Reproduction

• The menstrual cycle


  1. Blood from the uterus lining lost (a period)

  2. Bleeding stops, uterus lining starts to re-grow

  3. Egg released from one of the ovaries (ovulation)

  4. If the egg is fertilised the cycle stops until the baby is born
• Gametes


  The male gamete (sex cell) in animals is a sperm, the female gamete is an egg
• Gestation


  Process where the baby develops during pregnancy
• Fertilisation


  Joining of a nucleus from a male and female sex cell
• Amniotic fluid


  Liquid that surrounds and protects the fetus
• Placenta


  Organ that provides the fetus with oxygen and nutrients and removes waste substances. It also acts as a barrier, stopping infections and harmful substances reaching the fetus
• Adolescence


  The process in which a child changes into an adult, it involves both physical and emotional changes
• Puberty


  The physical changes alone in the time of adolescence, caused by sex hormones
• Gametes


  Male and female sex cells
• Fertilisation


  When a sperm and egg join to form an embryo
• Gametes


  • Specialised cells with adaptations to increase chances of fertilisation and successful development of a baby
• Conception


  1. Sperm fertilises an egg

  2. Ovaries produce eggs and hormones

  3. Egg travels to uterus

  4. Cervix allows sperm in and menstrual blood out

  5. Vagina connects cervix to outside
• Male reproductive system


  • Produces sperm cells and male sex hormones
  • Sperm pass through sperm ducts and mix with fluids to form semen
  • Semen exits through penis
• Female reproductive system


  • Ovaries contain eggs and produce female sex hormones
  • Oviducts move eggs to uterus
  • Uterus is where baby develops
  • Cervix keeps baby in place during pregnancy
  • Vagina is birth canal
• Gestation and birth


  1. Fertilised ovum divides to form embryo

  2. Embryo attaches to uterus and develops into fetus

  3. Fetus relies on mother for protection, oxygen, nutrients, waste removal

  4. Placenta provides oxygen, nutrients, removes waste

  5. Cervix relaxes and uterus contracts to push baby out through vagina
• Drugs, alcohol, and smoking during pregnancy can harm the fetus
• Caesarean section is a surgical method of delivering a baby when vaginal birth is not possible
• How long is the menstrual cycle

  28 days
• Definition of reproduction


  Reproduction is the production of offspring
• Reproduction


  When organisms produce new living things
• Plants and animals reproduce to make new individuals of the same species
• Asexual reproduction


  Only one parent, new individual is genetically identical to parent
• Sexual reproduction


  Two parents, offspring are genetically quite different to their parents
• Human reproduction


  Humans use sexual reproduction to produce their young, males and females have different reproductive systems and sex organs
• Sperm


  Sex cells produced in testes, have cell membrane, nucleus containing chromosomes, tail, and middle piece

  
• Egg


  Sex cells produced in ovaries, have nucleus containing chromosomes, cytoplasm, membrane, and jelly coat
• An egg is so big that a sperm looks tiny next to it
• Fertilisation


  Watch video clips on human fertilisation
• Menstrual cycle


  Lasts approximately 28 days
• Days 0 to 5

  1. Uterus lining breaks down

  2. This is called menstruation or the period
• Days 6-13


  1. Uterus lining will grow thicker with blood vessels

  2. Thickening is caused by the hormone oestrogen
• Day 14


  1. Ovulation will occur

  2. An ovum is released into the fallopian tube

  3. Oestrogen levels will begin to drop

  4. Progesterone will start to be produced in high levels

  5. Progesterone helps to maintain the uterus lining
• If fertilisation has not occurred


  • In the last few days of the cycle the hormones oestrogen and progesterone will drop
  • Causing the uterus lining to break down
• Amnion


  Surrounds the foetus and contains amniotic fluid
• Placenta


  Allows nutrients and oxygen to pass from the mother's blood to the baby's blood without the two mixing
• Amniotic fluid


  Supports the foetus and cushions against shocks and bumps
• Umbilical chord


  Attaches the foetus to the placenta
• Embryo


  Ball of cells for the first two months
• Sac


  Filled with amniotic fluid, protects the embryo
• Umbilical cord formation

  Begins to form between the embryo and its mother at six weeks