Chapter 20 Reproduction and Pregnancy Lesson Lesson 20

Chapter 20 Reproduction and Pregnancy Lesson Lesson 20. 1 20. 2 20. 3 20. 4 20. 5 Sexual Reproduction The Human Reproductive System Pregnancy Prenatal Care and Pregnancy Problems Reproductive System Diseases and Disorders

Lesson 20. 1 Sexual Reproduction

Warm-Up List 10 things that you already know about sexual reproduction and the male and female reproductive systems. As you read this chapter, add new information about these topics to your list. moodboard/thinkstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Asexual Reproduction Versus Sexual Reproduction • Asexual reproduction: process that requires only one cell and which produces offspring identical to that cell • Sexual reproduction: process by which the genetic material of two organisms—one male and one female—combine to create offspring – Each parent contributes a sex cell, or gamete • Male—sperm • Female—ovum Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Human Sexual Reproduction • Humans reproduce through sexual intercourse • During intercourse, sperm must be deposited within the vagina to cause pregnancy • Human cells have 46 chromosomes occurring in 23 pairs; one pair contains the sex chromosomes – A female has two X chromosomes in each cell – A male has one Y and one X chromosome – Each gamete has one half of the chromosome pair Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Cell Division and Fertilization • Mitosis: a cell copies its own genetic material and then divides into two identical cells • Meiosis: a cell splits own genetic material and then divides into two different cells • Fertilization: process by which the sperm and ovum combine to create a zygote; restores the full set of chromosomes to a gamete Jane Ades/National Human Genome Research Institute Click here for the “Mitosis and Meiosis” animation Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking Parents’ characteristics are transmitted to their children through a process called inheritance. However, not all characteristics are passed down to offspring. Why does this happen? Some genes are always expressed in offspring. These are known as dominant genes. Other genes are not always expressed. These are known as recessive genes. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Gender Determination • A person’s gender is determined by the sex chromosome contributed by the sperm cell • If a sperm with a Y chromosome fertilizes an ovum, the zygote is male • If a sperm with an X chromosome fertilizes an ovum, the zygote is female Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking What situation results in fraternal twins? What situation results in identical twins? • If a woman produces two ova that are each fertilized by a different sperm, the result is fraternal twins. • If a single, fertilized ovum develops, splits in two, and produces genetically identical babies, the result is identical twins. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Lesson 20. 2 The Human Reproductive System

The Female Reproductive System • Ovaries: contain immature eggs (ova); make estrogen and progesterone • Fallopian tubes: connect the ovaries to the uterus; guide the ova out of the ovaries • Uterus: hollow organ that can house and nurture a developing fetus • Vagina and cervix: the vagina (birth canal) connects to the uterus via the cervix Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Think Further What organs are included in the female external genitalia? Where are they each located? • • Mons pubis: above the labia and vaginal opening Labia majora: outer, larger folds of skin Labia minora: inner, smaller folds of skin Clitoris: above the vaginal opening Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Ovulation and Menstruation • Menstruation is the sloughing off of the endometrial lining of the uterus • A sequence of changes coordinated by sex hormones • Ovarian follicles begin developing • At the midpoint of the menstrual cycle, ovulation occurs and an ovum is released from the follicles • If no fertilization occurs, progesterone secretion stops and less estrogen is produced, triggering menstruation Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking What is the difference between the terms menarche and menopause? When does each occur in a woman’s life span? • Menarche is a girl’s first menstrual cycle and it usually occurs between 10 and 15 years of age. • Menopause is when menstruation stops and the ovaries stop releasing ova. This usually occurs when a woman is in her late 40 s or early 50 s. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

The Male Reproductive System • Testes: produce sperm and testosterone • Seminal vesicles and prostate: secrete fluid that mixes with sperm to form semen • Penis: the organ used for sexual intercourse; contains erectile tissue Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Think Further What is the purpose of the flagellum? Why is it important for reproduction? • The flagellum propels sperm through liquid to reach the ovum. • Without the flagellum, a sperm would have almost no chance of reaching an ovum and fertilizing it, thus creating a zygote. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Lesson 20. 3 Pregnancy

Cleavage • A type of mitosis that occurs in a zygote • The zygote develops a furrow, which deepens and appears to cleave, or split, into two new cells, which then cleave and create four cells and continue to divide • Five days after fertilization, cleavage has occurred seven times, forming a ball of 128 cells, or blastocyst • After eight to ten days, the blastocyst implants in the endometrium and is called an embryo Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Implantation • The process by which an embryo burrows into the endometrial lining of the uterus • The embryo develops a membrane called the chorion, which attaches to the endometrial tissue • This connection creates the placenta • An umbilical cord connects the placenta to the developing baby to provide nutrients Click here for the “Ovulation through Implantation” animation Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Think Further Chemicals such as alcohol can pass from the mother to a developing baby through the placenta. What disorder is caused when a pregnant women drinks alcohol? What are the effects of this disorder? • Fetal alcohol syndrome • Babies with fetal alcohol syndrome are underdeveloped and may have some brain damage that affects their ability to learn and communicate Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Embryonic and Fetal Development • Embryonic development – Organogenesis, when the organs take familiar forms and locations, is completed after eight weeks – The embryo is now a fetus • Fetal development – Occurs in the amnion, a fluid-filled sac that cushions and stabilizes the fetus – After nine months, most bones, organs, and muscles have developed Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

The Pregnancy Calendar • Gestation—the period of time from fertilization through birth—is typically nine months long • Doctors divide pregnancy into trimesters – First trimester: from fertilization through week 13 of gestation – Second trimester: week 14 through week 26 – Third trimester: from week 27 through the end of the pregnancy Andresr/shutterstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking What are some emotional changes and unpleasant side effects that women may experience during pregnancy? • Emotional changes: mood swings, depression, anxiety • Unpleasant side effects: nausea and vomiting (morning sickness), leg swelling, varicose veins, hemorrhoids, indigestion, constipation, frequent urination, backache, fatigue, difficulty sleeping Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Lesson 20. 4 Prenatal Care and Pregnancy Problems

Prenatal Care • Medical care provided for the mother and the fetus before birth • Receiving good medical care during and after pregnancy is vital for both the mother and the baby chaoss/i. Stock/thinkstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Food and Nutrition • Most expectant mothers should add about 300 calories to their daily diets • Foods and substances to avoid – – – Piotr Marcinski/shutterstock. com Nicotine (cigarettes) Alcohol Illegal drugs Canned tuna Unpasteurized products Raw or undercooked meat, eggs, and fish Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Think Further What kinds of physical activity should pregnant women engage in? What are the health benefits of regular exercise during pregnancy? • Pregnant women should choose lower-impact activities such as walking and swimming. • Regular exercise helps pregnant women maintain good circulation, blood pressure, and blood sugar levels. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Ectopic Pregnancy • A serious condition in which an embryo attaches and develops inside the fallopian tube • Caused by pelvic inflammatory disease or endometriosis • Can result in a ruptured fallopian tube, causing severe abdominal pain, bleeding, and shock • Women can reduce their risk of ectopic pregnancy by avoiding sexually transmitted infections and consulting their doctor if an infection is suspected Valua Vitaly/shutterstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Pregnancy Complications • Miscarriage: a pregnancy that ends before the 20 th week of gestation; spontaneous abortion • Preeclampsia: condition in which a pregnant woman experiences high blood pressure • Eclampsia: life-threatening emergency in which a pregnant woman’s blood pressure rises, causing seizures • Gestational diabetes mellitus: condition in which a woman’s body becomes incapable of producing insulin due to the hormones involved in pregnancy Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Think Further How often does a pregnant woman typically see her doctor? What is generally included in these doctor visits? • A pregnant woman typically sees her doctor monthly through the eighth month of pregnancy and weekly during the last month of pregnancy. • The first doctor visit might include lab tests for diabetes and sexually transmitted infections. At follow-up visits, the doctor performs a routine physical exam to measure a woman’s weight and blood pressure. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Health Risks for Teen Mothers and Their Babies Risks for teen mothers • Placenta previa • Preeclampsia • Prolonged labor • Premature delivery • Anemia Risks for babies of teen mothers • Low birth weight • Infant death • Chemical dependence • Poor growth • Infections Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Prenatal Care for Teen Mothers • Teen mothers should – Include lots of fresh vegetables, fruits, whole grains, lean meats, and water in their diets – Avoid sugars, empty calories, fast food, and soft drinks – Engage in moderate, low-impact exercise Paul Vasarhelyi/shutterstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking Complete each of the following lists. Expecting teen mothers should… Expecting teen mothers should not… • Sleep 6– 8 hours each night • Eat whole grains, fresh fruit and vegetables, and lean meats • Prevent STIs • Drink plenty of water • Exercise moderately • Take prenatal vitamins • • • Smoke Use drugs Drink alcohol Exercise excessively Diet to lose weight Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Lesson 20. 5 Reproductive System Diseases and Disorders

Menstrual Disorders • Common symptoms – – – Lack of menstruation Painful, irregular menstrual periods Excessive bleeding Changes in mood Depression or anxiety • Premenstrual syndrome (PMS) – Occurs before menstruation – Includes cramps, mood changes, and bloating • Premenstrual dysphoric disorder (PMDD) – severe PMS lightwavemedia/shutterstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Endometriosis • A condition in which endometrial tissue grows in abnormal places • Can cause – – Pelvic pain Diarrhea or constipation Abdominal bloating Fatigue • Major complication is infertility, or the inability to reproduce wavebreakmedia/shutterstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking What health problems does pelvic inflammatory disease (PID) cause? Can this disease be prevented? • Pelvic inflammatory disease causes inflammation and scarring of a woman’s pelvic reproductive organs, as well as chronic pelvic pain and ectopic pregnancy, leading to infertility. • Yes; pelvic inflammatory disease can be prevented by preventing sexually transmitted infections. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Female Cancers and Tumors • Cervical cancer: progresses slowly and can be detected with a Pap test, or Pap smear • Uterine cancer: grows in the endometrium; most common cancer of the female reproductive organs • Fibroid tumors: benign tumors of uterine muscle that can make pregnancy difficult or impossible • Ovarian cancer: grows in the ovaries and is often not detected until it has spread elsewhere • Ovarian cysts: noncancerous tumors in the ovaries • Breast cancer: the second leading cause of death in women Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Male Reproductive System Disorders • Prostatitis: inflammation or infection of the prostate; leads to pain and blood in the urine • Epididymitis: inflammation of the epididymis, the organ that stores immature sperm • Orchitis: inflammation of the testes • Cryptorchidism: failure of the testes to descend from the abdominal cavity Monkey Business Images/shutterstock. com Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Critical Thinking What is the most common cause of orchitis? What are the symptoms of orchitis? • Mumps is the most common cause of orchitis. • Symptoms include sudden testicular swelling, pain, and tenderness; nausea and vomiting; fever; and prostate enlargement and tenderness. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Male Cancers • Testicular cancer: grows in one or both of the testes – Treatable if detected early – Symptoms include testicular swelling and a painless lump on one or both testicles – Young men should conduct regular self-exams • Prostate cancer: grows in the prostate – Second most common cancer in the world – Most cases occur in men 65 years of age and older – Risk factors include age, smoking, and high-fat diet Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.