ch.8 BOOK notes and Lecture notes
ch.8 BOOK notes and Lecture notes Biol360
Cal State Fullerton
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This 8 page Class Notes was uploaded by Monique Magpayo on Sunday April 24, 2016. The Class Notes belongs to Biol360 at California State University - Fullerton taught by Maryanne Menvielle in Spring 2016. Since its upload, it has received 7 views. For similar materials see Biology of Human Sex in Biology at California State University - Fullerton.
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Date Created: 04/24/16
CHAPTER 8. BOOK NOTES PG 233243 IMPLANTATION: the attachment of the embryo to the endometrium FERTILIZATION takes place in an oviduct. There a sperm that has ascended the female reproductive tract from the vagina enters an ovum that was released from an ovary at the time of ovulation The fertilized ovum is commonly called an EMBRYO after it begins dividing The EMBRYO beings migrating down the oviduct toward the uterus, a journey of a few days MEANWHILE, the lining of the uterus is being put into readiness to receive an embryo This PROCESS is initiated by the PROGESTERONE that is secreted by the ovary (specifically by the CORPUS LETUEM) during the postovulatory phase of the woman’s menstrual cycle All being well, the embryo burrows into the endometrium a process called IMPLANTATION and beings to secrete a hormone known as HUMAN CHORIONIC GONADOTROPIN (hCG) This hormone PREVENTS the next menstruation from occurring, and a missed menstrual period is the usual way that a woman learns that she is pregnant Many embryos fail to implant, in such cases, the embryo simply disintegrates and its remains are washed out of the womans body during her next menstrual period. The woman would have no way of knowing that an embryo existed Thus, doctors say that pregnancy is “ESTABLISHED” only after successful implantation, NOT at fertilization The absence of a period at the expected time is not a totally reliable indicator of pregnancy Many women have irregular periods or delayed periods due to illness, stress or some other reason. Some spotting can occur even when a woman is pregnant Other symptoms to confirm pregnancy: Breast tenderness Fatigue Nausea (the beginning of “morning sickness” happens during the first 3 months of pregnancy) PREGNANCY TESTS are designed to test for the presence of hCG in the mothers blood or urine The most sensitive and expensive lab tests can detect hCG in the mothers blood almost immediately after implantation several days before a woman would notice a missed period At home pregnancy kit: most of these can detect by the firstday after a missed period,. And some can do so 3 days before a missed period. These tests aren’t as reliable as lab tests: a false negative will occur if the test is performed too early Good idea to perform a 2 test a few days after the first one The secretion of hCG is presumptive evidence of pregnancy Definitive clinical evidence of pregnancy can be obtained at 5 to 6 weeks by means of an ULTRASOUND SCAN: an imaging procedure that depends on the reflection of ultrasonic waves form density boundaries within the body. Also called ultrasonographic scan It can determine whether one or more embryos are present and by 2 to 3 weeks later it can detect the fetal heartbeat INFERTILITY: inability of man, woman, or couple to achieve pregnancy SUBFERTILITY: difficulty in establishing a pregnancy; arbitrarily defined as the absence of pregnancy after a couple has had frequent unprotected sex for 12 months Infertility or subfertility can be caused by problems in the man or in the woman If this condition results from a low sperm count or sperm quality, IN VITRO (IVF) fertilization may still make pregnancy possible An alternative is artificial insemination with donated sperm The most common cause of infertility is insufficient or poorquality sperm in the man’s semen The usual rule of thumb is that a man is likely to be subfertile if he has fewer than 20 million sperm per millimeter of semen or if the fraction of his sperm that move normally is less than 50% Sperm abnormalities can also impair fertility, but only if the percentage of abnormal sperm is very high above about 90% What causes insufficient or defective sperm?: Undescended testicles Sex chromosome anomalies Infections that cause blockage of the reproductive tract And intensive chemotherapy Can all cause irreversible reduction or failure of spermatogenesis Heating of the testes as can occur with too tight clothing or strenuous exercise causes a lowered sperm count that is usually reversible Environmental toxins can lower sperm counts and they are suspected of having contributed to a general reduction in sperm counts Normal aging is associated with gradual decrease in the volume of a man’s ejaculate and the concentration of motile sperm in his semen, as well as increase in the amount of damaged DNA in the sperm cell nuclei IN THESE CASES OF SPERM QUALITY A couple can still do things to get pregnant like: If sperm count is low, semen can be collected over a period of time and frozen. Then the entire collected amount can be placed in the woman’s vagina or directly in to her uterus at a time coinciding with OVULATION This process is called ARTIFICIAL INSEMINATION: an assisted reproduction technique that involves the placement of semen in the vagina or uterus with the aid of a syringe or small tube If the sperm come from the womans partner the technique is usually called ARTIFICIAL INSEMINATION BY THE HUSBAND OR AIH Men with normal sperm counts may also store their own sperm for future AIH use. Some sperm quality problems may require the use of IN VITRO FERTILIZATION (IVF): any of a variety of assisted reproduction techniques in which fertilization takes place outside the body IN VITRO means in glass – in a petri dish The standard IVF procedure: the woman is given hormones to promote the development of a group of follicles on a precisely timed schedule When the follicles are nearly ready to ovulate, a fine needle is passed into each follicle under ultrasound control, and the ovum is flushed out As many as 2 dozen ova can be harvested in a single procedure The collected ova are placed in a petri dish, and the man’s sperm are then added This procedure costs about $12,000 for a single cycle If the man’s sperm are not capable of performing even this simplified fertilization task, further variations on IVF are available: Regardless of the exact IVF procedure used, the artificially fertilized ova are usually kept in tissue culture for several days, during which they divide several times It is possible at this stage to remove a cell or two from the embryos without harming them, which allows the genetic makeup of the removed cells to then be determined This PREIMPLANTATION GENETIC SCREENING: testing of in vitro fertilization embryos for genetic defects prior to implantation Is useful if one of the parents carries a diseasecausing gene and the couple wants to ensure their child does not inherit it A number of CONCEPTUSES – often about 4 are then placed in the woman’s uterus simultaneously, in order to maximize the chance that at least one of them will implant and become a fetus If several implant the woman is offered the opportunity to have the number reduced by selective abortion (“fetal reduction”) Bit this practice can present risks to the remaining fetuses and it also presents ethical problems for some women A human embryo is called a CONCEPTUS A more common problem: IS NOT multiple but zero pregnancies Nearly 2/3rds of all IVF attempts do not lead to a successful pregnancies So couples have have3 to repeat the procedure several times ASSISTED REPRODUCTIVE TECHNOLOGY: (ART) in vitro fertilization and related technologies Problems with ovulation can often be treated with drugs An alternative is the use of donated eggs Fertility declines steadily with age in both sexes. AGE also raises the likelihood of fetal abnormalities such as down syndrome Sperm can be donated: ARTIFICIAL INSEMINATION BY DONOR (AID) In this procedure sperm from a third party are placed in the woman’s vagina or uterus SPERM BANKS: a facility that collects, stores, and provides semen for artificial insemination They provide suitable semen at fairly low cost Men donate semen by masturbation The donors are screened for heritable medical problems and for infections such as HIV Info about potential donor physical appearance, field of study or work, and other interests is usually available to potential recipients The most common site of abnormalities is the oviducts They can become scarred, obstructed, or denuded of cilia as a consequence of PELVIC INFLAMMATORY DISEASE (PID) a general term for infections of the uterus or oviducts usually caused by sexually transmitted organisms such as chlamydia or gonorrhea Another condition that can interfere with fertility is ENDOMETRIOSIS Irregular cycle of period may be caused by: weight loss, athletic training, stress, certain drugs, a pituitary tumor, or reduced ovarian function Sometimes failure to ovulate can occur in a woman who is experiencing normal periods Most ovulatory problems can be reversed by lifestyle changes, drug treatments, or psychotherapy (if the cause is an eating disorder for example) If the woman’s ova cannot be used, she can get them from donors It can be expensive because the donor must undergo hormone treatment followed by surgical aspiration of the ova from the ovaries. Typically paid a few thousand dollars, but there is a market for donors who are perceived to have desirable traits, and higher fees may be paid for such cases SURROGATE MOTHER: a woman who carries pregnancy on behalf of another woman or couple. Usually paid 20,00025,000 $ plus expenses so the total payment can go up to 60,000 or more Legal status of surrogacy varies from state to state. Many surrogates are military wives ADOPTION is low tech but often very successful for couples to have children. The main problem would be a severe shortage of preferred adoptees This decline in fertility has several causes including more frequent failures to ovulate, decreasing sperm counts and sperm quality, and an increased likelihood of spontaneous abortion early in pregnancy Children who are born to older parents, especially older mothers, also stand a greater risk of having chromosomal abnormalities DOWN SYNDROME: a collection of birth defects caused by the presence of an extra copy of chromosome 21 It usually includes mild or moderate intellectual disability and a characteristic facial appearance Increasing paternal age raises the chances that a child will suffer from physical malformations, as well as mental conditions such as down syndrome, autism, and schizophrenia This is because the sperm precursor cells are constantly dividing to produce new sperm Thus an older mans sperm are product of a greater total number of cell divisions, and each round of DNA replication carries some small risk of introducing a harmful mutation, Chronic exposure to toxins such as solvents or tobacco smoke increase the likelihood that a man’s children will have development problems A postmenopausal woman can become pregnant with the aid of reproductive technology: donated ova can be fertilized in vitro and the embryos placed in her uterus The pregnancy must be supported with hormone treatments Many embryos don’t survive, most of these defects occur at the very earliest stages of development If the ovum is fertilized by two sperm rather than one, the resulting embryo will have three sets of chromosomes rather than the normal two In some cases, environmental factors such as alcohol consumption, general anesthesia, or XRAY exposure at around the time of ovulation may trigger chromosomal abnormalities The great majority of abnormal conceptuses are lost at some point in their development Many fail to implant, and the mother is never aware of their existence Others implant briefly causing transient release of hCG and a slight prolongation of the postovulatory phase, but then dies so that menstruation ensues One major cause of fetal loss is blood group incompatibility, especially when the fetus possess the blood group antigen known as Rh FACTOR and the mother does not Rh FACTOR: an antigen on the surface of red blood cells that when present in a fetus but not in its mother, may trigger an immune response by the mother, resulting in life threatening anemia of fetus or newborn Rh incompatibility is inherited from father. Neg mother and pos father is common PLACENTA: the vascular organ, formed during pregnancy, that allows for the supply of oxygen and nutrients to the fetus and the removal of waste products problems arise when the mother develops antibodies against Rh and those antibodies cross and placenta and attack the fetus LECTURE NOTES The median age of women at the birth of their first child varies by state but the age is 25 Both eggs and sperm are produced by MEISOSIS It reduces the genetic material by half Egg and sperm cells have 23 Reduce by half so that when combined, equal 46 chromosomes Which is why it is produced by meiosis MEIOSIS also creates variation which makes our population develop and evolve. MEIOSIS HAS 2 DIVISIONS MEIOSIS 1: diploid – meiosis 1 (reduction division) = 2 haploids then MEIOSIS 2 (equational division) = 4 haploids DAUGHTER Chromosome in x shape mean chromosome is replicated already The production of eggs is called OOGENESIS. Egg cells are largest in body diagram: OOGONIUM goes through MITOSIS Then comes out a PRIMARY OOCYTE which goes through MEIOSIS 1 (then unequal division with an extreme small first polar body) Then first polar body may divide (haploid) and secondary oocyte (haploid) goes through MEIOSIS 2 (if fertilization occurs) Polar bodies die from the first polar body The secondary oocyte has an ovum (egg) and second polar body (haploid) and only the OVUM (egg) =MATURE EGG We have 4 daughter cells but one egg cell More on slide 16 SPERMATOGENESIS Spermatogonium (diploid)—GOES THROUGH MITOSIS to a PRIMARY SPERATOCYTE (diploid) that has AUTOSOMES ( LARGE X’s A a) and SEX chromosomes (small x and y)– Which go through MEIOSIS 1 and has a secondary spermatocyte (haploid) which goes through MEIOSIS 2 which has 4 SPERMATIDS (haploid) WHICH goes through maturation in the testicles. Testes has seminiferous tubules which make the sperm cells Matures and then is sperm (haploid) MATURE SPERM has an energetic tail and the spinal mitochondira moves the tail. How? Because mitochondria takes food and burn it to make energy Food comes from semen because there is sugar in semen. Semen has sugar to power the mitochondria. Nucleus has the DNA The tip is the ACROSOME which has enzymes necessary for the sperm to penetrate the egg cell VARIATION: independent assortment: 8 million combos for a single individuals gametes Random fertilization results in 70 trillion ways two peoples gametes can combine Recombination adds even more Semen contain 20100 million sperm per cubic centimeter A single ejaculation can contain over 500 million sperm Sperm is small and need a lot of stamina to swim through the woman;s system Best time for intercourse to get pregnant is 12 days BEFORE ovulation BASAL BODY TEMP to predict ovulation PROGESTERTONE released after ovulation raises a woman’s base body temp Tracking body temp can help a woman determine when she ovulated, and patterns over several cycles can help predict ovulation For best accuracy, temp must be taken before getting out of bed, at the same time every morning Or OVULATION PREDICITON TEST: measure the amount of LH (lutenizing hormone) in the urine LH spikes 24 hours before ovulation So it should be taken from a few days before expected ovulation until ovulation occurs Test is ready by comparing the color of test line to a control; most tests are positive when the control line is as dark as the test line Another way to test ovulation: CERVICAL FLUID: the consistency of cervical mucus is an indication of fertility Cervical mucus gets watery approaching ovulation Fertile cervical mucus is eggwhite consistency: Dry/sticky Creamy Watery Eggwhite Spotting Menses Home fertility testing tests the amount of FSH (follicle stimulating hormone) in women Approaching menopause, FSH levels get high because her ovaries have stopped responding to it so the levels coming from the pituitary are very high to stimulate the ovaries A high level of FSH indicates that a woman might have trouble getting pregnant Tests for presence of sperm and sperm motility in men These tests are not useful for young women under the age of 30 Best sex position for pregnancy: man on top because sperm is right at cervix Causes of infertility in women: ovulation problems, pituitary or ovarian tumor, underactive thyroid gland, and polycycstic ovary syndrome PCOS, antisperm secretions cause unknown, blocked oviduct by an infection caused by STI, PID, or IUD (a contraceptive in the uterus), endometriosis (endometrial tissue growing in the wrong place with adhesions that move the ovary away from the oviduct and pressure form the tissue growing can cause infertility Infertility work up WOMEN Cervical mucus test: test quality and quantity of mucus ULTRASOUND EXAM: uterine tumor= fibroid tumor HORMONE LEVELS : by blood test to see if hormone levels are at their proper place HYSTEROSALPINGOGRAM: looks to see if the oviducts are blocked by placing a dye in the uterus and through an x ray the doc can see where that dye travels It should travel all the way through the oviduct and come out the other end , if the doc cant see that it may be due to the blockage within the oviduct LAPAROSCOPY: SURGICAL and can pick up problems like endometriosis which cant be picked up by ultrasound ENDOMETRIAL BIOPSY: the lining of the uterus endometriosis is biopsied and that sample is checked, it is done at a particular point of the menstrual cycle. we need to see if the endometrium can support an embryo Causes of infertility in men: LOW SPERM COUNT: Hormonal imbalance Varicocele . varicose vein in scrotum Certain drugs IMMOBILE SPERM: Abnormal sperm shape Infection ‘ Malfunctioning prostate Makes antibodies against own sperm Immune disorder Result of reversed vasectomy INFERTILITY WORK UP MEN Evaluate medical history Scrotal varicocele , can be repaired to form normal sperm Semen analysis: volume of 1.5 cc: too low, count of 20 million: lower limit Sperm motility Sperm form INFERTILITY TREATMENT NOT IN BOOK ZIFT and GIFT: ZIFT: zygote intra fallopian transfer. It puts fertilized EGGS in the oviduct UNLIKE in vitra where they put EMBRYOS GIFTl gamete intra fallopian transfer: eggs and sperm are both placed in oviduct and hopefully fertilization comes naturally PGD: PREIMPLANTATION GENETIC DIAGNOSIS
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