What is the connection between testosterone and hair growth?

The testosterone is a steroid hormone included in a group called androgens. Found in both males in females, it is produced by testicles in males and ovaries in females. Adrenal glands also produce the hormone in small amounts.

Testosterone is the primary male sex hormone. It plays an important role in the development of testis and prostate. The hormone is responsible for various body changes we undergo in the adolescent years, related with sexual maturation. The characteristics such as deepening of voice, growth of body hair and the development of interest in sex are all triggered by testosterone.

In the years of puberty, the body starts to produce more androgens, mostly testosterone. The produced testosterone circulates around the body and gets attached to the androgen receptors in the hair follicles. The hair have a growth cycle composed of three phases namely anagen - the active growth stage, catagen - the transitional stage and telogen - the dying stage. This cycle repeats itself throughout our lifetimes, which is the reason for continuous hair growth. In the case of body hair, the telogen phase is longer than anagen phase, opposed to the cycle of scalp hair where anagen phase is far longer.

There are two types of hair on our bodies, vellus and terminal. Vellus hair are finer and lighter than the terminal hair, with less visibility. They cover the human body from birth itself. Terminal hair, on the other hand, are darker, thicker and visible. The follicles are sensitive to androgens, the sensitivity depending on the genes. Since the hair follicles are sensitive to androgens, the raising level of the hormones causes the formation of thick hair. The androgens transform vellus hair to terminal hair. The transformation depends upon the sensitivity of the hair follicles to the androgens. Normally, pubic hair is the first to appear, in both men and women. Since androgenic levels in males are about 7 times that in females, the males tend to have more body hair than females. The distribution of the androgenic hair throughout the body depends on the follicles' sensitivity to testosterone.

As the people enter their middle age, the terminal hair follicles may begin to revert into vellus follicles. Though the scientists have no clear picture about it, it is supposed to be the decrease in circulation of the hormones. This results in the slow death of hair follicles and the reduction in body hair.

You might also like:

Who is the world's oldest woman to give birth? At what age?

Having pregnancy when you are above fifty years of age is always risky. Too many complications can arise when you conceive when you are stepping in to the old age and find your body starts to disobey yourself. But there are some women who have showed incredible, which some may call stupid, courage to defy the challenges of their age and given birth to offspring. These women had their detractors and supporters, and many health problems, but they achieved what they had been hoping for, a child; in fact more than one.

As of latest information, the oldest woman in the world to become a mother is Omkari Singh Panwar from India. Panwar, hailing from a remote village in the state of Uttar Pradesh, undertook such a risk to have a son, thereby to provide her husband an heir as well. She became the oldest mother in the world when she gave birth to twins in 2008. She was 70 years old then. The historical birth took place in the hospital of Muzaffarnagar, 7 hours-drive away from New Delhi. Panwar gave birth to premature twins, a boy and a girl, both weighing around two pounds. Omkari and her husband Charan Singh, aged 77 at the time, were already parents of two daughters who themselves had five children among them. But the couple wanted a son to continue their legacy in the highly patriarchal Indian social system.

Panwar gave birth following the controversial IVF (In Vitro Fertilization) treatment which cost around 3, 50,000 INR, despite the opposition from her local community and many medical experts. To pay for the treatment, they sold the family's holdings, their buffalos, mortgaged their land, spent their life savings and even took out a credit card loan. The children were delivered by Gynecologist Nisha Malik. The son was named Akashvani and the daughter Barsaat. Unfortunately, Barsaat didn't survive too many years.

Omkari has, however, no birth certificate to prove that she is the oldest mother in the world, which, in fact, matters little to her. She calculates her age in relation with the independence of India in 1947, when she was 9 years old.

The person previously regarded as the oldest mother had been an Indian as well; Rajo Devi Lohan, from the village of Hissar was 69 when she gave birth to a daughter. However, the oldest verified mother is Maria del Carmen Bousada de Lara from Spain. She was 66 when she gave birth to twins following IVF treatment. The record for the oldest woman to conceive naturally is held by Dawn Brooke, who was 59, from Britain.

You might also like:

What is DNA fingerprinting?

Also called genetic fingerprinting, DNA profiling and DNA typing, DNA fingerprinting is a technique of identifying a specific individual, rather than just a species, using the characteristics of his DNA (de-oxy ribonucleic acid). It was developed in 1985, by Sir Alec Jeffreys. It was commercialized in 1987. The technique is now used to test parentage, identify a body deformed beyond identification and to identify criminals and victims in a crime scene.

DNA fingerprinting process (click to enlarge)

Even though every person is unique, the vast majority of a person's DNA, 99.9% to be exact, would match exactly that of other humans, making differences between two people rather difficult to find. It is the remaining 0.1% that determines the genetic difference between people. DNA fingerprinting primarily includes the collection and analysis of VNTR (variable number tandem repeats), unique sequences in the chromosomes. It uses a specific type of DNA sequence, called microsatellite, to make the identification a lot easier. Microsatellites are short pieces of DNA which repeat many times in a given person's DNA. In a given area, microsatellites tend to be highly variable, making them ideal for DNA fingerprinting. By comparing a number of microsatellites in a specific area, one can identify a person with relative ease.

The sections of DNA used in a DNA fingerprinting, even though highly variable, are passed down from parents to children. Although not all of the sections will be passed on, the children would have pairs only the parents have. By comparing a group of these sections, scientists can determine paternity and maternity. Owing to its high success rate, it is used in various parts of the world for paternity and maternity verification.

The DNA fingerprinting has a seminal role in forensics as well. In past comparing normal fingerprints used to be done to identify a person, which required obtaining distinguishable fingerprints of him. However, since all of the DNA sections are contained in every cell of a body, a person can be identified by tests on any piece of his body, be it a strand of hair or a drop of blood. This method is used to identify a criminal or a victim in crimes. In case of victims, even if the body is disfigured past identification by normal means, DNA fingerprinting can be employed for it.

However, despite the wide acceptance and its increasing popularity, the DNA fingerprinting is also controversial due to the concerns over the ill-use of the DNA profile. Sometime its use in investigations comes under fire. There are also incidents where criminals even planted fake DNA evidence on their bodies.

You might also like:

How does eating carrots change your skin color?

Carrot is one of the most nutritive vegetables in nature. Low in calories and saturated with vitamin A (retinol), falcarinol, minerals and antioxidants, it is essential for our health. The orange color of carrot is due to the presence of carotenoids, a group of lipid-soluble compounds. The major component of carotenoids is a chemical named beta-carotene which protects our skin from the damage caused by ultraviolet rays from the sun. Beta-carotene is converted into vitamin A in liver. The vitamin is necessary for healthy eyes and reproduction. The carotenoids including carotene contribute to the natural color of human skin.

However, as the old saying goes, too many carrots can turn you orange. Yes, that is true. Eating excessive amount of carrots can cause a person's color to turn to a yellow-orange shade, a condition named cartenosis. Also known in the names of carotenemia, xanthemia and xanthosis, the state arises from the habitual consumption of carrots, usually the daily drinking of carrot juice. It is mostly found in vegetarians and young children and most apparent in light-skinned people since the less amount of melanin. Infants who are starting to take in solid food are often fed with excessive amount of vegetables including carrots which may result in carotenosis. People regard carrot as a safe food, which prompt them to consume it in more than necessary amounts.

Usually the carotene is converted into Vitamin A in liver. But the increased intake of carrots raises the levels of carotene in the blood. This carotene is carried in plasma to the peripheral tissues of our body. The excess amount is then stored in the fat under our skin and secreted through sweat resulting in the yellow-orange pigmentation on the skin. The color will appear most prominently on the nose, the palms of hands and the soles of feet, where the skin layer is comparatively thicker.

Carotenosis is generally a harmless condition. It doesn't produce any other ill effects, and can be solved by cutting back the consumption of carrots. The levels of carotene in blood will drop quickly even though the skin may take several weeks to change back to normal color due to the carotene accumulated in the tissues.

People develop carotenosis by taking excessive supplements of beta-carotene as well, which is a harmful medical condition named hypervitaminosis A. It can be accompanied by symptoms like blurred vision, dizziness and bone pain. Immediate medical consultation is suggested in those cases.

You might also like:

How does body generate and use electricity?

It might be the light bulb, television, computer, fan and similar things that would come first to our mind when we hear the word electricity. A form of energy, electricity is defined as the flow of electrons. It was one of the revolutionary discoveries in the world history that changed the course of the world. But long before Michael Faraday built the dynamo, there had been electricity – in our own bodies.

Though it may seem hard to believe, a better part of our body functions are carried out using electricity. Our brains can't work without electricity. The brain sends messages to various parts of our body in the form of electric signals.

As I said earlier, electricity is the flow of electrons. It is the same principle that works behind the electricity in our body as well, although in our body, the charge is jumping from one point to another. The electricity in our body is generated from chemical sources. The human body is made up of billions of atoms. The elements we consume all have such atoms which consist of positively charged protons, negatively charged electrons and the uncharged neutrons.

The cells in our body are negatively charged in general. It is due to the imbalance between potassium and sodium ions inside and outside the cell. The electricity is produced by a mechanism called sodium-potassium gate. In their rest state, the cells have a greater number of potassium ions than sodium ions inside, and there are more sodium ions outside. The inside of the cell stays negatively charged because the potassium ions are negative. Since sodium ions are positive, the area immediately outside the cell membrane would be positive. This charge difference is too small to produce electricity and the cells continue in a rest.

However, when body needs to send a message from one point to another, the sodium-potassium gate opens. Thus, the sodium and potassium ions are able to move freely into and out of the cell and they do. The negative potassium ions leave the cell, attracted to the positive charge outside the cell membrane, and the sodium ions enter the cell towards negative charge. This movement results in a switch in the concentrations of the two ions and it generates an electrical impulse. This impulse triggers the gate on the next cell to open, like a chain reaction. This is the way the electrical impulse travels from one part of the body to another.

The electricity generated through this way is what controls the working of our heart, nervous system and so on.

You might also like:

Why vultures don't get sick from eating rotten meat?

The humans can barely stand the smell of rotting flesh, let alone think about eating it. The mere thought will bring us a sick feeling. Many animals on the other hand, eat dead meat without any problems. And when it comes to the case of vultures, it is nothing short of incredible. They have no qualms about eating carrion that has been decaying for quite a while. In fact, they prefer to have such a kind of meal. Vultures can feed on dead animals in any stage of decomposition. Though they are known to prefer mammal carrion, they would also eat carcasses of reptiles, fishes and other birds. The vultures usually locate their food with sight or smell.

The decayed meat is playing ground for different kinds of bacteria that are dangerous to human body. These include the bacillus anthraces, which are known for causing anthrax. These bacteria are poisonous to most of the creatures. Studies have found out that the stomach of vultures is filled with two species of bacteria, both very dangerous. The first one is the flesh-degrading fusobacterium, which causes blood infections and the other one is clostridium, which can produce deadly botulism toxins. These are also found on the face of the birds. Yet, vultures seem fine with it. The question is how do they do it?

The major part of the vultures' ability to eat decaying carrion can be attributed to the highly acidic character of the gastric juices in their body. These juices are so strong that they will kill most of the deadly bacteria before they can get into intestines and begin their activities. To get a clearer picture, you would like to know that the stomach acids of vultures are 10 to 100 times stronger than those in humans. While the human gastric juices have acidity around 2 on the pH scale, the vultures' is close to zero. That is, the digestive system of the vultures is very harsh compared to humans or any other scavengers.

It seems that the vultures have developed a strong digestive system over the years, especially considering they are spending their whole lives near rotten flesh. It is also apparent that they have built some tolerance to the deadly clostridia and fusobacteria. Interestingly, these bacteria seem to help the digestion in the birds by breaking down the rotten flesh. The immunity towards these toxic bacteria appears to have evolved over thousands of years. However, there are things that even vultures can't stand. Lead and certain drugs, which are incidentally fine to humans, are toxic to them.

You might also like:

Can snakes swim? If yes, how do they swim?

Most of the animal species are born with the ability to swim, so are the snakes. All species of snake can swim, no matter the type of water. The prime reason you don't see all snakes in your local pond but in your garden is that many species prefer land to water. Most of the snakes like to live in the dry land while some species spend their entire lives in water. It is the latter category that we usually call water snakes.

The snakes use different kinds of terrestrial locomotive techniques. At least five of the techniques have been identified, lateral undulation being the one most often used among them. All kinds of snakes swim in almost an identical way and it is highly similar to lateral undulation. This is the same mode they employ to move along a smooth surface as well. The snakes primarily use the surface tension of the water to glide along. They curve their bodies in a certain way while traveling through the water. They would swerve to one side first and then the other, and would repeat that motion. It is like they are drawing a big 'S' with their body continuously in the water. These undulations start at the head and continue down the length of the body. Just like the cars of a train follow the engine; their bodies would follow the movement of the head of the snakes. Each time they turn, they put force on the water behind them, and the resulting opposite momentum pushes them forward. The tail in particular serves to provide the momentum forward.

Since the water does not provide a solid platform like land, the swimming is more difficult for snakes. However, most species are adept in it. The water residents have acquired a more flattened structure through evolution to aid their movements. Some species have paddle-like tails and nostrils placed on backside to aid the movement.

Some species are better swimmers than others. Some water dwelling species can travel even for miles without stopping. There are also some differences in the swimming style of various kinds of snakes. For example, the venomous cottonmouth snakes, inhabiting the coastal plains of America, often hold their head a little above the water surface while moving. This is identified as a defensive mechanism, to sense the approach of other predators. But many other water snakes glide under the water, their head in level with rest of their body. The slightly differing swimming styles often help to identify the venomous from harmless ones.

You might also like:
back to top Subscribe