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Unlock This CourseHuman reproduction is the biological process by which new human beings are produced. It involves specialised organs, cells called gametes and complex hormone systems that work together to create new life. Understanding how our reproductive systems work is crucial for making informed decisions about health and relationships.
Key Definitions:
The male system produces sperm and delivers them to the female system. Key organs include the testes (produce sperm and testosterone), penis (delivers sperm) and various tubes and glands that help transport and nourish sperm.
The female system produces eggs, provides a place for fertilisation and development and supports pregnancy. Key organs include ovaries (produce eggs and hormones), fallopian tubes (where fertilisation occurs) and uterus (where babies develop).
The male reproductive system is designed to produce millions of sperm cells and deliver them effectively. Each part has a specific role in this process.
The testes are the primary reproductive organs in males. They hang outside the body in the scrotum because sperm production requires a temperature slightly lower than normal body temperature. Inside each testis are tiny tubes called seminiferous tubules where sperm are made.
Takes about 74 days from start to finish. Millions of sperm are produced daily from puberty onwards through a process called spermatogenesis.
Testosterone controls sperm production and male characteristics like deeper voice and facial hair. It's produced by special cells in the testes.
Sperm travel through epididymis (where they mature), vas deferens and urethra. Glands add fluids to create semen.
A healthy male produces about 300 million sperm per day! Each sperm is only 0.05mm long but can swim at speeds up to 4mm per minute. Only one sperm out of millions will successfully fertilise an egg.
The female reproductive system is more complex than the male system because it must not only produce eggs but also support a developing baby for nine months if pregnancy occurs.
Unlike males who produce new sperm continuously, females are born with all the eggs they'll ever have - about 1-2 million! By puberty, this number drops to around 400,000. Each month, usually one egg matures and is released in a process called ovulation.
The menstrual cycle is a roughly 28-day process controlled by hormones. It prepares the body for potential pregnancy each month.
The lining of the uterus (endometrium) breaks down and is shed through the vagina. This is the 'period' that lasts 3-7 days.
An egg matures in the ovary while the uterus lining starts to thicken again, preparing for a possible pregnancy.
The mature egg is released from the ovary and travels down the fallopian tube. This is when pregnancy is most likely to occur.
If the egg isn't fertilised, hormone levels drop and the cycle begins again. If fertilised, pregnancy hormones maintain the uterus lining.
Fertilisation occurs when a sperm successfully penetrates an egg, usually in the fallopian tube. This creates a single cell called a zygote that contains genetic material from both parents.
After fertilisation, the zygote begins dividing rapidly as it travels towards the uterus. By the time it reaches the uterus (about 6-7 days later), it's become a ball of cells called a blastocyst. If it successfully implants in the uterus wall, pregnancy begins.
Even under ideal conditions, the chance of conception in any given cycle is only about 20-25%. Many factors affect fertility, including age, health, timing and lifestyle factors like smoking or excessive alcohol consumption.
Contraception prevents pregnancy by stopping fertilisation or implantation. Different methods work in various ways and have different effectiveness rates.
Condoms, diaphragms and caps physically block sperm from reaching the egg. Condoms also protect against STIs.
Pills, patches and injections use hormones to prevent ovulation or change the uterus lining. Very effective but don't protect against STIs.
IUDs and implants provide protection for years. Some release hormones while others create a physical barrier to fertilisation.
STIs are infections passed from person to person through sexual contact. They can affect anyone who is sexually active, regardless of age or gender.
Common STIs include chlamydia, gonorrhoea, herpes and HIV. Many STIs show no symptoms initially, which is why regular testing is important for sexually active people. The most effective prevention is using condoms consistently and correctly.
Use condoms every time, get regular health checks, limit number of partners and communicate openly with partners about sexual health history.
Many STIs are completely curable with antibiotics if caught early. Others, like herpes and HIV, can be managed with medication but aren't curable.
If you're sexually active, regular STI testing is crucial even if you have no symptoms. Many STIs can cause serious health problems if left untreated, including infertility. Free, confidential testing is available at sexual health clinics across the UK.