The reproductive systems make it possible to create new human life. All people are born with sexual organs that begin to develop during puberty, due to the activity of hormones. Puberty marks the end of childhood and the beginning of adolescence. It usually starts around age 10 for girls and age 11 for boys.
During this stage, physical changes happen in both sexes: body hair begins to grow, height increases, perspiration becomes stronger, and the sexual organs develop.
What Does the Reproductive System Do?
Table of Contents
The reproductive system matures during adolescence and is different in males and females. In both, special sex cells called gametes are produced. In males, these are called sperm cells (spermatozoa), and in females, they are called egg cells (ova or ovules).
Human Reproductive System
What Is Reproduction?
Reproduction is a vital function of all living beings. It is the process through which organisms have offspring, allowing new life to begin. In humans, reproduction is sexual, which means it involves the participation of two people: one male and one female.
There is also something called asexual reproduction, where a single cell divides to form two identical cells—but this does not happen in humans.
Human Fertilization
Egg and Sperm Fertilization
The union of the egg and the sperm is called fertilization. This process creates the first cell of a new human being, called the zygote. After fertilization, the zygote begins to divide and grow, and it stays in the mother’s uterus during pregnancy. After around 9 months, when the fetus is fully developed, the baby is born.
The term embryo is used during the early stages of development. It is called a fetus once it starts to look like a human.
The Female Reproductive System
In both the male and female reproductive systems, some organs are located outside the body—these are known as the external genitalia. Other organs are located inside the body, in the abdomen—these are called the internal genitalia.
Female Reproductive System: Parts and Functions
The female reproductive system includes both external and internal organs.
External Organ: Vulva
The vulva is the outer part of the female reproductive system. It includes two openings:
- The urinary opening, where urine comes out.
- The vaginal opening, which is part of the reproductive system.
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Internal Organs:
- Ovaries
- Fallopian tubes
- Uterus
- Vagina
Ovaries
There are two ovaries, one on each side of the uterus. They are oval-shaped, about the size of an almond, and located in the lower abdomen (pelvis). The ovaries:
- Produce eggs (also called ova)
- Release hormones like estrogen and progesterone
These hormones help prepare the uterus for a possible pregnancy.
What Is Ovulation?
Once a month, one of the ovaries releases a tiny egg—this is called ovulation.
The egg travels through a fallopian tube to the uterus.
Before ovulation, estrogen makes the lining of the uterus thicker with blood and tissue, preparing it for a possible pregnancy.
If the egg meets a sperm and is fertilized, it attaches to the lining of the uterus and begins developing into a baby.
Fallopian Tubes
There are two fallopian tubes, which are long, thin tubes that connect the ovaries to the uterus.
They catch the egg released during ovulation.
If sperm are present in the tube, fertilization may occur here.
How Does the Female Reproductive System Work?
The Menstrual Cycle
If the egg is not fertilized, it doesn’t attach to the uterus wall.
Instead, the uterus sheds its extra blood and tissue.
This mixture of blood, tissue, and the unfertilized egg exits the body through the vagina.
This is called the menstrual period or simply period.
This cycle happens about once a month for many years—except during pregnancy—until a stage called menopause, when the ovaries stop releasing eggs.
What Is Menstruation?
The start of menstruation (your first period) is a sign that a girl is becoming a woman.
This usually happens between the ages of 8 and 13 and is part of puberty, when hormones cause changes like breast development.
The first menstrual period is called the menarche.
It shows that the reproductive system is mature and working.
Uterus
The uterus is a muscular organ where a baby can grow during pregnancy.
It connects to the vagina through a narrow part called the cervix.
Every month, the inner layer of the uterus—called the endometrium—builds up in case of pregnancy.
If no pregnancy happens, this layer breaks down and leaves the body as menstrual blood through the vagina.
Vagina
The vagina is a muscular canal that connects the uterus to the outside of the body.
It is protected by folds of skin called the labia minora and labia majora.
At the point where the labia minora meet, there is a small and very sensitive organ called the clitoris.
During sexual intercourse, the vagina allows the penis to deposit sperm.
It also allows the baby to exit the body during childbirth.
Male Reproductive System: Organs and Functions
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External Genitalia
Scrotum
The scrotum is a pouch of skin that holds and protects the testicles.
It helps keep them at a slightly cooler temperature than the rest of the body, which is important because sperm can’t develop properly at normal body temperature.
Penis
The penis is a spongy organ covered in skin. Its rounded, cone-shaped tip is called the glans.
The skin that covers the glans is called the foreskin (in some people, this may be removed in a procedure called circumcision).
During ejaculation, the penis releases semen, a fluid that carries millions of sperm.
Urine also exits the body through the penis, using the same tube called the urethra.
Testicles (Testes)
The testicles are two small organs located inside the scrotum.
They produce two important things:
- Sperm cells (also called gametes)
- The male sex hormone, called testosterone
Sperm leave the testicles through a series of small tubes. They mix with fluids to form semen, which exits the body through the urethra.
Internal Organs
Prostate
The prostate is about the size of a walnut and is shaped like an upside-down pyramid.
It surrounds part of the urethra, right below the bladder.
It’s made of muscle and glandular tissue and helps produce some of the fluid found in semen.
Seminal Vesicles
The seminal vesicles are two small sacs that produce a liquid rich in nutrients that feeds the sperm.
This liquid also helps sperm move more easily.
Sperm
Sperm cells are very small and swim using their tails—kind of like tiny tadpoles.
They move in large groups—more than 100 million at a time!
Epididymis
After being produced in the testicles, sperm are stored in a tube called the epididymis, where they mature.
Vas Deferen
The vas deferens are long tubes that carry the mature sperm from the epididymis to the urethra.
Urethra
The urethra is a tube that serves two purposes:
- It carries urine from the bladder to the outside of the body.
- It carries semen out during ejaculation.
Even though both fluids use the same tube, they never come out at the same time.