Sistema Reprodutivo Humano: Órgãos e Funções

In this article, we will explore the main parts of the human reproductive system and their functions through various stages of life, from puberty to old age. We will discuss both male and female reproductive systems, including the organs and processes involved in fertilization, pregnancy, and childbirth.

Female Reproductive System

The female reproductive system consists of several essential components:

Ovaries

Two symmetrical ovaries are located on either side of the uterus, approximately level with the opening of each Fallopian tube. They produce hormones such as estrogen and progesterone, which regulate menstrual cycles and prepare the body for pregnancy. Each ovary contains about 7 million oocytes (immature egg cells) prior to birth, but only around 300,000 remain after puberty. These follicles release mature eggs during ovulation.

Uterus

The uterus is a muscular organ shaped like a pear, capable of expanding greatly when pregnant. It has three layers: the endometrium lining, the myometrium middle layer, and the perimetrium outermost layer. The cervix, a narrow lower end of the uterus, connects to the vagina. During intercourse, sperm travels up the vagina, through the cervix, into the uterine cavity, where it can potentially meet the released egg. If fertilization occurs, the embryo implants itself into the endometrial lining.

Fallopian Tubes

These two tubes extend from the upper part of the uterus to the ovaries. Eggs pass down one tube, usually on the right side, following the movement of cilia and muscular contractions. Sperm is transported along the other tube, waiting for the egg's arrival. Once the egg reaches the ampulla portion of the tube near its midpoint, sperm may enter via capacitation, binding to molecules on the surface of the egg. Fertilization occurs in the ampulla, and the resulting zygote quickly descends the tube toward the uterus.

Vagina

This tubular structure extends from the vulva, a woman's external genitalia, to the cervix. It serves multiple purposes: protection against bacteria, lubrication, childbirth, and menstruation. When a woman becomes sexually excited, blood flow increases in the vaginal walls and fluid production increases, providing natural lubrication.

Male Reproductive System

The male reproductive system is composed of the following major parts:

Testicles

Located outside the body in the scrotum, two testicles contain millions of spermatozoa (mature sperm cells), held in tiny sacs called seminiferous tubules. Each testicle is about 4 cm long and 2 cm wide, with a weight of around 30 grams in an adult. They also produce androgens such as testosterone, which control male secondary sexual development.

Vas Deferens

Each vas deferens begins at the upper end of each testis, passes through the inguinal canal, and eventually merges into one spermatic cord on either side. These muscular ducts transport mature sperm from the epididymis to the urethra.

Prostate Gland

This small gland surrounds part of the urethra just below the bladder. It secretes fluid that mixes with sperm during ejaculation, providing nutrients and protection for the sperm. The prostate gland also contributes mucus-like substances called prostatic fluid.

Epididymis

Attached to each testis, this coiled tube contains millions of tiny tubules where immature sperm cells transform into mature ones over several days. Sperm are stored here until they reach maturity and can be released upon stimulation by hormones or sexual activity.

Urethra

The urethra is a common channelway shared by both urine and semen. In males, it originates from the bladder and extends along the length of the penis before exiting through the opening at the penile tip (urethral meatus). During ejaculation, sperm travels up the urethra to exit via the external urethral orifice.

In summary, the human reproductive system involves a complex network of organs and structures designed for fertilization, pregnancy, and childbirth. Understanding these processes can help individuals make informed decisions about their sexual health and overall wellness.