Week 16: Reproductive System
Match the structure at the left with the appropriate description at the right. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
1. A Pap smear is a test for detecting cancer of this structure: Cervix 2. Milk produced by the mammary glands drains into these structures: Lactiferous ducts 3. This structure supports the internal female reproductive organs in the pelvic cavity: Broad ligament 4. The corpus spongiosum in the penis is homologous to this structure: Vestibular bulbs 5. The vaginal and urethral openings are located in this region: Urogenital triangle 6. These structures provide support for the mammary glands: Suspensory ligaments
Match the structure at the left with the appropriate description at the right. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
1. In addition to the urethra, this muscular duct travels through the prostate gland: Ejaculatory duct 2. Spermatozoa become functionally mature while in this structure: Epididymis 3. This structure has a urinary and reproductive function: Urethra 4. The corpus spongiosum is found in this structure: Penis 5. Interstitial (Leydig) cells, found in this structure, produce testosterone: Testis 6. This structure transports sperm cells from the epididymis to the ejaculatory duct: Ductus deferens 7. This two-chambered structure contains the testes: Scrotum 8. Secretions from this structure are a component of semen: Seminal gland
Match the structure at the left with the appropriate description at the right. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
1. This structure passes posterior to the urinary bladder and urethra, and anterior to the rectum: Vagina 2. Fertilization usually occurs in the ampulla of this structure: Uterine tube 3. Like the penis, this structure has corpora cavernosa: Clitoris 4. This structure encloses the vestibule: Labia minora 5. During fetal development, primordial follicles are produced by this structure: Ovary 6. The vaginal and urethral openings are located in this region: Vestibule
Exercise 32 Review Sheet: The Female Reproductive System
Both the male and female reproductive systems develop from similar embryonic tissue. In fact, during the first few weeks of development, male embryos are indistinguishable from female embryos. As development proceeds, however, two distinct and special organ systems form. The male reproductive system contains a pair of testes, accessory ducts and glands, and external genitalia, which include the scrotum and penis. The female reproductive system contains a pair of ovaries and uterine tubes, a uterus, vagina, and external genitalia, which include the labia majora, labia minora, vestibule, and clitoris.To complete this Review Sheet, please complete the questions and activities below.
My doctor explained that Clomid works by "tricking the brain into thinking that estrogen levels in the body are low." She explained that this is what leads to the extra stimulation of the ovaries to encourage eggs to be released. One of the references for Clomid said this happens because there is less negative feedback. Can you explain to me how this "trick" and the decreased negative feedback are related? Why would these factors lead to the stimulation of the ovaries?
Clomid interferes with the ability of the hypothalamus and pituitary gland to measure the rising estrogen levels that occur during the menstrual cycle. During the normal cycle the rising estrogen levels produce negative feedback, which leads to a drop in LH and FSH levels. Clomid prevents this from happening, so LH and FSH levels remain high. The elevated levels of gonadotropins stimulate the ovaries and promote follicle development.
Angela is curious about how Clomid works to stimulate her ovaries. Her doctor told her that this drug works by "tricking the brain into thinking that the levels of estrogen in the body are low." Which of the following statements help explain why this would lead to a stimulation of the ovaries?
Clomid prevents estrogen from exerting negative feedback, so LH and FSH levels remain high and continue to stimulate the ovaries.
My doctor also explained that birth control pills "trick the body into thinking it is pregnant." She explained that women do not normally ovulate when they are pregnant. Can you explain to me why a pregnant woman does not ovulate? How is this related to how the birth control pill works?
During a pregnancy, the placenta produces estrogen and progesterone. The levels of these hormones rise throughout the pregnancy and help to maintain the uterus and prepare the mammary glands for lactation. These hormones produce negative feedback which leads to the inhibition of the release of gonadotropins from the pituitary. The low levels of LH and FSH mean that no new follicles can develop during the pregnancy. Birth control pills produce levels of estrogen and progesterone in the body that mimic this effect.
My doctor told me that if I take Clomid, I would be taking it on days five through nine of my normal menstrual cycle. She explained that this is when it will have the greatest chances of stimulating the ovaries. What is going on during this part of the menstrual cycle that would makes it the best time to take this drug?
During days five through nine of the menstrual cycle, the rising estrogen levels are exerting negative feedback on the hypothalamus and anterior pituitary. This would normally lead to a drop in LH and FSH levels. By taking Clomid during this time, this negative feedback can be reduced and LH and FSH levels can remain high to stimulate the ovaries. This stimulation leads to the development of mature follicles.
In the information about Ortho Tri-Cyclen, it mentions that the hormones in the pill make cervical mucus thicker and stickier. Does this happen during my natural cycle? How are estrogen and progesterone involved in this process?
During the normal menstrual cycle, the viscosity of the cervical mucus changes under the influence of estrogens and progesterone. During the first 14 days of the cycle, the rising estrogen levels cause the mucus to become thin and watery. This change helps to facilitate the passage of sperm through the cervical canal. The rising progesterone levels during the second 14 days cause the mucus to thicken again.
Angela's doctor instructed her to take Clomid on days five through nine of her cycle. Which of the following best explains why this would be the ideal time to take this fertility drug?
During this time of the normal menstrual cycle, rising estrogen levels are producing negative feedback and a drop in LH and FSH levels. Clomid prevents this from happening.
What is the role of estrogen on luteinizing hormone (LH) production?
Estrogen may have either an inhibitory or an excitatory effect on LH production depending on the overall estrogen levels. Estrogen exerts negative feedback on LH production until estrogen levels reach a certain concentration, and then estrogen exerts positive feedback on LH production, which promotes ovulation.
After DNA replication, each individual chromosome becomes a homologous pair.
False After DNA replication, each chromosome is composed of two sister chromatids.
Some of the references talk about how "negative feedback" is involved in understanding how these drugs work. Can you explain what is meant by negative feedback?
Feedback makes reference to the idea that the output of a system "feeds back" to influence the input of that same system. A frequently used example is the thermostatic control of the temperature of a house. As the temperature falls inside the house, the thermostat measures the drop and sends a signal to the furnace to turn on. The result is that the temperature of the house begins to rise. In negative feedback, the effect on the input is that it will reverse the direction in which the variable is changing. In the house example, the dropping temperature begins to rise.
Define the following terms. Match each key term to the appropriate description. Make certain each sentence is complete before submitting your answer.
Gametogenesis: the process by which sperm and ova are formed Fertilization: the union of an ovum and sperm to produce a zygote Spermatogenesis: the process of developing many haploid sperm Oogenesis: the process of developing the ova Diploid: a cell that contains two sets of chromosomes Haploid: a cell that contains one set of chromosomes Zygote: the diploid fertilized ovum Gamete: sex cells AKA sperm and ova Spermiogenesis: the process by which sperm mature and develop Meiosis: a special type of cell division that produces 4 haploid gametes
What is the role of the granulosa cells in the ovarian cycle?
Granulosa cells guide the development of the oocyte. Granulosa cells are directly connected to the oocyte by gap junctions, allowing for direct communication between the oocyte and granular cells. These cells guide each other's development.
My doctor told me that birth control pills contain small amounts of estrogen and progesterone, and these hormones prevent me from ovulating. I don't understand how giving me these hormones in a pill would prevent me from ovulating. I assume that this has something to do with the levels of the gonadotropins that I asked about earlier. Can you explain this to me?
In female reproductive physiology, estrogen and progesterone levels have an effect on the output of the gonadotropins-this is an example of a negative feedback system. When estrogen and progesterone levels rise, they inhibit the release of the two gonadotropins from the pituitary. The birth control pill takes advantage of this effect by causing blood levels of estrogen and progesterone to rise so that they inhibit gonadotropin release. Without sufficient gonadotropin release, the gonads are not stimulated. In the case of female reproductive physiology, this means that follicles will not develop and release an egg.
Which of the following is an effect of luteinizing hormone (LH) after ovulation?
It maintains the corpus luteum. LH maintains the corpus luteum. Increased levels of estrogen promote the release of LH at ovulation, but the increased levels of progesterone after ovulation inhibit the release of LH, which causes the degradation of the corpus luteum.
What is the fate of the corpus luteum if pregnancy occurs?
It secretes progesterone and some estrogen for about three months. If pregnancy occurs, the corpus luteum prevents another menstrual cycle by releasing progesterone and estrogen until the placenta can take over and maintain those hormone levels.
Match the female reproductive structures with their functions. Match each key term to the appropriate description. Make certain each sentence is complete before submitting your answer.
Labia: Enclose and protect external reproductive structures Greater vestibular gland: Secretes mucus to lubricate vaginal opening Uterus: Houses developing embryo/fetus Vestibule: Recess containing external openings of vagina and urethra Uterine tube: Moves oocyte or fertilized ovum toward uterus Vagina: Copulatory organ; birth canal Ovary: Produces oocytes and female sex hormones Clitoris: Erectile tissue
Which is true of linked genes?
Linked genes tend to be inherited together unless crossovers occur. Linked genes occur on the same chromosome, so they would be passed on together unless separated by crossovers.
Match the male reproductive structures with their functions. Match each key term to the appropriate description. Make certain each sentence is complete before submitting your answer.
Penis: Copulatory organ Ductus deferens: Stores sperm; moves sperm to the ejaculatory duct Epididymis: Stores sperm; moves sperm to the ductus deferens Ejaculatory duct: Transports sperm from the ductus deferens to the urethra Bulbourethal gland: Secretes mucus to lubricate glans penis Urethra: Transports semen out of the penis Scrotum: Houses the testes Seminal vesicle: Produces alkaline secretion with nutrients and prostaglandins Prostate gland: Secretes slightly alkaline substances with anticoagulants Testis: Produces sperm and testosterone
Match these vocabulary terms to their meanings.
Reproductive organs that produce eggs and sperm are called gonads. Mammary ducts secrete milk in the lactating breast.. The structure formed when an ovum and sperm join together is a(n) zygote. A procedure that removes the prepuce from around the tip of the penis is called circumcision. circumcision returned
An ectopic pregnancy occurs when the early embryo implants at a location outside the uterus. A common site for an ectopic pregnancy is in a uterine tube. Identify a situation that could explain how this happens.
Scar tissue due to tubal infection prevents movement of the embryo.
Choose the statement that correctly describes reproductive tract anatomy in males.
The ejaculatory duct conveys semen into the prostatic urethra.
Match these vocabulary terms to their meanings.
The endometrium is the nutritive layer of the uterus prepared for the possibility of a fertilized egg. The labia minora are the lips that enclose the vestibule of the female external genitalia. The acrosome is the structure at the tip of a sperm that contains enzymes to gain access to an egg during fertilization. Stem cells that give rise to sperm are spermatogonia. The middle embryonic germ layer that forms everything except the epidermis of the skin, nervous system, and epithelial linings and glands is the mesoderm.
Which of the following differentiates the follicular and luteal phases of the ovarian cycle?
The follicular phase occurs directly before ovulation, and the luteal phase occurs directly after ovulation. The follicular phase is the period in which the dominant follicle prepares for ovulation and secretes large amounts of estrogen. The luteal phase occurs after ovulation as the corpus luteum secretes progesterone and some estrogen.
Which of the following explanations would help Angela understand how the birth control pill helps prevent her from ovulating?
The hormones in the pill produce negative feedback, which leads to a drop in FSH levels.
If one or both testes do not complete the migration into the scrotum and remain in the abdominal cavity, they must be surgically moved into the scrotum. If the testes remain in the abdominal cavity, what will be the result?
The individual will be sterile because body temperature is too high for viable sperm production.
Angela is confused by the statement her doctor made about how the birth control pill "tricks the body" into thinking it is pregnant. Which of the following pieces of information would help her better understand why pregnant women do not ovulate?
The placenta of a pregnant woman produces estrogen and progesterone. These hormones exert negative feedback, which leads to a reduction of LH and FSH levels.
Exercise 31 Review Sheet: The Male Reproductive System
The reproductive system is unique to all other organ systems in the body because it is not necessary for the survival of the individual, but its activities are absolutely required for sustaining the human species. Unlike other organs that are functional throughout life, the reproductive organs are inactive until puberty. At this time, which normally occurs between 11 and 15 years of age, the reproductive organs respond to increased levels of sex hormones by growing rapidly and becoming functionally mature structures. In males, the sex hormones are called androgens. The primary androgen is testosterone. In addition to its role in the development and maturation of male sex organs, testosterone also stimulates the growth of bones and skeletal muscle and affects the development of the central nervous system. To complete this Review Sheet, please complete the questions and activities below.
Match these prefixes, suffixes and roots to their meanings.
The root word gon- means "reproductive." The root word zyg- means "joined together." The root word lact- means "milk." The root word circum- means "around."
In my research, I found that the levels of "gonadotropins" in the body are critical to understanding how the drugs Clomid and Ortho Tri-Cyclen work. What are gonadotropins? What role do they play in fertility?
The two gonadotropins are luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones are released from the pituitary gland under the influence of gonadotropin-releasing hormone (GnRH) that is produced by the hypothalamus. LH and FSH are called gonadotropins because they stimulate the gonads.
What would happen if fertilization occurred normally, but the corpus luteum did not produce progesterone?
The uterine lining will shed its functional zone.
Predict what might happen if the broad ligament and other supporting ligaments were damaged by infection or injury.
The uterus would prolapse or displace in a downward direction.
Match these prefixes and suffixes to their meanings.
The word root meso- means in the middle or intermediate. The word root labio- means lips. The word root acro- means end, tip, or height. The word root sperm- means seed or sperm. The word root -metrium means layer of the uterus.
I read an article that mentioned that women on Clomid may be more likely to get pregnant with twins, triplets, or more! The article said that normally there is a dominant follicle that releases a single egg, but Clomid can potentially make lots of follicles release an egg in a given month. How does Clomid do that?
Under the influence of rising LH and FSH levels, several follicles are allowed to develop further at the start of the normal menstrual cycle. Not all of these follicles are in the same stage of development. The more mature follicles begin producing estrogen. As estrogen levels rise, negative feedback leads to a reduction in LH and FSH levels. Follicles rely on a steady supply of FSH in order to continue their development. As FSH levels begin to fall, only the most mature follicles can continue to develop because of their increased sensitivity to this hormone. The less mature follicles will begin to degenerate. Eventually, a single "dominant" follicle is all that remains and it will continue to develop. Clomid reduces the negative feedback that normally leads to a drop in LH and FSH levels, so even the less mature follicles can continue their development. This leads to the possibility of multiple eggs being released and increases the risk of multiple births.
Clinical Case Study: Angela's Story: A Case on the Reproductive System
You are a columnist for a popular website that deals with women's health issues. Visitors to the site can submit their stories and questions through an "Ask the Expert" link on the site. In this scenario, a 26-year-old woman has posted her story and some questions regarding reproductive health.My name is Angela. I am a 26-year-old married woman with no children. My husband, Doug, and I have been trying to get pregnant for over two years now and my doctor has suggested that I consider fertility drug treatments. The irony of our situation is that I have been taking a birth control pill for five years to prevent getting pregnant, and now my doctor suggests that I take another drug to help me get pregnant. When I went off birth control about a year ago, my menstrual cycle became very irregular. I had been taking a birth control drug called Ortho Tri-Cyclen. To be perfectly honest, I don't understand how it works because my periods were more regular when I was on the pill than when I went off of it. My doctor told me that the pill works because it tricks your body into thinking that it is pregnant. That just confused me even more. When I looked back on my decision to take birth control pills, I realized that I did not really understand how they work. I just do not want to make that mistake again. Before I consider taking any more drugs, I want to understand more about how they work. The drug we're looking into is called Clomid. I asked my doctor a bunch of questions, but I still feel confused. I looked up some stuff online when I got home. Here is some information that I learned from a website about how Ortho Tri-Cyclen works: Estrogen and progestin work in combination to suppress the hypothalamic-pituitary-gonadal (HPG) axis. This suppression leads to a decrease in the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus and luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary. Maturation of the dominant follicle is inhibited under the decreasing levels of FSH and LH. Hormonal contraceptive use also leads to an an increase in the viscosity of the cervical mucus, which inhibits sperm penetration and movement through the cervical canal. I am hoping that you would be able to help me understand how these drugs actually work.
Which of the following is NOT produced by meiosis?
a liver cell Liver cells are somatic cells, and they are all produced by mitosis, not by meiosis.
At which point in the uterine cycle are the ovarian hormone levels at their lowest?
at the beginning of the menstrual phase The ovarian hormone levels are lowest at the beginning of the menstrual phase. Their low levels are what trigger menstruation.
When does ovulation occur in the uterine cycle?
at the end of the proliferative phase A surge in luteinizing hormone triggers ovulation at the end of the proliferative phase of the uterine cycle, around day 14.
During cellular division, the replication of DNA occurs __________.
before mitosis and meiosis I Replication must occur before mitosis, which includes the separation of sister chromatids. Replication must occur before meiosis so that sister chromatids can be separated in meiosis II. Replication does not occur between meiosis I and II.
Besides causing genital warts, human papillomavirus (HPV) has been associated with what type of cancer?
cervical
When does the total number of chromosomes get reduced from 46 pairs to 23 individual chromosomes?
during meiosis I Chromosome pairs are separated during anaphase I, and this first division is called the "reduction division."
Pelvic inflammatory disease (PID) associated with untreated gonorrheal infections results in fallopian tube scarring and infertility. What other disorder would a female with PID be at high risk for?
ectopic pregnancy
Angela has a question about the levels of gonadotropins in the body. Which of the following hormones are considered gonadotropins?
follicle-stimulating hormone and luteinizing hormone (LH)
Meiosis starts with a single diploid cell and produces
four haploid cells.
Which of the following is a likely result of meiosis?
four sperm, each with 23 chromosomes
During prophase I of meiosis,
homologous chromosomes stick together in pairs.
A cell preparing to undergo meiosis duplicates its chromosomes during
interphase
Which hormone is most responsible for triggering ovulation?
luteinizing hormone (LH)
During what stage of meiosis do chromosomes align on the spindle equator in homologous pairs?
metaphase I Homologous chromosomes form tetrads in prophase I and align on the spindle equator as homologous pairs in metaphase I.
How many possible combinations of zygotes could theoretically occur between the same parents?
more than 70 trillion When considering the number of chromosome combinations due to independent assortment and the possibility of random fertilization, the number of possible zygote combinations is well over 72 trillion. This does not include the increased variation due to crossovers.
Chromosomes can exchange genetic information during a process called "crossing over." This occurs when homologous chromosomes are lined up in pairs. When does this happen?
prophase I
The correct order of events during meiosis is
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.
During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?
prophase I.
When do chiasmata form?
prophase or metaphase of meiosis I Chiasmata can occur only when homologous chromosomes synapse. This occurs only during prophase and metaphase of meiosis I.
Which of the following is NOT a reason for genetic variation within the human population? -the random fertilization of eggs by sperm -the exchange of genetic material between chromatids in meiosis I -the random arrangement of homologous chromosomes during metaphase of meiosis I -the different numbers of maternal and paternal chromosomes an individual may inherit
the different numbers of maternal and paternal chromosomes an individual may inherit A healthy zygote contains 23 pairs of homologous chromosomes. One chromosome from each homologous pair comes from the mother, and the other comes from the father, so every individual has 23 maternal and 23 paternal chromosomes.
Why do chiasmata form during meiosis?
to form gametes that are genetically unique Unlike mitosis, meiosis has the purpose of producing haploid cells that are all genetically unique. Chiasmata form and genetic material is exchanged between chromatids of homologous chromosomes to provide genetic variation in each daughter cell.
What is the purpose of meiosis?
to produce haploid reproductive cells Meiosis occurs in order to produce haploid gametes that can join via sexual reproduction. Gametes can then join to make a new diploid cell that contains a combination of the parents' genetic material.
