P.+REPRODUCTIVE+PHYSIOLOGY

=REPRODUCTIVE PHYSIOLOGY = =

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Pamela Wandry

OVERVIEW

The reproductive system is the most interesting system of the human body. Just think of it, all these things that go on inside our bodies with out us even realizing it and all of it happening with the ultimate goal of a new life. Sperm and eggs are produced in the testes and ovaries by a process call meiosis. Each one, the sperm and the egg, contain 23 chromosomes which makes them haploids. When fertilization occurs between a sperm and an egg they end up making a zygote that has 46 chromosomes which makes it a diploid. Each zygote gets 23 pairs of chromosomes from their mom and 23 pairs from their dad. Twenty-two of these pairs are autosomal chromosomes and the last pair are sex chromosomes. Males have one X chromosome and one Y chromosome, and females have two X chromosomes. The gender of a zygote is determined by the fathers sperm. Some of his sperm contain the X chromosome and some of them contain a Y chromosome. One of the X chromosomes in females becomes inactive and is then called a Barr body. For the first 40 days after conception all zygotes have similar gonads. Until testis-determining factor (TDF) is released to cause conversion into testes, gonads have the potential the become either ovaries or testes. The TDF is made by the sex-determining region (SRY) of the Y gene. Within 43-50 days after conception, the seminiferous tubules (STs) appear. STs are responsible for producing sperm in adults. The testosterone producing lydig cells appear about 65 days after conception. If there is no TDF present, ovaries will develop. Functional ovaries or ovarian follicles will appear around 105 days after conception. About 8 weeks along, testosterone secreting lydig cells start up and peak around 12 to 14 weeks along. After the peak the testosterone will reduce to very low levels until the individual reaches puberty. The testes don't descend into the scrotum until right before birth. Spermatogenesis needs a lower temperature then the temperature of the body. If the testes are not descended (cryptorchidism), spermatogensis will not happen. Male accessory sex organs, epidiymis, vas deferens, seminal vesicles, and ejaculatory ducts, come from wolffian ducts. The Uterus and fallopian tubes, female accessory sex organs, come from Mullerian ducts. Around days 25-50 the ducts are both present, permitting the female and male sex organs to start to develop.

ESSENTIAL QUESTIONS ** Describe the ovarian cycle and menstruation cycle. Describe what happens at each stage and the role of hormones. ** **.**

At approximately 11-13 years of age in an adolescent female, approximately 2 years after the start of breast development begins, there are changes in the hypothalamus of the brain that will allow an increased secretion of the hormone GnRH (gonadotropin releasing hormone), which will stimulate LH (luteinizing hormone) and FSH (follicle stimulating hormone) from the anterior pituitary. Therefore, puberty and menstruation first occurs due to the increased secretion of LH and thus FSH from the anterior pituitary gland. The increased pulsatile secretion of LH causes the ovaries to produce the sex hormone of estradiol-17B or estrogen, which will produce more of the characteristic body changes, such as, developed breasts, pubic hair, axillary air, and the growth spurt. In the female menstrual cycle there are two cycles that happen simultaneously, the ovarian cycle and the menstrual cycle.

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The menstrual cycle of every women varies greatly and for demonstration purposes of this assignment, our female subject will be on a 28 day cycle. In the follicular phase of the ovarian cycle,which lasts from day one to about day 14 (day one is the first day of menstruation), FSH stimulates the ova (egg) to develop in the ovary. As the ova matures, LH levels increase under the influence of estrogen (estradiol) and reaches its high point in the blood ( LH surge) about 16 hours prior to ovulation. In the ovulation phase, the increased surge of LH cause the egg to rupture out of the follicle on day 14 of the menstrual cycle. The follicle itself prior to ovulation had become very thin due to the influence of FSH, allowing the rupture to occur. Therefore, ovulation occurs because of the sequential efforts of both LH and FSH. The luteal phase is the phase that occurs after ovulation. The empty follicle that the egg erupted from is influence by LH to become a new structure called the corpus luteum. The corpus luteum now will secrete both estrogen and progesterone hormones. Progesterone levels will continue to rise in the body and will peak at approximately day 21 of the cycle. Progesterone is needed to maintain the uterine lining if the egg has been fertilized, so it can implant. It also works as a negative feedback mechanism and prevents the development of new follicles and thus, ensures that ovulation does not occur during this time frame. If pregnancy does not occur, the corpus luteum's excretion of progesterone and estrogen falls to very low levels (about day 28) and this withdraw of hormones causes menstruation to occur and also allows for a new follicle to begin to develop.
 * The Ovarian Cycle consists of the follicular phase, ovulation, and the luteal phase.**



The menstrual cycle is what changes are occurring to the endometrium of the uterus during the ovulation cycle. The proliferative phase (coincides with the ovarian follicular phase), the endometrium lining of the uterus is developing (thickening) due to the effects of estrogen that is being secreted by the growing follicle in the ovary. The secretory phase (coincides with the ovarian luteal phase), increasing progesterone secretion along with the effects of estrogen causes the endometrium lining of the uterus to become thick and spongy, and store glycogen in preparation for nourishing an embryo in case fertilization should occur. The menstrual phase takes place when no fertilization occurs or if the egg does not implant into the endometrium, and the ovarian hormones level drops, which will cause the endometrial lining to break down and be shed out of the body via route of the vagina. The menstrual cycle starts during the follicular phase. During this phase, the follicles are stimulated by FSH from the anterior pituatary gland in the brain. The follicle, then grows and secretes large amounts of estradiol (estrogen), it peaks at approximately day 13, and this peak stimulates the LH from the anterior pituitary gland in the brain. This positive feedback then will stimulate ovulation (release of an egg) at day 14. After ovulation has occurred, the empty follicle is stimulated by LH to become the corpus luteum (which will secrete progesterone and estrogen); when this occurs, the ovary is in the luteal phase of the ovarian cycle. The secretion of progesterone and estrogen increases and will provide a negative feedback control of FSH, LH, and GnRH secretion. Due to negative feedback (if no pregnancy occurs), the corpus luteum will regress, leading to a decrease in progesterone and estrogen secretion, when this occurs, the luteal phase comes to an end. The decrease in the progesterone and estrogen from the corpus luteum will cause the endometrium of the uterus to sloth off, resulting in menstruation. On the first day of menses, another egg is already being developed and preparing to start its own journey down the fallopian tube in approximately 14 days. Pamela Wandry
 * The Menstrual Cycle consists of a proliferative phase, secretory phase, and menstrual phase.**

When a girl is born they have about 2 million oocytes. Each one is in a ovarian follicle which is a hollow ball of cells. When puberty is hit, the girl will only have 400,000 left. 400 of these will go through ovulation and the rest will go through apoptosis. Primary follicles contain the primary oocytes that have not undergone the mitotic division. At first the primary follicles only have one layer of follicle cells. After FSH stimulation, some of the oocytes and the follicles will get bigger. Granulosa cells that fill the follicle and surround the oocyte are formed by the follicular cells dividing. Vesicles are formed when some of the primary follicles continue to grow. When this happens they are called secondary follicles. A mature or graafian follicle is formed when the secondary follicle continues to grow and fuses it's vesicles and forms an antrum or fluid filled cavity. There is a gelatin like fluid between the oocyte and the granulosa cells called zona pellucida which prevents penetration of sperm. About 10-14 days after the start of menstruation there will only be one surviving follicle. This surviving graafian follicle creates a bulge on the ovary and starts to secrete larger amounts of estrogen. When ovulation occurs, an egg is released into the uterin tube by the graafian follicle. If the oocyte is not fertilized it will simply degenerate. If the oocyte is fertilized meiosis II will occur and a polar body will be formed. A corpus luteum is formed from an empty follicle because of stimulation from LH. The corpus luteum secretes progesterone and estrogen and if it is not fertilized it will become nonfunctional remnant.

The mentral cycle is usually about 28 days, longer for some women and shorter for others. Menstruation is when the endometrial lining of the uterus is shed and the woman bleeds. The follicular phase is from day 1 to ovulation. The luteal phase is the time between ovulation and menstruation. Menstrual phase, proliferative phase, and secretory phases are when the changes in the endometrium happen. During the follicular phase a few of the primary follicles will make it to be secondary follicles but by the end only one follicle will survive and become a graafian follicle. Estradiol, which is secreted by the follicles as they are growing, it at its peak around day 12. The FSH, which is secreted from the anterior pituitary gland, heavily influence the follicular growth and their secretion of estradiol. It is thought that there is more FSH in the early part of the follicular phase then at the end of the phase. FSH receptors can be found in the granulosa cell because of FSH secretion. The follicles then gain more sensitivity to the FSH. Because of this the influence of the FSH and stay with the follicles even though the accual level of FSH does not keep increasing. In the later part of the follicular phase the FSH and esteradiol stimulate LH to be produced, which helps the graafian cell to be more prepared for the next phase. The hypothalamus increases GnRH because of the rise in estradiol and the rise in GnRH causes an increase in LH secretion. Positive feedback causes and LH surge. The LH surge is what stimulates ovulation to occur. After ovulation occurs, a corpus luteum is formed by LH from an empty follicle. The corpus luteum then secretes higher levels of progesterone and estrogen. During the luteal phase, the progesterone levels are at their highest about a week after ovulation takes place. If the corpus luteum is not fertilized it will just degenerate. This will cause the menstruation to begin and the whole cyle can start all over again. The endometrium undergoes many changes during menstration. These changes occur as a result of estrogen and progesterone levels. The proliferative phase happens during the follicular phase. At this time estrogen levels are increasing. The estrogen causes the endrometrium lining to thicken and allow sperm penetration because of the cervical mucus changing constistancy to thin and watery. The Secretory phase happens during the luteal phase. At this point the endometrium would be ready for an implantation. Progesterone causes the uterine glands to be developed and the cervical mucus to now become sticky and thick. Progesterone and estrogen cause a thickening of the endometrium. The last phase is the menstrual phase, in which the corpus luteums degeneration causes the progesterone and estrogen levels to decrease. This is also when the endometrium dies and is shed and is the end of the menstruation cycle and the whole thing starts all over again at the beginning.

SUMMARY

HUMAN SEXUAL RESPONSE Sexual response is similar in both male and female and is often divided into four phases: excitation, plateau , orgasm and resolution. __** THE EXCITATION PHASE AKA AROUSAL **__ __** THE PLATEAU PHASE **__ __** THE ORGASM PHASE **__ __** THE RESOLUTION PHASE **__ Attempts have been made to develop new methods of male contraception which include compounds that suppress gonadotropin secretion, such as testosterone or a combination of progesterone and a GnRH antagonist. Another is gossypol which interferes with sperm development. These drugs can be effective but have unacceptable side effects. The most widely used surgical procedure used for male contraceptive is a vasectomy. This is where each vas deferens are cut and tied or a valve or similar device is inserted. A vasectomy interferes with sperm transport but does not directly affect the secretion of androgens from Leydig cells in the interstitial tissue. Spermatogenesis continues but the sperm cannot be drained from the testes so the sperm accumulate in crypts that form in the sminiferous tubules, epididymis, and ductus deferens. The crypts present sites for inflammatory reactions in which spermatozoa are phagocytosed and destroyed by the immune system. Approximately 70% of men with vasectomies develop antisperm antibodies. These antibodies do not appear to cause autoimmune damage to the testes, but they do significantly diminish the possibility of reversing a vasectomy and restoring fertility.
 * Characterized by myotnia (increased muscle tone) and vasocongestion ( the engorgement of a sexual organ with blood), resulting in erection of the nipples in both male and female. This effect is more intense in females.
 * Clitoris swells and the labia minora swell to more than twice their previous size.
 * Vasocongestion of the vagina leads to secretion of fluid, producing vaginal lubrication, also causes considerable enlargement of the uterus and in women who breast-fed a baby, the breast may enlarge as well.
 * Clitoris becomes partially hidden behind the labia minora.
 * The erected nipples become partially hidden by continued swelling of the areolae(pigmented areas surrounding the nipples).
 * Pronounced engorgement of the outer third of the vagina produces the human sexual response called the "orgasmic platform".
 * Only lasts a few seconds.
 * The uterus and orgasmnic platform of the vagina contract several times. This is ejaculation in a male.
 * The body returns to preexcitation conditions.
 * Men enter a refractory period following an orgasmn which they may produce an erection but are not able to ejaculate.
 * Women lack a refractory period and are capable of multiple orgasms.
 * __MALE FERTILITY__ **
 * Approximate volume of semen for each ejaculation is 1.5 to 5 mL.
 * The bulk of semen (45% to 80%) is produced by the seminal vesicles, and 15% to 30% is contributed by the prostate.
 * Usually there are between 60 and 150 million sperm/mL of ejaculate.
 * A sperm concentration below around 20 million/mL is called oligospermia, meaning few sperm and is associated with decreasd fertility.
 * A sperm count below 50 million per ejaculation is clinically significant in male infertiity. Oligospermia may be caused by many factors that can be temporary or permanent. These include:
 * 1) Heat from a sauna or hot tub.
 * 2) Various pharmaceutical drugs.
 * 3) Lead and arsenic poisoning.
 * 4) Illicit drugs such as marijuana, cocain and anabolic steroids.
 * Some men and women have antibodies against sperm antigens, which is very common in men with vasectomies. Some antibodies do not appear to affect health, they do reduce fertility.

__** CYCLE CHANGES IN THE ENDOMETRIUM **__
Changes occur in the endometrium because the development of the endometrium is timed by the cyclic changes in the secertion of estradiol and progesterone from the ovarian changes in the endometrium. The three phases include:

__** THE PROLIFERATIVE PHASE **__ __** THE SECRETORY PHASE **__ __** THE MENSTRUAL PHASE **__ Amanda Rolstad
 * Occurs while the ovary is in it's follicular phase.
 * The increasing amounts of estradiol secreted by the developing follices stimulate growth of the stratum funtionale of the endometrium.
 * Coiled blood vessels called spiral arteries develop in the endometrium in humans and other primates.
 * Estradiol may also stimulate the production of receptor proteins for progesterone at this time which is preparation for the next phase.
 * Occurs when the ovary is in it's luteal phase.
 * Increased progesterone secretion stimulates the development of uterine glands where combined actions of estradiol and progesterone and the endometrium becomes thick, vascular, and spongy in appearance and the uterine glands become more engorged with glycogen following ovulation and is therefore prepared to accept and nourish an embryo if fertilization occurs.
 * Occurs as a result of the fall in ovarin hormone secretion during the late luteal phase.
 * Necrosis and sloughing of the stratum functionale of the endometrium may be produced by constriction of the spiral arteries.

APPLICATION

As a nurse I specifically would love to eventually work on the OB floor of a hospital. Something I would have to work with on a routine basis on the OB floor would be genetic screening of newborns. This is a relatively easy procedure as a nurse as it uses blood from a prick of the newborns foot. This single drop of blood can be used to test for many genetic disorders such as phenylketonuria, hypothyroidism, cystic fibrosis, hemoglobin disorders, among others. This simple test is very important in identifying these disorders for the early treatment and maintenance of the disorder to prevent further complications. Another important part of my job as an OB nurse could be umbilical cord blood banking. This is done to preserve the umbilical hematopoietic stem cells needed to replenish the blood cell forming ability of bone marrow that has been damaged. This is important especially for chemotherapy patients. If the cord blood is saved by the individual it limits the possibility of rejection after the procedure but the umbilical cord blood can also be donated which could save many more lives.

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CASE STUDY **[|What Happened to 28 Days?]**

=What Happened to 28 Days? A Clicker Case About the Human Menstrual Cycle= by
 * Tamar L. Goulet**, Department of Biology, University of Mississippi

Handout
Karen walked into the crowded café and looked around the room until she spotted her friend, Ann. Ann had found a table for two towards the back of the room. She was bent over the university newspaper as Karen approached her. “Hey! Here’s my favorite newlywed,” proclaimed Karen. Ann looked up from the paper and nodded a hello. Karen stared at her friend, her eyebrow slightly raised. “I know you’ve been married for two months, and hence the honeymoon is over,” she smirked, “but come on, it can’t be bad yet,” Karen half stated, half asked. “We’re fine,” Ann mumbled softly. “Then why the long face?” asked Karen. “Having a hard time in one of your courses?” she suggested. “No,” sighed Ann. “I’m doing really well in my courses, and it’s nice to come home and be with John,” said Ann as she gazed at her wedding ring. “Sooo…?” asked Karen. Ann looked straight at Karen. Karen thought she could read confusion and panic in Ann’s strained face. “I’m late,” blurted out Ann. “Is there any way I could be pregnant?” “Well… you are married, to the man you love, birds and bees, that sort of thing… I guess that means you could be,” stated Karen. “When were you, umm, guys together?” asked Karen. “It’s called sex,” said Ann rolling her eyes. “Since when have you been shy around me? The thing is we have not had sex a lot this month. John went to a meeting, and we want to start taking precautions because we want to be married for a while and finish school before we start our family. So, in the last month we really only had sex once and that was, I think, in a ‘safe’ part of my cycle.” “Did you use some form of protection that one time?” asked Karen as she leaned closer to Ann. “Well, no,” replied Ann. “I told you, I thought it was safe. It was on day 16 of my cycle. So there is no way, right?” Karen looked at her friend. “What?” asked Ann. “You’re the biology major. You’ll tell me there is no way, right?” Karen pulled out a sheet of paper from her notebook. “I need to ask you a few questions,” Karen said.

Questions
Are you sure of the date when your menstrual cycle started?
 * 1) If you were Karen, what questions would you ask?

Do you know that the safe part of your cycle can vary by 1-2 days?

Do you know that the first day of your menstrual cycle is actually the first day of your period?

What was the date you started your period?

How long is your menstrual cycle?


 * 1) Ask a friend who is not taking hormonal birth control how long her menstrual cycle is. Bring the answer to class.

My friend's menstrual cycle is 28 days long.

For the power point, I answered the questions at the bottom where you can add notes in each of the slides.

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