Category Human Body

Inside the reproductive system

The testes and penis, which are outside the body, are connected by a series of internal tubes and glands. The whole male reproductive system is adapted to produce, mature, and transport sperm to where they can fertilize a female egg.

Sperm factory

Inside the testes, sperm cells are constantly being made. They form inside coiled tubes called seminiferous tubules, before moving to the epididymis where they mature. From there, they can move into the vas deferens, ready to leave the body.

Vas deferens

The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. Sperm from each testis pass through this tube towards the penis.

Prostate gland

The prostate gland is a walnut-sized structure that is located below the urinary bladder in front of the rectum. The prostate gland contributes additional fluid to the ejaculate. The prostate gland adds substances that protect and nourish the sperm cells.

Erectile tissue

This fills with blood to make the penis stiff enough to enter the woman’s vagina to deliver sperm.

Seminal vesicle

The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of the bladder. This releases fluid that combines with sperm cells to make semen.

Urethra

The urethra is the tube that carries urine from the bladder to outside of the body. In males, it has the additional function of expelling (ejaculating) semen when the man reaches orgasm. Sperm-carrying semen leaves the body through this tube.

Penis

The penis is the male organ for sexual intercourse. It has three parts: the root, which attaches to the wall of the abdomen; the body, or shaft; and the glans, which is the cone-shaped end of the penis. The penis transfers sperm into woman’s vagina.

Testis

The testes are oval organs about the size of very large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Also called testicles, the two testes make and release sperm cells.

Scrotum

The scrotum is the loose pouch-like sac of skin that hangs behind the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The testes are supported and protected by this pouch or skin and muscle.

Sperm cells

Sperm cells are among the tiniest human cells but the nucleus carries half the genetic instructions for creating a new life. Sperm are well adapted to produce enough energy for the long swim to the female egg.

 

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The male reproduction organs’ role in creating new life is to make sperm (sex cells). The sperm swim to a female egg, where one of them joins with it to create a fertilized egg that will grow into a baby.

A man’s main reproductive organs are the testes and penis. The two tests are where sperm are made and stored. Each testis is connected to a tube, which carries sperm to the penis. On the way, the sperm mix with other substances to make a liquid called semen. During the act of sexual intercourse, the penis becomes stiff and is inserted into a woman’s vagina, where it releases the sperm-containing semen.

The entire male reproductive system is dependent on hormones, which are chemicals that stimulate or regulate the activity of cells or organs. The primary hormones involved in the functioning of the male reproductive system are follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone.

FSH and LH are produced by the pituitary gland located at the base of the brain. FSH is necessary for sperm production (spermatogenesis), and LH stimulates the production of testosterone, which is necessary to continue the process of spermatogenesis. Testosterone also is important in the development of male characteristics, including muscle mass and strength, fat distribution, bone mass and sex drive.

 

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Inside the reproductive system

The uterus is in the middle of the lower abdomen, between the bladder and the rectum. The two ovaries are on either side of the uterus, connected to it by the fallopian tubes.

Inside the ovary

The ovaries contain many thousands of immature eggs, each enclosed in a bag-like follicle. Every month, hormones trigger a process where one of the eggs starts to outgrow the others. When it is mature, the egg is released from the ovary.

Right ovary

The ovary is a ductless reproductive gland in which the female reproductive cells are produced. Females have a pair of ovaries, held by a membrane beside the uterus on each side of the lower abdomen. The ovaries store, then release eggs.

Right fallopian tube

The uterine tubes, also known as oviducts or fallopian tubes, are the female structures that transport the ova from the ovary to the uterus each month. Each fallopian tube connects an ovary with the uterus.

Uterus

This hollow, stretchy organ is where the embryo develops. It functions to nourish and house a fertilized egg until the fetus, or offspring, is ready to be delivered.

Cervix

The cervix is the lower portion of the uterus, an organ of the female reproductive tract. The cervix is the point where the uterus opens into the vagina. Anatomically and histologically, the cervix is distinct from the uterus, and hence we consider it as a separate anatomical structure.

Bladder

This stretchy bag stores and releases urine. The bladder is a pyramidal shaped organ, which sits in our pelvis (the bony structure which helps form our hips).
The main function of the bladder is to store urine, and under the appropriate signals, release it into a tube which carries the urine out of the body.

Rectum

The lowest part of the large intestine is where faeces are stored. The rectum begins at the height of S2-S3 and ends at the perineum. It is about 12 to 16 cm long.

Vagina

The vagina is a fibromuscular (made up of fibrous and muscular tissue) canal leading from the outside of the body to the cervix of the uterus or womb. It is also referred to as the birth canal in the context of pregnancy. The uterus is linked to the outside of the body by this stretchy tube.

Pelvic floor

The uterus and bladder are supported by these strong muscles. These muscles extend across the pelvic region, below other muscles that give humans the ability to walk upright.

 

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Every month or so, a woman’s body goes through the process of preparing for a possible pregnancy. This sequence is called the menstrual cycle.

Phase 1

Egg ripens: Prompted by hormones, an immature egg starts to grow inside a soft casing called a follicle. Your period may last 2 – 7 days, with most fluid being lost in the first two days.

Phase 2

Egg is released: The uterus lining thickens to prepare to receive an egg. Meanwhile, the follicle bursts and releases a ripe egg into the fallopian tube.  During this phase, due to the oestrogen, your skin could be smoother, your breasts a little bigger and any discharge will be clear.

Menstrual cycle: This shows a typical 28-day menstrual cycle. In fact, it can take from 21 to 35 days to complete, and the times between stages vary a good deal.  

Phase 3

Egg arrives in the uterus: At this point, if the egg is fertilized, it embeds itself in the uterus wall and starts to grow. You may feel slightly ‘bloated’ as this phase can trigger fluid retention throughout your body – but it’s not dangerous and doesn’t last.

Phase 4

Menstruation: If the egg is not fertilized, both the egg and the uterus lining fall apart and leave the body along with some blood. This is called menstruation, or having a period. This sudden change can cause mood swings (also called PMS Pre-Menstrual Stress) and you may also experience cramps as the uterus contracts in readiness to shed the built-up layer – which takes you back to Phase 1; having your period.

 

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From her teenage years to about her mid-fifties, the role of a woman’s reproductive organs is, combination with a man’s sex cells (sperm), to create a new human life – a baby.

A woman’s main reproductive organs are her ovaries and uterus. The two ovaries are where eggs are stored, then released at regular intervals. If an egg is fertilized by male sperm, the job of the uterus is to nurture and protect the egg as it develops – first into an embryo, then a foetus, which grows into a baby, ready to be born.

The vast majority of the eggs within the ovaries steadily die, until they are depleted at menopause. At birth, there are approximately 1 million to 2 million eggs; by the time of puberty, only about 300,000 remain. Of these, only about 500 will be ovulated during a woman’s reproductive lifetime. Any remaining eggs gradually die out at menopause.

 

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The water inside our bodies is salty – in fact, it is as salty as seawater. Salt, or sodium, help maintain the body’s water balance – the amount of salt dissolved in the blood tells the hypothalamus how much water the kidneys should release as urine, and how much to keep. Alongside potassium, salt also plays an essential role in helping nerve cells make signals.

The human body contains many salts, of which sodium chloride (AKA common table salt) is the major one, making up around 0.4 per cent of the body’s weight at a concentration pretty well equivalent to that in seawater. A child’s body contains the equivalent of 28 teaspoons of salt, while an adult’s body has 40 teaspoons.

So a 50kg person would contain around 200g of sodium chloride – around 40 teaspoons. Since we lose salt whenever we sweat, it has to be continually replaced.

While excessive consumption of it has been linked to high blood pressure and stomach cancer, salt is a vital part of body chemistry, playing a key role in many functions, from the quality of blood to transmission of nerve signals.

 

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The hypothalamus in the brain is responsible for monitoring water level. If it detects too little or too much water, it responds by telling the pituitary gland to release hormones that communicate with me kidneys and other organs.

Too little water

A shortage of water in the body is called dehydration. The body needs to take in more water and also to conserve the water already inside it.

• Low water alert: The pituitary gland releases a hormone into the bloodstream.
• Feeling thirsty: The hormone triggers an urge to drink.
• Dry mouth: The mouth feels dry, as water is sent to areas that need it more.
• Kidneys: The kidneys receive instructions to remove less water from the blood, so the body produces less urine.

Too much water

Too much water in the body is called overhydration. This condition is rare, but can be caused by illness or by drinking a large amount very quickly. Cells become too waterlogged to work and the blood pressure becomes too high.

• High water alert: The hypothalamus orders blood vessels to widen, which reduces blood pressure.
• Kidneys: The kidneys are ordered to extract more water from the blood, making more urine.

 

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Urine can provide valuable clues about health. Dark urine is a sign that a person is dehydrated and needs to drink more. Tests can also detect pregnancy, some infections, hormone changes, and diabetes.

To test urine, a testing strip is dipped into a sample. The coloured bands react to different chemicals in the urine, revealing any abnormalities.

Urine is 94 per cent water. The rest is made up of dissolved substances the body has no use for. They include sodium, which is excess salt, and urea, the waste produced by the liver.

At the microscopic level, your body is constantly working to keep you healthy, even while you sleep. Complex chemical processes take place throughout the body, including the breakdown of proteins known as amino acids. When your body breaks down amino acids, ammonia is left over as waste. That’s not something you want in your body for long—ammonia is toxic to human cells.

Since ammonia is toxic to your body, you need a way to remove it. That happens partly in the liver, where the ammonia is broken down into the less-toxic chemical, urea. Urea then combines with water and gets flushed into your bladder through the kidneys as urine, protecting your body from its own chemical processes.

 

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Water does many different jobs. It helps provide a transport system around the body. It also regulates body temperature, and lubricates parts so they work better.

Blood

Blood is mostly water, so it flows easily through blood vessels. Your blood is 92% water. Water carries nutrients and oxygen to all cells in the body.Water is required for breathing.Water moistens oxygen for breathing

Lymph

Watery lymph flows around the body, recycling chemicals and fighting germs. The lymphatic system works to keep body fluid levels in balance and to defend the body against infections. It is made up of a network of lymphatic vessels that carry lymph — a clear, watery fluid that contains proteins, salts, and other substances — throughout the body.

Saliva

Saliva moistens foods to help with eating and also kills germs in the mouth. Saliva is 99% water and 1% protein and salts. The normal daily production of saliva varies between 0.5 and 1.5 liters. The whole unstimulated saliva flow rate is approximately 0.3-0.4 ml / min. 

Sweat

Sweat is released through skin pores to help cool the body down. Composed of about 99 percent water, sweat evaporates on the skin’s surface, cooling the body and keeping it from overheating.Sweat secretions help you in other ways, too. They include dermcidin, an antibiotic peptide that appears to regulate bacteria growth on the skin and may fight infection.

Urine

Urine is a mix of excess water and chemicals from the blood. This colorless urine is sometimes due to drinking an excess of water, while other times it can signal a problem with the kidneys. If your urine is consistently clear or absent of color, you should see a doctor.

Joints

Many moving joints have a lubricating layer of liquid, called synovial fluid. With its egg white–like consistency, the principle role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement. Synovial fluid is a small component of the transcellular fluid component of extracellular fluid.

Tissue fluids

Body tissues contain water, with lean tissue holding more than fatty tissue. Water is also contained inside organs, in gastrointestinal, cerebrospinal, peritoneal, and ocular fluids. Adipose tissue contains about 10% of water, while muscle tissue contains about 75%.

Cell cytoplasm

Cells need water for the chemical reactions that take place inside them. Water is also in the environment outside the cell. For example, water inside cells makes up about 46 percent of your body’s mass, and water outside the cells in body fluids accounts for another 23 percent.

 

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The amount of water in a person depends on their age, gender and weight. The more water-rich muscles they have, the higher their water content. As we grow older, muscles shrink and water levels drops.

A newborn baby is almost three-quarters water – and the proportion of water in the body drops gradually from then on. Men contain more water than women, as they usually have more water-containing muscle.

The average adult male is about 60% water. The average adult woman is about 55% water because women naturally have more fatty tissue than men. Overweight men and women have more water, as a percent, than their leaner counterparts.

The percent of water depends on your hydration level. People feel thirsty when they have already lost around 2-3% of their body’s water. Mental performance and physical coordination start to become impaired before thirst kicks in, typically around 1% dehydration.

Although liquid water is the most abundant molecule in the body, additional water is found in hydrated compounds. About 30-40% of the weight of the human body is the skeleton, but when the bound water is removed, either by chemical desiccation or heat, half the weight is lost.

Body chemistry

Water is essential ingredient of body cells. The millions of chemical reactions that power life take place in the water contained in the body’s cells. Different body tissues contain varying amounts of water, depending on their function. Muscle contains three times more water than bone.

 

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