6. The Reproductive System

It helps us to have children. Human reproduction is sexual: male and female. Males and females create reproductive cells or gametes (spermatozoid for male, and ovule or egg cells for females). When these two cells get toguether they create a new human beigh.

Male reproductive system
Testicles: there are 2. They produce sperm cells (spermatozoids). They are protected by skin: scrotum.
Penis: It has the urethra inside to expulse the sperm out of the body and in the female reproductive system.
Vas deferens: (canal deferente). take the sperm from testicles --> seminal vesicles --> prostate -> urethra.
Prostate and seminal vesicles (vesícula seminal) are glands that produce liquids to mix with the sperm cells to produce semen.

Female reproductive system
It has different parts: external (vulva) and internal:
The ovaries are 2 organs that produce ovules.
The Fallopian tubes: connect the ovaries to the uterus to transport ovules.
The uterus is a hollow (hueco) organ with muscular walls. When a woman is pregnant it expans and give space for the baby. The lower part is called cervix to connect with the vagina.
The vagina: muscular canal to connect the uterus and the vulva (outside of the body).
The vulva: external part.

Puberty and sexual maturation

Between the age of 11-17 we go through puberty: the reproductive system mature and secondary sex characteristics appear.

Puberty in boys: They start creating spermmatozoids (millions). Their voice is deeper, hair grows in the face, chest, pubic area and under the arms, muscles develop. This can continue until 26 years old.

Puberty in girls:). Hair grows in the pubic area and uder the arms, breasts grow, hips are rounded, voice changes. This can continue until 24 years old.

They start creating ovules, one every 28 days. This is the menstrual cycle:
1.Ovulation: the ovaries releases an ovule every 28 days, that goes to the Fallopian tubes.
2.Preparation of the uterus: during the 14 days after ovulation the ovule travels to the uterus and stais there. The uterus' walls continue getting thicker.
3.Menstruation or period: in the day 14 after ovulation, if there is no fertilization, the ovule, the walls of the uterus and blood are eliminated during 3-6 days
4. The uterus' walls prepare to take the next ovule and get thicker.

Fertilisation, pregnancy and birth

When an spermatozoid fertilises an ovule the menstrual cycle doesn't occur and the woman gets pregnant.

Fertilisation: when the spermatozoid and the ovule get toguether in the Fallopian tubes they form a new cell called zygote. The zygote travels down the Fallopian tube to the uterus dividing into many cells to form an embryo. Six days later the embryo sticks in the uterus 

Pregnancy: When the embryo is in the uterus it stars growing to form a foetus and later a baby for 9 months. Two new organs form inside the uterus:

- The amniotic sac: its a sac with a liquid (amniotic fluid) that protects the foetus.

- The placenta: is an organ attached to the uterus. It is connected to the fetus by the umbilical cord. It gives the foetus oxygen and nutrients from the mother's blood and expulses the carbon dioxide and waste.

Birth: When the baby leaves the uterus through the vagina. The uterus and vagina dilate (gets wider), uterus contract and the amniotic sac breaks. The baby goes through the vagina and we cut the umbilical cord creating the belly button. When the baby is out the uterus expulse the placenta and amniotic sac.