Lesson Video: The Male Reproductive System | Nagwa Lesson Video: The Male Reproductive System | Nagwa

Lesson Video: The Male Reproductive System Science

In this video, we will learn how to describe the main structures of the male reproductive system and explain how they are adapted to carry out their functions.

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Video Transcript

In this video, we will learn how to describe the main structures of the male reproductive system. We will also explain how each part of the male reproductive system is well adapted to carry out their functions in sexual reproduction.

The main function of the male reproductive system is, you guessed it, reproduction. In fact, it is specifically responsible for part of the process of sexual reproduction in humans, which involves two parents combining half of each of their genetic material to produce offspring. This combining of genetic material occurs through a process called fertilization.

Fertilization involves a sex cell from a biological male fusing with a sex cell from a biological female. Sex cells are sometimes called reproductive cells or gametes. A biological male’s sex cells are called sperm cells, and a biological female’s sex cells are called egg cells. They each contribute half of the genetic material of a parent so that the cell produced in fertilization, which is called a zygote, has a full set of genetic material.

Did you know that a healthy biological male’s reproductive system can produce 1,500 sperm cells every second? In fact, just one milliliter of healthy semen, the fluid that contains sperm, can contain as many as 300 million sperm cells. The main function of these sperm cells is to fertilize a biological female’s egg cell in sexual reproduction. Let’s take a closer look at how sperm cells and semen are produced by taking a tour of the male reproductive system.

Here, we can see an outline of some of the main structures in the reproductive system of a typical biological male from a side view. The sperm cells’ journey begins in the testes, which are sometimes referred to as a biological male’s sex organs or gonads. Biological males usually have two testes, each of which is called a testis. A testis is the shape of a small chicken egg, around three to five centimeters long and three to four centimeters wide at their thickest point, though this will vary. It is also normal for the two testes of an individual to vary in size.

The testes are a special type of organ called a gland. They are responsible for producing sperm cells and also for producing sex hormones. We will explore this second function in more detail later. First, let’s continue to describe the different male reproductive organs.

The testes are found within a sac of skin called the scrotum, which usually hangs from the male’s body. The scrotum is helpful, as its external location keeps the testes at a temperature a few degrees lower than the rest of the normal body temperature. This cooler temperature is more suitable for the sperm production process. After they are produced in the testes, sperm cells are stored in the long, coiled tubes that make up the epididymis, located just outside each of the testes.

To fertilize a biological female’s egg cell, sperm needs to journey through the male’s reproductive system and out of his body. This usually occurs when a male is sexually aroused during or in anticipation of copulation, which is often referred to as sexual intercourse or simply sex. If sperm cells enter a female’s reproductive system, they might be able to fertilize one of her egg cells.

Let’s keep track of the pathway that sperm cells take as they travel from the testes to exit the male’s body with green arrows. We’ve already covered the first two stages that occur before the male is aroused. When a male is sexually aroused, the sperm cells travel from the epididymis along a series of tubelike structures called ducts. The first duct they enter is called the vas deferens or a sperm duct. This makes sense, as it transports sperm. Human males tend to have two sperm ducts, one leading from each of the testes. Where the two sperm ducts meet, the sperm cells move into another duct called the urethra. You might already know that both biological males and biological females have a urethra, as one of its key roles is transporting urine from the bladder out of the body.

Although the bladder is located close to the reproductive organs, it is not a part of the reproductive system. Instead, the bladder is responsible for storing urine before it is removed from the body via the urethra, in a process called urination. The urethra starts at the base of the bladder to allow this to occur. In biological males only, the urethra has another important job. It transports sperm cells from the sperm ducts out of the male’s body through a process called ejaculation. Let’s clear some space so we have room to discuss a few things that need to happen first.

The male reproductive system has several small organs called accessory glands, which release fluids: the prostate gland, two seminal vesicles, and two Cowper’s glands. These fluids, which are called seminal fluids, are really helpful as they provide a liquid that sperm cells can swim through as they pass through the male’s urethra and possibly into a female’s vagina. Remember, the mixture of these seminal fluids and sperm cells is called semen. Seminal fluid contains nutrients to nourish the sperm cells, helping to keep them alive and functioning. It is also alkaline. This is so it can neutralize the slightly acidic environment in the male urethra and a female vagina, to help the sperm cells survive for longer. Let’s add some black arrows onto our diagram to show where seminal fluids are added to the sperm cells.

The prostate is a muscular gland located just below the bladder. The fluid the prostate gland produces is added to sperm cells when they travel into the urethra from the sperm duct. At a similar time, the two seminal vesicles, which are located behind the bladder, add another fluid component to the sperm cells, making up between 50 percent to 80 percent of the total semen volume.

The Cowper’s glands also add fluid to the sperm cells. These two small glands sit below the prostate gland on either side of the urethra. The Cowper’s glands are partly responsible for releasing preejaculatory mucus, which, as the name implies, may naturally be released from the urethra when the male is sexually aroused before ejaculation has occurred. This mucus is helpful in lubricating and neutralizing the urethra to prepare for the transport of sperm cells out of the body. Sometimes, preejaculatory fluid contains some sperm cells. Therefore, if it comes into contact with a female’s reproductive organs, it might still cause fertilization and, as a result, pregnancy.

Once liquid semen has been formed, it is ready to be released from the male’s body. In biological males, the urethra extends through an organ called the penis. The penis is an important organ in sexual reproduction, and it is also responsible for urination in males. The penis is found just above the scrotum. It is made of spongelike tissue and can grow in size upon sexual arousal due to an increase in blood flow, changing from soft and flaccid to erect and rigidly upright. This feature helps it to enter the female reproductive system during sexual intercourse, so it can deposit semen into a female’s vagina.

The urethra ends in a hole, sometimes called a urosexual opening, at the tip of the penis. As we mentioned earlier, the process of sperm cells, which are contained within semen, being released from the penis through this opening is called ejaculation.

Let’s quickly recap the journey of the sperm cells by looking at the male reproductive system from a front view this time instead. Sperm cells are produced in the testes. They are then stored in the epididymis just outside the testes. Sperm cells are then transported into the sperm ducts. Where the two sperm ducts meet, sperm cells are transported into the urethra. Seminal fluids are added to the sperm cells by the prostate gland, seminal vesicles, and Cowper’s glands to form liquid semen. This semen, containing the sperm cells, can then be ejaculated out of the male’s body from his penis via the urethra. If semen then enters a female’s vagina, one of the sperm cells might be able to fertilize an egg cell.

We mentioned earlier that the testes can produce sex hormones. What does this mean? In humans, hormones are produced by cells within specific types of glands, like the testes. Hormones are chemical messengers. This means they travel throughout the body, usually via the bloodstream, to deliver instructions to specific target cells or organs. This can cause a particular group of target cells to respond in a particular way. The testes produce the majority of sex hormones in the male body. The main sex hormone produced by the testes is testosterone. Testes are usually only found in biological males.

Interestingly, small amounts of testosterone are also usually produced in biological females, even though they don’t have testes. Similarly, typically female sex hormones, like estrogen, are also released from the testes but in smaller quantities.

Let’s take a closer look at what testosterone does. Testosterone is responsible for the growth of various parts of the male reproductive system, including the prostate gland and seminal vesicles. It can also control the development of male secondary sexual characteristics. These are physical characteristics, not directly involved in reproduction, that start to develop when a person reaches puberty. Puberty is a period during adolescence when an individual reaches sexual maturity and becomes physically capable of reproduction. However, they are unlikely to be mentally or emotionally ready yet.

Many secondary sexual characteristics differ between the two biological sexes: males and females. For example, some typical secondary sexual characteristics in males include their voice breaking and becoming considerably deeper and the growth of facial and body hair. It may also include the growth of more muscle. Let’s apply what we’ve learned about the male reproductive system to some practice questions.

What is the difference between sperm and semen? (A) Semen is a collection of male sex cells, and sperm is the fluid that surrounds them. (B) Sperm are the male sex cells, and semen is sperm cells that have been mixed with seminal fluid. (C) Sperm are the molecules released by the testes, and semen is the molecules released by the bladder. Or (D) there is no difference between the two.

Sperm cells are the sex cells of a biological male. Their main function is to fertilize a biological female’s sex cell, the egg cell, to create new life. Sperm cells are produced in a male’s testes and need to travel through his reproductive system to eventually leave his body if they are going to be successful in fertilization. As the sperm cells are transported through the male, as represented by the green arrows on the diagram, several fluids, called seminal fluids, are added to them.

Seminal fluids are produced by three key glands in the male reproductive system, which have been shown here in blue: the prostate, seminal vesicles, and Cowper’s glands. Among their other benefits, seminal fluids are helpful, as they provide a liquid through which sperm cells can swim. The mixture of sperm cells and seminal fluid is called semen. If semen enters the reproductive system of a biological female, the sperm cells it contains might be able to fertilize an egg cell. This means we have found the main difference between sperm and semen. The correct answer is (B). Sperm are the male sex cells, and semen is sperm cells that have been mixed with seminal fluid.

Let’s try another question together.

What part of the male reproductive system is responsible for producing the majority of the male sex hormones?

Hormones are chemical messengers that travel through an organism’s body to have an effect on specific target cells and organs. In humans, hormones are produced by cells within specific organs called glands. Hormones are usually released into the bloodstream, which transports them to their target cells.

This question mentions sex hormones specifically and asks us which part of the male reproductive system is responsible for producing them. Well, the glands in a biological male’s reproductive system that are responsible for producing the majority of sex hormones are called the testes. The main sex hormone produced by the testes is testosterone. Testosterone is responsible for the growth of various parts of the male reproductive system. It also controls the development of male secondary sexual characteristics. These are physical characteristics, not directly involved in reproduction, that usually start to develop when a person reaches puberty. Typical secondary sexual characteristics in males include their voice becoming deeper and the growth of facial and body hair.

Now we know the correct answer to this question. The part of the male reproductive system responsible for producing the majority of male sex hormones are the testes.

Let’s recap some of the key points we have covered in this video about the male reproductive system. The testes of a biological male are responsible for producing sperm cells and sex hormones. Sperm is first transported from the testes to the epididymis, where they are stored. Just before ejaculation, many of the sperm cells are then transferred into the sperm ducts and into the urethra, which moves sperm to the tip of the penis, where it can be ejaculated from the body. As sperm travels through the male reproductive system, fluids are added to them by the prostate, seminal vesicles, and Cowper’s glands to form liquid semen. The main sex hormone released from the testes is testosterone, which controls the development of secondary sexual characteristics in biological males.

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