Unit 1: Reproduction - Female and Male Reproductive Systems

Female Reproductive System

• Vagina: Leads from the outside of the body to the cervix; site where sperm are deposited during intercourse.

• Cervix: Neck of the uterus consisting of a muscular ring that surrounds the uterine outlet; expands widely during childbirth up to $10\,\text{cm}$.

• Uterus: Muscular-walled organ (womb) in which the baby develops and grows.

• Fallopian Tubes: Connect the ovaries to the uterus; site where fertilisation occurs.

• Ovaries: Produce and release eggs; control female sex hormones.

Male Reproductive System

• Penis: Becomes erect before and during intercourse; ejects sperm into the vagina.

• Scrotum: External pouch containing two testes; maintains sperm at a lower temperature than internal body heat.

• Testes: Produce sperm and the male sex hormone testosterone (singular: testis).

• Urethra: Tube that transports semen and urine; bladder exit closes during intercourse to prevent the two fluids from mixing.

The Menstrual Cycle

• Purpose: Produces an egg and prepares the uterus to receive a fertilised egg.

• Cycle Length: Averages $28\,\text{days}$; can be irregular, making conception timing difficult and calendar-based 'safe sex' unreliable.

• Key Phases:

  • Menstruation: Days $1\text{ to }5$; uterine lining and blood break down and exit the body.

  • Repair Phase: Days $5\text{ to }13$; new uterine lining develops.

  • Ovulation: Occurs around day $14$; an ovary releases an egg into the fallopian tube.

  • Receptive Phase: Days $14\text{ to }21$; uterus is ready to receive an egg (fertile window spans the $14\text{th}\text{ to }21\text{st}$ days; uterus is fully ready by day $16$).

  • Premenstrual Phase: Days $22\text{ to }28$; unfertilised egg leads to the breakdown of the uterine lining before menstruation restarts at day $28$.

Fertilisation and Conception

• Conception Process: Sperm deposited in the vagina travel through the cervix and uterus into the fallopian tube.

• Fertilisation: Occurs when a single sperm fertilises an egg in the fallopian tube between a few minutes and $5\,\text{days}$ after intercourse.

• Implantation: The fertilised egg migrates to the uterus and embeds into the lining between $5\text{ and }15\,\text{days}$ post-intercourse.

• Pregnancy Symptoms: Typically manifest between $2\text{ and }8\,\text{weeks}$ after intercourse.

Contraception Methods

• Barrier Methods:

  • Male Condom: $98\%$ effective; prevents sperm entry and protects against Sexually Transmitted Infections (STIs); carries risk of tearing, slipping, or latex allergy.

  • Female Condom: $95\%$ effective; inserted into the vagina to block sperm and STIs; risk of incorrect placement or tearing.

  • Diaphragm with Spermicide: $92\%$ effective if used correctly; rubber dome fitted by a doctor; must remain in place for $6\,\text{hours}$ after intercourse; spermicide deactivates sperm; does not protect against STIs.

• Hormonal and Intrauterine Methods:

  • Combined Pill (Oestrogen/Progesterone): $99.8\%$ effective; prevents ovulation, thickens cervical mucus, and thins the uterine lining; unreliable if taken $12\,\text{hours}$ late or with antibiotics; reduces ovarian, womb, and colon cancer risks.

  • Contraceptive Implant: Measures $2\,\text{mm} \times 40\,\text{mm}$; placed under the skin of the upper arm; steadily releases hormones for up to $3\,\text{years}$; does not protect against STIs.

  • IUD (Intrauterine Device / Copper Coil): $99\%$ effective; T-shaped plastic device releasing copper; lasts $5\text{ to }10\,\text{years}$; non-hormonal; stops implantation and alters cervical mucus.

  • IUS (Intrauterine System): Over $99\%$ effective; T-shaped device releasing progestogen; lasts $5\,\text{years}$; makes periods lighter or stops them; safe while breastfeeding.

  • Contraceptive Patch: Over $99\%$ effective; releases oestrogen and progesterone through skin; replaced every $1\,\text{week}$; unsuitable for smokers.

  • Vaginal Ring: Over $99\%$ effective; releases oestrogen and progesterone; replaced every $1\,\text{month}$.

• Surgical and Behavioural Methods:

  • Female Sterilisation: Over $99\%$ effective; fallopian tubes are blocked or cut; permanent surgical procedure.

  • Male Sterilisation (Vasectomy): Cuts or blocks sperm ducts; simpler and safer than female sterilisation; alternative contraception required until tests confirm semen is sperm-free.

  • Natural / Calendar Method: Avoiding intercourse during fertile days; highly unreliable.

  • Abstention: $100\%$ effective against both pregnancy and STIs.

Benefits of Family Planning

• Financial Preparation: Budgeting for equipment (pram, cot, car seat), loss of maternal income, housing needs, and exploring child benefits.

• Work Timetable: Determining ideal leave periods and employment adjustments (part-time work, career breaks, or identifying a primary stay-at-home parent).

• Parental Responsibility: Aligning lifestyle, childcare expectations, and social routines to minimise conflict.

• Home Organisation: Creating a child-safe environment (safety locks on medicines) and reallocating space (converting guest rooms to nurseries).

• Childminding Logistics: Researching nursery options, grandparent support, or flexible work schedules in advance.

Causes and Treatments of Infertility

• Definition: Inability of a couple to conceive and achieve pregnancy.

• Causes:

  • Low Sperm Count: Ejaculate contains fewer than $20\,\text{million}$ sperm needed for successful fertilisation.

  • Ovulation Failure: Ovaries fail to mature or release eggs.

  • Blocked Fallopian Tubes: Prevents egg and sperm from meeting.

  • Thick Cervical Mucus: Obstructs sperm transit through the cervix.

  • Hysterectomy: Surgical removal of the uterus.

  • Sexually Transmitted Infections (STIs): Conditions such as Chlamydia and gonorrhoea.

  • Testicular Cancer: Damage to testes impairs sperm production and semen quality.

  • Endometriosis: Uterine lining tissue grows outside the womb, damaging fallopian tubes or ovaries.

• Treatments:

  • Fertility Drugs: Hormones administered to stimulate ovulation.

  • Surgical Repair: Operations to clear or reconstruct blocked fallopian tubes.

  • IVF (In Vitro Fertilisation): Egg and sperm are fertilised outside the body; resulting embryos are placed into the uterus.

  • DI (Donor Insemination): Uses anonymous donor sperm for fertilisation procedures.

  • GIFT (Gamete Intra-Fallopian Transfer): Mixture of eggs and sperm is transferred directly into the fallopian tubes for internal fertilisation.

  • ICSI (Intra-Cytoplasmic Sperm Injection): Direct injection of a single sperm into an egg before uterine transfer.

  • Surrogacy: Embryo created via IVF is carried to term by a surrogate mother; utilized when a woman lacks a functional uterus.

Hormones in Reproduction

• General Definition: Chemical messengers produced in glands and transported via the bloodstream.

• POOP Acronym:

  • Progesterone: Maintains early pregnancy; prepares womb lining for implantation; relaxes uterine muscles; assists breast milk duct growth; strengthens pelvic muscles.

  • Oestrogen: Female sex hormone driving sex organ development; thickens the uterine lining; regulates the menstrual cycle alongside progesterone.

  • Oxytocin: Triggers uterine contractions during labour; widens birth canal; relaxes pelvic joints; reduces postpartum bleeding; aids placental delivery; administered medically via drip, gel, or pessary to induce labour.

  • Prolactin: Produced in the pituitary gland; controls milk synthesis and lactation; stimulated by infant suckling; modulates immune regulation in the reproductive tract.

Questions & Past Paper Discussion

• Question: Describe the menstrual cycle (3 marks)

  • Response: The menstrual cycle is a $28\,\text{day}$ cycle. Ovulation happens on day $14$ when the ovary releases an egg into the fallopian tube. If unfertilised, the uterine lining breaks down (premenstrual phase) and bleeding occurs as blood and uterine fragments leave the body (menstruation), followed by the growth of a new uterine lining (repair phase).

• Question: Explain conception (3 marks) (Past paper 2023)

  • Response: Sperm is released into the vagina during intercourse and travels through the cervix and uterus. A sperm fertilises an egg in the fallopian tube. The fertilised egg then travels to the uterus and implants into the uterine lining.