Your hair grows from tiny holes in your skin called hair follicles. These hair follicles contain clusters of special cells that reproduce and make new hair cells. The new hair cells are added to the root of the hair, which causes it to grow longer. However, the hair follicles do not produce all of the pigments that give your hair its color.
Humans have several different types of hair. One type is called lanugo. This type of hair starts to grow in the third or fourth month of fetal life and is shed before birth or shortly after birth. The rest of the body has vellus, which is also known as down hair. This type of hair covers most parts of the body except the palms, soles, and undersides of the fingers.
Hair is important for many mammals. It helps regulate body temperature, protects the body from cold, and offers camouflage and other defensive functions. It also extends the sense of touch beyond the skin. Some animals, such as polar bears, use hair to detect a threat. Polar bears, for example, use their fur to hide their cubs in snow and protect themselves from the elements.
Hair comes in three different types of layers: cuticle, cortex, and medulla. Each layer is composed of two or three different types of cells. The cuticle is the outermost layer and is made of flattened cells that overlap and protect the hair shaft. This layer of the hair protects the cuticle from damage by trapping moisture within.
Hair development is a continuous process and every mature follicle goes through several phases. Each stage has distinct functions. Some of these functions include protection against external factors, production of sebum and apocrine sweat, regulation of body temperature, and social and sexual interaction. Hair development is regulated by a variety of factors, including age, nutritional status, and hormonal status.
Hairstyles also vary depending on the culture of the wearer. Some subcultures have different rules and preferences. For example, the Chinese have a traditional hairstyle called the queue. This hairstyle was worn by the Manchus of central Manchuria and the Han Chinese during the Qing dynasty. In this tradition, the hair on the front of the head was shaved every ten days, mimicking male pattern baldness. This hair was then braided into a long pigtail.
The earliest hairs on human skin are the lanugo hairs. These are the fine, unpigmented hairs that are shed before birth. In contrast, the terminal hairs are dense, pigmented, and sometimes curly. These hairs cover the head, armpit, and pubic areas after puberty. The hair follicles may also alter their structure as a response to circulating hormones.
Hair follicles can also become infected with fungi. This can lead to hair loss and bald spots. The affected areas may look red, scaly, and itchy. In some cases, blisters oozing pus will appear on the scalp. In children, the symptoms may also include swollen glands on the neck and low-grade fever.