PNA200 Week 3 Reproductive System PDF

PNA200: Semester 2 Week 3: Reproductive System ___ Male Reproductive System Functions 1. Testes produce sperm and the male sex hormone testosterone a. The sperm cell is a germ cell that fertilizes the X-cell in the oocytes b. Testostero...

PNA200: Semester 2 Week 3: Reproductive System ___ Male Reproductive System Functions 1. Testes produce sperm and the male sex hormone testosterone a. The sperm cell is a germ cell that fertilizes the X-cell in the oocytes b. Testosterone provides the male secondary sex characteristic and the libido 2. The ducts transport, store and assist in the maturation of the sperm 3. The accessory sex glands secrete most of the liquid portion of semen a. When a male ejaculates, the sperm cells are in the liquid portion of the semen b. The liquid portion provides nutrients to the sperm cells 4. Penis contains the urethra; a passageway for the ejaculation of semen and excretion of urine Male Reproductive System  2 - Includes the testes, epididymis, ductus (vas) deferens, ejaculatory ducts, urethra, seminal vesicles, prostate, bulbourethral (Cowper’s) glands, scrotum, and penis In Male Gonads - Testicles: 2 total, one on each side, held by a bag of muscles and fat tissues called the scrotum Highly vascularized to provide oxygen and nutrients Testes are separated into lobules; inside each lobule, there are tubules called Seminiferous Tubules There are 200-300 lobules per testicle and 1-3 seminiferous tubules per lobule Seminiferous tubule ○ Where sperm production occurs Starts at the base (edges of the tubules) and ends at the lumen (empty space of the tubules) then gets released ○ Holds 2 important cells that are within the surface of the tubules These are not sperm cells, they only assist with the production of sperm Sertoli Cells: Nourish sperm cells, secretes fluid for sperm transport and produce the hormone inhibin ⤷ Inhibin regulates sperm production (name implicates, the stop/inhibit of sperm production if it becomes too much) ⤷ Found inbtwn the spermatogenic cells and recognizes sperm cells to nourish them Leydig Cells: Located between the seminiferous tubules; they secrete testosterone-androgen (Andro- = Male) that promotes the development of the male sex characteristics and libido ** Mid Video questions/answers (Scrotum)** 1. How does the scrotum protect the testes? - Through optimal temperature for sperm production; through adipose (fat) tissues acting as an insulator around the testes  3 - Testes are located outside of the body; when the external environment is cold the scrotum's smooth muscles contract to bring the testes closer to the body and utilize the body temperature to warm them up - Warm external environments → Scrotum muscles relax, bringing the testes away from the core body temperature to cool them down 2. Julio and his wife have been trying unsuccessfully to become pregnant. The fertility clinic suggested that the problem may have to do with Julio’s habits of wearing very close-fitting briefs during the day and taking a long nightly soak in his hot tub. What effect would this have on fertility? - Sperm production is optimal at a temperature slightly below normal body temperature. The higher that results from Julio wearing very close-fitting briefs and soaking in the hot tub inhibits sperm production and survival and therefore fertility. Spermatogenesis - Sperm + Genesis = Creation/Formation Of Sperm - The process by which sperm cells are produced (meiosis in the male reproductive system) - Meiosis = a cell division where a cell with 23 pairs of chromosomes (46 single chromosomes/ diploid cells) is divided into 4 cells each having 23 chromosomes (not in pairs) - Process… Spermatogonium (46 chromosomes/23 pairs) ○ A cell that contains 2n (double chromosomes/46) undergoes a mitosis process that duplicates itself into 2 identical spermatogonia each still having 46 chromosomes Primary Spermatocyte Stage (46 chromosomes/23 pairs) ○ Each spermatogonia is differentiated and converted into two primary spermatocytes A fancy way to say it gets prepared for meiosis Meiosis I (After meiosis I = 23 chromosomes/46 chromatids) ○ After differentiation, primary spermatocytes (diploid cells) still have 46 chromosomes In this stage, DNA replicates and crosses over  4 ○ The primary spermatocytes divide into 2 secondary spermatocytes (haploid cells) containing 23 chromosomes each Each chromosome has 2 chromatids Meiosis II (After meiosis II = 23 chromosomes) ○ Each spermatocyte is divided into 2 spermatids (2→4) ○ In this process, the nucleus is divided into each of the 4 new spermatids ○ Spermatids are not yet a mature sperm cell Spermiogenesis ○ Spermatids are differentiated/converted into spermatozoa (sperm cells) Each haploid spermatid develops into a single sperm ○ The head of a sperm cell is the only part that enters the egg cell as it contains the nucleus (DNA); the neck contains the mitochondria that provides ATP It is the only part that is equipped with acrosomes (enzymes that break the egg cell wall) allowing it to enter ○ Approx. 300 million sperm cells are produced per day and live max 48 hours in a female reproductive system If within 48 hours, there is ovulation in the female, there is a chance for pregnancy ** Mid Video Question/Answer** In order, the principal events of spermatogenesis are… - Differentiation of a primary spermatocyte from a spermatogonium → production of a haploid secondary spermatocyte in meiosis I → separation of chromatids to form spermatids in meiosis II, development of a single sperm cell through spermiogenesis Hormonal Control Of Sperm and Testosterone Production - Hypothalamus secretes releasing hormones → Anterior pituitary gland, that releases stimulating hormones → Endocrine glands, that will secrete their own hormone - When levels INCR, it triggers negative feedback on the hypothalamus and anterior pituitary gland  5 - Hypothalamus releases GnRH (gonadotropin-releasing hormones) → hypophyseal portal → anterior pituitary gland → gonadotrophs, release FSH (follicle secreting hormone) and LH (luteinizing hormone) ➔ Luteinizing hormone → acts on Leydig cells to secrete testosterone ◆ It is a water-soluble hormone that binds its receptors to the cell membrane of the Leydig cells via secondary messenger ◆ Testosterone will either convert to dihydrotestosterone (DHT) or act on the Sertoli cells Dihydrotestosterone (DHT)... ○ Male pattern of development (before birth) ○ Enlargement of male sex organs and expression of male secondary ex characteristics (starting at puberty) ○ Anabolism (protein synthesis) Sertoli Cells… ○ Aids in the process of spermatogenesis so that spermatocytes can turn into sperm cells Testosterone can also act on the hypothalamus to stop the secretion of GnRH and LH if those levels become too high ➔ Follicle-secreting hormones → Acts on Sertoli cells to accelerate the process of spermatogenesis ◆ In contrast, Sertoli cells will release inhibin to act on the anterior pituitary to stop the secretion of FSH to slow down the process of spermatogenesis **Mid Video Question/Answer** Which male reproductive hormone and its function are mismatched? - FSH: stimulates spermatogenesis - LH: stimulates the anterior pituitary gland to release FSH - Inhibin: inhibits FSH secretion - Testosterone: development of male sex organs  6 Male Reproductive Ducts - 3 ducts that transport sperm cells… Epididymis: receives the sperm cells from the seminiferous tubules where the sperm matures and acquires the ability to become mobile and fertilize ○ Can store the sperm cells for 10-14 days ○ Helps them propel by peristalsis → vas deference Vas Deference: Pushes the sperm → the Ejaculatory Ducts, and stores the sperm cells for up to several months ○ Vasectomy: “tube ties” the tying of the vas deference to close the path where sperm cells cannot come out Ejaculatory Ducts: Formed by the union of the ductus deferens and seminal vesicles ○ Carries sperm to the urethra - Pathway = Seminiferous tubules → ducts epididymis → ducts deferens → ejaculatory ducts → urethra **Video Question/Answer** Phil has promised his wife that he will get a vasectomy after the birth of their next child. He is a little concerned about the possible effects on his virility. What would you tell Phil about the procedure? - Vasectomy cuts the ducts deferens so that the sperm cannot be transported out of the body. The function of the testes is not affected. The Leydig cells secrete the hormone testosterone, which maintains male sex characteristics and sex drive. A vasectomy will not affect production of the hormone or its transport to the rest of the body via the blood. Male Reproductive Glands - Seminal Vesicles (Glands): Secretes a basic alkaline, viscous thick fluid containing fructose (for ATP), prostaglandins (for sperm mobility and viability) and clotting proteins (for the sperm to coagulate) Accounts for 60% of semen volume Coagulation is a protective mechanism to protect the sperm cells from the acidic environment  7 - Prostate: A single, donut-shaped gland that secretes a milky, slightly acidic fluid (pH of 6.5) containing citric acid (ATP), proteolytic (protein breaking) enzymes, acid phosphatase (liquefication process of semen), and seminal plasmin (antibiotic) Accounts for 25% of semen volume Benign Prostatic Hyperplasia (BPH): Prostate usually gets bigger with age; if too enlarged it will blow up the urethra and will cause urination problems ○ Hyperenlargement indicates prostate cancer Prostate Specific Antigen (PSA): A protein-breaking enzyme that marks the prostate health in males ○ Is secreted with the enlargement of the prostate; if too enlarged → indicates cancer - Bulbourethral (Cowper’s) Glands: Secrete a basic alkaline fluid during sexual arousal that neutralizes acids from urine and mucus for lubrication - Semen = A mixture of sperm and seminal fluid Volume of an average ejaculate = 2.5-5mL with 50-150 million sperm cell per mL pH is alkaline/basic (approx. 7.2-7.7) to combat the acidity of the vagina for survival **Video Question/Answer** 1. Trace the course of sperm through the system of ducts from the seminiferous tubules → urethra - Seminiferous tubules → ducts epididymis → ducts deferens → ejaculatory ducts → urethra 2. Semen contains - Alkaline secretions from the seminal vesicles - Protein-digesting enzymes from the prostate gland - Mucus secretions from the bulbourethral glands - All of the above 3. Mike has just been diagnosed with an enlarged prostate (Benign prostatic Hyperplasia). What are the symptoms of this condition? What is the effect on the semen of removal of the prostate? - Symptoms of BPH include frequent urination, nocturia, hesitancy, DECRd force, and urinary retention. - Prostatic secretions supply a milky appearance to the semen, nutrients for the sperm, and clotting enzymes such as Prostate Specific Antigen (PSA) that liquefies the semen  8 - Without the prostatic contribution, the semen volume would DECR about 25% ** MALE SIDE NOTES** - follicle secreting hormones & testosterone act on Sertoli cells - Luteinizing hormones act on Leydig cells - Sertoli cells secrete their own hormones (inhibin) that act on the anterior pituitary gland that stops the release of FSH to slow down the production of sperm cells - Testosterone stops the release of GnRH and LH - Inhibin stops the release of FSH - Scrotum regulates testes temperature; high temperatures can kill the sperm cells - only the head of the sperm cells enters the egg cells and only provides the nucleus to it Female Reproductive System - 2 main differences between male and female reproductive systems… Male Female Continuous Cyclic Produce millions of sperm cells any time After puberty, they produce 1 egg cell every approx. 28 after puberty days The reproductive system starts at puberty Starts before birth, stops after birth, continues after and lasts a lifetime puberty, and stops at menopause (approx. 45 years old)  9 Ovaries - Follicles: a group of cells that protect the egg cell; Starts as germinal epithelium Follicles grow into a Mature Graafian Follicle and contains the egg cell Ovulation: Mid-cycle, this follicle ruptures and releases the egg cell ○ Ruptured follicle converts into a corpus luteum (aka, yellow body) ○ Corpus luteum Produces 4 Hormones… Progesterone Relaxins Estrogens Inhibins ○ If a woman is pregnant, corpus luteum stays in the body for approx 3 months ○ If no pregnancy is present, corpus luteum degenerates into corpus albicans (aka, white body); leading to menstruation, then the cycle starts again  10 - “Germinal epithelium → growing follicle → Mature Graafian Follicle (contains the oocyte) → mature Graafian follicle ruptures and releases oocyte (ovulation) → Corpus luteum (yellow body) → **NO PREGNANCY** corpus luteum degenerates → corpus albicans (white body) → menstruation → cycle repeats” **Video Question/Answer** Which structure produces progesterone, estrogens, inhibin, and relaxin? - A - B - C - D Oogenesis - Meiosis I (1 primary oocyte → 1 secondary oocyte and first polar body) During fetal development meiosis I begins; The Oogonium differentiates into a primary oocyte ○ Females are born with a limited number of primary oocytes After puberty, the primary oocyte completes meiosis I, which produces 1 secondary oocyte and 1 first polar body that may or may not divide again ○ This happens during every cycle (28 days) Of the two divided cells, the one containing the cytoplasm = secondary oocyte; the one not containing the cytoplasm = polar body ○ The polar body will not survive without a cytoplasm Although 1 primary oocyte is divided into 2 secondary oocytes, you really only come out with one cuz the other one dies  11 - Meiosis II (1 secondary oocyte → 1 ovum and 1 second polar body) The secondary oocyte and first polar body are then ovulated The process of oogenesis will stop here if the secondary oocyte is not fertilized After fertilization, meiosis II resumes and the oocyte splits into an ovum and a second polar body The nuclei of the sperm cell and ovum unite forming a diploid (2n) zygote (the first cell of the fetus) **Video Question/Answer** Which statement is NOT true concerning oogenesis? - Primary oocytes begin meiosis I during fetal development but doesn't complete it until after puberty - The secondary oocyte completes its development into an ovum shortly after ovulation occurs - During meiosis I, a secondary oocyte and a first polar body are produced - At ovulation, a secondary oocyte is released from the ovary Ovarian Tubes  12 - 2 Ovaries: Secretes the ovum at every cycle → uterine (fallopian) tubes/oviduct that connect the ovaries to the uterus Fertilization happens in the oviducts During ovulation, the oocytes stay in the fallopian tube; the sperm enters the fallopian tube and fertilizes the oocyte in the tube, the zygote then will implant itself in the uterus - Uterus: aka, Womb; where the baby grows, and source of menstrual flow Has 3 layers ○ Endometrium: innermost layer; undergoes a process of thickening and thinning during a menstrual cycle This process either prepares itself for the potential implantation of a fertilized egg or sheds itself if no pregnancy occurs Blood vessels will grow here to provide nutrients to the fertilized egg ○ Myometrium: mid-layer made of thick smooth muscle Site of attachment of oxytocin → causes muscle contractions during childbirth to push the baby out ○ Perimetrium: outer layer - Cervix: Lower part of the uterus that connects to the vagina Allows menstrual blood to flow from the uterus → vagina Remains closed and firm to protect the growing fetus; softens and dilates to prepare for childbirth - Vagina: Located between the bladder and rectum; a receptacle for the penis, outlet for menstrual flow, and passageway for childbirth Coated with good bacteria, and fluids, and is acidic to kill bad bacteria to prevent infection Hymen: a thin fold of mucosa covering the vaginal opening ○ Embryotically, it keeps germs and dirt out of the vigina ○ In infants and children, it prevents things from being pushed into the vagina A damaged hymen is an indicator for abuse and incest  13 **Video Question/Answer** The uterine tubes transport secondary oocytes - From the ovaries to the uterus - From the ovaries to the cervix - Between the cervix and vagina - From the uterus to the ovaries Which statement does NOT describe the uterus? - The superior dome-shaped portion of the uterus is the body - The innermost lining of the uterine wall is the endometrium - The narrow portion of the uterus opening into the vagina is the cervix - The myometrium forms the bulk of the uterine wall The vagina - Functions as an outlet for child birth - Has an acidic environment to repel microbial growth - Contains smooth muscle that can stretch - As described by all choices Female Reproductive Phases - Menstruation Phase (days 1-5 ): Start of the cycle when the endometrium sheds, resulting in menstrual bleeding Levels of estrogen and progesterone are low, which triggers the shedding of the endometrium The cervix remains low, firm, and slightly open to allow the blood to flow out - Follicular/Preovulatory Phase (days 6-14): The body prepares for ovulation; the pituitary glans releases FSH, which stimulates the growth of ovarian follicles Estrogen levels rise as the follicles develop, leading to the thickening of the uterine lining in preparation for a possible pregnancy The cervix softens, rises, and opens slightly as estrogen INCRs and cervical mucus become thin and stretchy to allow sperm to move easily through the cervix  14 - Ovulation Phase (day 14): Occurs when a mature egg is released from the dominant follicle in the ovary; usually happens during the 14th day but can vary A surge in LH triggers ovulation. Estrogen peaks just before ovulation Cervix is high, soft, and open; the mucus is the most fertile (thin, slippering, and stretchy) to allow sperm to travel through the cervix to meet the egg - Luteal/Postovulatory Phase (days 15-28): After ovulation, the empty follicle turns into the corpus luteum, which produces progesterone to maintain the uterine lining Progesterone levels rise, and estrogen levels remain elevated to support the pregnancy. If pregnancy does not occur, progesterone levels drop, leading to the start of mensturation Hormones - GnRH is released from the hypothalamus → hypophyseal portal system → anterior pituitary gland to secrete LH and FSH - GnRH is the main hormone that starts the generation of male and female reproductive systems at puberty - FSH will stimulate the growing follicles, while LH peaks during ovulation - LH will cause the release of secondary oocyte - When taking a pregnancy test, if the test comes out positive, that means that the woman is ovulating - A characteristic of ovulation = the surge of LH hormone done by positive feedback - Lh will maintain the corpus luteum in the production of progestogen and estrogen - When FSH stimulates the growing follicles the growing follicles are going to secrete estrogen which will INCR and thicken the wall of the uterus to prepare for potential pregnancy - Progesterone will enhance the function of estrogen and maintain the endometrium layer that estrogen has built - Once the levels of progestogen drop, the layer will shed causing menstruation - If there is pregnancy, the corpus luteum is maintained meaning estrogen and progesterone levels are also maintained until the baby is born  15 - When childbirth occurs, progesterone levels drop and oxytocin levels INCR, stimulating contractions FSH LH Estrogen Progesterone Stimulates the growing Peaks during ovulation INCRs and thicken the Enhances the function follicles walls of the of estrogen endometrium to prepare for potential pregnancy Stimulates the growth Causes the release of Levels are maintained Maintains the of growing follicles the Secondary Oocyte by the corpus luteum endometrium that which will, in turn, when pregnant; lasts estrogen has built secrete Estrogen until the baby is ready to be born Surge of LH = When progesterone ovulation levels drop, the endometrium walls shed = menstruation Sustains the corpus Levels are maintained luteum to maintain the by the corpus luteum production of Estrogen when pregnant; last and Progesterone until the baby is ready to be born Menstrual Cycle Terminologies -Amenorrhea: Absence of menstruation during the reproductive years - Menorrhagia: Menstrual bleeding lasting longer than 7 days - Dysmenorrhea: Pain with menstruation or menstrual cramps - Metorrhagia: Uterine bleeding at irregular intervals, particularly between the expected menstrual periods - Menopause: End of menstrual cycles. Diagnosed after you've gone 12 months without a period Menopause results from the fact that we are not producing any follicle cells and oocyte 2 and the levels of estrogen drop significantly  16 **Video Question/Answer** Which pair is mismatched? - LH triggers ovulation - Relaxin inhibits contractions of the myometrium - FSH stimulates the release of GnRH - Progesterone helps maintain endometrium for implantation of the fertilized ovum Which does NOT occur during the ovarian cycle? - Several ovarian follicles grow and enlarge during the menstrual phase - A surge of LH results in ovulation - In the postovulatory stage, the corpus luteum is formed under the influence of LH - The postovulatory phase generally occurs between days 1-5 in a 28 day cycle In the uterine cycle… - The discharge of blood and tissue cells from the endometrium occurs during the post-ovulatory phase - Secretion of progesterone and estrogens by the corpus luteum promotes growth of the endometrium in the postovulatory phase - Estrogens produced by growing ovarian follicles in the menstrual phase will stimulate the repair of the endometrium - Declining levels of relaxin cause sloughing off the endometrium Birth Control Methods and Abortion - Birth control methods include surgical sterilization (Vasectomy, tubal ligation), non-incisional sterilization, hormonal methods, intrauterine devices, spermicides, barrier methods (condoms), and periodic abstinence - Oral contraceptives of the combination type contain estrogen and progestins in concentrations that DECR the secretion of FSH and LH, inhibiting the development of ovarian follicles and ovulation Contains low doses of progesterone and estrogen that can be taken orally or via skin patches Low levels of these hormones will trigger negative feedback on the hypothalamus and the anterior pituitary gland causing FSH and LH to not be produced  17 When FSH and LH are not produced the follicles will not grow; even if they do grow, LH will not peak, causing no ovulation - Abortion: the premature expulsion from the uterus of the products of conception; may be spontaneous or induced **Video Question/Answer** Oral contraceptives reduce the likelihood of pregnancy by... - Inhibiting the release of FSH and LH by the anterior pituitary gland - Destruction of the secondary oocyte after ovulation has occurred - Blocking the uterine tubes with scar tissue - Interfering with corpus luteum formation Protection against sexually transmitted diseases is more likely when using ____ for birth control - Oral contraceptives - Barrier methods - Intrauterine devices - Vaginal rings Changes in males and females during puberty include - Bursts of FSH and LH secretion - The development of secondary sexual characteristics - The potential for sexual reproduction - All of the above The onset of the first menses in females is ____ while the permanent end of menses is ____. - Ovulation, menopause - Menarche, menopause - Puberty, menopause - Menopause, menarche