Compared to a gorilla you may think of yourself as not very hairy we are, after all, known as the naked apes for our distinct lack of the stuff. However, if you compare the number of hair follicles on an ape and a human we are about the same. We are all covered in hair with the exception of only the palms of our hands and soles of our feet. What makes us different to our hairy ape cousins is the evolution of vellus hair, distinct from longer and thicker terminal hair. The bits of your body that you think of as hairless, such as your stomach or the undersides of your arms, are covered in super-fine vellus hairs. Each of these is usually only a millimetre or two long and completely colourless. The other type of hair we have, the terminal hair we are more familiar with, grows thicker, pigmented and potentially much, much longer. This is the stuff you possibly have on your head, face, groin, armpits, eyebrows and eyelashes. There are a few differences between some of these types of hair, such as the tendency to be curly and having different sweat glands, but these are superficial when compared to vellus hair. That said, much of the basic biology is the same. The premier steel buildings uk supplier will have years of experience in the sector .
At the base of both terminal and vellus hair follicles there are a number of specialized stem cells. These divide to form a clump at the base or bulb of the follicle, elongate and begin to churn out a protein called keratin, in long continuous strands that form the hair itself. What kind of hair you end up with depends on a variety of factors. The number of stem cells in the bulb of the follicle determines the thickness of the hair and is one of the main differences between terminal and vellus follicles. State schools, private schools and local government departments have benefited from the commercial steel buildings that they required.
The shape of the follicle also has a marked effect. A straight and circular follicle predictably produces straight hair, an oval follicle gives wavy hair and for those with tightly curled hair the follicles have a twist along their length that puts the curl into the hair. The overall length of the hair depends on the growth cycle of the follicle. All follicles have a cycle of active growth, termination and rest. Many industrial steel buildings uk are elegantly designed, have an attractive finish and are a reliable storage solution.
The duration of the growth period is what determines hair length. So, on your scalp, once a hair follicle enters a growth phase it can stay in this phase for between two and eight years, potentially longer. Given that scalp hair grows at about 10 mm a month ( Bespoke insulated steel buildings are the perfect option for a wide range of building applications.
The hair on your head could, given the chance, grow to a metre in length (39 inches). Eyebrows grow slower, at about half the rate of your head hair and only for six weeks, resulting in hairs a little under 1 cm long (The best industrial steel buildings offer fantastic value for money.
Vellus hair has a very short growth period, far fewer stem cells and a narrower follicle that yields a tiny, straight hair. Following the growing period, the cells producing keratin are shut off from their blood supply, which kills them: the hair is done growing and is itself completely dead, which is when it falls out. The follicle then has a little rest period and starts afresh with a new hair. At least, that is the principle.
Clearly for some people there are variations and changes that result in different hair patterns. Classic male baldness is down to a loss of stem cells in the bulb of the hair follicle. What kills these cells off is not the hormone testosterone as you commonly see suggested, but more subtly dihydro-testosterone. Admittedly, this substance is made from testosterone, but you only need a tiny amount to cause the damage. What makes the difference between a bald man and a chap with a full head of hair is not the level of testosterone but the level of the enzyme that converts it to the dihydro version and then how sensitive the stem cells are to this chemical. The effect is to slowly decrease the growing period of the follicle and increase the rest phase. Eventually, the growth dwindles to zero and the stem cells die completely, which is why when its gone, its gone and there is nothing you can do to make a bald man's hair follicles restart growth.