Human reproduction by David
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Human reproduction by David

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Human reproduction by David Human reproduction by David Presentation Transcript

  • PRIMARY SEXUAL CHARACTERISTICSThe reproductive systems are the primary sexual characteristics. We alreadyhave them when we are born and they are different for male and female.
  • The external characteristics which differentiate men from women are called secondary sexual characteristics. Other changes are specific to each sex: Girls develop breasts and their hips get wider. Boys get deeper voices.
  • Reproductive cells carry out the function of reproduction. Sperm are the male reproduction cells. They are small. They have a head and a long tail called a flagellum. They are produced in large numbers from the time of puberty. Ova are the female reproductive cells. They do not move. From puberty, an ovum matures every month.
  • The female reproductive system is made up of: The ovaries produce the ova. The uterus is where the baby develops. The Fallopian tubes connect the ovaries to the uterus. The vagina connects the uterus to the outside of the body. The vulva is the external part of the female reproductive system.
  • The male reproductive system is made up of these organs:The testicles are outside the body. They produce sperm. They arecovered by a bag of skin called the scrotum.The vas deferens take sperm from the testicles to the urethra.The urethra takes the sperm outside the body.The seminal vesicles and prostate produce seminal fluid and send it tothe urethra.The penis is outside the male reproductive system.
  • Fertilisation occurs when an ovum and sperm join inside theFallopian tubes and they create a single cell called zygote.The zygotegoes down the Fallopian tubes, it is implanted in the wall of the uterusand it becomes an embryo.
  • Pregnancy lasts about 9 months an ends in a birth. During the early stages, different structures are created to protect the embryo. The placenta takes nutrients and oxygen from the mother’s blood to the embryo. The umbilical cord connects the embryo to the placenta. The amniotic sac protects the embryo. The baby develops step by step. After 3 months: The embryo has all its organs. It becomes a foetus. After 5 months: The baby’s body develops and it starts moving and the mother feels it. After 9 months: The baby is readyto be born and it weighs 3 kilos.
  • The process of giving birth is called labour. Labour takes place in three phases: Dilation: Rhythmic contractions make the opening of the vagina and vulva is big enough for the baby to come out. Expulsion: The baby is born and the doctor cuts the umbilical cord. Afterbirth: The placenta comes out of the mother’s body.