Puberty and Human Reproductive Health: Changes and Processes

Posted on Dec 10, 2024 in Biology

What is Puberty?

Puberty is a period in a person’s life when significant changes occur. These changes are both physical and psychological, affecting appearance, body function, personality, and relationships with others. It typically begins around the ages of 10 or 11, but the exact age varies for each individual.

Physical Changes During Puberty

In Boys:

• Growth of pubic hair, beard, mustache, and body hair
• Widening of shoulders and chest
• Increased muscle mass
• Voice change
• Growth of penis and testicles
• Beginning of sperm production

In Girls:

• Growth of pubic and armpit hair
• Changes in body fat distribution
• Development of mammary glands
• Widening of hips
• Onset of menstruation
• Development and maturation of sex organs

What Regulates Estrogen and Progesterone?

Estrogen and progesterone are female sex hormones produced by the gonads. Estrogen, produced by the ovaries, is responsible for the development of female sexual characteristics (such as mammary glands, pubic and armpit hair) and the control of the menstrual cycle. Progesterone’s function is to prepare the uterus to receive and maintain a fertilized egg during each half-cycle and to stimulate breast enlargement.

Secondary Sexual Characteristics

Secondary sexual characteristics are those that appear at maturity due to the action of sex hormones.

In Girls:

The main changes include the appearance of pubic and armpit hair, changes in body fat distribution, development of mammary glands, widening of hips, the onset of menstruation, and the development and maturation of sex organs.

In Boys:

It is characterized by the appearance of pubic hair, beard, mustache, and body hair, increased bone density and muscle mass, voice change, and the growth of the penis and testicles, which begin to produce sperm.

Hormones Responsible for Egg and Sperm Formation

Testosterone is the hormone responsible for sperm formation. Estrogen is the hormone responsible for the formation of ova (eggs).

Egg and Sperm

The female gametes are eggs. They are very large cells that move with great difficulty. When an egg leaves the ovary, it passes into the fallopian tubes, where it can be fertilized by a sperm or die.

The male gametes are sperm. They are very small and mobile, with the ability to fertilize an egg and form a new being. In their mature state, they are composed of a head, a middle part (neck), and a tail. They can live for up to three days inside the female genital tract.

Vas Deferens and Urethra

The vas deferens are small ducts through which sperm reach the seminal vesicles and connect with the urethra.

The urethra is the canal that runs through the penis and ends at the urinary meatus.

Physiognomy of Bodies

Definitions:

Spermatogenesis: The process of formation of male gametes, or sperm. It takes place inside the testicles and begins at puberty, continuing throughout a male’s reproductive life.

Oogenesis: The process of formation of female gametes, or ova. Eggs begin to develop in the third month of fetal development, with about two million produced. They remain inactive until puberty. Thereafter, under hormonal influence, approximately every 28 days until menopause, a mature egg is released that can be fertilized or not. If fertilized, a child is conceived; otherwise, it is expelled from the body.

Gonads: Sex glands that produce male and female gametes and sex hormones. The ovaries are the female gonads that produce eggs, and the testes are the male gonads that produce sperm. They also produce sex hormones: androgens in males (the most important being testosterone) and estrogens in females (the most important being progesterone).

Menstrual Cycle: The time between the first day of one menstrual period and the first day of the next. This period is usually about 28 days but can vary.

Zygote: A cell with two sets of chromosomes formed by the fusion of a female gamete with a male gamete before it begins to divide.

Pregnancy: The state of a woman after fertilization until birth, during which the zygote develops into a new individual.

Sterility: The inability of a person to reproduce due to various factors.

Mucous Plug: Thick mucus that prevents the passage of germs into the uterine cavity. It is expelled during the first stage of labor.

External Genitalia: The reproductive organs found outside the body and are visible. In males, these are the penis and scrotum; in females, they are the mons pubis and the vulva (labia majora and minora, clitoris, vaginal opening, and urethra).

Embryo: An organism from the fertilized egg stage until it shows evidence of its future structure or is capable of independent life.

Fetus: An embryo of a viviparous animal after it has developed the characteristics that will shape its further development until birth.

Menopause: The period when menstruation naturally ceases.

Parturition (Childbirth): The process by which a new individual is born at the end of pregnancy, involving the expulsion of the fetus and placenta.

Methods of Fertility: Techniques by which an egg is fertilized by a sperm.

In Vitro Fertilization (IVF): An assisted reproduction method where an egg is extracted from the mother and sperm from the father. The egg is fertilized in a laboratory setting, and after two days, the embryo is implanted into the mother’s uterus.

Amniotic Fluid: A clear, yellowish liquid that surrounds the fetus inside the uterus during pregnancy and is contained in the amniotic sac. Its functions include protecting the fetus, allowing its mobility, maintaining a constant temperature, and enabling growth.

What is the Endometrium?

The endometrium is a membrane lining the uterine cavity. During the menstrual cycle, the endometrium undergoes many changes, including growth, regression, and bleeding, all regulated by hormones. During menstruation, the endometrium sheds. After menstruation, it regenerates. Initially, its thickness is small (1-2 mm), but it grows to 3-5 times that size over the following days.

What is Semen?

Semen is the fluid expelled during ejaculation. It is composed of sperm, fluid from the seminal vesicles, and fluid produced by the prostate.

Sperm Journey to Fertilization

Sperm are formed in the testes. During intercourse, they travel through the vas deferens and the urethra, mixing with prostatic fluid and seminal fluid. They are then deposited into the vagina. After passing through the uterus, they reach the fallopian tubes. If ovulation has occurred, a sperm will encounter an egg. Only a few sperm reach the egg, and typically only one will penetrate and fertilize it.

What is the Placenta?

The placenta is a round, flat organ that develops in the uterus during pregnancy. It acts as an intermediary between the mother and the developing fetus, and a portion of the umbilical cord is attached to it.

Organ for Substance Exchange Between Mother and Child

The umbilical cord is the organ that allows the exchange of substances between the mother and the child. The mother sends nutrients and oxygen to the fetus, while the fetus sends carbon dioxide and waste products to the mother for elimination.

The Navel: Our First Scar

Everyone has a scar on their belly called the navel. It is the remnant of the umbilical cord, which connected us to our mothers in the womb, providing nourishment and oxygen. At birth, the cord is cut, allowing the newborn to breathe and eat independently. The remaining portion heals, forming the navel, which can be either inward or outward.

At around nine months, the fetus is typically fully formed and ready for birth. When labor begins, the uterus contracts, dilating the vagina to facilitate the baby’s passage. These contractions cause the rupture of the amniotic sac, the membrane containing the amniotic fluid, releasing the fluid. This is often referred to as”water breakin” or”breaking the bag”

Stages of Labor

Dilation of the Cervix: Begins with contractions of the uterine walls and dilation of the cervix. Contractions lead to the rupture of the amniotic sac, releasing the amniotic fluid.

Expulsion of the Fetus: Contractions of the uterine walls and pressure from the abdominal muscles push the fetus through the vagina to the outside.

Expulsion of the Placenta: After the baby is born, the umbilical cord is cut, leaving the scar known as the navel. The placenta then detaches from the uterine walls and is expelled along with other remnants of the fetal membranes.

Contraception Methods

Contraceptive methods can be classified into three types:

Those that prevent sperm from reaching the egg:

• Male and female condoms
• Diaphragm
• Intrauterine device (IUD)
• Spermicides
• Tubal ligation
• Vasectomy
• Periodic abstinence methods (Ogino, basal temperature, Billings, coitus interruptus)

Those that prevent the formation of the egg:

• Contraceptive pill

Those that prevent the implantation of the ovum in the endometrium:

• Intrauterine device (IUD)
• Postcoital contraception

Sexually Transmitted Infections (STIs)

Here is a table summarizing some common STIs:

What are Congenital Diseases?

Congenital diseases are those that are present at birth. They arise due to alterations during the complex process of embryonic and fetal development, which can be caused by various external agents or genetic factors.