attaches to the uterine lining. This process is referred to as implantation. Implantation provides protection and nourishment.

Cycles of the Female Reproductive System

There are two cycles of the female reproductive system: 1. Ovarian cycle- ovary function 2. Uterine cycle- uterus function