Unit 16: Human Reproductive System

• Requires two parents, a male and a female, and involves special cells called gametes (sex cells) • Occurs in multicellular organisms • The new organisms are not identical to the parents • inherit characteristics from both parents

• Production of new organisms from a single parent • Usually occurs in unicellular organisms such as the amoeba • New cells identical to the parent • A single amoeba reproduces itself by dividing into two new cells (division)

• Puberty is a period where the body undergoes various physical changes and matures sexually • Puberty is necessary for the human body to prepare itself for sexual reproduction • Puberty begins when sex hormones are produced in the reproductive organs • eg oestrogen in ovaries and testosterone in testis

Ovaries release Ova (Egg) Menstruation Begins Breasts begins to develop Hips become broader and rounder

Sex Hormones released Hair grows in armpits and around reproductive organs Sex organs become larger Height and weight increase

Testis produce Sperms Voice Deepens Hair grows on face and body Muscle strength increase

• Produce fluids in which the sperms swim in • The mixture of sperms and fluid is called semen • Semen contains nutrients and lubricating effect to help the sperm move better

• A bag of skin which holds the testes outside the body • The testes are outside the body because it requires a lower body temperature to produce healthy sperms (enrichment)

• The testes produce male sex cells called sperms. • Each sperm is very small and shaped like a tadpole. • The sperm is the smallest cell in the human body

• Carries sperms from the testis to the penis

• A tube which carries sperms and urine at different times

• The organ from which sperm-carrying fluid leaves the body and is deposited in the body of the female

• The ovaries produce eggs or ova (singular: ovum). • Normally, one ovum is produced (released) each month. • The ovum is the female sex cell. • It is the largest cell in the human body (and is the size of this full stop).

• A tube which carries ova released from the ovary to the uterus • It waits for the sperm to reach for a few days before getting passed out of the system

• A pear-shaped structure where an embryo grows and develops

• The narrow opening of the uterus; it widens during the birth of a baby

• A tube which links the uterus to the outside of the body • Organ in which sperms are deposited and the passage though which a baby is born

• To provide nutrients to embryo if fertilised or sheds if egg is unfertilised and repairs itself every menstrual cycle

• The fusion of sex cells is called fertilization • 3 stages in human reproduction on how life is formed: Fertilisation, Pregnancy, Birth • Nucleus of the cell contains the genetic information (DNA) in chromosomes

Can move on its own with the help of the tail Nucleus located in the head segment Nucleus containing 23 chromosomes About 2 million of sperms per ejaculation

Cannot move on its own Nucleus located in the cell Nucleus containing 23 chromosomes Only one egg released in every 28-day cycle

• The process of passing down the genetic material from one generation to the next during sexual reproduction is called heredity • The nucleus in each human cell contains 46 chromosomes (23 pairs) • The chromosomes carry genes containing information that controls the growth and appearance of a child • Unlike ordinary cells, the ovum and the sperm have 23 single chromosomes each • During fertilisation, the 23 single chromosomes in each nucleus come together to form 23 pairs of chromosomes • Thus, a child receives half its genetic information from the mother (through the ovum) and half from the father (through the sperm)

• The thickened lining of the uterus is shed if fertilisation does not take place • It is discharged through the vagina together with blood • Menstruation occurs • Unfertilised egg, uterine lining and blood is discharged

• The lining on the wall of the uterus thickens with many blood vessels formed in it. • This process prepares the uterus for the implantation of the embryo if fertilisation occurs