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Human reproduction.

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Human reproduction
Human reproduction
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Human reproduction.

  1. 1. 1 SCIENCE 6. UNIT 3. HUMAN REPRODUCTION. C.E.I.P. SANTA ANA (Madridejos) CONTENTS: 1.– Changes on the body. Puberty: Secondary sex characteristics. 2.– Male reproductive system. 3.– Female reproductive system. 4.– Reproductive cells. Male cells—Female cells. Menstrual cycle. 5.– Fertilisation and pregnancy. 6.– Childbirth. USEFUL WORDS: .– sexual reproduction .– asexual reproduction .– primary sexual characteristics .– secondary sexual characteristics .– adolescence .– puberty .– hormones HUMAN REPRODUCTION is the process in which human beings produce more human beings similar to themselves. Human reproduction is sexual. A male and a female produce a new baby. Reproduction is one of the vital function that living beings do. All living beings can produce more beings similar to them- selves, so human beings can also produce more human beings similar to them. In nature, there are two kinds of reproduction: asexual repro- duction and sexual reproduction. a.– Asexual reproduction: when only one individual produces new living beings on its own (descendents). The new living being inherits only the genes from that parent. b.– Sexual reproduction: when a male and a female produce new living beings. The new living being inherits genes from both, its mother and its father. On a baby, you can distinguish his/her primary sexual characteristics: his/her reproductive organs. 1.– CHANGES ON THE BODY IN PUBERTY: SECONDARY SEXUAL CHARACTERISTICS. Before the moment a baby is born, reproductive organs of boys and girls are different. These differences from males and females are called primary sexual characteristics. Secondary sexual characteristics are features that distinguish the two sexes, but that are not directly part of the reproductive system. Secondary sexual characteristics are changes in boys and girls during the adolescence or puberty. Puberty is a period of time when a child’s body changes into an adult body (from 11 to 18 year for girls, and from 13 till 18 for boys ). There are physical and psychological changes, and its reproductive system reach maturity. Sexual glands produce hormones. Males produce testosterone and females oestrogen that control these changes. Breasts development Facial hair Pubic hair Widen hipsPubic hair Broad shoulders Increase of hair on body, arms and legs Muscle development Mature genital organs FEMALE Girls: .– Breasts development. .– Hips widen. .– The first menstrual cycle comes. Boys: .- Adam’s apple is visible and voice gets lower. .– Shoulders get broader and muscle development. .– Hair on the face, body, arms and legs appears. .- Testicles mature and produce sperm. Boys and girls: .- Appearance of pubic and armpit hair for boys and girls. armpit 1 Adam’s apple MALE
  2. 2. 2 C.E.I.P. SANTA ANA (Madridejos) 2.– MALE REPRODUCTIVE SYSTEM. Male reproductive system produces male’s reproductive cells (sperm). It produces millions of sperm a day. 1.- Testicles or testes are two small round organs placed outside the ab- dominal cavity. They are covered by skin called scrotum. They produce millions of sperm a day. 2.- Vas deferens are two tubes from testicles to seminal vesicles. Sperm travels through them. 3.- Seminal vesicles are two glands next to the bladder. They produce sem- inal fluid that mixes with the sperm. Bladder 4.- Prostate gland is a gland under the bladder. It produces prostate fluid that mixes with the sperm. 5.- Urethra is a tube that con- nects vas deferens and bladder to the exterior. Sperm or urine travel through the urethra to the exterior. 6.- Penis is a cylindrical organ that contains the urethra. Scrotum 1 6 2 Bladder 3.– FEMALE REPRODUCTIVE SYSTEM. Female reproductive system has got two functions: A.– It produces female’s reproductive cells (egg cell or ovum). B.– It protects and feeds the new human being (embryo) till the birth. 1.- Ovaries are two organs (the size of an almond). They produce and develop egg cells. Ovaries release an egg a month through the Fallopian tubes. 2.– Fallopian tubes or oviducts are two tubes that connect the ovaries to the uterus. 3.– Uterus or womb is a cavity with thick muscular walls. It contains the em- bryo during the nine months of pregnancy. Muscular walls of uterus. Cervix is the lower part of the uterus. 4.– Vagina is a muscular tube that connects the uterus with the outside of the body. 5.– Vulva is the external organ in the female repro- ductive system, that protects the entrance to the vagina.5 12 3 4 .– testicles .– vas deferens .– seminal vesicles .– prostate .-urethra .– penis .– ovaries .– uterus .– fallopian tubes .– vagina .– vulva5 2 3 4
  3. 3. 3 C.E.I.P. SANTA ANA (Madridejos) 4.– REPRODUCTIVE CELLS. Human beings have sexual reproduction. Male individuals produce male sex cells (sperm) and female individuals produce female sex cells (egg cell or ovum). Each sex cells have got genetic information, so new offspring will have some characteristics from the father and others from the mother. 4.1.– SPERM (male sex cell). Testicles produce millions of sperm a day, but they only can live for a few hours. They are very small and they are formed by three parts: .– Head that contains the nucleus with the genetic infor- mation. .– Midpiece .– Tail to move very fast looking for the egg cell. 4.2.– EGG CELL or OVUM (female sex cell). Girls have all their female reproductive cells in follicles in their ovaries from they were born. From puberty, one these eggs ma- tures and is released every month. It’s round and much bigger than sperm. It has got a nucleus with the genetic information. It hasn’t got active movement. 4.3.– MENSTRUAL CYCLE. About every 28 days, one ovary releases an egg that is called ovulation. An egg lives only during 24 - 48 hours. The uterus walls are thickening to prepare to develop the egg just in case the egg is fertilised. If the egg is not fertilised, it will die and it will be expelled with the rest of the uterus lining (menstruation or period). When menstruation begins, it is important to have a good hygiene. Head Midpiece Tail Sperm Egg cell under a microscope 1.- Menstruation: The unfertilised egg and the mucosal tissue with blood vessels from uterus are expelled. (about 1st - 6th days) 2.- Preparation of the egg: A follicle in an ovary ma- tures an egg. Uterus lining starts to grow and thick again 4.-Preparation of the uterus: The uterus lining continues to thicken. The egg moves into the uterus. If the egg is unfertilized, the uterus lining breaks down. 3.- Ovulation: The follicle releases an egg. It falls down through the Fallopi- an tube to the uterus. (Fertile time) Egg released Ovary Follicle 7 6
  4. 4. 4 C.E.I.P. SANTA ANA (Madridejos) 5.A.– FERTILISATION. When the man deposits millions of sperm in the woman’s vagina, many of them move up the vagina, into the uterus and finally into the Fallopian tubes. If they find an egg, they will try to get inside, but only one sperm will enter. This process is called fertilization, and the fertilised egg becomes a zygote (the first cell of the embryo) 1.– The egg is released from the ovary and goes down through the Fallopian tube to the uterus. 2.– Sperm enter through the vagina, and travels to the Fallopian tube. 3.– Lots of sperm get the egg, but only one will enter and a zygote is formed 4.– The zygote divides and forms an embryo. 5.– The embryo implants on the uterus wall to grow and develop. Fertilisation is the fusion of a sperm with an ovum to produce a new organism. Zygote is the first cell of the embryo. 5.B.– PREGNANCY. Pregnancy lasts for about nine months (38 - 40 weeks) and finishes in childbirth. The embryo is developing, and brain, heart, arms and other organs are formed. After 8 weeks, it’s called foetus. At the beginning, placenta, umbilical cord and amniotic sac are formed. After the 4th month the fetus can hear, open the eyes, move inside… During last three months, the fetus grows and the organs mature. Pregnancy is the time the embryo/foetus is developing inside the mother’s uterus. Placenta is an organ formed on the wall of the uterus and supplies nutrients, oxygen… from the mother’s blood. Umbilical cord links the placenta to the fetus. It contains arteries and veins to transport blood with oxygen, nutrients... Amniotic sac is a bag with liquid inside (amniotic fluid) to protect the fetus. It’s formed at the same time as the placenta USEFUL WORDS: .– fertilisation .– egg .– sperm .– zygote .– embryo .- fetus / foetus .– placenta .– umbilical cord .– amniotic sac .– amniotic fluid 10 8 9 12 11
  5. 5. 5 C.E.I.P. SANTA ANA (Madridejos) 6.– CHILDBIRTH. About 9th month of pregnancy, the fetus is totally mature and ready to be born. It’s about 50cm high and weights about 3,3 kg. It’s time for labor or childbirth. Normally, baby’s head goes out first. But sometimes, the fetus is upside-down and he/she can’t go out, so the doctor has to make a surgical operation called caesarean birth. USEFUL WORDS: .– labor or childbirth .- caesarean birth .– dilation .– expulsion .– placenta delivery Labor has got three stages: .– Dilation .– Expulsion .– Placenta delivery 1.- Dilation: 6 - 12 hours (or more in first child). It begins with regular uterine contracti- ons and ends with full dilation of the cervix (about 10cm) 2.– Expulsion: the fetus is pushed out through the vagina by the contractions of the uterus. When the fetus comes out the doctor cuts the umbilical cord (its scar is the navel). After a few seconds, the baby starts to cry and breath. 3.– Placenta delivery: is the last stage of the labor. Contractions of the uterus expel the pla- centa and the rest of tissues. 15 13 14

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