The Male Reproductive System

The male reproductive system is a collection of organs and other structures in the pelvic region. Most of the structures are located outside the body. The male reproductive system has two major functions: producing sperm and secreting testosterone. Sperm are male gametes. Testosterone is the main sex hormone in males. You read about Testosterona in the posts about endocrine system.
Sexual Development in Males
All the reproductive organs are present by birth. However, they are immature and unable to function. The reproductive organs grow very little during childhood and do not mature until puberty.
Puberty is the period during which humans become sexually mature. In the United States, boys generally begin puberty at about age 12 years. The testes produce testosterone that promotes most of the physical changes of puberty
Changes in Males During Puberty
Changes in Reproductive Organs
Testes grow larger Penis grows longer
Other reproductive structures grow Sperm production begins
Other Physical Changes
Pubic hair grows
Facial and body hair grow
Bone density increases
Long bones grow
Muscle mass and strength increase
Bones in face grow
Adam’s apple grows
Apocrine sweat glands develop
Shoulders widen
Voice deepens
Changes in the reproductive organs are called primary sex characteristics. Other changes, that are not directly related to reproduction are called secondary sex characteristics.
Male Reproductive Organs
The male reproductive organs include the penis, testes, and epididymis. Several ducts and glands are also parts of the male reproductive system. These organs are shown in Figure.
The penis is a cylinder-shaped organ. It is the copulatory organ. It contains the urethra. The urethra is a tube that carries urine – excretory system- out of the body and also the sperm – reproductive system-.
The two testes or testicles are the male gonads. They are egg-shaped organs. Their functions are to produce sperm and to secrete testosterone. The testes are contained in the scrotum. As you can see from Figure, the scrotum is a sac that hangs down outside the body. By hanging away from the body, the testes keep sperm at a temperature lower than normal body temperature. The lower temperature is needed for sperm production.
The epididymis is a tube that is about 6 meters long in adults. It is tightly coiled, so it fits inside the scrotum. It rests on top of the testes. The epididymis is where sperm mature. The epididymis also stores sperm until they leave the body.
Other parts of the male reproductive system include the vas deferens that carries sperm from the epididymis to the urethra. The main glands are the prostate and the seminal vesicles. They secrete substances that become part of semen.
Semen is a milky liquid that is ejaculated from the urethra. Semen contains secretions from the glands as well as sperm. The secretions control pH and provide the sperm with nutrients for energy.

REPRODUCTIVE SYSTEM VOCABULARY

We are going to begin with the most important concepts of this subject.
1. Fertilization: Union of a sperm and egg; occurs in a fallopian tube.
2. Fetus: Stage of a developing baby between the end of the 8th week after fertilization and birth.
3. Eggs: Female gametes or sex cells.
4. Embryo: Stage of a developing baby between implantation and the end of the 8th week after fertilization.
5. Epididymis: Male reproductive organ where sperm mature and are stored until they leave the body.
6. Estrogen: Main sex hormone in females.
7. Fallopian tubes: Female reproductive organs through which eggs pass to reach the uterus and where an egg may unite with a sperm.
8. Follicle: Nest of cells in an ovary that enclose an egg; protects egg during maturation prior to ovulation.
9. Implantation: Process in which the ball of cells that will become an embryo embeds in the lining of the uterus.
10. Menstruation: Monthly shedding of the lining of the uterus through the vagina; also called a menstrual period.
11. Penis: Male reproductive organ that carries urine and sperm out of the body.
12. Placenta: Spongy mass of blood vessels from the mother and fetus that allows substances to pass back and forth between the mother’s blood and the fetus’s blood.
13. Ovaries: Female reproductive organs that produce eggs and secrete estrogen.
14. Ovulation:Release of an egg by an ovary.
15. Semen: Milky liquid that contains sperm and secretions of glands; passes through the urethra and out of body.
16. Sperm: Male gametes or sex cells.
17. Testosterone:Main sex hormone in males.
18. Testes: Male reproductive organs that produce sperm and secrete testosterone.
19. Uterus: Female reproductive organ where a baby develops until birth.
20. Vagina: Female reproductive organ where sperm are deposited and through which a baby passes to leave the mother’s body during birth.
21. Umbilical cord: Tube containing blood vessels that connects a fetus to the placenta.
22. Zygote: Cell that forms when a sperm and egg unite; the first cell of a new organism.

The reproductive system

You are supposed to remember the most important about reproduction becouse you studied last year. In case you had forgotten, in this post we will begin with a review of the last year.

Reproduction is the biological process by wich new individual organism are produced. It ensures the perpetuation of the species.

There are two main types of reproduction:

Asexual reproduction requires only one parent which produces new, genetically identical living beings.
Sexual reproduction requires two parents: a male and a female. The descendants have a combination of genetic material contributed from both parents.

Sexual reproduction in animal usually requires two members of the opposite sex, a male and a female. Each member has different reproductive organs called gonads. These organs make reproductive cells called gametes.

The male gonads are the testicles and the male gametes are the spermatozoa.

The female gonads are the ovaries and the female gametes are the ova.

Fertilisation is the union of an ovum and a spermatozoon. They form a zygote.

There are two types of fertilisation:

External fertilisation when the union of the gametes occur s outside the female body. It is typical of the acuatic animal.

Internal fertilisation is the fusion of gametes which occurs inside the female body. It involves copulation, which is the transmision of spermatozoa of the male into the female reproductive system trough a copulating organ. It is typical the most of terrestrial animal.

Human living beings have this type of fertilisation . In next post we will find informatión about human reproduction.