Reproductive System in Animals Student Notes PDF

Prepared by : Ms Norlaila Najwa bt Rahman  Learning Outcome On completion of this chapter, students should be able to: Identify the anatomy of human male and female reproductive systems and functions of the gonads. Describe the processes of oogenesis and spermato...

Prepared by : Ms Norlaila Najwa bt Rahman  Learning Outcome On completion of this chapter, students should be able to: Identify the anatomy of human male and female reproductive systems and functions of the gonads. Describe the processes of oogenesis and spermatogenesis. Outline the process of artificial insemination (AI) and in vitro fertilisation (IVF). Define sexually transmitted infection as an infection that is transmitted via body fluids through sexual contact. Discuss the human immunodeficiency virus (HIV) is an example of an STI. Explain how the spread of STIs is controlled. Describe the methods of transmission of HIV. Discuss how HIV infection may lead to AIDS. Describe the development of a pollen grain, and formation of male gamate in plants. Describe the development of ovule, embryo sac and formation of female gamete in plants Compare different types of asexual reproduction Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  It is the organ system by which humans reproduce and bear live offspring Take place as internal fertilization by sexual intercourse Why we need to reproduce? - To ensure survival of the species Prepared by : Ms Norlaila Najwa bt Rahman  Male Reproductive Anatomy The purpose of the organs of the male reproductive system is to perform the following functions: - to produce, maintain and transport sperm (the male reproductive cells) and protective fluid (semen) - to discharge sperm within the female reproductive tract -to produce and secrete the male sex hormones responsible for maintaining the male reproductive system Prepared by : Ms Norlaila Najwa bt Rahman  Male Reproductive Anatomy External reproductive organs – scrotum and penis Internal reproductive organs: - Gonads that produces sperm and reproductive hormones - Accessory glands that secrete product essential to sperm movement - Ducts that carry the sperm and glandular secretion Prepared by : Ms Norlaila Najwa bt Rahman  Male Reproductive Anatomy Testes - produce sperm and male hormones Epididymis - sperm matures and stored Vas deferens - transports mature sperm to the urethra Urethra - tube that carries urine from bladder to outside of the body / carries sperm outside from the body Penis - male organ for copulation, the release of semen and urination Scrotum - A pouch of skin that encloses the testes /maintain the testes at temperature suitable for sperm production Sperms are delivered in a thick, whitish mixture of fluids called semen. Prepared by : Ms Norlaila Najwa bt Rahman  Male Reproductive Anatomy Accessory gland The semen contain secretions from: Seminal vesicle - produce a sugar rich fluid (fructose) that provide energy to sperm Prostate gland - secretes an alkaline fluid to neutralize the acidic environment in the vagina and increasing sperm cell motality Bulbourethral glands - release mucous secretion to lubricates penis, facilitating its penetration into the vagina Prepared by : Ms Norlaila Najwa bt Rahman Male Reproductive System Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  Female Reproductive System Function : - produce egg (ova) - produce sex hormone ( estrogen/progesterone) - support and protect developing embryo - give birth to a new baby Internal Genitalia Structure : Vagina - accepting the penis and sperm during sexual intercourse - canal that join the cervix to the outside of the body - also is known as birth canal Prepared by : Ms Norlaila Najwa bt Rahman  Female Reproductive System Cervix - lower portion or neck of the uterus - produce mucus that provides lubrication & sperm transport Uterus - hollow organ that is the home to a developing fetus Ovaries - produce eggs and hormones Fallopian - tunnels for the egg cell to tubes travel from the ovaries to the uterus - where fertilization happen Prepared by : Ms Norlaila Najwa bt Rahman  Female reproductive System Endometrium - innermost layer as a lining for the uterus - during menstrual cycle, the endometrium grows to a thick, blood vessel rich, glandular tissue layer - represent an optimal environment for the implantation of a blastocyst - during pregnancy, the blood vessels in the endometrium furthur increase in size and number forming placenta - placenta supplies oxygen and nutrition to the embryo and fetus Prepared by : Ms Norlaila Najwa bt Rahman  Female Reproductive System Female external genitalia, known as vulva Labia majora - enclose and protect the other external reproductive organs -part around the vagina which helps lubrication during intercourse Labia minora - surround the vaginal and urethral openings / entrance of the vagina Clitoris - it plays an important part in sexual excitement in females -very sensitive to stimulation and can become erect Prepared by : Ms Norlaila Najwa bt Rahman  Female Accessory Reproductive Organ The breast contain the mammary glands, connective & fatty (adipose) tissue The mammary gland is present in both sexes but normally only females produce milk - they have no function in males The mammary glands consist of hundreds of small milk- producing lobules that secrete milk which drains into a series of ducts opening at the nipple Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  Sexual Reproduction Humans carry out sexual reproduction to ensure the continuity of the species Sexual reproduction = the production of new individual resulting from the joining of the gametes The resulting offspring will not be genetically similar to the parents, but having genetic information from both parents increases genetic variation - higher chance of surviving environmental changes Prepared by : Ms Norlaila Najwa bt Rahman  Spermatogenesis Spermatogenesis is the process of sperm cell production Takes place in seminiferous tubules within each testes Millions of sperm are produced everyday after puberty in young man A typical ejaculation may contain 100-300 million sperm,but only one will fertilize with egg Prepared by : Ms Norlaila Najwa bt Rahman  Spermatogenesis Spermatogenesis begins with undifferentiated cells, the spermatogonia in walls of the seminiferous tubules Spermatogonia which are diploid cells, divide by mitosis and produce more spermatogonia Some enlarge and become primary spermatocytes, which undergo meiosis and produce haploid gametes. Each primary spermatocyte undergoes first meiotic division, which produce two haploid secondary spermatocyte. During the second meiotic division, each of the two secondary spermatocytes gives rise to two haploid spermatids. Each spermatid differentiates into a mature sperm. Prepared by : Ms Norlaila Najwa bt Rahman Spermatogenesis Prepared by : Ms Norlaila Najwa bt Rahman  Sperm cell Function - to move and carry the genetic information to the egg Structure: Head - the largest head region of the sperm that contains DNA - Acrosome contains protein and enzymes that help the sperm penetrate the egg Midpiece - the narrow middle part of the cell that contains mitochondria to provide the energy for the movement of the flagellum Tail : The wavelike motion of the flagellum propels the sperm forward Prepared by : Ms Norlaila Najwa bt Rahman Regulation of male reproduction Prepared by : Ms Norlaila Najwa bt Rahman  Oogenesis Oogenesis is the formation of ovum or egg starts in the ovaries of the fetus before birth Before birth, oogonia divide many times by mitosis. Some oogonia differentiate to become primary oocytes that undergo meiosis Only one functional ovum is produced from each primary oocyte. The other cells produced are polar bodies that degenerate. Prepared by : Ms Norlaila Najwa bt Rahman  Ovum Secondary oocyte large and non – motile it is carried along the oviducts from the ovary to the uterus by ciliated cells lining the tubes and by muscular contraction of the tubes Zona pellucida - stop more than one sperm fertilizing the egg Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  In vitro fertilisation (IVF) In vitro fertilisation (IVF) is one of several techniques available to help people with fertility problems have a baby. During IVF, an egg is removed from the woman's ovaries and fertilised with sperm in a laboratory. The fertilised egg, called an embryo, is then returned to the woman's womb to grow and develop. Hormones that would be injected to stimulate egg cell development Follicle stimulating hormone /FSH Luteinizing hormone / LH Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman  Artificial insemination (AI) Artificial insemination (AI) is a procedure by which one manually deposits a sperm suspension, fresh or frozen-thawed, into the female reproductive tract to overcome logistical problems associated with natural mating. Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman Prepared by : Ms Norlaila Najwa bt Rahman STIs & HIV/AIDS  Unprotected sexual intercourse can lead to the transfer of pathogens via exchange of body fluids  Infections passed on in this way are known as sexually transmitted infections (STIs)  An example of an STI is HIV (Human Immunodeficiency Virus), the virus that usually leads to the development of acquired immunodeficiency disease (AIDS)  HIV can also be spread via sharing needles with an infected person, blood transfusions with infected blood and from mother to fetus through the placenta and mother to baby via breastfeeding Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman How HIV Affects the Immune System  Immediately after infection, people often suffer mild flu-like symptoms  These symptoms pass and for a period of time infected people might not know they are infected  The virus infects a certain type of lymphocyte of the body's immune system  Normally lymphocytes seek out and destroy pathogens that enter the body, producing antibodies that attach to pathogens, enhancing phagocytic activity  However, HIV avoids being recognised and destroyed by lymphocytes by repeatedly changing its protein coat  It then infects a certain type of lymphocyte and uses the cells’ machinery to multiply  This reduces the number of lymphocytes of the immune system, and also the number of antibodies that can be made  This decreases the body’s ability to fight off infections, eventually leading to AIDS (Acquired immunodeficiency) Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman Controlling the Spread of STIs The spread of STIs such as HIV are best controlled by: Limiting the number of sexual partners an individual has Not having unprotected sex, but making sure to always use a condom Getting tested if unprotected sex or sex with multiple partners has occurred Raising awareness by education programmes Prepared by : Ms Norlaila Najwa Najwa bt bt Rahman Rahman Prepared by : Ms Norlaila Najwa bt Rahman  Plant reproduction 2 way: Sexual reproduction 2 gametes (male and female) Asexual reproduction Vegetative part Apomixis (unfertilized seed) Prepared by : Ms Norlaila Najwa bt Rahman Plant Reproduction Prepared by : Ms Norlaila Najwa bt Rahman Pollination Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  Asexual Reproduction in Plants Many plants are able to propagate themselves using asexual reproduction - cloning themselves Asexual reproduction is the production of new individuals whose genes all come from one parent without fusion of egg and sperm relies entirely on mitotic cell division all progeny are genetically identical to parents and to each other Prepared by : Ms Norlaila Najwa bt Rahman  Example Vegetative method: Tuber Underground stem Thickened and fleshy end (due to large amount of nutrient storage) E.g.: potato, carrot Prepared by : Ms Norlaila Najwa bt Rahman  Vegetative method: plantlet Present of plantlet ( small plant/meristemic tissue) along at leaf margin Develop when drop to ground E.g.: kalanchoe Prepared by : Ms Norlaila Najwa bt Rahman Vegetative method : Suckers Prepared by : Ms Norlaila Najwa bt Rahman  Apomixis Apomixis is a form of asexual reproduction in plant in which seeds are produced without pollination or fertilization A diploid cell in the ovule gives rise to an embryo The ovules mature into seeds, which are dispersed Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  Learning Outcome On completion of this chapter, students should be able to: Describe asexual and sexual fertilization in animal Describe the 4 mechanisms of asexual reproduction Describe internal and external fertilization in animal Describe the reproductive system of hermaphrodite animals. Describe the development of the embryo in viviparous, oviparous and ovoviviparous Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman What is Reproduction? - is the creation of new individuals Why reproduce? - to prevent extinction of the species and to ensure the continuity of the species How to reproduce ? 2 ways :  1)ASEXUAL  2)SEXUAL Prepared by : Ms Norlaila Najwa bt Rahman  “ASEXUAL REPRODUCTION IS A SINGLE PARENT PRODUCE GENETICALLY IDENTICAL OFFSPRING”  Only required 1 parent/ 1 Individual  Undergo mitotic cell division  genetic copy of the parent  Why asexual?  Sessile (inability to move)  Low population density of mates/partner  Who has the ability?  Most Invertebrates  E.g. : sponges, cnidarians, rotifers (sea organism), flatworm, annelids Prepared by : Ms Norlaila Najwa bt Rahman 1. FISSION 2. BUDDING 3. FRAGMENTATION 4. PATHENOGENESIS Prepared by : Ms Norlaila Najwa bt Rahman  process undergo by a parent cell that separate the offspring into two (binary fission) or more (multiple fission) individuals of approximately the Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  In which new individuals arise from outgrowths of existing parent body  May attached or separated to become new individual  E.g.: in certain species of coral and hydra Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  A single parent has the ability to break of its body into fragment of several pieces which each piece regenerates into complete new animal E.g.: Sea stars genus Linckia, flatworm Prepared by : Ms Norlaila Najwa bt Rahman  A process in which an egg develops without being fertilized (“virgin development”)  clone of the mother  E.g. : most insect (bees, wasp) arthropods, some lizards, fishes Prepared by : Ms Norlaila Najwa bt Rahman Advantages Disadvantages Energy efficiency (required minimum One parent to take care all the offspring mobility and single individual) or parent disappear (e.g. fission) Fast and favourable for stress condition Lack of adaptation or adapts very slowly and less requirement to produce high when condition change quantity of offspring high survival chances in unchanging catastrophe (disaster) can affects whole environment (mimic their parent) species due to one infected individual (since they are all genetically identical) may lead to high risk of species extinction Prepared by : Ms Norlaila Najwa bt Rahman  Sexual reproduction is the fusion of 2 types of gametes from 2 parents 1. Male parent(sperm) 2. Female parent (ovum)  forming a zygote (fertilized egg) which develop into non- identical individual to either both parentical Prepared by : Ms Norlaila Najwa bt Rahman  What is fertilization? “the union of egg and sperm” 2 form of fertilization Internal Fertilization External Fertilization Prepared by : Ms Norlaila Najwa bt Rahman  Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract  Male generally delivers sperm cells into body of female  E.g.: human , mammals, most terrestrial animal  Requires between male and female animals for efficient fertilization Prepared by : Ms Norlaila Najwa bt Rahman  Terrestrial animals typically use internal fertilization so as to prevent exposure and desiccation of gametes and embryos. Internal fertilization offers more protection to the gametes and embryos, but at a potential survival cost to the parent Prepared by : Ms Norlaila Najwa bt Rahman  Requires Why ? To attract the opposite sex Prepared by : Ms Norlaila Najwa bt Rahman  Sex pheromones are pheromones released by an organism to attract an individual of the opposite sex, encourage them to mate with them, or perform some other function closely related with sexual reproduction.  Chemicals released by one organism that can influence the physiology and behavior of other individuals of the same species  Small, volatile(evaporate)/water-soluble molecules disperse into environment and active in tiny amounts  Function : mate attractant Prepared by : Ms Norlaila Najwa bt Rahman  Internal Fertilization Advantages Disadvantages 1. Provide greater protection  High energy consumption due 2. high chances of survival to complex courtship, mating - Retain the embryo, which and gestation (pregnancy) that develops inside the may lead to possibility of female’s reproductive tract dying parent hidden from predator  Required parental care for the 3. Sexually selected physical young throughout gestation or traits until the eggs hatch  Required many specialized sexual reproductive organs for reproduction Prepared by : Ms Norlaila Najwa bt Rahman  EXTERNAL FERTILIZATION  Ovum fertilized by sperm in the external environment outside from sexual reproductive organ of parent body. Prepared by : Ms Norlaila Najwa bt Rahman  EXTERNAL FERTILIZATION § Specific habitat is important such as damp, moist or water. Why ? -to prevent the gametes from drying -to allow the e.g. fishes , amphibian, mollusk susceptible to environmental influences, such as predators and pH changes usually release large quantities of gametes to compensate for losses the process of releasing gametes into the water is called spawning. Prepared by : Ms Norlaila Najwa bt Rahman  External Fertilization Advantages Disadvantages Low energy expenditure due Large number of gametes to very little effort for must be produced to ensure gametes to randomly meet high possibility of both and no internal development sperm and egg encounter (gestation ) Required specific habitat No parental care required, such as seasonal, climates, optimal habitat is a survivor or temperature due to the key delicate nature of the Less sexual reproduction gametes organ required Many zygotes are produced Eggs but only a few survive due to high predator exposure Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman  Single individual  Sequential Hermaphrodites which the individual is born as one sex, but can later change into the opposite sex depends on condition e.g. some fishes (such as blue coral fish, clown fish ), jelly fish, gastropod  Simultaneous Hermaphrodites has both male and female sexual organs at the same time which self-fertilization often occurs. E.g. earth worms, tapeworm, slug Prepared by : Ms Norlaila Najwa bt Rahman  Sequential Hermaphrodites an individual reverses its sex during its lifetime Bluehead wrasse live in a group consisting of a single male and several females when the male dies, the largest (usually oldest) female in the group becomes the new male Within a week, the transformed individual is producing sperm instead eggs Prepared by : Ms Norlaila Najwa bt Rahman Asexual vs Sexual Reproduction Prepared by : Ms Norlaila Najwa bt Rahman REPRODUCTION ASEXUAL REPRODUCTION SEXUAL REPRODUCTION METHODS Parent Single parent Require two unisexual parent; female & male or hermaphrodites Gamete Specialized reproductive Specialized reproductive cells are not formed cells; sperms (male gamete) and ovum / eggs (female gamete) Meiosis None Occur at some stages to produce haploid cell or gametes Progeny Genetically identical to its Not identical to parents parents except for those undergo mutation Prepared by : Ms Norlaila Najwa bt Rahman ( Prepared by : Ms Norlaila Najwa bt Rahman  Development of the embryo Prepared by : Ms Norlaila Najwa bt Rahman  Expulsion of undeveloped eggs rather than give birth to live young (lay egg). v t h e e g g s m ay h a v e b e e n fertilized internally before released v Usually required internal fertilization v E.g.: birds, reptiles Prepared by : Ms Norlaila Najwa bt Rahman  Ovoviviparity  The offspring enclosed in eggs however the egg still be incubated inside the mother’s body until they ready to hatch  Involved Internal fertilization  The young depends on stored yolk for growth nourishment rather than on transfer nutrient from mother  E.g.: shark Prepared by : Ms Norlaila Najwa bt Rahman Prepared by : Ms Norlaila Najwa bt Rahman