Unit 3. Human reproduction

NATURAL SCIENCE

UNIT 3. HUMAN REPRODUCTION

The test will be next MONDAY 22nd November 2021

What is reproduction? The reproduction function allows humans to have babies. Human reproduction is sexual that means we need a male and a female. The sexual cells specialized in reproduction are called gametes: 

• Male reproductive cells are spermatozoa.
• Female reproductive cells are ovules

 The development of the reproductive system During puberty (11-17 years old) there are some changes in our bodies: 

• The reproductive system becomes active.
• Secondary sex characteristics appear: physical changes.
• Sexual maturity begins with some changes in our personality.
  

MALE REPRODUCTIVE SYSTEM It consists of: 

• Testicles: are two oval-shaped organs that produce spermatozoa. They are found inside the scrotum.
• Penis is an organ where the urethra runs through it.
• Accessory glands are the prostate and seminal vesicles. They produce fluids that mix with the spermatozoa to form semen. 
• Vas defenders are two tubes that connect the testicles to the accessory glands.

FEMALE REPRODUCTIVE SYSTEM It consists of: 

• Ovaries: are two oval-shaped organs that produce ovules.
• Fallopian Tubes: connect the uterus to the ovaries.
• Uterus: is the organ where the baby grows.
• Vagina: connect the uterus with the exterior of the body.
• Vulva: is the external part of the female reproductive system that protects the vagina and the urethra.

PUBERTY 

Puberty marks the beginning of sexual maturation (11-17 years old). During puberty there are some changes in our bodies: 

PUBERTY IN BOYS 

Testicles produce spermatozoa and the accessory glands start to work. 

• Their voices get deeper.
• Hair grows (face, pubic area and body)
• They grow taller and develop larger muscles.

 PUBERTY IN GIRLS 

The ovaries produce ovules and have the menstrual cycle. 

• Their breasts grow and their hips become rounder.
• Hair grows (pubic and body)
• They grow taller and develop larger muscles.

MENSTRUAL CYCLE 

It is a process that last 28 days and it has 3 parts: 

• OVULATION: occurs when the ovaries release an ovule. The ovule travels from the ovary through the Fallopian tubes to the uterus.
• PREPARATION OF THE UTERUS: this happens during 16 days after ovulation. Here it develops a lining of small blood vessels
• MENSTRUATION: the ovule, the lining of the uterus and a small amount of blood are eliminated from the body. It last from 3 to 6 days.

THE PROCESSES INVOLVED IN REPRODUCTION 

• FERTILISATION

 Fertilisation occurs when an ovule and a spermatozoa join together and form a zygote in the Fallopian tubes. 

• DEVELOPMENT OF AN EMBRYO

 This period lasts 9 months or 40 weeks. 

• First term: the zygote develops into an embryo. The embryo grows inside the amniotic sac that contains amniotic fluid. An organ called placenta develops and it is attached to the uterus and the embryo through the umbilical cord.
• Second term: the embryo becomes a foetus and the organs start to develop.
• Third term: the foetus continues to grow. The foetus can survive from the 7^th month of pregnancy.
• BIRTH

When it is time for a baby to be born, the amniotic sac breaks. The baby and the placenta leave the mother´s body and the umbilical cord is cut.

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