Human Reproductive System: Sexuality, Anatomy and Fertilization
Human Sexuality and the Reproductive System
Human sexuality is part of our body and our identity. It includes our sexual orientation, our gender identity and our biological sex. The reproductive organs are the sexual organs: the ovaries and uterus in females, and the testicles and penis in males.
Each individual's biological sex is determined at fertilization by the chromosome type carried by the sperm, which fertilizes the egg.
Puberty and Adolescence
Puberty is the stage when the body reaches sexual maturity and becomes capable of reproduction. During adolescence, people develop secondary sexual characteristics and undergo psychological changes. Their interests in friendships and attraction also begin to develop, and they become able to make their own decisions about their maturation, independent of their parents.
These changes are driven by hormones. In girls, the ovaries increase their production of estrogen and progesterone. In boys, the testicles increase their production of testosterone.
The Male Reproductive System
The male reproductive system is responsible for producing and delivering sperm. It includes the following structures:
- Testicles: Two oval organs located inside the scrotum. Sperm are produced in the seminiferous tubules from germ cells.
- Epididymis: Tubes where sperm are stored and matured.
- Ducts: Sperm move through these ducts, receiving fluids from several glands, including the bulbourethral glands.
- Fluids: These fluids make up semen and provide sperm with nutrients and a medium in which to move.
- Urethra: The sperm leave the body through the urethra.
Each sperm cell has a flagellum (tail), which allows it to swim.
The Female Reproductive System
The female reproductive system is formed by the ovaries, the uterus, the fallopian tubes and the vagina. The ovaries contain the egg cells, which are protected by follicular cells.
The female sexual cycle has an average duration of 28 days. During the cycle, a follicle develops and an egg is released. This process is called ovulation.
- Ovulation: The egg is released from the ovary and enters the fallopian tube.
- Fertilization: If sperm are present in the female reproductive tract, fertilization can occur in the oviduct, forming a zygote. This is how a new human life begins.
From Zygote to Pregnancy
The zygote divides by mitosis several times, forming a blastocyst. The blastocyst implants in the wall of the uterus, and the pregnancy continues.
If fertilization does not occur, the mature egg is not fertilized and dysfunctional, so it is reabsorbed into the female tract. The inner layer of the endometrium, which lines the uterine walls, then sheds, producing menstruation.
Key Point
Fertilization is the function of the male gametes (sperm) combining with the female gamete (egg).