Structure and function of the scalp
The scalp is the part of our skin that surrounds our head and protects it from external damage such as UV radiation, pathogens and chemicals. The skin also serves, as in other parts of the body, for heat exchange and fluid regulation, thus protecting against overheating and cooling. It is composed of several layers.
The uppermost layer is called the epidermis. Below this is the dermis – the leather skin, which is attached to the subcutaneous tissue – the subcutis. In addition to the hair roots, sweat and sebaceous glands and nerves are embedded in these layers.
Itchy scalp
An itchy scalp can have many causes. A rough distinction is itching of the scalp caused by external skin irritations, which also lead to drying of the scalp, skin diseases such as neurodermatitis, parasite or fungal infections, allergic reactions and psychosomatic complaints. It is important to find out the cause in order to be able to take specific countermeasures.
The central messenger substance that ultimately causes us to feel itchy is histamine. It is secreted in the brain, which makes us feel the need to scratch. Scratching leads to injury of the skin.
Depending on how strong the itching is felt and then scratched, deeper skin layers can also be damaged. The result can be an increase in itching. In addition, the damaged skin is more susceptible to colonization by bacteria and viruses, which can also worsen the symptoms and lead to a severe feeling of illness.
Normally, the sebaceous glands of the skin produce an oily substance that wraps around the scalp like a protective shield and protects it from dehydration and chemical-toxic substances. If this barrier is broken, the skin becomes more susceptible, which ultimately results in skin irritation and itching. Excessive shampooing or the use of many other hair care products, such as hairspray or hair dye, can help break down this barrier and, in the course of time, can also cause the body to become sensitized to substances contained in it and to react allergically during further use.
