Science II

Module 6

Reproduction and development

SCIE 112 Integrated Sciences 2

 Maduración sexual  Changes in puberty  Structures and function of the female reproductive system  Menstrual cycle  Breast function  Structures and function of the male reproductive system  Fertilization and pregnancy  Embryonic development  Stages of labor 

Through this module we will be studying the following topics:

 The human reproductive system is extremely important in life, because it gives man and woman the ability to produce descendants together, thus ensuring the survival of the species.

 Unlike the other systems of the body, the structures of the female and male reproductive system are completely different in structure and function. Differences marked mainly by the influence of the main sex hormones, which stimulate the development, maturation and function of the organs according to the sexual role of individuals.

 Through this module, we will explore the structure and function of the sexual organs and describe the two types of cells involved in the process of fertilization and gestation of a new being. Finally, the different stages of pregnancy and the development that occurs in the fetus until the moment of delivery are described.

Introduction

 During the puberty stage (± 10 – 14 years), the hypothalamus begins to release the gonadotropin-releasing hormone GnRH, which acts on the pituitary gland to produce two hormones important in the sexual functioning of the individual;

 Follicle stimulating hormone (FSH) - causes the gonads, testicles and ovaries, to begin to mature and produce their gametes, sperm and eggs respectively.

 Luteinizing hormone (LH) causes the main sex hormones to begin to be produced  estrogen and progesterone  Testosterone  From that moment on, the development of secondary sexual characteristics

begins to occur.

Maduración sexual

 It is equipped to produce eggs and to house and nourish the growing fetus in the womb. It is divided into:

 External genitalia (the vulva):  labia majora  labia minora  clitoris  vaginal opening

Aparato reproductivo femenino

 Internal genitalia (the vulva):  Vagina  Uterus  Uterine tubes  Ovaries

 The function of the breasts is the production of milk for feeding the child after delivery.

 Breast milk provides antibodies for the protection of the baby during the first months of life.

 The breasts are located in the anterior part of the chest

 It has the nipple surrounded by the areola where the mammary glands where milk is produced are located

 They also play a significant role in sexual stimulation.



Female reproductive system

 A woman's menstrual cycle consists of approximately 28 days.

 It is counted from the first day of bleeding in one month to the first day of bleeding the following month.

 It is determined by hormonal changes in the woman's body, which cause each month:

 The ovarian cycle  Uterine changes 

Menstrual Cycle

His function is to produce sperm and transport them to the vagina as an organ of copulation External genitalia: penis scrotum Internal genitalia: testes epididymis vas deferens urethra Accessory glands: the seminal vesicles, the prostate gland and the Cowper's glands produce secretions that together constitute semen, which nourish and protect spermatozoa

Male reproductive system https://s-m

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ovum It is surrounded by two protective layers; radiated crown and zona

pellucida Its nucleus has 23 chromosomes

since it was produced by means of meiosis

The estimated time of viability of the egg is from 48 to 36 hours

Reproduction: gametes Sperm

It has a head and a tail The head has digestive enzymes to destroy the protective layers of the

egg The tail allows it to move until it

reaches the uterine tubes The estimated life span of a sperm is

24 hours

 During copulation, sperm exit through the vas deferens to the urethra and ejaculate into the semen, being deposited in the woman's vagina.

 Once there, they begin their journey through the uterus until they reach the uterine tubes where they will meet the egg and fertilization will occur.

 The zygote is formed, which is the first stage of a pregnancy.



Fertilization

 After fertilization, the zygote begins to move until it reaches the uterus, during that process it undergoes multiple cell divisions.

 6 -10 days later it implants into the uterine walls in the form of a hollow ball of cells called a blastocyst.

 It will continue its development until it becomes an embryo and then a fetus.

 The gestation process lasts 40 weeks.



Human Development

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 The developing embryo is protected and nourished by:

 the amniotic sac – sac that surrounds and protects the developing embryo.

 the placenta – structure that generates connections with the mother's blood through the blood vessels of the uterine wall.

 the umbilical cord – allows communication between the fetus and the placenta



Human Development

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During the first three months (week 0-12) the formation of the nervous system begins and the heart begins to beat.

Embryonic development: first trimester

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In the second trimester (week 13-28): The formation of the circulatory system is completed The skeleton begins to organize Ends the maturation of the nervous system Maturation of bronchi and lungs begins Hair appears Performs movements detected by the mother Sex can be recognized

Embryonic development: second trimester

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 In the last trimester (week 29-40) all organs are formed and their development is completed

 Increase in size and weight  Changes orientation, with

the head towards the cervix in preparation for childbirth



Embryonic development: third trimester

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Labor is the whole series of events that happen up to the birth of the baby. Dilation – elevated oxytocin levels cause uterine contractions, dilation of the cervix, and rupture of the amniotic sac Expulsion – dilation of the uterus reaches 10 cm, active labor begins Birth – the baby is expelled and the umbilical cord is cut Delivery – the placenta comes out

El parto

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