Chapter 6 Sexual Reproduction In Man
Chapter OutLine • CHAPTER 6.2 • SEXUALLY TRANSMITTED DISEASES • (Online Learning) CHAPTER 6.1 THE HUMAN REPRODUCTIVE SYSTEM • Male • Female • Sperm • Ovum • CHAPTER 6.3 • CONTRACEPTION & ABORTION • Chapter 6.1.1 • Puberty • Chapter 6.1.2 • Anatomy and Function of Reproductive System • Chapter 6.1.4 • Copulation & Fertilization • Chapter 6.1.5 • Post-Fertilization • Structure & Function of: • Placenta • Amniotic Sac • Amniotic Fluid • Umbilical Cord Ovary Oviduct Uterus Cervix Vagina Testis Epididymis Sperm duct Glands Penis Structure of Gametes • Chapter 6.1.3 • Menstrual Cycle
Introduction REPRODUCTION Is the biological process where new individuals (known as “offsprings”) are produced from old ones (known as “parents”).
Types of Reproduction REPRODUCTION • Asexual Reproduction • Sexual Reproduction • Sexual Reproduction Asexual reproduction does not involve fusion of two reproductive cells. Only one parent is required. Offspring are identical. Sexual reproduction involves fusion of two reproductive cells (gametes). Produces variation in offspring.
Stages in Sexual Reproduction in Humans • Puberty • Child Birth • Copulation • Fertilization • Post-fertilization
Chapter 6.1.1 Puberty ~ Chapter 6.2.2 Anatomy of the Human Reproductive System
Learning Objectives • By the end of the lesson, you should be able to: • state some of the physical changes that occur during puberty and early adolescence. • identify on diagrams of the male reproductive system and give the functions of: testes, scrotum, sperm ducts, prostate gland, urethra and penis. • identify on diagrams of the female reproductive system and give the functions of: ovaries, oviducts, uterus, cervix and vagina. • compare the male and female gametes in terms of size, numbers and mobility.
Puberty – A time of change • Begins at the age of about 11 for girls and 13 for boys. (1) Brain releases hormones Ova and Sperm develops Ovaries and testicles produce female and male sex hormones Secondary sexual characteristics
Secondary Sexual Characteristics • For the Male 1. 11-15 yrs 2. Growth of hair 3. Growth of muscles / genitals 4. Deepening of voice / occurrence of pimples 5. Confusion, love/hate (puppy love), giggly excitement. • For the Female 1. 9-13 yrs 2. Hair growth 3. Development of breasts & hips 4. Menstruation begins 5. Confusion, love/hate (puppy love), giggly excitement.
Male Reproductive System • Organs • Testis • Epididymis • Sperm Duct • (vas deferens) • Glands • Bulbourethral gland • Prostate gland • Seminal vesicle • Penis
Male Reproductive System • Penis – Function • Insertion into vagina when erect • Process of Ejaculation • Arterioles leading to blood spaces in penis will dilate • Blood enters blood spaces, causing erectile tissues to filled with blood • Muscles of epididymis contract • Semen is released
Female Reproductive System • Organs • Ovary • Oviduct • (Fallopian tube) • Uterus • (Womb) • Endometrium • (Uterine wall lining) • Cervix • Vagina
Male and Female Gametes membrane nucleus head middle piece tail cytoplasm ovum (female gamete) sperm (male gamete)
Chapter 6.1.3 The Menstrual Cycle
Learning Objectives • By the end of the lesson, you should be able to: • describe the menstrual cycle with reference to the alternation of menstruation and ovulation, the natural variation in its length, and the fertile and infertile phases of the cycle.
Menstrual Cycle • Menstrual Cycle • A cycle of events that takes place within the female reproductive organs. • Average period of the cycle is 28 days. • Regulated by hormones (progesterone and oestrogen) • Menstruation – monthly discharge of uterine lining during Day 1 to 5. • View Video • View Animation
Menstrual Cycle • Menstruation • Day 1 to 5 • Endometrium thickness reaches minimum • Menses • Follicular Phase • Day 6 to 14 • Endometrium thickness increases with rich supply of capillaries • Ovulation: Day 14 • Fertile: Day 11 - 16 • Luteal Phase • Day 14 to 28 • Maintenance of uterine lining in preparation for implantation • Day 28 • If no implantation takes place, endometrium breaks down • Menses
Chapter 6.1.4 Copulation & Fertilization
Learning Objectives By the end of the lesson, you should be able to: recognise that in sexual reproduction a new individual is formed through the union of an egg and a sperm. recognise that a new individual formed through sexual reproduction receives genetic information from its mother (via the egg) and its father (via the sperm).
Fertilization • Process involving the fusion of the male and female gametes to form the zygote. This process restores the diploid number of chromosomes. These are structures containing hereditary/genetic material found in the nucleus of cells. • 46 Chromosomes in most human cells • 23 chromosomes in sperm cell or egg
Fertilization • Takes place in the oviduct • Only one sperm will successfully fuse with egg. • Head and middle piece attached to egg membrane • Tail detaches • Nucleus of sperm enters egg • Membrane of egg change dislodge other sperms • Fusion of sperm and egg nuclei takes place. • Fertilization restores the diploid number of chromosomes (23 pairs in humans) • The fertilized egg will be implanted into the endometrium, which will supply the egg with nourishment.
Chapter 6.1.5 Post-Fertilization
Learning Objectives By the end of the lesson, you should be able to: describe fertilisation and early development of the zygote simply in terms of a ball of cells which becomes implanted in the wall of the uterus. state the function of the amniotic sac and amniotic fluid. describe the function of the placenta and umbilical cord in relation to exchange of dissolved nutrients, gases and excretory products (no structural details are required).
Embryonic Development Zygote • The Embryo • Hollow ball of cells • Eventually implanted into the endometrium
Embryonic Development • Implantation • Embryo becomes implanted into the uterine lining • The outer layer of cells starts to produce tiny finger-like projections, known as villi (singular: villus) into the endometrium • Placenta Development • The embryonic villi becomes embedded in the uterine lining • Together the maternal tissues (the uterine lining) and the embryonic tissues (the villi) forms the placenta. Diagrammatic representation
Embryonic Development Summary • Zygote: • - Undifferentiated ball of cells • - Implantation takes place 3 to 4 days after fertilization • Endometrium thickens throughout this period and develops rich network of blood capillaries to nourish foetus. • Foetus also protected in a fluid-filled sac known as the amnion. • Embryo • - Simple tissue layers • Foetus • - Recognizable organs