Essentials of the Living World 7th Edition Chapter 30: Reproduction and Development Lecture Outline PDF

Because learning changes everything. ® Chapter 30 Reproduction and Development Lecture Outline Essentials of the Living World Seventh Edition George Johnson, Joel Bergh © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw...

Because learning changes everything. ® Chapter 30 Reproduction and Development Lecture Outline Essentials of the Living World Seventh Edition George Johnson, Joel Bergh © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  30.1 Asexual and Sexual Reproduction 1 Asexual reproduction produces offspring that are genetically identical to the parent. Mitosis is the process of cell division that is involved. Examples are. Fission in which one organism splits in two. Budding occurs where part of the parent’s body becomes separated from the rest and differentiates into a new individual. © McGraw Hill, LLC 2  Figure 30.1: Asexual reproduction in protists Access the text alternative for slide images. © McGraw Hill, LLC 3  30.1 Asexual and Sexual Reproduction 2 Sexual reproduction occurs when a new individual is formed by the union of two cells. These cells are called gametes, which are formed by meiosis in the sex organs, or gonads. The union of a sperm and an egg produces a fertilized egg, or zygote. In vertebrates, the zygote will develop by mitosis into a multicellular organism. © McGraw Hill, LLC 4  30.1 Asexual and Sexual Reproduction 3 Parthenogenesis is a special type of reproduction in which offspring are produced from unfertilized eggs. For example, in honeybees, a queen mates only once and stores sperm. If no sperm are released, the eggs develop into drones, which are male. If sperm are released, the eggs develop into other queens or workers, which are female. © McGraw Hill, LLC 5  30.1 Asexual and Sexual Reproduction 4 Hermaphroditism is a reproductive strategy in which one individual has both testes and ovaries and so can produce both sperm and eggs. Most hermaphroditic organisms require another individual to reproduce. During mating, each switches roles from producing eggs to producing sperm. © McGraw Hill, LLC 6  30.1 Asexual and Sexual Reproduction 5 In mammals, sex is determined early in development. The reproductive systems of human males and females appear similar for the first 40 days after conception. If the embryo is XY, it is a male and will carry a gene on the Y chromosome whose product converts gonads into testes. The sex-determining gene is SRY (sex-determining region of the Y chromosome). If the embryo is XX, it is a female and the gonads will become ovaries. © McGraw Hill, LLC 7  Figure 30.2: Sex determination Access the text alternative for slide images. © McGraw Hill, LLC 8  30.1 Asexual and Sexual Reproduction 6 In humans, a child’s “assigned sex” is based on the physical appearance of the newborn child: Does it have male or female genitalia? Not everyone has a gender identity that matches their assigned sex. Is the expression of the innermost sense people have about who they are. Sexual orientation is how a person views others as potential romantic and sexual partners. Exists on a continuum, from attraction to someone of the same gender, to someone of a different gender, to any gender, to not having attraction to anyone. © McGraw Hill, LLC 9  30.2 Males 1 Sperm is the human male gamete and is highly specialized for its role as a carrier of genetic information. Sperm do not successfully complete their development at 37°C (98.6°F). The sperm-producing organs, called testes, are found in a sac, called the scrotum, which hangs between the legs and maintains the two testes at a temperature about 3C cooler than the rest of the body. © McGraw Hill, LLC 10  Figure 30.3: The male reproductive organs Access the text alternative for slide images. © McGraw Hill, LLC 11  30.2 Males 2 The testis is composed of several hundred compartments. Each compartment is packed with large numbers of tightly coiled tubes called seminiferous tubules. These are the sites for spermatogenesis. The process of spermatogenesis begins in germinal cells toward the outside of the tubule. As the cells undergo meiosis, they move toward the lumen of the tubule. © McGraw Hill, LLC 12  Figure 30.4: The testis and formation of sperm Access the text alternative for slide images. © McGraw Hill, LLC 13  30.2 Males 3 After a sperm cell is manufactured within the testis, it is delivered to a long, coiled tube called the epididymis. The sperm cell is not motile when it first arrives at the epididymis and must remain there for at least 18 hours before motility develops. Mature sperm consist of a head, body, and tail. From the epididymis, the sperm is delivered to another long tube, the vas deferens. When sperm is ejaculated, it travels from the vas deferens to the urethra. © McGraw Hill, LLC 14  Figure 30.5: Human sperm cells David M. Phillips/Science Source © McGraw Hill, LLC 15  30.2 Males 4 The penis is an external tube containing two long cylinders of spongy tissue. Below and between them is a third cylinder of spongy tissue that contains the urethra in its center. The penis is designed to inflate. When nerve impulses from the CNS cause the arterioles leading into this tissue to expand, blood collects within these spaces. Continued stimulation by the CNS is required for erection to continue. © McGraw Hill, LLC 16  Figure 30.6: Structure of the penis © McGraw Hill, LLC 17  30.2 Males 5 While erection can be achieved without any physical stimulation of the penis, physical stimulation is required for semen to be delivered. Stimulation, such as by repeated thrusts into the vagina, leads first to the mobilization of sperm. Muscles encircling the vas deferens contract, moving the sperm along the vas deferens to the urethra. The stimulation finally results in the strong contraction of muscles at the base of the penis. Ejaculation is the forceful ejection of 2 to 5 ml of semen. © McGraw Hill, LLC 18  30.2 Males 6 Semen contains sperm and a collection of secretions from glands. These secretions, such as from the prostate gland, provide metabolic energy sources for the sperm. There are several hundred million sperm in the small volume of semen ejaculated. Males with fewer than 20 million sperm per ml are considered sterile. © McGraw Hill, LLC 19  30.3 Females 1 In females, eggs develop from cells called oocytes. These are located in the outer layer of compact masses of cells called ovaries. All the oocytes needed for a lifetime are already present at birth. During each reproductive cycle, one or a few of these oocytes are initiated to continue their development. This process is called ovulation. © McGraw Hill, LLC 20  Figure 30.7: The female reproductive system Access the text alternative for slide images. © McGraw Hill, LLC 21  30.3 Females 2 At birth, a female’s ovaries contain some 2 million oocytes, all of which have begun the first meiotic division. At this stage, they are referred to as primary oocytes. Each primary oocyte waits to receive the proper developmental signal to continue on with meiosis. The signal is FSH and LH and very few of the oocytes will receive it. © McGraw Hill, LLC 22  30.3 Females 3 With the onset of puberty, females mature sexually. At this time, the release of FSH and LH initiates the resumption of meiosis in a few oocytes. In humans, usually only a single oocyte continues to mature. The other oocytes will regress. Only about 400 of the approximately 2 million oocytes a woman is born with are actually ovulated. © McGraw Hill, LLC 23  Figure 30.8: The ovary and formation of an ovum Access the text alternative for slide images. © McGraw Hill, LLC 24  30.3 Females 4 The fallopian tubes (also known as uterine tubes, or oviducts) transport eggs from the ovaries to the uterus. In humans, the uterus narrows to a muscular ring called the cervix. The uterus is lined with a stratified epithelial membrane called the endometrium. The surface of the endometrium is shed during menstruation. © McGraw Hill, LLC 25  Figure 30.9a: The oviducts extend out from the uterus Access the text alternative for slide images. © McGraw Hill, LLC 26  30.3 Females 5 To fertilize an egg successfully, the sperm must make its way far up the fallopian tube. The egg is moved down the fallopian tube by contractions of smooth muscle lining the tube. Sperm swim against the current created by these contractions. An egg loses its capacity to develop within 24 hours of ovulation. Sperm can remain viable for up to 6 days. © McGraw Hill, LLC 27  30.3 Females 6 When the sperm reach the oocyte, they must penetrate through two protective layers. A layer of granulosa cells and the zona pellucida. When the first sperm makes it through the layers, the oocyte blocks the entry of other sperm. The oocyte also completes meiosis II, forming a haploid ovum. When the female haploid nucleus joins with the male haploid nucleus, the egg is fertilized and becomes a zygote. A fertilized egg attaches itself to the endometrial lining to continue development. © McGraw Hill, LLC 28  Figure 30.9b: Fertilization occurs in the oviducts Access the text alternative for slide images. © McGraw Hill, LLC 29  30.4 Hormones Coordinate the Reproductive Cycle 1 The female reproductive cycle, called a menstrual cycle, is composed of two distinct phases. The follicular phase in which an egg reaches maturation and is ovulated. The luteal phase where the body prepares for pregnancy. © McGraw Hill, LLC 30  30.4 Hormones Coordinate the Reproductive Cycle 2 The follicular phase corresponds to days 0 to 14 of the reproductive cycle. The anterior pituitary starts the phase by secreting FSH and LH in small amounts. Initially, several follicles (a follicle is an oocyte and its surrounding tissue) are stimulated to grow. The follicles begin to secrete the female hormone estrogen. © McGraw Hill, LLC 31  30.4 Hormones Coordinate the Reproductive Cycle 3 The low but rising levels of estrogen in the bloodstream act as negative feedback. The output of FSH and LH are reduced. This ensures that only one oocyte matures at one time. A rise in estrogen signals the end of the follicular phase. © McGraw Hill, LLC 32  30.4 Hormones Coordinate the Reproductive Cycle 4 The luteal phase occurs during days 14 through 28 of the reproductive cycle. The higher levels of estrogen begin to have a positive- feedback effect on FSH and LH secretion. The surge in LH causes ovulation and the wall of the follicle bursts. The follicle is released into one of the fallopian tubes. LH directs the repair of the ruptured follicle so that it fills in to become the corpus luteum. © McGraw Hill, LLC 33  30.4 Hormones Coordinate the Reproductive Cycle-5 The corpus luteum secretes progesterone which inhibits FSH and LH secretion. Progesterone also completes the body’s preparation of the uterus for fertilization, including the thickening of the endometrium. If fertilization does not occur, production of progesterone slows and eventually stops. The decreasing levels of progesterone cause the thickened layer of the endometrium to be sloughed off. This process, menstruation, usually occurs about midway between successive ovulations. © McGraw Hill, LLC 34  Figure 30.10: The human menstrual cycle Access the text alternative for slide images. © McGraw Hill, LLC 35  30.4 Hormones Coordinate the Reproductive Cycle 6 If fertilization does occur high in the fallopian tube, the zygote undergoes a series of cell divisions, called cleavage, while traveling toward the uterus. At the blastocyst stage, it implants in the uterine lining. The embryo secretes human chorionic gonadotropin (hCG). This maintains the corpus luteum and prevents menstruation. Because hCG comes from the embryo and not from the mother, pregnancy tests checks for hCG. © McGraw Hill, LLC 36  Figure 30.11: The journey of an ovum (b) Ed Reschke/Getty Images Access the text alternative for slide images. © McGraw Hill, LLC 37  30.5 Embryonic Development 1 During cleavage, the mammalian zygote divides rapidly into a larger and larger number of smaller and smaller cells. Further divisions result in a hollow ball of 500 to 2,000 cells. This is called the blastocyst. © McGraw Hill, LLC 38  30.5 Embryonic Development 2 The blastocyst contains a fluid-filled cavity called the blastocoel. Within the blastocyst is an inner cell mass concentrated at one pole that goes on to form the developing embryo. The outer sphere of cells, called the trophoblast, releases hCG. © McGraw Hill, LLC 39  30.5 Embryonic Development 3 The implantation of the blastocyst in the uterine lining initiates the formation of membranes. The amnion encloses the developing embryo. The chorion forms from the trophoblast and interacts with uterine tissue to form the placenta. The placenta connects the developing embryo to the blood supply of the mother. © McGraw Hill, LLC 40  30.5 Embryonic Development 4 In the third week of embryonic development the embryo begins its development into tissues and organs. The notochord is a flexible rod that forms along the midline of the embryo. The neural tube forms above the notochord and later becomes the spinal cord and brain. Somites form along the side of the notochord and will become muscles, vertebrae, and connective tissue. © McGraw Hill, LLC 41  30.6 Fetal Development 1 Organogenesis, the process of forming body organs, begins in the fourth week of human pregnancy. This is a crucial time during development because the proper course of events can be interrupted easily. Alcohol use during pregnancy is one of the leading causes of birth defects, producing fetal alcohol syndrome. Most spontaneous abortions (that is, miscarriages) occur during this period. © McGraw Hill, LLC 42  30.6 Fetal Development 2 During the second month of pregnancy, great changes in morphology occur as the embryo takes shape. It begins to look distinctly human. Development is essentially complete at the end of the third month. Only the lungs and brain need to develop more. The developing human is now referred to as a fetus instead of embryo. © McGraw Hill, LLC 43  Figure 30.13: The developing human 1 (a, b - top) Bradley Smith Access the text alternative for slide images. © McGraw Hill, LLC 44  Figure 30.13: The developing human 2 (c - top) Dopamine/Science Source; (d - top) Tissuepix/Science Source Access the text alternative for slide images. © McGraw Hill, LLC 45  30.6 Fetal Development 3 The second trimester is a time of growth. During the fifth month, the head and body become covered with fine hair, called lanugo, which will later be lost. By the end of the sixth month, the fetus still cannot survive outside the uterus without special medical intervention. © McGraw Hill, LLC 46  30.6 Fetal Development 4 The third trimester is a period of rapid growth. All of the growth is fueled by the mother’s bloodstream, passing into the fetal blood supply within the placenta. The placenta contains blood vessels that extend from the umbilical cord into tissues that line the uterus. © McGraw Hill, LLC 47  Figure 30.14: Structure of the placenta Access the text alternative for slide images. © McGraw Hill, LLC 48  30.6 Fetal Development 5 At approximately 40 weeks from the last menstrual cycle, the process of birth begins, including labor and delivery. Oxytocin and prostaglandins work by positive feedback to stimulate uterine contractions. The mammary glands are prepared to nourish the baby after birth. Prolactin stimulates milk production usually by the third day after delivery. Oxytocin is released following the infant suckling at the breast and initiates milk release. © McGraw Hill, LLC 49  Figure 30.15: Stages of childbirth Access the text alternative for slide images. © McGraw Hill, LLC 50  30.6 Fetal Development 6 Growth continues rapidly after birth. Different organs grow at different rates. Allometric growth refers to the fact that different parts of the body grow or cease growing at different times. Neurological growth of the baby continues long after birth. © McGraw Hill, LLC 51  30.7 Contraception and Sexually Transmitted Diseases 1 Birth control is a way to avoid reproduction without avoiding sexual intercourse. Contraception methods differ from one another in their effectiveness and their acceptability to different couples. Abstinence. Prevention of egg maturation. Prevention of embryo implantation. Sperm blockage. Sperm destruction. © McGraw Hill, LLC 52  Figure 30.17: Three common birth control methods Bob Coyle/McGraw Hill © McGraw Hill, LLC 53  30.7 Contraception and Sexually Transmitted Diseases 2 Sexually transmitted diseases (STDs) are diseases that spread from one person to another through sexual contact. Gonorrhea: Caused by a bacterium, Neisseria gonorrhoeae. Produces symptoms of discharge from the penis or vagina. In women, if left untreated, it could lead to pelvic inflammatory disease (PID), which could cause sterility. © McGraw Hill, LLC 54  30.7 Contraception and Sexually Transmitted Diseases 3 Chlamydia: Caused by the bacterium Chlamydia trachomatis. Women usually experience no symptoms until the infection is established. Can also lead to PID. Syphilis: Caused by the bacterium Treponema pallidum. Left untreated, it can lead to heart disease, mental deficiency, and nerve damage. © McGraw Hill, LLC 55  30.7 Contraception and Sexually Transmitted Diseases 4 Genital herpes: Caused by the herpes simplex virus type 2 (HSV-2). The most common STD in the United States. Causes red blisters on the penis or on the labia, vagina, or cervix. Cervical cancer: 70% is caused by human papillomavirus (HPV). A new vaccine which blocks HPV can be given to women not yet exposed to the virus. © McGraw Hill, LLC 56