Why do men and women look different?
The features that make men unique from women, such as this man's beard, are controlled by the sex hormones. The production of the sex hormones is a key role of the male reproductive system.
The Male Reproductive System Functions
Dogs have puppies. Cats have kittens. All organisms reproduce, obviously including humans. Like other mammals, humans have a body system that controls reproduction. It is called the reproductive system. It is the only human body system that is very different in males and females. The male and female reproductive systems have different organs and different functions.
The male reproductive system has two main functions:
- Producing sperm.
- Releasing testosterone into the body.
Sperm are male gametes, or reproductive cells. When a male gamete meets a female gamete, they can form a new organism. Sperm form when certain cells in the male reproductive system divide by meiosis, resulting in cells with half the amount of DNA as a regular "body" cell. More precisely, sperm cells are haploid sex cells, having one set of chromosomes. Regular body cells are diploid, having two set of chromosomes. As there are 46 chromosomes in a diploid human cell, how many are in a human sperm cell?
When males grow older, they produce millions of sperm each day. The male reproductive system also maintains and transports and delivers sperm and a protective fluid, known as semen.
Testosterone is the main sex hormone in males. Hormones are chemicals that control many body processes. Testosterone has two major roles:
- During the teen years, testosterone causes the reproductive organs to mature. It also causes other male traits to develop. For example, it causes hair to grow on the face and allows for muscle growth.
- During adulthood, testosterone helps a man to produce sperm.
When a hormone is released into the body, we say it is "secreted." Testosterone is secreted by males, but it is not the only sex hormone that males secrete. Males also secrete small amounts of estrogen. Even though estrogen is the main female sex hormone, scientists think that estrogen is needed for normal sperm production in males.
Testosterone, the main sex hormone in males, allows men to build larger muscles than women.
- gamete: Reproductive cell, such as sperm or egg.
- meiosis: Process in cell division during which chromosome number is halved in order to produce gametes.
- reproductive system: Organ system that produces gametes and secretes sex hormones.
- sperm: Male gamete, or reproductive cell.
- testosterone: Main sex hormone in males.
- The main functions of the male reproductive system are to produce sperm and secrete testosterone.
- Testosterone, the main sex hormone in males, causes the reproductive organs to mature and other male traits to develop.
Use the resource below to answer the questions that follow.
- Male Reproductive System at http://kidshealth.org/parent/general/body_basics/male_reproductive.html
- In addition to the reproductive system, the testes are part of which other organ system? Why?
- What composes the male genitals?
- What occurs during the first stage of puberty in boys?