jueves, 30 de noviembre de 2017

6º. Unit 3 .REPRODUCTION.



HUMAN REPRODUCTION
   

The miracle of life
 Like other living things, human beings reproduce. It's what keeps the population going. In humans, the male and female reproductive systems work together to make a baby. 
http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sites/Web/skoool/bio/step/human_fert/CM_standalone.swf

Fertilisation

During sexual intercourse the man's penis releases semen into the woman's vagina. Sperm cells travel in semen from the penis and into the top of the vagina. They enter the uterus through the cervix and travel to the egg tubes. If a sperm cell meets with an egg cell there, fertilisation can happen. Fertilisation happens when an egg cell meets with a sperm cell and joins with it.
The fertilised egg divides to form a ball of cells called an embryo. This attaches to the lining of the uterus and begins to develop into a foetus (pronounced "fee-tuss") and finally a baby.

Female Reproductive System

Ovaries

The two ovaries contain hundreds of undeveloped female sex cells called egg cells or ova. Women have these cells in their bodies from birth - whereas men produce new sperm continually.

Egg tubes

Each ovary is connected to the uterus by an egg tube. This is sometimes called an oviduct or Fallopian tube. The egg tube is lined with cilia, which are tiny hairs on cells. Every month, an egg develops and becomes mature, and is released from an ovary. The cilia waft the egg along inside the egg tube and into the uterus.

Uterus and cervix

The uterus is also called the womb. It is a muscular bag with a soft lining. The uterus is where a baby develops until its birth.
The cervix is a ring of muscle at the lower end of the uterus. It keeps the baby in place while the woman is pregnant.

Vagina

The vagina is a muscular tube that leads from the cervix to the outside of the woman's body. A man's penis goes into the woman's vagina during sexual intercourse. The opening to the vagina has folds of skin called labia that meet to form a vulva. The urethra also opens into the vulva, but it is separate from the vagina, and is used for passing urine from the body.

Male Reproductive System

About the Male Reproductive System

Most species have two sexes: male and female. Each sex has its own unique reproductive system. They are different in shape and structure, but both are specifically designed to produce, nourish, and transport either the egg or sperm.
Unlike the female, whose sex organs are located entirely within the pelvis, the male has reproductive organs, or genitals, that are both inside and outside the pelvis. The male genitals include:
  • the testicles
  • the duct system, which is made up of the epididymis and the vas deferens
  • the accessory glands, which include the seminal vesicles and prostate gland
  • the penis
http://kidshealth.org/en/parents/male-reproductive.html#

Testes

The two testes (one of them is called a testis) are contained in a bag of skin called the scrotum. They have two functions:
  • to produce millions of male sex cells called sperm
  • to make male sex hormones, which affect the way a man's body develops.

Sperm duct and glands

The sperm pass through the sperm ducts, and mix with fluids produced by the glands. The fluids provide the sperm cells with nutrients. The mixture of sperm and fluids is called semen.

Penis and urethra

The penis has two functions:
  • to pass urine out of the man's body
  • to pass semen into the vagina of a woman during sexual intercourse.
The urethra is the tube inside the penis that can carry urine or semen. A ring of muscle makes sure that there is no chance of urine and semen getting mixed up.
http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/reproduction/revision/1/