Male sexual and reproductive organs

The male sexual organs include the penis, testicles and prostate gland. The male sex hormones are also important for a man’s sexuality and sex life. 

Transcript

The male reproductive system includes the penis; the testes and epididymides, held within the scrotum; the vas deferens, and internally, the seminal vesicles, and the prostate gland. 

The penis is the male sex organ. It is made up of the shaft and the head. The head of the penis is covered by a moveable piece of skin called the foreskin. 

The urethra is a tube that runs from the bladder, through the middle of the penis, to carry urine out of the body.  

The penis has a rich blood supply, as well as a muscle layer and nerves. When sexually aroused the blood flow increases and the penis becomes erect.  

The testes produce sperm and the hormone testosterone. Next to each testis is the epididymis, a tube where sperm is stored. When the penis is erect sperm moves from the epididymis and through the vas deferens to the seminal vesicles.  

The seminal vesicles make a fluid that mixes with sperm. 

The prostate gland, is about the size of a walnut. It surrounds the first part of the urethra and adds more fluid to the sperm. 

During orgasm, the prostate squeezes this fluid into the urethra and out of the body. 

For information about cancers that can start in the male reproductive system, go to cruk.org/cancer-types.

The penis and testicles

The penis is partly inside and partly outside the body. It’s made up of several types of tissue. These include skin, muscle, blood vessels and nerves. Inside the penis is the urethra. Urine and semen flow through this tube and eventually pass out of the small slit at the end of the penis (the meatus).

The end of the penis is also known as the head of the penis (glans). It’s normally covered by a piece of skin called the foreskin (prepuce). But some men may have had the foreskin removed during an operation called a circumcision. This operation is usually done at birth but may be done later in life.

For most men the ridge below the head of the penis (the frenulum) is the most sensitive part of their penis. The penis has a rich blood supply, as well as a muscle layer and nerves. When sexually aroused the blood flow increases and the penis becomes erect.

The scrotum is the pouch of skin that hangs below the penis and holds both testicles (testes). The testicles are part of the male reproductive system.

From the age of puberty the testicles produce sperm, which can fertilise a female egg. Next to each testicle is the epididymis, a tube where sperm is stored. The testicles produce the male sex hormone, testosterone.

The prostate gland

The prostate is a small gland about the size of a walnut. It surrounds the top part of the tube that carries urine from the bladder to the penis (the urethra). The same tube also carries semen. The prostate produces a thick clear fluid, which is an important part of the semen.

The growth and function of the prostate gland depends on the male sex hormone testosterone, which is produced in the testes.

Other organs

A man’s back passage (anal area), chest and nipples may be very sensitive during sexual activity. Like women, men are all different and there may be other parts of their body that are more sensitive.

Male sex hormones

Testosterone is the main male sex hormone. It is made in the testicles. Testosterone is the main cause of male qualities such as:

• a deep voice
• body hair growth
• muscle development
• the ability to have an erection
• sex drive (libido)

Last reviewed: 

18 Oct 2021

Next review due: 

18 Oct 2024

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Reproductive system – Better Health Channel

Summary

Read the full fact sheet

• Ova (eggs) are made in the ovaries, and sperm in the testicles.
• The genetic material of the ova and sperm combine to make the characteristics of the child.
• If the ovum (egg) is unfertilised, the lining of the womb comes away (a period).
• Sperm production requires a temperature around 2 °C lower than that of the body, which is why the testicles are housed in the scrotum.
• The only function of the sperm is to fertilise a female egg and create new life.

New life begins when an egg from a woman is fertilised by sperm from a man. Eggs (ova) are made in the ovaries, and sperm in the testicles. The ovaries and testicles (gonads) also make sex hormones.

The female reproductive system

The female reproductive organs are the vagina, womb (uterus), fallopian tubes and ovaries:

• Vagina – a muscular canal around 7.5 cm long that extends from the neck of the womb to the genitals, or vulva.
• Uterus (womb) – a muscular organ, shaped like an upside down pear. Its lining is called the endometrium. The neck or entrance to the womb is the cervix, which has a small hole in its centre called the os.
• Fallopian (uterine) tubes – these tubes extend from the womb, one on each side. They both open near an ovary. These tubes carry the egg (ovum) from the ovary to the womb.
• Ovaries – two small almond-shaped glands that contain ova. Sex hormones are also made by the ovaries.

The menstrual cycle

Hormones secreted by the ovaries and a small gland in the brain called the pituitary gland control the menstrual cycle. The average menstrual cycle is around 28 days.

After a period, rising levels of the hormone oestrogen help to thicken the lining of the womb (the endometrium). At mid-cycle, an egg is released from one of the ovaries (ovulation). If the egg is fertilised on its journey down the fallopian tube, it lodges in the womb lining.

If the egg is unfertilised, falling levels of the hormone progesterone make the womb lining come away. This is called a period, or menstruation. The cycle then repeats.

When you want to have a baby you can improve your chance of getting pregnant if you know about ovulation and the ‘fertile window’ in the menstrual cycle. Read more on ovulation and the fertility windowExternal Link.

The egg (ovum)

A woman’s entire egg supply is developed when she is still an unborn baby. At the start of puberty, the eggs are ripened inside the ovary and one is released every month.

Each egg contains genetic material. At menopause, the ovaries stop making hormones and eggs are no longer ripened or released.

Female reproductive system problems

Some reproductive health conditions women may experience include:

• endometriosis – the presence and growth of functioning endometrial tissue in places other than the uterus
• polycystic ovarian syndrome (PCOS)
• fibroids – non-malignant tumours of the womb
• infertility – inability to become pregnant
• painful periods
• premenstrual tension
• sexually transmissible infections (STIs) – bacterial or viral infections acquired through sexual contact, some of which can cause cancer or infertility.

The male reproductive system

The male reproductive organs are the penis, the testicles, the epididymis, the vas deferens and the prostate gland:

• Penis – contains tissue that fills with blood during sexual arousal, making the penis erect (or ‘hard’). Semen is a mixture of sperm and fluid from the male reproductive organs. It exits the penis, through the urethra, during ejaculation.
• Testicles (testes) – oval sex glands located in a skin sack called the scrotum. Sperm and sex hormones are made by the testicles. Keeping the testicles outside of the body means they have a lower temperature than the rest of the body, which is important for sperm production.
• Epididymis – a series of small tubes attached to the back of each testicle. The epididymis collects and stores sperm.
• Vas deferens – the epididymis eventually becomes the vas deferens, a larger tube that transports sperm to the urethra (the urinary passage from the bladder).
• Accessory sex glands – including the prostate gland, seminal vesicles and the bulbourethral glands. These glands contribute nourishing fluid to the sperm.

Male reproductive hormones

Hormones are chemical messengers made by glands in the body. Androgens are the hormones that make men ‘male’.

Androgens are responsible for sexual functioning, fertility and secondary sexual characteristics such as muscle mass, height, deep voice and body hair (including the beard). The most important androgen is testosterone, which is manufactured in the testicles.

The sperm

The sperm is the male reproductive cell. Its role is to fertilise an egg. It contains the man’s genetic material.

A sperm is tadpole-shaped and around 60 microns in length (one micron is a millionth of a metre). It has a lashing tail, which helps it to ‘swim’ towards a waiting egg. Sperm production continues throughout a man’s life, from puberty into old age but the quality of a man’s sperm declines from about age 45.

Male reproductive system problems

Some of the reproductive health conditions men may experience include:

• impotence – a problem with getting or keeping an erection
• infertility – the inability to achieve a pregnancy due to low sperm production, blockages or other factors
• prostate disease – benign prostate enlargement and prostate cancer
• sexually transmissible infections (STIs) – bacterial or viral infections acquired through sexual contact.

Where to get help

• Your GP (doctor)
• Obstetrician or Obstetrician-gynaecologist
• Fertility specialist
• IVF clinic
• Victorian Assisted Reproductive Treatment Authority (VARTA)External Link Tel. (03) 8622 0500
• Sexual Health Victoria (SHV)External Link. To book an appointment call SHV Melbourne CBD Clinic: (03) 9660 4700 or call SHV Box Hill Clinic: (03) 9257 0100 or (free call): 1800 013 952. These services are youth friendly.
• Healthy MaleExternal Link Tel. 1300 303 878

• Testosterone deficiencyExternal Link, Healthy Male.

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what they are and why they are needed

Visual examples of evidence of evolution – rudimentary organs and parts of the human body – have long lost their original functions, turning into useless appendages. At the same time, the human body is unlikely to get rid of them in the foreseeable future. Evolutionary anthropologist Dorsa Amir spoke about where “extra details” come from in our body.

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Evolution

Today, some parts of the human body are useless, despite the fact that in the past they played an important role. Business Insider spoke with Dorsa Amir, an evolutionary anthropologist at Boston College, to learn more about what she calls “evolutionary vestiges.” Amir explained that if any part of the body ceases to be beneficial, but generally remains harmless, then it begins an “evolutionary journey.” A kind of “magnificent eight” of such travelers from rudimentary organs are:

1. Appendix

The classic vestigial organ of the human body is the appendix. Perhaps it is he who is the most famous of the “useless” human appendages. Many years ago, he helped people digest food rich in fiber. While many vertebrates still rely on this organ, over time it has lost its usefulness for humans – we have switched to a much more varied diet and have ceased to need such coarse food. However, even in this state, it cannot be called completely meaningless – often beneficial symbiont bacteria settle in the appendix, without which digestion is unthinkable.

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2. Longus palmar muscle

If you put the back of your wrist on the table and connect your thumb with your little finger, you will see a tubercle of the swollen muscle. This vestige is known as Musculus palmaris longus, which once helped our ancestors to climb trees dexterously and, according to the Encyclopædia Britannica, formed prehensile limbs. However, around 3.2 million years ago, we began to walk on two legs, and this muscle atrophied over time. 10% of people do not have it at all – but the presence of such vestigial organs does not make their hands less strong or tenacious.

3. Powerful Jaws and Wisdom Teeth

A large jaw with thick jaw muscles is needed to bite and thoroughly grind coarse food with teeth. Over time (due to the same change in diet), our jaws have become smaller and thinner – hence the problems with wisdom teeth, which used to play the role of molars. Amir says that modern food is too soft, and we no longer need special molars for “grinding”. Nicknamed wisdom teeth, because they appear in a person already at a conscious age, they are an excellent example of a vestigial organ of our body.

4. Arrector pili

This strange Latin name refers to special muscle fibers that cause goosebumps when contracted. Now they only prove the presence of rudimentary organs in humans, while in our ancestors these muscles helped to better isolate the air gap and, if necessary, puff up hair to appear larger. It seemed very effective, but with the loss of most of the hairline, the need for such a reaction also disappeared. 9this part was the tail.

Indeed, at about 5-8 weeks after conception, a real tail can be observed in human embryos. By the time a person is born into the world, he disappears – the vertebrae merge and form the coccyx. The tail bones were useful for stabilizing the body during movement, however, when we stood on two legs, the need for an additional “rudder” was gone. The coccyx is useful only as an example of the rudimentary human organs and is useless in itself. But sometimes babies are born with a rudimentary tail – surgeons remove it with a simple operation.

6. Pinna Muscles

These muscles control the movements of the visible part of the ear, but most people have lost the ability to use them. Of course, among us there are unique people who can literally twitch their ears, but the muscles of the auricle are still referred to as rudimentary human organs. They help mammals to better capture sounds, which in turn directly affects the chances of survival. In addition, ear movements are often used to express emotions, as can be seen in domestic dogs and cats. A person has a flexible, movable neck for these purposes, so he doesn’t have to move his ears at all.

7. Pyramidal muscle

It turns out that the rudimentary organ, which is the appendix, has an “extra neighbor” in the lower part of the abdomen. The pyramidal muscle is located there. True, a person cannot have it at all (about 20% of people are born without it), however, there are also those who have two of these muscles. Regardless of the number, these muscles do not affect the abdominal muscles in any way.

8. Male nipples

During embryonic development, boys and girls have the same genitals, but over time, in boys, testosterone triggers the transformation of the genitals into male. But nipple formation begins before the active testosterone phase – so men are born with nipples even though they can’t breastfeed. But nipples in men help to understand the difference between vestigial organs and atavisms. Atavism (an indecent word, which, according to the conviction of the heroes of Bulgakov’s “Heart of a Dog”, should not be expressed) still denotes not an “extra” organ, but one that was with distant ancestors. In this case, the sometimes manifested polynipple is an atavism, while the male nipples are a classic example of a vestigial organ.

human body proportions – Gamedev on DTF

We continue to talk about the base of character creation, this time about body drawing schemes and physique features. The first part of the series is here.

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The article is a retelling of these videos from the artist Sauer.

Basic human proportions

One of the most important factors in drawing the human figure is proportion. Have you ever seen how children draw people? Often the drawing looks “childish” not because of the lack of details or the right shadows, but because the legs are shorter than the arms or the hands are larger than the feet.

All bodies are different and no body is perfect. Do not confuse correct body proportions with ideal ones. Even if you are not the greatest artist in the world, as long as the proportions in your figure drawing are accurate, realism and integrity will be maintained.

We see bodies all the time, that’s why it catches the eye when the proportions are not respected. The human body is one of the most complex forms on the planet. Proportions are the first thing to learn when drawing bodies because they teach you to be anatomically correct. This can be achieved by mapping out the body and determining how the joints relate to each other.

Create your own scheme

A figure with correct proportions, regardless of gender and other things, is determined by the location of the joints, which is unchanged. If the location of the joints changes, we immediately notice the catch, the figure looks strange to us. This is our basis for proportions.

Draw your own diagram. It will help you a lot in learning the material.

Start by drawing an oval at the top of the sheet, pointed end down. This will be the head. And mark down eight segments the same size as the head, the last of which will be the earth. Number them from one to eight.

During the Renaissance, the “ideal” height for a man was eight heads. It is clear that few people actually have such a height. Even the northern Europeans who served as the basis for this model. They were closer to seven heads high, but this is still the best model to start with, as it makes it easier to understand the ratios.

Taz

Next add the hip bone, the most important part of the body. This is our center of gravity and stability.

Simplistically draw it as a flat circle between marks three and four, the hip joints will be at the fourth mark – these are the small circles that you see on the sides. The width of the pelvis is approximately one and a half to two heads. Now you can draw the spine connecting the head to the pelvis.

Legs and knees

Suppose our figure is standing, feet vertically at the level of the hip joints:

The knee joints are at the sixth mark, this line goes straight under the knee caps. When the leg is extended, the knee joint is in a straight line with the hip and ankle, as shown in the left figure in the picture. But this line is conditional. To complete the leg, connect the hip joint to the inside of the patella and then the outside of the knee to the inside of the ankle like the figure on the right.

This is a very simplified but accurate representation of the actual bone structure and it helps to draw the human foot naturally. It will expand from the hip and narrow towards the knee, then expand again. This will also help to place the muscles at a later stage in your drawing.

Breast and navel

The chest and lungs are the third most important body shape after the head and pelvis:

In a simplified form, this is an oval that starts exactly between one and two and ends at the third mark. But it’s best to cut off the bottom of the oval, as shown in the image above, to mimic a real chest.

The empty space between the chest and pelvis is very important. It is soft and can be different: fat stomach, soft or flat stomach. And this is also the place where the spine is most mobile. You should remember this and do not connect the torso with the pelvis together like two large blocks, as this will deprive your figure of plasticity. The width of the oval for the chest is about the same as that of the pelvis.

A couple more details. The nipples are located at the “two” mark. To determine how far to place them from each other, draw two parallel lines from the sides of the head down, slightly going inside the outline of the head. And the navel falls on the third mark. Notice the blue dots on the right side of the image.

Shoulders

The line of the shoulders is approximately in the middle between the first and second marks, and the width of the shoulders is two to three times the width of the head:

But their visual position can vary greatly. To begin with, the line of the shoulders is slightly curved down, but when the shoulders are tense, the bend can rise up and appear higher. In addition, the trapezius muscle, which visually connects the shoulder to the neck from the front, varies greatly from person to person.

If the figure is very muscular or has a lot of fat, the line of the shoulders may appear so high that the neck will not be visible. Conversely, an underdeveloped trapezius muscle, often seen in very young women, gives the impression of a long neck. It is important that there is no confusion between the actual position of the shoulder line and its apparent position on the depicted body.

Arms and hands

The wrists are at the fourth mark just below the hip joints. The fingers end approximately in the middle of the thigh, which corresponds to the fifth mark.

Elbow joints are a little tricky, but we’ll get to that in more detail later. For now, let’s mark them as elongated ovals located on the third mark.

Profile figure

Start again by drawing the head – the same egg shape, but with a tapered end pointing diagonally downwards. And lower the vertical line from the crown to the ground.

When the figure is standing upright, you can draw the pelvic bone almost like a head: the shape will be the same, but narrower. Shoulder and knee approximately on the same vertical line. They are at the same level as before.

Spine in profile

Laterally, the spine is shaped like a flattened S:

From the base of the skull, the line runs down and back until it reaches the farthest point at shoulder level. Note that the shoulder joints protrude forward of the spine. This is because the line of the shoulders is actually an arc, as shown in the top view picture (in the blue circle).

Then the spine comes forward again and sticks out a little above the pelvis. This happens at the level of the lower back, and the depth of the curve can vary, making it look like the character has a curved back. Finally, it changes direction again and ends at the coccyx.

Chest and legs in profile

The rib cage is close to the spine, and in a sufficiently taut body, standing straight, the chest naturally moves forward.

The hip joint is slightly forward of our vertical axis, and this is balanced by the fact that the ankle is slightly behind it. Therefore, the line from the hip to the knee, and then to the ankle, slopes back and has alternating directions of bends: from the hip joint to the front of the knee joint, from the back of the knee joint to the ankle joint.

The overall effect of this pose is a visual arc from head to chest (shown in green on the right of the image). When this arc straightens or reverses, we feel insecure or stooping in the posture.

Arms in profile

The upper part of the arm drops fairly straight from the shoulder so that the elbow may be in line with it or lean back slightly.

The arm is never fully extended at rest, so the forearm will not be vertical. The arm is slightly bent, the wrist drops forward directly over the thigh bone. When the hand is relaxed, the fingers are slightly bent, as shown here.

On this we have dealt with the basic human proportions. And this scheme will help to combine everything that was said earlier:

Male and female proportions

Male and female proportions are so different from each other that even the skeleton or its individual parts can identify the sex. However, keep in mind that there is no significant difference on the vertical axis. Gender does not affect the position of the joints, they will not move up or down. But gender plays a significant role in the width of certain parts of the body, creating variations in the figure.

How can the main figure be made more feminine or masculine?

At the structural level, there is only one big detail that needs to be mastered, and everything else is just useful little things.

Childbearing thighs

The main difference between male and female proportions is the ratio of shoulder to hip width:

In women, the pelvic bone is much wider than in men, since they must be able to carry and give birth to a child. This is a key detail that affects the structure of the rest of the body.

In women, the hips are the widest part of the body, and the narrow waist contrasts with them, while in men, the widest part of the body is the shoulders, and the waist is almost the same as the hips. Thus, the overall female silhouette is an hourglass, while the male one has a more trapezoidal shape.

Waistline and elbows

For women, the waist is at the level of the navel, for men it is slightly lower. This makes the man’s torso visually longer.

It is important to remember that men’s elbows should not be in line with their lower waist. The navel remains the reference point for the elbow joint. Unlike the female figure, if the waist of the man is visually where the trousers begin, the elbows will be higher.

Rounded vs. Angular

It is useful to sketch women with more rounded forms and men with more angular forms, as this reflects the overall impression of each body type.

The female body consists of soft rounded shapes. If it is not trained, not athletic, it accumulates more fat under the skin. Male bodies are more angular. If they are muscular, they have sharper lines. Of course, this is not always the case: you can use angular shapes, for example, for a thin woman and soft ones for a full man.

However, note that a fairly slender female body has a slightly curved belly and rounded buttocks, while men tend to have a flatter belly and buttocks.

Hip joints

Small but important detail – hip joints:

Draw the hip joints of the woman outside of the pelvic bone. They protrude a little more prominently on the body, and this helps to capture this feature of the female. Conversely, depict the male hip joints inside the pelvic bone.

Small parts

In both sexes, the palm and sole of the foot are about twice the width of the face. But in men they are longer in relation to the face than in women. The female spine is often more flexible and noticeably more curved than the male, and finally, on average, men are usually taller than women.

Why bother?

How important is all this, why do we need this information? Let’s look at it visually: the image below shows what happens when a man is drawn with female proportions, and vice versa:

Even with the addition of gender stereotypes regarding hair and the like, due to the ratio of shoulders and hips, the bodies look completely different than usual. Therefore, it is very important to keep proportions in mind when creating a character.

Proportions and age

Look at these four figures:

The proportions of the first two figures here correspond to their size. The third figure shows what you get if you draw a child with the proportions of an adult. It works if you’re drawing a fairy or Ant-Man, but it definitely doesn’t look like a child.

This also works the other way around. The fourth drawing shows an adult male drawn with childish proportions, and an adult with such a shape looks strange, he looks more like a giant child.

Practice!

Let’s put some of these theories into practice. First, we need to be observant, look at the people around us. Pay attention to what in their structure distinguishes them from each other. Look closely at children and people of different nationalities to see how they differ in their structure.

Secondly, you can dig out some of your childhood photos at different stages and sketch out the main figure.