IB Sexual Reproduction PDF

SEXUAL REPRODUCTION Quarter 2 Lesson 1 : Sexual Reproduction in Animals ◦Reproduction ◦the process by which all living organisms produce one of their kinds to ensure the survival of the species. ◦Sexual reproduction ◦occurs in many animals through sex cells which are produced during meiosi...

SEXUAL REPRODUCTION Quarter 2 Lesson 1 : Sexual Reproduction in Animals ◦Reproduction ◦the process by which all living organisms produce one of their kinds to ensure the survival of the species. ◦Sexual reproduction ◦occurs in many animals through sex cells which are produced during meiosis. The ovaries in female produce egg cells while the testes in males produce the sperm cells. ◦Species differ in their methods of reproduction. ◦This is explained by the fact that they have body structures that permit them to reproduce in a particular way in the environment where they live. ◦When an egg cell and a sperm cell unite, fertilization takes place. ◦ The fertilized egg cell is called zygote, a diploid cell. Sexual Reproduction in Animals ◦Sexual reproduction is a mode of reproduction involving the fusion of haploid female gamete (egg cell) and haploid male gamete (sperm cell) to produce a zygote. ◦It produces offspring with novel combination of genes. ◦Animals reproduce sexually in different ways. A. Reproduction in Earthworms ◦The earthworm is a unique type of invertebrate (animal without backbone) because it produces both eggs and sperm. ◦Animals with both male and female organs are said to be hermaphroditic. ◦need a mate to reproduce. ◦two worms line up inverted from each other so sperm can be exchanged. A. Reproduction in Earthworms ◦To mate or copulate, two worms join their anterior portions along their ventral surfaces, with their anterior ends pointing to opposite directions. ◦Each worm discharges sperm (from segment XV) into the sperm-receiving sacs (at segment IX and X) of the other. ◦Then the two worms separate. A. Reproduction in Earthworms ◦The clitellum, (which extends from segment XXXI to XXXVII) of each worm secretes a slime or mucous ring. ◦By contracting slowly, the worm gradually pushes the clitellum toward its anterior end.  A. Reproduction in Earthworms ◦Then when it passes over segments IX and X, the worm discharges sperm into it. ◦The clitellum is continuously pushed over until it dropped to the ground. ◦It is now called cocoon, A. Reproduction in Earthworms ◦Fertilization takes place inside the cocoon and the development of the embryo, then young earthworms come out after three months. ◦Fertilization of the egg and development of the embryo in earthworms are both external, that is B. Reproduction in Frogs ◦The frog represents the majority of vertebrates, which are either male or female. ◦The reproductive system of the frog is closely associated with the urinary tract. ◦Female frogs have two ovaries (which lie close to the kidneys) that produce many eggs and two oviducts with a ciliated, funnel-shaped opening. ◦The movement of the cilia creates a current in the fluid inside the body cavity; the current sweeps the eggs into the oviducts. ◦As the egg passes through the oviducts, they are coated with a jelly-like material. ◦During mating, the male frog clutches the female from the back. ◦The pressure helps the female expel the eggs into the water outside after which the frog discharges sperm over them. ◦The water causes the jelly- like material surrounding the eggs to swell, becoming something like a well-beaten egg white where fertilization of the eggs as well as the development of the embryos takes place. ◦ Soon tiny tadpoles emerge from this “frothy nest”. ◦Like in earthworms, fertilization of the egg and development of the embryos in frogs are both external, outside the body of the  C. Reproduction in Chicken ◦As with most bird species, roosters and hens don’t have external genitalia. ◦ Instead both partners procreate using an external C. Reproduction in Chicken ◦The sperm of roosters travel down tubes called vas deferens then to the sperm sacs. ◦During mating – an unceremonious affair called cloacal kiss that lasts less than 20 seconds, the sperm leave the male through the opening called cloaca, and enter the female through an entrance to her reproductive tract called the oviduct. ◦From there, the sperm make their ◦In a trip that may take a week or more, the sperm swim through the hens shell gland, then to the isthmus, followed by the magnum and finally the infundibulum. ◦There, they await the arrival of the eggs in the process called ◦As the hen’s eggs (begin as yolks in the ovary) is released and pass through the infundibulum, they are fertilized by the waiting sperm. ◦The egg white gathers around the yolk in the magnum while the shell membranes are laid down in the isthmus. ◦As the shell forms and ◦ The hen drops the fertilized egg out of her body, incubates her eggs, that is sits and warm them. ◦ Thus, unlike in earthworm and frog, fertilization in chicken takes place inside the body of the female but the development of the embryo is outside the female’s body. Human Reproduction  Human reproductive system ◦ Organ system by which humans reproduce. In females the ovaries sit near the openings of the fallopian tubes, which carry eggs from the ovaries to the uterus. The cervix extends from the lower end of the uterus into the vagina, whose opening, as well as that of the urethra, is covered by four folds of skin (the labia); the clitoris, a small erectile organ, is located where the labia join in front. ◦The activity of the ovaries and uterus goes through a monthly cycle of changes menstruation throughout the reproductive years except during pregnancy and nursing. ◦Menstruation, Periodic discharge from the vagina of blood, secretions, and shed mucous lining of the uterus (endometrium). The endometrium prepares to receive a fertilized egg by thickening and producing secretions. If the egg released by the ovary is not fertilized, the endometrium breaks ◦In males, the testes lie in a sac of skin (the scrotum). A long duct (the vas deferens) leads from each testis and carries sperm to the ejaculatory ducts in the prostate gland; these join the urethra, which continues through the penis. In the urethra, sperm mixes with secretions from the ◦In early embryos, the reproductive systems are undetermined. ◦ By birth the organs appropriate to each sex have typically developed but are not functioning. ◦They continue to grow, and at puberty their activity increases and maturation occurs, CONDOM - small, thin pouches that cover your penis during sex and collect semen PILLS - is a type of birth control that is designed to be taken orally by women. The pill contains two important hormones: progestin and estrogen Hormonal Ring ◦ How the ring works ◦ The ring steadily releases the hormones oestrogen and progestogen into your bloodstream, which prevents the release of an egg each month. ◦ It also thickens the cervical mucus, which makes it more difficult for sperm to move through the cervix, and thins the lining of the womb so a fertilised egg is less likely to implant itself. IUD ◦ An intrauterine device, also known as intrauterine contraceptive device or coil, is a small, often T-shaped birth control device that is inserted into the uterus to prevent pregnancy. IUDs are one form of long-acting reversible ◦ An IUD works as soon as it's put in and lasts for 5 to 10 years. injectable contraceptives ◦Depo-Provera is a well- known brand name for medroxyprogesterone acetate, a contraceptive injection that contains the hormone progestin. Depo- Provera is given as an injection every three months. Depo-Provera typically suppresses ovulation, keeping your Surgical Sterilization ◦Sterilization is a permanent method of a birth control. Sterilization procedures for women are called tubal sterilization or female sterilization. The procedure for men is called vasectomy. Sterilization is considered a safe procedure with few complications. Surgical Sterilization ◦Vasectomy is a form of male birth control that cuts the supply of sperm to your semen. It's done by cutting and sealing the tubes that carry sperm. Vasectomy has a low risk of problems and can usually be performed in an outpatient setting under local anesthesia. Implant ◦ The contraceptive implant (Nexplanon) is a small flexible plastic rod that's placed under the skin in your upper arm by a doctor or nurse. It releases the hormone progestogen into your bloodstream to prevent pregnancy and lasts for 3 years. coïtus interruptus ◦The meaning of COITUS INTERRUPTUS is coitus in which the penis is withdrawn prior to ejaculation to prevent the deposit of sperm into the vagina. Calendar Rhythm Method ◦ The rhythm method, also called the calendar method or the calendar rhythm method, is a form of natural family planning. To use the rhythm method, you track your menstrual history to predict when you'll ovulate. This helps you determine when you're most likely to conceive. Patch ◦The birth control patch is a type of contraception that contains the hormones estrogen and progestin. You wear the patch to avoid becoming pregnant. Once a week for three weeks, you place a small patch on your ◦ Infection with herpes simplex virus (HSV), known as herpes, is common globally. HSV type 1 (HSV-1) is typically transmitted by oral-to-oral contact and causes infection in or around the mouth (oral herpes), but it can also cause genital herpes. HSV-2 is mainly sexually transmitted and causes genital herpes. ◦ Both oral and genital herpes are mostly asymptomatic or unrecognized but can cause painful blisters or ulcers at the site of infection, ranging from mild to severe. Infection is lifelong, and symptoms can recur over many years. Some medications are available to reduce the severity and frequency of symptoms, but they cannot cure the infection. Mycoplasma genitalium (MG) ◦ Mycoplasma genitalium (MG) is a sexually transmitted infection (STI) with many of the hallmarks of its better- known counterpart, chlamydia. You can have MG without knowing it, or have symptoms; it can affect men and women, and it can be treated with antibiotics. HPV infection is a viral infection that commonly causes skin or mucous membrane growths (warts). There are more than 100 varieties of human papillomavirus (HPV). Some types of HPV infection cause warts, and some can cause different types of cancer. Most HPV infections don't lead to cancer. But some types of genital HPV can cause cancer of the lower part of the uterus that connects to the vagina (cervix). Other types of cancers, including cancers of the anus, penis, vagina, vulva and back of the throat (oropharyngeal), have been linked to HPV infection. These infections are often transmitted sexually or through other skin-to-skin contact. Vaccines can help protect against the strains of HPV most likely to cause genital warts or cervical cancer. HOW TO PREVENT STD’S? ◦ABSTINENCE QUIZ #2