sexual reproduction in humans

    Cards (19)

    • Vagina
      A canal linking the cervix of the uterus to the outside of the body. Birth canal, accommodates penis during sexual intercourse.
    • Cervix
      Opening through which the foetus exits during childbirth.
    • Uterus
      Organ which provides protection and support for the embryo and foetus prior to birth.
    • Fallopian tube
      Tubes connecting the ovaries and the uterus. The ovum travels down the fallopian tube during ovulation.
    • Ovaries
      • Organs which produce ova and secrete hormones. Homologous to the testis.
      • Cortex (outermost layer, made up of stroma and developing follicles)
      • Medulla (made up of stroma, blood vessels, and nerves)
      • Hilum (innermost layer, made up of blood vessels and nerves)
    • Penis
      An organ which delivers sperm to the vagina during sexual intercourse.
    • Scrotum
      Provides protection for the testis.
    • Epididymis
      Storage for spermatozoa.
    • Vas deferens
      Duct which connects epididymis and ejaculatory duct.
    • Testis
      • Glands which produce spermatozoa and hormones. Homologous to the ovaries.
      • Lobules divided by septa
      • Seminiferous tubules (where spermatozoa are manufactured)
    • Spermatogenesis
      1. Primordial germ cells divide to form spermatogonia
      2. Spermatogonia grow to form primary spermatocytes
      3. Primary spermatocytes undergo first meiotic division to form secondary spermatocytes
      4. Secondary spermatocytes undergo second meiotic division to form spermatids
      5. Spermatids differentiate and grow to form spermatozoa
    • Oogenesis
      1. Primordial germ cells divide to form oogonia
      2. One oogonium continues to grow to form a primary oocyte
      3. First meiotic division forms one secondary oocyte and one polar body
      4. Second meiotic division of secondary oocyte forms one ootid and one polar body
    • Fertilisation
      1. Sperm cluster around ovum, one penetrates zona pellucida
      2. Acrosome reaction, membranes fuse
      3. Cortical reaction, meiosis II completes
      4. Chromosomes combine to form diploid zygote
    • Implantation
      1. Zygote undergoes cleavage to form blastocyst
      2. Blastocyst develops villi and implants in uterine lining
    • Endocrine glands
      Glands which secrete hormones directly into the bloodstream
    • Menstrual cycle
      1. Day 1 - Menstruation, FSH stimulates follicle growth, oestrogen increases
      2. Day 14 - Ovulation, LH surge causes follicle rupture
      3. Day 15 - Luteal phase, corpus luteum secretes oestrogen and progesterone
      4. Day 28 - If unfertilised, corpus luteum shrinks, oestrogen and progesterone fall
    • Birth
      1. Uterus stretches, triggers oestrogen release
      2. Oestrogen increases sensitivity to oxytocin
      3. Oxytocin causes uterine contractions, positive feedback loop
      4. Oxytocin inhibits progesterone, placenta detaches
      5. Prolactin peaks, promotes lactation
    • Placenta
      • Enables transfer of substances between mother and foetus
      • Secretes human chorionic gonadotropin, maintains corpus luteum and hormone levels
    • The placenta is large, thin, and has a rich countercurrent blood supply to maximise diffusion of substances
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