Development Of Organisms And Continuity Of Life: Sexual Reproduction In Humans
16.4 Sexual Reproduction In Humans
Male Reproductive System
| Structure | Function |
|---|---|
| Testes | Produce sperm + testosterone |
| Scrotum | Holds testes outside body for lower temperature |
| Sperm ducts | Carry sperm to urethra |
| Prostate gland | Adds fluid to form semen |
| Urethra | Passage for semen + urine |
| Penis | Transfers sperm into female |
Female Reproductive System
| Structure | Function |
|---|---|
| Ovaries | Produce eggs (ova), oestrogen, progesterone |
| Oviducts (fallopian tubes) | Transport eggs, site of fertilisation |
| Uterus | Site for embryo implantation and development |
| Cervix | Entrance to uterus |
| Vagina | Receives sperm during intercourse |
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Gametes Adaptations
- Sperm cell: Tail for swimming, mitochondria for energy, acrosome with enzymes to penetrate egg.
- Egg cell: Large energy stores, jelly coat that hardens after fertilisation.
Fertilisation
- Fusion of sperm and egg nuclei.
- Forms diploid zygote → develops into embryo.
- Embryo implants in uterine lining.
Menstrual Cycle
- Controlled by FSH, LH, oestrogen, progesterone.
- Day 1–5 → menstruation (uterus lining shed).
- Day 6–14 → lining builds up, ovulation at ~day 14.
- Day 15–28 → progesterone maintains lining; if no fertilisation → lining breaks down.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course
Pregnancy & Development
- Amniotic sac + fluid protect embryo.
- Placenta → exchange of nutrients, gases, waste between mother and fetus.
- Umbilical cord → connects fetus to placenta.
Key Point
- Some viruses (e.g., HIV, rubella) can cross placenta and harm fetus.