Human Reproductive System: Anatomy and Function
The Male Reproductive System
The male reproductive system includes:
- Testes: Two organs that produce sperm and testosterone. They are located outside the abdominal cavity in a pouch called the scrotum.
- Genital Tract: The epididymis and vas deferens, which collect and transport sperm from the testicles to the exterior through the urethra.
- Accessory Glands: The prostate and seminal vesicles produce secretions that allow the maturation of sperm and serve as a vehicle, constituting semen.
- Penis: The external organ that allows sperm to be deposited in the vagina. It consists of erectile tissue that expands during excitation due to a large influx of blood, producing an erection.
Sperm Production
Sperm production takes place in the seminiferous tubules of the testes. Sperm require a temperature slightly lower than body temperature, which is why the testicles are located outside the abdominal cavity. Sperm travel from the seminiferous tubules to the urethra, mixing with secretions from the prostate and seminal vesicles (semen).
Sperm are the male gametes and contribute the father’s genes to the future embryo. A sperm consists of:
- Head: Contains the nucleus with chromosomes and a cap with enzymes needed to penetrate the egg.
- Midpiece: A cylinder containing numerous mitochondria that provide the energy needed for movement.
- Tail: A flagellum that enables movement.
The Female Reproductive System
The female reproductive system produces female gametes (eggs) and female sex hormones. It includes:
- Ovaries: Two glands located on each side of the uterus, about 4 cm long, that produce eggs and female sex hormones.
- Genital Tract: The Fallopian tubes, uterus, and vagina. These are the ducts that carry eggs from the ovaries to the uterus, where the embryo develops until birth. The uterus is located between the bladder and rectum and is pear-sized.
- External Genitalia (Vulva): Formed by the labia minora and majora, which protect the vaginal opening, the urethral opening, and the clitoris.
Eggs: These are large cells. They consist of a nucleus and cytoplasm with abundant nutrients for the future embryo.
Fertilization and Fetal Development
Fertilization: The union of an egg and a sperm.
Fetal Development:
- Amnion: A membrane that forms the amniotic cavity in which the embryo is suspended. It contains amniotic fluid, which bathes the embryo and protects it from shocks and vibrations.
- Placenta: An organ connected to the embryo and the wall of the mother’s uterus via the umbilical cord (formed by arteries and veins). The placenta allows oxygen and nutrients to reach the embryo and collects waste products.
Contraceptive Methods
Various methods exist to prevent pregnancy:
- Condom: A thin sheath of rubber placed on the erect penis. It retains sperm and prevents penetration into the vagina. It offers dual protection: contraception and prevention of sexually transmitted diseases.
- Birth Control Pills: Contain female hormones that prevent ovulation. They must be taken daily and can cause side effects.
- Intrauterine Device (IUD): A small plastic and metal device placed in the uterus that prevents embryo implantation. It is placed by a doctor and can remain in the uterus for about 3 to 4 years.
- Diaphragm: A disk placed at the bottom of the vagina to cover the cervix and prevent sperm from entering the uterus.
- Spermicide: A cream containing chemicals that destroy sperm.
- Tubal Ligation or Vasectomy: Surgical operations that prevent the passage of eggs or sperm, respectively.