Topic 3: Human Reproduction

CORE CONTENT:

Purpose and puberty

• the main purpose of reproduction is for the gametes (male and female sex cells) to combine for the continuation of the species

• puberty is the stage in the human life cycle when sexual organs mature for reproduction. This process is initiated when the pituitary gland releases hormones into the blood stream, triggering the testes and ovaries to release sex hormones (testosterone and oestrogen)

• testosterone (from the testes) and oestrogen (from the ovaries) cause secondary sexual characteristics such as menstruation, breast development, pubic hair, facial hair, deepening of the male voice

Reproductive organs

• the male reproductive organs include the penis, sperm duct (vas deferens), testes (produces sperm cells), scrotum, urethra

• the female reproductive organs include the vagina, uterus, ovaries (contain egg cells/ ova), oviducts (Fallopian tubes)

Stages of reproduction

• once a month, one of the ovaries releases a ripe egg in a process called ovulation

• in preparation for a fertilised egg, the uterus develops a thick layer of blood

• if fertilisation does not take place, menstruation occurs

• menstruation is the breakdown of the thick layer of blood in the uterus, which is released through the vagina

• the menstrual cycle is usually a 28 day cycle

• during copulation, the erect penis is inserted into the vagina and semen is released (ejaculation)

• fertilisation is the fusion of the sperm and egg, producing a zygote

• if fertilisation takes place, the fertilised egg is implanted in the blood layer in the uterus, and pregnancy results

• the developing embryo/foetus is attached to the uterus wall by the placenta which plays a vital role in feeding and removing waste from the foetus

• the stage of pregnancy in humans (gestation) is about 40 weeks

• pregnancy can be prevented by using contraceptives such as condoms to prevent the sperm reaching the egg

• condoms also prevent the transmission of HIV/AIDS and other STDs (sexually transmitted diseases), if used effectively