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Reproductive System

Reproductive System. Sandra Benito and Pau Miquel. Human Reproductive System. N ot critical for survival Fundamental for the continuation of species P roduces, stores and releases gametes ( specialized – independent - sex cells ) Allow s the fusion between egg and sperm

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Reproductive System

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  1. Reproductive System Sandra Benito and Pau Miquel

  2. Human Reproductive System • Not critical for survival • Fundamental for the continuation of species • Produces, stores and releases gametes (specialized – independent - sex cells) • Allows the fusion between egg and sperm • Said fusion produces a zygote • Single cell from which human later develops • Embryo development: • Baby is underdeveloped - no organs yet • Six weeks - female and male are the same • Seven weeks - female and male organs begin to form: • Male – testes • Female – ovaries

  3. Human Reproductive System (2) • Testes: • Produce testosterone (male sex hormone) • Required for sperm generation and male development • Ovaries: • Produce estrogen and progesterone (female sex hormones) • Estrogen is required for egg formation and female development • Progesterone prepares the uterus for embryo development • Produce eggs • Gonad (organ that produces gametes) • Active sex cells are developed at puberty • End of puberty - fully developed sex organs • Begins when hypothalamus signals pituitary glands to produce increased levels of follicle-stimulating hormones (stimulates formation of ova or sperm) and  luteinizing hormone (stimulates ovulation)

  4. Male Reproductive System • Release of follicle-stimulant and luteinizing hormone • Produces testosterone in testes • During puberty it "activates" male development • Sperm is stored in scrotum (ideal temperature) • Within the testes - seminiferous tubules (produce semen) • Main structures: • Testes - organ producing sperm • Epididymis - organ storing sperm • Vas deferens - tube-like structure connecting epididymis and seminal vesicle • Urethra - structure that transports semen • Penis - male sex organ

  5. Sperm Development • Sperm (aka spermatozoon, semen) - male sex cell • Derived from cells in testes - undergo meiosis (cell division) - form haploid nucleus of mature sperm • Structure: head, mid-piece and flagellum • Head - contains condense nucleus • Tip of the cap – enzymes • Mid-piece - contains mitochondria • Flagellum - provides movement • Sperm is produced in the seminiferous tubules - move into the epididymus • Sperm mature and are stored

  6. Sperm Development (2) • Some move into the vas deferens • Structure that extends from scrotum to the abdominal cavity • Eventually joins the urethra – penis • Glands lining the RP • Seminal vesicles • Prostate • Bulbourethral gland • Produce seminal fluid (rich in nutrients) • Combination of sperm and seminal fluid = semen

  7. Sperm Release Sexual excitement in male - ANS prepares for sperm delivery Erection Ejaculation - penis is inside the FRP Sperm is ejected by muscle contractions 200 - 600 million sperm in an average ejaculation

  8. Female Reproductive System • Main structures: • Ovaries: The female gonad that produces eggs • Fallopian tubes: Fluid filled tubes through which an egg passes after its release from an ovary • Uterus: Organ in which a fertilized egg can develop • Vagina: Canal that leads from the uterus to the outside of the body

  9. Egg Development and Release • Each ovary has approx 400,000 follicles • Follicle: Cluster of cells surrounding the egg that helps it mature • Only ~400 eggs are released in the lifetime of a female • Eggs go through meiosis, only one survives • Ovulation: • Egg leaves follicle and enters Fallopian tube where fertilization may occur • Egg enters uterus

  10. Menstruation • Cycle: Once in ~28 days • Four phases: • Follicular phase: • Development of egg/follicle • 8 -10 days • Ovulation: • Egg leaves follicle and enters Fallopian tube to (maybe) be fertilized • Luteal phase: • Remains of follicle (now called corpus luteum) release estrogen and progesterone • These stimulate cell growth and tissue development in uterus • Menstruation: • If no fertilization occurres corpus luteumdesintegrates • This reduces estrogen and progesterone, which leads to the lining of the uterus deataching • Tissue, blood and the unfertilized egg are discharged through vagina

  11. Fertilization and Development Egg fertilization - human development begins Debate - does life begin once the egg is fertilized?

  12. Fertilization • Sperm + egg = fertilization • Process • Semen is ejaculated through penis into vagina • Penis enters vagina below the cervix • Semen swim through uterus • Semen enter the Fallopian tubes • 1% will reach the upper region of each tubule • Egg - protected by layer of enzymes • Semen attaches - it releases other enzymes • Sperm head releases nucleus into egg • Egg is fertilized • Fertilized egg = zygote

  13. Early Development Cell division begins Attach to uterus wall further on First cell divisions inside Fallopian tube Four days = 50 cells within embryo Morula Continued growth - fluid develops within embryo Blastocyst Seven days = blastocyst attaches to uterus wall Secretes enzymes - attach to tissue

  14. Early Development (2) Gastrulation Group of cells are formed Two layers --> three Cell migration = gastrulation Ectoderm, mesoderm, endoderm Primary germ layers: organs and tissues will develop After implantation, embryo develops Layer of membranes that protect and feed

  15. Early Development (3) • Amnion and chorion • Placenta • Third week - nervous and digestive systems develop • Chorion becomes placenta • Vital organ - respiration, feeding and excretion • Connected to umbilical chord

  16. Early Development (4) • Certain substances or viruses may filter through placenta • Drugs • Alcohol • Measles • Eighth week - embryo becomes fetus • Three months - major organs and tissues have formed • Umbilical chord (connects placenta and fetus) develops • Muscular system - start to move • Amnion - sac filled with fluid

  17. Later Development • 4-6 months after fertilization: • Skeleton forms • Hair grows • After 7 months: • 35 cm and 850 g • Fetus can survive outside the uterus if life supporting equipment is available

  18. Child birth • Nine months after fertilization • When and why? • Not completely known • Oxitocin releases causing contractions • Contractions eventually lead to birth by pushing out the baby • Umbilical cord needs to be cut • Baby starts breathing, digesting and maintaining its body temperature immediately • Twins: • Fraternal: two eggs fertilized • Identical: zygote splits into two

  19. Early years • Rapid growth (triple mass in 12 months) • Infancy (0-2 years old): • Nervous system develops coordinated body movements, crawling and walking • First teeth appear • Start to understand and use language • Childhood (2 years old – puberty): • Language acquired • Motor coordination perfected • Permanent teeth • Personality develops • Adolescence (puberty – adulthood): • Surge in sex hormones • Growth spurt • Personality changes

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