A&P2 module6

The Uterus

The uterus is a hollow, thick-walled muscular organ shaped like an inverted pear connecting the uterine tubes and vagina, and it is in a forward-tilted position between the bladder and rectum (Figure 6.1, Figure 6.5). The uterus has three layers: the outer serous perimetrium, middle muscular myometrium, and inner glandular endometrium. The muscular myometrium expands during pregnancy to hold the growing fetus and contracts during labor to push the baby out of the uterus. The inner endometrium layer is where the embryo completes development. The inner layer is shed monthly (~28 days) if the female is not pregnant, which is known as menstruation or menses. Figure 6.5 Anterior view of the uterus (blue) in context with the duct system and pelvis. Note the uterus is located centrally, protected by the pelvic bones. The uterus can be divided into three regions: fundus, body, and cervix. The upper part of the uterus is the fundus, the height of which can be measured from the top of the pubic bone during pregnancy to provide growth rates and a crude indication of an abnormality (breech presentation or twins). The middle section, the body (Figure 6.6), receives the fertilized ovum, where it becomes implanted in the endometrium to receive nourishment and develop from ovum to embryo to fetus and gestate until childbirth (Figure 6.6). The lower portion of the uterus, the cervix, connects the uterus to the vagina and changes in size and texture (Figure 6.6). Just prior to ovulation, the cervix swells, softens, and secretes mucus, allowing sperm better access to and viability within the uterus. When a female becomes pregnant, a mucus plug develops in the cervix and prevents any bacteria or pathogens from entering the uterus, thus protecting the health of the developing fetus. A firm, closed cervix also holds the developing fetus in the uterus until it reaches full term. Figure 6.6 Posterior view of the uterus and vagina. The vagina is faded so the cervix (blue) portion of the uterus can be viewed.

A breastfeeding mother becomes pregnant with another child. The pediatrician recommends that she supplement her nursing child with formula. Explain why this recommendation was made

This was recommended because milk will not be produced during pregnancy. Estrogen and progesterone stops milk production

What is the term used to describe the production of sperm and how long does this take?

Spermatogenesis is the production of sperm and it can take between 64-72 days.

Name the three types of ligaments associated with the ovaries and the function of each.

1. Broad ligaments- holds/keeps the ovaries in place in the pelvis 2. Ovarian ligaments- these attach the ovaries to the uterus 3. suspensory- attaches the ovaries to the pelvis wall.

Match the description with its corresponding structure. Structure:

1. Cervix - H. Protects fetus from bacteria 2. Fallopian tube- A. Captures egg during ovulation or e. fertilization site 3. Fundus- M. Upper part of uterus 4. Isthmus-D. End of oviduct closest to uterus

List 3 functions of the female reproductive system. Three functions are:

1. being the developmental site of a baby after egg fertilization occurs. 2. Producing eggs 3. Producing estrogen

The Female Reproductive System 16. What is the function of the mucosal lining in the vaginal wall?17. The _____ is a fat pad located in front of the pubic symphysis and is covered with hair after puberty.18. The _______is an outer fold of skin that is located posterior to the mons pubis.19. The urethral orifice is located ________ the vaginal orifice.20. Describe the structure of the mammary glands21. Is milk produced during pregnancy?22. What is colostrum?23. What is oogenesis?24. Describe the steps of oogenesis from primary oogonia to a mature ovum.25. What is the function of estrogen and progesterone?26. What are the three phases of the menstrual cycle?27. What is contained in the menstrual flow?28. Describe the proliferative phase.29. Describe the secretory phase.

16. The mucosal lining of the vagina lies in folds and can extend which is important when the vagina serves as the birth canal and it also facilitates intercourse.17. Mons pubis18. labia majora19. anterior to20. A mammary gland contains one to two dozen lobules, each with its own mammary duct. The duct begins at the nipple and divides into numerous other ducts ending in blind sacs called alveoli. In a non-lactating breast, the ducts far outnumber the alveoli since alveoli are made up of cells that can produce milk.21. Milk is not produced during pregnancy because prolactin is needed for lactation (milk production) to begin. Prolactin is suppressed by estrogen and progesterone.22. A yellowish-white fluid which has a similar composition to milk but contains a higher concentration of protein23. Oogenesis is the production of eggs in the ovaries which occurs during development of the fetus in the womb and is complete by the time of birth.24. Oogonia (Female stem cells), undergo mitotic division into two daughter cells known as primary oocytes. These primary oocytes are covered by follicles, known as primary follicles. This process is completed by birth. The anterior pituitary gland starts to secrete follicle-stimulating hormone (FSH) when a female reaches puberty. FSH causes a few follicles to mature each month. The primary oocyte in the follicle undergoes its first meiotic division into two daughter cells: the secondary oocyte and the first polar body. If the secondary oocyte is united with a sperm after ovulation the second meiotic division occurs which produces a second polar body and an ovum with 23 chromosomes.25. Estrogen is important in the production of eggs and the menstrual cycle. It is also responsible for secondary sex characteristics. Progesterone is necessary for the maintenance of pregnancy but does not promote secondary sexual characteristics.26. the menstrual phase, the proliferative phase, and the secretory phase.27. detached tissue of the endometrium and blood28. The proliferative phase occurs during days 6-14 as the endometrium rebuilds in response to increasing estrogen levels. Ovulation of an egg typically occurs in the ovaries on day 14. Ovulation is triggered when the anterior pituitary (in the brain) releases luteinizing hormone (LH) as a response to high levels of estrogen.29. During this phase the corpus luteum begins to secrete progesterone. Progesterone causes an increased blood supply in the uterus and secretion of nutrients, preparing the uterus for implantation. If fertilization has not occurred, the corpus luteum dies and the endometrium blood supply decreases because of decreased progesterone which begins the menstrual phase again.

30. Describe the structure and function of the testes.31. Where is the site of sperm maturation?32. What would happen if the testes do not descend into the scrotum?33. What is the length of sperm maturation? Why?34. What is the site where the vas deferens enters the abdomen?35. What is the ejaculatory duct?36. What is a vasectomy?37. The fluids of the semen are contributed by what three glands?38. What is semen?39. Discuss the function of the antibiotics found in semen.40. What do the seminal vesicles contribute to the contents of semen?41. What does the prostate gland contribute to the contents of semen?42. What do the bulbourethral glands secrete?43. Describe the formation of sperm from spermatogonia.44. Describe the parts of a mature sperm.45. What is the purpose of the hormone testosterone?

30. The testes have the function of sperm and testosterone production. Testosterone is a hormone produced by the interstitial cells inside the connective tissues. Each testis has hundreds of lobules and each lobule contains several seminiferous tubules where the site of sperm production takes place.31. The epididymis32. If the testes do not descend into the scrotum, gametes may not be produced because sperm production requires an environment cooler than body temperature.33. Maturation for about 20 days is required for the sperm to gain the ability to swim.34. inguinal canal35. The ejaculatory duct connects with the urethra to provide a means for the sperm to exit the body.36. A vasectomy can be performed as a permanent form of birth control. In this procedure, the vas deferens is cut and tied off which permanently prevents sperm from exiting the body to fertilize an egg.37. The seminal vesicles, the prostate and the bulbourethral glands38. A thick, whitish fluid that contains sperm and accessory gland secretions.39. It kills any bacteria in the male urethra or female reproductive system which would kill the sperm to kill any bacteria in the urethra which would kill the sperm.40. The seminal vesicles secrete a thick, viscous fluid containing nutrients (fructose, vitamin C, and prostaglandins) for use by the sperm.41. It secretes a milky alkaline fluid helping to increase the motility of the sperm.42. The alkaline mucus secreted by the bulbourethral glands clears and neutralizes the acidity of any urine inside the urethra.43. Sperm are formed from spermatogonia in the seminiferous tubules located in the testes. The spermatogonia are stem cells that go through mitotic divisions (with 46 cells each) beginning at birth until puberty. Once a male enters puberty his anterior pituitary gland begins to secrete follicle stimulating hormone (FSH). When FSH is secreted the spermatogonia undergo cell division; one of the cells continues the stem cell line. The other cell, known as the primary spermatocyte, undergoes meiosis. Meiosis produces four gametes with (with 23 chromosomes each) known in the male reproductive system as spermatids. All four spermatids become viable gametes.44. The head is almost entirely nucleus containing the cell DNA with a crown called the acrosome which contains enzymes that breakdown the membrane of the egg to allow the sperm to penetrate. The midpiece contains numerous mitochondria that generate the locomotive energy needed by the sperm. The tail is a typical flagellum which is used to propel the sperm through the female reproductive tract.45. Testosterone stimulates the sex drive and growth in males. It also stimulates secondary sex characteristics such as broad shoulders, deep voice, increased muscle size and bone density, and increased hair.

Enter the correct fetal trimester with each development process listed below.

3rd trimester fetus regulates its own body temperature 1st trimester brain, spinal cord, and limbs begin to form 2nd trimester mother typically begins to feel fetal movement

Sexual Reproduction, Pregnancy and Fetal Development46. Why are offspring different from their parents?47. What is a haploid cell? A diploid cell?48. What is meiosis?49. How many chromosomes does a zygote contain?50. What determines the sex of the developing fetus?51. What is the corona radiata?52. How long are male and female gametes viable?53. Describe the order of development from a fertilized egg to a fetus.54. The presence of _____ in urine will result in a positive pregnancy test taken at home.55. Describe the supportive cells formed in the blastocyst.56. The skin and nervous tissue develop from the ----------- layer of the blastocyst.

46. In sexual reproduction, the offspring inherits half its genes from one parent and the other half from the other parent. Therefore, an offspring has a different combination of genes than either parent. In this way, variation is introduced and maintained.47. A diploid cell is found throughout the body containing 46 chromosomes. A haploid cell is a gamete cell containing 23 chromosomes.48. During meiosis, gametes divide to form four gametes each with only half of the chromosomes needed (23).49. 46 (full number for human development)50. Sex is also determined by the chromosomes. Males have one X chromosome and one Y chromosome. Females have two X chromosomes.51. Follicle cells surrounding the egg52. Sperm are viable for 3-5 days after ejaculation, depending on the environment, and an egg can survive for up to 24 hours after ovulation.53. The zygote (fertilized egg) spends about three to four days undergoing mitosis in the oviducts forming the morula and another three to four days undergoing mitosis while unattached in the uterus, forming the blastocyst as the endometrium prepares for implantation. Upon implantation some cells in the blastocyst begin to develop into three layers which become the embryo. By the end of week eight the embryo is considered a fetus.54. HCG (human chorionic gonadotropin)55. Other cells of the blastocyst form supportive cells for embryonic function: the amnion, placenta and umbilical cord. The amnion forms a sac filled with fluid to cushion and protect the fetus. The placenta is a temporary organ that carries out nutritive, respiratory, excretory and endocrine functions for the embryo. The baby continues to grow in the uterus with nutrition provided by the placenta for nine months until it is time for delivery. The umbilical cord attaches the embryo to the placenta.56. Ectoderm

Sexual Reproduction, Pregnancy and Fetal Development 57. The inner endoderm layer forms the _________.58. The cardiovascular system develops from what layer of the blastocyst?59. Describe the steps of the formation of the neural tube.60. What supplement is recommended to prevent neural tube defects?61. Around what week does the heart begin to have blood flow?62. During what trimester do fingerprints develop?63. What trimester do the testes descend into the scrotum?64. What causes the cervix to dilate during labor?65. What is the second stage of labor?66. What is the third stage of labor?67. What stage of labor is the longest?68. Review all figures in the module.

57. The inner endoderm layer forms the glands (thyroid, parathyroid and thymus), solid organs (liver and pancreas) and the lining of the hollow organs of the digestive and respiratory systems.58. Mesoderm59. The lateral sides of the ectoderm move together (convergence) forming the epidermis superficially. The neural fold forms underneath the epidermis, becoming the neural crest. The neural plate becomes the neural groove and then finally the neural tube once convergence is complete. The anterior portion of the neural tube becomes the brain and the rest forms the brainstem and spinal cord.60. Folic acid61. Week 362. 2nd trimester63. 3rd trimester64. The uterus contracts, which pushes the baby's head against the cervix causing it to dilate (widen).65. Delivery of the baby66. Delivery of the placenta67. Dilation of the cervix68. See figures in module

Mammary Glands

A mammary gland (female breast tissue) contains one to two dozen lobules, each with its own mammary duct (Figure 6.9). The duct begins at the nipple and divides into numerous other ducts ending in blind sacs called alveoli. In a non-lactating breast, the ducts far outnumber the alveoli since alveoli are made up of cells that can produce milk. Milk is not produced during pregnancy because prolactin is needed for lactation (milk production) to begin. Prolactin is suppressed by estrogen and progesterone. A few days after delivery, milk production begins. Prior to milk production, the breasts produce a watery, yellowish-white fluid called colostrum, which has a similar composition to milk but contains a higher concentration of protein. Figure 6.9 Internal view of a mammary gland, with the lobules highlighted in blue.

Vaginal Canal

A small opening at the cervix leads to the vaginal canal (Figure 6.7). The vagina is an elastic muscular tube that leads from the cervix of the uterus to the outside of the body. The vaginal wall consists of an inner tissue layer, intermediate muscle layer, and outer tissue layer. The wetness and moisture of the vaginal surface is achieved by mucous from the cervix. The outer layer is made of elastic fibers, blood vessels, lymph vessels, and nerves. The elastic fibers give the vaginal wall its strength and elasticity. The mucosal lining of the vagina lies in folds and can extend, which is important when the vagina serves as the birth canal, and it also facilitates intercourse. The vagina has several functions: It receives the male penis during sexual intercourse, provides the outlet for menstrual blood during menstruation, and serves as the birth canal for a baby. Figure 6.7 Lateral view of the vaginal canal (vagina, in blue).

What cell is produced by union of a human egg and a human sperm cell and how many chromosomes does it possess?

A zygote cell is formed and it will have 46 chromosomes.

A pregnant woman is experiencing sudden sharp groin pain, based upon location of her symptoms, which of the following ligaments is being affected? a. Broad ligament b. Uterosacral ligament c. Round ligament

C

What is the identity and source of the substance that causes a positive home pregnancy test?

Corpus luteum simulation secretes progesterone by the blastocysts secreting HCG, which in turn yields a positive pregnancy.

Fetal Development

Development of a fetus in the uterus is divided into three trimesters. The first trimester is month 1-3, the second trimester is month 4-6, and the third trimester is month 7-9. Key body systems begin to develop in the first trimester, including the nervous and cardiovascular systems. Just after implantation, around week 3, the heart begins to beat. By around week 6, the fetal heart beat can often be detected on an ultrasound. The head shape is formed by this time but is disproportionately large for the majority of the first trimester. During week 5, an important step called neurulation occurs. Neurulation is the formation of the neural tube from the outer folds of the ectoderm. Figure 6.22 below demonstrates the key steps of the formation of the neural tube. The first picture at the top shows the regions of the ectoderm. The blue portions on the lateral sides move together (convergence) forming the epidermis superficially. The neural fold (in green) forms underneath the epidermis, becoming the neural crest. The neural plate, in purple, becomes the neural groove and then finally the neural tube once convergence is complete. The anterior portion of the neural tube becomes the brain, and the rest of the neural tube forms the brainstem and spinal cord. If neurulation does not completely close the neural tube, a disorder called spina bifida occurs. People with spina bifida have varying levels of sensory and/or motor disabilities, depending on the region and extent of the neural tube dysfunction. Pregnant mothers are recommended to take supplemental folic acid to prevent neural tube defects. Figure 6.22 The process of neurulation forms the neural tube. The neural tube becomes the brain, brainstem, and spinal cord. By the end of week 8, the embryo is now considered a fetus and begins to move but is still too small during the first trimester for fetal movement to be felt by the mother. Arms and legs begin to form, and by week 13, the fetus has moveable joints, fingers, and toes. The eyes, ears, and nose begin to form but are not yet on the correct location on the head. During the second trimester (Figure 6.24), the eyes, ears, and nose move to the correct position on the face. The head and body grow to proper proportions. Around the 16th week, the eyes are developed enough to detect light and dark. Unique fingerprints develop on the hands. The mother begins to feel the fetal movement in the second trimester, generally around 18-21 weeks. Lanugo (fetal hair) develops on the fetus' body to keep it warm. The fetus develops sleep/wake cycles, and the heart beats in a regulated pattern. The third trimester (Figure 6.24) is characterized by continued development of the systems already in place. For males, the testes descend into the scrotum (Figure 6.23). The baby increases in weight and begins to develop fat under the skin. Sucking reflexes, which are vital for feeding, begin to develop around week 32. Two important developmental milestones for a baby's survival outside the uterus include lung maturation and temperature self-regulation. By the end of pregnancy, a typical baby is around 19-22 inches long and weighs 6 to 10 lbs. (Figure 6.24).

6.3: Sexual Reproduction, Pregnancy, and Fetal Development

Humans reproduce through sexual reproduction, which involves sex cells called gametes (Figure 6.20). The gametes are specialized as eggs (oocytes) in females or sperm (spermatocytes) in males. Copulation is sexual union to facilitate the reception of sperm by a female. In sexual reproduction, the offspring inherits half its genes from one parent and the other half from the other parent. Therefore, an offspring has a different combination of genes than either parent. In this way, variation is introduced and maintained. Such variation is an advantage to the species if the environment is changing because an offspring may be better adapted to the new environment than either parent. Human cells throughout the body typically contain 46 chromosomes. These are called diploid cells because they have 2n or the full number of chromosomes. Diploid cells undergo mitosis during cell division. During mitosis, as a cell grows, it divides into two cells each containing the same 46 chromosomes. Gamete cells are called haploid cells (n) because they contain 23 chromosomes instead of 46 (Figure 6.20). When gametes mature, the cell divides two times. The first division of the gametes is a mitotic division, which provides two new cells that have the whole set of chromosomes (46). Mitosis occurs in all cells in the body to maintain life. The second division of gamete cells is known as meiosis, which only occurs in reproductive cells. During meiosis, gametes divide to form four gametes, each with only half of the chromosomes needed (23). When a sperm gamete and an egg gamete combine to form the zygote, or fertilized egg, it has a total of 46 chromosomes again. After fertilization, the zygote continues to divide by mitosis, developing into a baby (Figure 6.20). These 46 chromosomes determine the entirety of the genetic characteristics of the offspring, such as eye color and skin color. Sex is also determined by the chromosomes. Males have one X chromosome and one Y chromosome. Females have two X chromosomes. Therefore, the sex of a couple's offspring is determined by the father's sperm cell (whether the offspring receives an X or Y chromosome from the sperm cell).

For fertilization to take place, why must sexual intercourse take place in the period that starts two days before and ends one day after ovulation?

Sexual intercourse has to happen within this timeframe because sperm is viable for 3-5 days after ejaculation and an egg can survive for unto 24 hours after ovulation.

Oogenesis

Oogenesis (Figure 6.10) is the production of eggs in the ovaries that occurs during development of the fetus in the womb and is complete by the time of birth. Therefore, at birth, a female has all the immature eggs that she can later ovulate during her reproductive lifetime, which extends from puberty to about her 50th year of life. The end of the female reproductive lifetime is known as menopause. Female stem cells, known as oogonia, undergo mitotic division into two daughter cells known as primary oocytes. These primary oocytes are covered by follicles, known as primary follicles. This process is completed by birth. The anterior pituitary gland starts to secrete follicle-stimulating hormone (FSH) when a female reaches puberty. FSH causes a few follicles to mature each month. The primary oocyte in the follicle undergoes its first meiotic division into two daughter cells: the secondary oocyte and the first polar body (Figure 6.10). A polar body is produced so that the chromosomes divide properly, but all the cytoplasm is "donated" from the polar body to the secondary oocyte in case of fertilization. It takes tremendous amounts of cellular energy to sustain life during the first several cell divisions, so the secondary oocyte needs to maintain as much of the cell contents as possible. If the secondary oocyte is united with a sperm after ovulation, the second meiotic division occurs, which produces a second polar body and an ovum with 23 chromosomes. The ovum and the sperm combine their chromosomes to form a fertilized egg with 46 chromosomes. The first polar body may or may not undergo a second meiotic division. Therefore, females produce two to three polar bodies and one viable gamete or ovum with 23 chromosomes. If the secondary oocyte does not combine with a sperm, it dies, and menstruation occurs. Around the time of ovulation, the anterior pituitary secretes a second hormone called luteinizing hormone (LH). LH causes the follicle to become the corpus luteum, which is necessary for maintaining pregnancy. Figure 6.10 Oogenesis begins with a primary oocyte and ends with 2-3 polar bodies and one mature ovum.

Define oogenesis and when it occurs in a human female.

Oogenesis is where the production of eggs occur. Oogenesis occurs during the development of the fetus in the womb. It's completed by the time the baby is born.

Female Hormones

Ovaries are also involved in the production of two hormones: estrogen and progesterone. Estrogen is important in the production of eggs and the menstrual cycle. It is also responsible for secondary sex characteristics. Secondary sex characteristics are not directly involved in the sexual reproductive process but develop changes that occur throughout the body beginning in puberty. These secondary sex characteristics include: enlarged breasts, widening of the pelvis, and fat deposits in the breast, hips, and buttocks. Progesterone is necessary for the maintenance of pregnancy but does not promote secondary sexual characteristics. The ovarian cycle (Figure 6.11) is closely integrated with the menstrual cycle (uterine cycle). Every month, the ovaries release hormones (estrogen and progesterone) that cause changes to the endometrium of the uterus, preparing for implantation if fertilization occurs. If fertilization does not occur, the endometrium is shed (approximately every 28 days). The menstrual cycle (Figure 6.11) can be divided into three phases: the menstrual phase, proliferative phase, and secretory phase. The menstrual phase (Figure 6.11) begins on day 1 when all but the innermost basal layer of the endometrium is shed and continues through day five. The detached tissue of the endometrium and blood flow from the uterus into the vagina and exit the body via the vaginal orifice as the menstrual flow. The proliferative phase occurs during days 6-14 as the endometrium rebuilds in response to increasing estrogen levels. Ovulation of an egg typically occurs in the ovaries on day 14. Ovulation is triggered when the anterior pituitary (in the brain) releases luteinizing hormone (LH) as a response to high levels of estrogen. The final phase of the cycle is the secretory phase (Figure 6.11), which occurs during days 15-28. During this phase the corpus luteum begins to secrete progesterone. Progesterone causes an increased blood supply in the uterus and secretion of nutrients, preparing the uterus for implantation. If fertilization has not occurred, the corpus luteum dies and the endometrium blood supply decreases because of decreased progesterone, which begins the menstrual phase again. Figure 6.11 Female hormones control the ovarian cycle and the uterine cycle (menstrual cycle).

Labor and Delivery

Pregnancy concludes in the birth of the baby through labor and delivery, which typically occurs during the 40th week but varies from 38 weeks to 42 weeks (Figure 6.25). Labor and delivery of the baby can be divided into three stages: dilation of the cervix, delivery of the baby, and delivery of the placenta. The first stage, dilation of the cervix, is the time it takes for the woman's cervix to dilate to ten centimeters. During this stage, the uterus contracts, which pushes the baby's head against the cervix, causing it to dilate (widen). This stage of labor is the longest, lasting an average of 6-10 hours. Oxytocin is a hormone that is released from the posterior pituitary gland to stimulate contractions in the myometrium of the uterus. As contractions continue, oxytocin is increasingly released until the baby is born. The second stage, delivery of the baby, is the time it takes for the baby to be pushed out of the birth canal after full dilation has been accomplished (Figure 6.25). During this stage, the mother uses abdominal muscles to push the baby, with the help of the uterus contracting, through the cervix and out the vagina. This stage is much shorter, lasting an average of 50 minutes in a first delivery and 20 minutes in later ones. After the child is born, the umbilical cord is tied and cut. Babies are typically born head first, but if the baby is in a different position, such as a buttock-first (breech), it can cause complications for the mother and child. In breech and other especially long and difficult deliveries, a cesarean section is performed, in which the baby is delivered through a surgical incision made through the abdominal and uterine walls. The third stage, delivery of the placenta, is when the placenta is pushed out of the birth canal (Figure 6.25). The placenta is referred to as the afterbirth. This should typically occur within 15 minutes of the birth of the child. The entire placenta needs to be delivered or removed after birth or uterine bleeding will continue. Figure 6.25 The stages of labor and delivery. Stage 1 of labor and delivery is represented by the top 2 diagrams in which contractions initiate and, the cervix dilates. Stage 2 of labor and delivery is represented in the bottom left diagram in which full dilation has been achieved, and the baby is pushed through the birth canal. Stage 3 of labor and delivery is depicted in the final diagram in which the placenta is delivered.

Match the description with its corresponding structure. Structure:

Spermatogonia k. Sperm-producing stem cells. Spongy urethra e. Runs through penis to external opening. Acrosome b. Contains enzymes that break down egg membrane. Ectoderm i. Skin producing layer of blastocyst

The female reproductive system includes what internal organs? What is ovulation? How often does it occur? What is the ovarian cycle? What does the ovarian follicle become after ovulation? What is the purpose of the corpus luteum? What are the three sections and three coats of the oviducts? What is the function of the fimbriae? An egg is most often fertilized in what region? Describe the shape and location of the uterus. What are the three layers of the uterus? What is the function of the myometrium? What are the three regions of the uterus? What is the fundus? What is the function of the cervix just prior to ovulation? What are the three layers of the vaginal wall?

The Female Reproductive System Internal organs: the ovaries, the oviducts (fallopian or uterine tubes), the uterus, and the vagina. The release of a mature egg; occurs approximately every 28 days. An egg is released from the ovarian follicle. The corpus luteum It helps maintain pregnancy if an egg is fertilized; if not, it disintegrates. Infundibulum, ampulla and isthmus and three coats: the outer serous coat, the middle muscular coat, and an inner mucosa coat. The fimbriae capture an egg from the ovary at the time of ovulation. When an egg (oocyte) bursts from follicle within an ovary during ovulation, it is swept into an oviduct Ampulla The uterus is a hollow, thick-walled muscular organ shaped like an inverted pear connecting the uterine tubes and the vagina and, in a forward-tilted position between the bladder and the rectum. The outer serous perimetrium, the middle muscular myometrium and the inner glandular endometrium. It expands during pregnancy to hold the growing fetus and contracts during labor to push the baby out of the uterus. Fundus, body, and cervix The height of the fundus can be measured from the top of the pubic bone during pregnancy to provide growth rates and a crude indication of an abnormality (breech presentation or twins). Just prior to ovulation, the cervix swells, softens and secretes mucus allowing sperm better access to and viability within the uterus. An inner tissue layer, intermediate muscle layer and outer tissue layer

Describe, in detail, the structure and function of mature sperm.

The accessory organs of the male reproductive system (epididymis, vas deferens, and urethra) are in the duct system. The duct system provides a place where sperm can mature and are eventually released from the body. The testes produce sperm which are matured in the epididymis. The epididymis are tightly coiled tubules that start at the superior end of the testes and eventually move inferiorly along the posterior lateral side of the testes. In order for sperm to be able to swim the must mature because the swimming process can last about 20 days. After maturing they move to the vas deferens by muscular contractions. The vas deferens moves superiorly through the inguinal canal and turns posteriorly over the bladder and finally descends inferiorly to the base of the prostate gland. This is where the duct of the seminal vesicle connects to form the ejaculatory duct. Which then connects the urethra which is where the sperm leaves the body. The spermatic cord is where the vas deferens and it surrounds the vas deferens as well as other blood vessels and nerves. The smooth muscles in the vas deferens contract when males become sexually aroused. Sperm then enters the urethra.

The Duct System

The duct system contains the accessory organs of the male reproductive system, the epididymis, vas deferens (or ductus deferens), and the urethra. The duct system provides a place for sperm to mature, and then sperm are expelled from the body at the appropriate time. Sperm produced by the testes mature within the epididymis (Figure 6.14), which are tightly coiled tubules that start at the superior end of the testes and then travel inferiorly along the posterior lateral side of the testes. Maturation for about 20 days is required for the sperm to gain the ability to swim. Figure 6.14 Lateral view of the epididymis, located posteriorly to each testis and the vas deferens (blue). Once the sperm have fully matured, they are propelled into the vas deferens by muscular contractions (Figure 6.14, Figure 6.15). The vas deferens is contained in the spermatic cord, held in place by the spermatic fascia, which surrounds the vas deferens as well as other nerves and blood vessels. The vas deferens travels inside the spermatic cord superiorly through the inguinal canal. In males, the inguinal canal is the location in the anterior abdominal wall for the spermatic cord to enter (Figure 6.15). After entering the abdominal wall, the vas deferens continues to rise and approximately follow the pelvis until it turns posteriorly over the bladder. The vas deferens descends inferiorly to the base of the prostate gland where it connects with the duct of the seminal vesicle to form the ejaculatory duct (Figure 6.17). The ejaculatory duct connects with the urethra to provide a means for the sperm to exit the body. During arousal, the smooth muscles in the vas deferens contract and sperm enter the urethra, part of which is inside the penis. A vasectomy can be performed to lead to permanent sterility. In this procedure, the vas deferens is cut and tied off, which permanently prevents sperm from exiting the body to fertilize an egg. A vasectomy, however, does not affect testosterone production; therefore, male secondary sex characteristics remain intact. Figure 6.15 Anterior view of the Vas deferens (right) and the spermatic fascia (blue, left). The floor of the inguinal canal is formed by the inguinal ligament. Figure 6.16 Posterior view of the duct system and accessory organs. The bulbourethral glands are highlighted bilaterally in blue. The urethra travels from the bladder through the penis carrying urine (Figure 6.17). The urethra is part of both the male reproductive and urinary systems because it functions to transport both sperm and urine to the outside of the body. Only reproductive or urinary function can occur at a given time. The urethra consists of three regions: prostatic urethra, membranous urethra, and spongy urethra. The prostatic urethra is surrounded by the prostate gland. The membranous urethra begins at the end of the prostatic urethra and travels to the penis. The spongy urethra runs through the penis and opens to the outside at the external orifice. Figure 6.17 Cross section of the bladder and prostate gland to show the three sections of the male urethra: prostatic, membranous (blue), and spongy.

Duct System

The female reproductive system also contains a duct system like males. The duct system includes the oviducts, uterus, and vaginal canal. The oviducts (Figure 6.4), also called uterine or fallopian tubes, extend from the ovaries to the uterus. Each tube has three sections: infundibulum, ampulla, and isthmus and three coats: the outer serous coat, middle muscular coat, and inner mucosa coat. The oviducts are not physically touching the ovaries but instead have finger-like projections, called fimbriae (Figure 6.4), on the infundibulum end of the tube farthest from the uterus. The fimbriae capture an egg from the ovary at the time of ovulation. When an egg (oocyte) bursts from the follicle within an ovary during ovulation, it is swept into an oviduct by the combined action of the fimbriae and the beating of the cilia that line the oviducts. The egg is quickly moved into the ampulla (Figure 6.4) region of the tube where it is most often fertilized. The ampulla region nourishes the fertilized egg or zygote during its early cell divisions. The mucosa layer of the ampulla provides nourishing fluid that allows repeated cell divisions. Over the next several days, the combination of muscular contractions and cilia move the egg through the isthmus toward the uterus. The isthmus (Figure 6.4) opens into the uterus, delivering the developing embryo into the uterine cavity when it is time for implantation. Figure 6.4 There are two oviducts, one on each side of the uterus. Each oviduct comes into proximity with an ovary. The fimbriae (blue) are a part of the infundibulum region located.

Vulva

The female reproductive system also includes the vulva (external genitalia) consisting of the mons pubis, vestibule, labia majora, labia minora, clitoris, urethral, and vaginal orifices (Figure 6.8). The mons pubis is a fat pad located in front of the pubic symphysis and is covered with hair after puberty. The vestibule surrounds the urethral and vaginal orifices. The labia majora is an outer fold of skin that is located posterior to the mons pubis. The labia minora is a second set of skin folds surrounded by the labia majora. At the anterior end of the labia majora is the clitoris. The orifices or openings for the urethra and vagina are located inside the labia minora. The urethral orifice is anterior to the vaginal orifice. Figure 6.8 External view of the vulva.

6.1: Female Reproductive System

The female reproductive system includes internal organs: the ovaries, oviducts (fallopian or uterine tubes), uterus, and vagina as well as external genitalia collectively known as the vulva. The female reproductive system must produce eggs and estrogen as well as maintain the development of a fetus after fertilization of an egg occurs. Figure 6.1 Lateral view of the female reproductive organs in context. Note the uterus is located between to the bladder (anteriorly) and the rectum (posteriorly).

Pregnancy

The female uterus provides a safe place for the baby to grow until it reaches appropriate development. Pregnancy begins with fertilization of an egg by a sperm forming a zygote (Figure 6.20). Sperm are viable for 3-5 days after ejaculation, depending on the environment, and an egg can survive for up to 24 hours after ovulation. For fertilization to occur, copulation must take place by one day after ovulation and can occur as early as two days before ovulation. Fertilization typically occurs in the oviducts where the egg releases chemicals that attract the sperm. Sperm cells release enzymes that break apart the corona radiata (Figure 6.20), follicle cells surrounding the egg. Once this is accomplished, more sperm release acrosomal enzymes that make a hole in the membrane of the egg, allowing one sperm cell to combine with the egg. When the union of egg and one sperm occurs, the membrane of the egg instantly chemically changes, preventing other sperm from penetrating the egg. The zygote begins frequent mitotic cell divisions as it travels in the oviducts. The zygote spends about three to four days undergoing mitosis in the oviducts, forming the morula, and another three to four days undergoing mitosis while unattached in the uterus, forming the blastocyst, as the endometrium prepares for implantation. Because of progesterone release from the corpus luteum, the endometrium increases its blood supply and secretes glycogen. Both actions help sustain the blastocyst before it implants in the endometrium. The corpus luteum is stimulated to secrete progesterone because the blastocyst secretes human chorionic gonadotropin (HCG). The presence of HCG in urine will result in a positive pregnancy test taken at home. The blastocyst implants into the endometrium of the uterus around day 7 (Figure 6.21). Upon implantation, some cells in the blastocyst begin to develop into three layers, which become the embryo: the ectoderm, mesoderm, and endoderm. Other cells of the blastocyst form supportive cells for embryonic function: the amnion, placenta, and umbilical cord. The amnion (Figure 6.21) forms a sac filled with fluid to cushion and protect the fetus. The placenta (Figure 6.21) is a temporary organ that carries out nutritive, respiratory, excretory, and endocrine functions for the embryo. The fetus continues to grow in the uterus with nutrition provided by the placenta for nine months until it is time for delivery. The umbilical cord (Figure 6.21) attaches the embryo to the placenta. Figure 6.21 A blastocyst beginning to implant on the uterine wall. The yolk sac becomes part of the digestive system. The amnion is a sac that is filled with protective fluid. The placenta and umbilical cord provide nutrition and excrete wastes for the developing embryo. The skin and nervous tissue develop from the outer ectoderm layer. The inner endoderm layer forms the glands (thyroid, parathyroid, and thymus), solid organs (liver and pancreas), and the lining of the hollow organs of the digestive and respiratory systems. All other tissues, including the cardiovascular system, red blood cells, and muscle develop from the middle mesoderm layer.

Semen Production

The male reproductive system also contains accessory glands that produce semen, a thick, whitish fluid that contains sperm and accessory gland secretions. Some of the components of the semen are fructose (sugar for fuel), prostaglandins (facilitates movement), relaxin (enhances motility), an alkaline pH (protective), and an antibiotic to kill any bacteria in the male urethra or female reproductive system, which would kill the sperm. About 200 to 500 million sperm are expelled from the penis during ejaculation. The fluids of the semen are contributed by three glands: the seminal vesicles, prostate, and bulbourethral glands. The paired seminal vesicles (Figures 6.16, 6.17) lie at the base of the bladder where they each join with a vas deferens to form an ejaculatory duct that enters the urethra. As sperm pass from the vas deferens into the urethra, the seminal vesicles secrete a thick, viscous fluid containing nutrients (fructose, vitamin C, and prostaglandins) for use by the sperm. Just below the bladder is the prostate gland (Figures 6.16, 6.17), which secretes a milky alkaline fluid helping to increase the motility of the sperm. In older men, the prostate gland may become enlarged, constricting the urethra and making urination slow or difficult. Slightly below the prostate gland, on either side of the urethra, is a pair of small glands called bulbourethral glands (Figures 6.16, 6.17), which secrete an alkaline fluid, the first secretion to be released during an ejaculation. The acidity of urine in the urethra is detrimental to sperm. The fluid secreted by the bulbourethral glands clears and neutralizes the acidity of any urine remaining inside the urethra. Urination and ejaculation cannot occur at the same time.

External Genitalia

The male reproductive system also contains two external genitalia: the penis and scrotum. The penis is a cylindrical organ that hangs in front of the scrotum (Figure 6.18). Spongy, erectile tissue containing distensible blood spaces extends through the shaft of the penis. The penis has two parts: the shaft and glans penis. The shaft is the long cylindrical part of the penis, made up of a left and right corpus cavernosum and one corpus spongiosum. The glans penis is the enlarged tip of the penis. At birth, a fold of skin called the foreskin is located on the glans penis (Figure 6.18). Figure 6.18 Internal structure of the penis. During arousal, nervous system reflexes cause an increase in arterial blood flow to the penis. During an erection, the spaces fill with blood in the erectile tissue and the penis, which is normally limp, stiffens and increases in size. An erection functions to enable the penis to be inserted into the vagina when sexually aroused to deposit semen into the female's reproductive tract. The scrotum is a pouch of skin that holds the testes outside of the body just posterior to the penis, held in place by the spermatic fascia. The testes must be located outside of the body for sperm production. The skin of the scrotum can adjust to outside temperature, contracting when outside temperatures are cold, allowing the sperm to get additional heat from the body and expanding when temperatures are warm to keep sperm away from the higher body temperature.

6.2: Male Reproductive System

The male reproductive system includes the following organs: the testes, epididymis, vas deferens, seminal vesicles, prostate gland, bulbourethral glands, urethra, and penis. The male gonads are paired testes, which are suspended within fascia sacs of the scrotum. Figure 6.12 Lateral view of the male reproductive system in context with the rectum, bladder, and supportive musculature. A cross section of the prostate gland is shown in blue to view the urethra, which travels from the bladder, through the prostate, and into the penis.

Spermatogenesis

The male reproductive system's main functions are to produce sperm and testosterone. Production of sperm is known as spermatogenesis and can take a total of 64-72 days to complete. At the onset of puberty, a male begins to make sperm. Unlike females, who have all their eggs at birth, men continue to produce sperm throughout their lifetime. Sperm are formed from spermatogonia in the seminiferous tubules located in the testes. The spermatogonia are stem cells that go through mitotic divisions (with 46 cells each) beginning at birth until puberty. Once a male enters puberty, his anterior pituitary gland begins to secrete follicle stimulating hormone (FSH). When FSH is secreted, the spermatogonia undergo cell division; one of the cells continues the stem cell line. The other cell, known as the primary spermatocyte, undergoes meiosis. Meiosis produces four gametes with (with 23 chromosomes each) known in the male reproductive system as spermatids. All four spermatids become viable gametes. The spermatids are not mature sperm yet and must undergo spermiogenesis. Spermiogenesis is the final stage of spermatogenesis, where the surplus cytoplasm is stripped away forming the mature sperm. Mature sperm have three parts: the head, midpiece, and tail (Figure 6.19). The head is almost entirely nucleus containing the cell DNA with a crown called the acrosome, which contains enzymes that break down the membrane of the egg to allow the sperm to penetrate. The midpiece contains numerous mitochondria that generate the locomotive energy needed by the sperm. Tremendous amounts of energy are needed to swim all the way through the female reproductive tract to contact an ovum. The tail is a typical flagellum, which is used to propel the sperm through the female reproductive tract. Figure 6.19 Parts of a mature sperm.

The Ovaries

The ovaries are the main reproductive organ in females (Figure 6.2). The ovaries are two glands that are almond shaped. One ovary is on each side of the uterus below the uterine tubes. Figure 6.2 Superior/Anterior view of the uterus, bladder, and ovaries. There are two ovaries, one on each side of the uterus. Inside each ovary are ovarian follicles, which each hold an immature egg (Figure 6.3). Ovulation, or release of a mature egg, occurs approximately every 28 days. In the ovarian cycle, an egg is released from the ovarian follicle, which becomes the corpus luteum after ovulation. The corpus luteum helps maintain pregnancy if an egg is fertilized; if not, it disintegrates. Figure 6.3 Internal view of an ovary. The ovary contains developing ovarian follicles THAT rupture and release an egg when hormonally signaled.

An older male patient reports to his doctor that he has recently been experiencing difficulty with urination. What might the doctor suspect is the problem? Explain your answer given what you know from the module in regards to the male anatomy.

The problem may be caused by an enlarged prostate gland. When this occurs it constricts the urethra which makes urination slow or difficult.

After human egg and sperm cells combine, by what process does the offspring grow in size?

The process it called mitosis where it develops into a human baby.

Male Hormones

The second function of the male reproductive system is production of the hormone testosterone. Testosterone production begins during puberty in a male when the anterior pituitary gland secretes luteinizing hormone (LH) and follicle stimulating hormone (FSH) together. Testosterone stimulates growth in males. It also stimulates secondary sex characteristics, such as broad shoulders, deep voice, increased muscle size and bone density, and increased hair.

Testes

The testes (Figure 6.13) and the penis are the main organs of the male reproductive system. The testes have the function of sperm and testosterone production. Testosterone is a hormone produced by the interstitial cells inside the connective tissues. Each testis has hundreds of lobules, and each lobule contains several seminiferous tubules (Figure 6.13) where the site of sperm production takes place. Once produced, the sperm travel to the epididymis, where they mature and remain until they are expelled to the outside of the body. The testes begin their development inside the abdominal cavity, but they descend into the scrotal sacs as development proceeds. Sterility is the inability to produce gametes, which occurs if the testes do not descend into the scrotum. Sterility occurs because sperm production requires an environment cooler than body temperature. Figure 6.13 Cross section of the testes containing the seminiferous tubules, the site of sperm production. Sperm travel to the epididymis for maturation.

Describe, in detail, the development of primary oocytes to form a fertilized egg

When a females reaches puberty the anterior pituitary gland begins secreting FSH. On a monthly basis this hormone causes some follicle to mature and the primary oocyte has its first meiotic division into 2 daughter cells, which are the secondary oocyte and the first polar body. When the secondary oocyte pair with a sperm after ovulation the second meiotic division happens. This produces an ovum with 23 chromosomes and a second polar body. The combined chromosomes of the ovum and the sperm form a fertilized egg that has 46 chromosomes.