Sexual reproduction in humans
Section: Biology | Syllabus: Cambridge IGCSE Combined Science (0653)
The Male Reproductive System
The parts of the male reproductive system can be identified on diagrams, along with their functions:
- Testes - produce sperm cells
- Scrotum - the sac that holds the testes outside the body, keeping them cooler than body temperature for sperm production
- Sperm ducts - carry sperm from the testes to the urethra
- Prostate gland - produces fluid that is added to the sperm to form semen
- Urethra - carries semen out of the body through the penis
- Penis - deposits semen into the vagina during sexual intercourse
Sperm travel from the testes, along the sperm ducts, to the urethra, where they are expelled through the penis
The Female Reproductive System
The parts of the female reproductive system can be identified on diagrams, along with their functions:
- Ovaries - produce egg cells
- Oviducts - carry an egg from an ovary to the uterus; fertilisation usually occurs here
- Uterus - the muscular organ where an embryo implants and develops
- Cervix - the ring of muscle at the base of the uterus; it dilates during birth
- Vagina - receives the penis during intercourse and forms the birth canal
An egg released from an ovary travels along the oviduct, where it may be fertilised, towards the uterus
Fertilisation in Humans
Fertilisation is the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell).
The Menstrual Cycle
The menstrual cycle is a monthly cycle of changes in the ovaries and in the lining of the uterus, lasting on average 28 days (knowledge of sex hormones is not required):
- In an ovary, an egg matures and is released - this is called ovulation, and occurs approximately once a month
- The lining of the uterus thickens after menstruation, ready to receive a fertilised egg
- If the egg is not fertilised, the thickened lining breaks down and is lost through the vagina as blood - this is menstruation, and marks the start of the next cycle
The uterus lining thickens each cycle to prepare for a possible pregnancy, then breaks down if fertilisation does not occur
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