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Mar 17, 2024 · The hair shaft is the visible, nongrowing portion of a hair protruding from the skin. This part of the hair is not anchored to the hair follicle. The hair shaft has three layers: a central medulla, a keratinised cortex and an outer layer, known as the cuticle, which is highly keratinised and forms the thin hard cuticle on the outside of the hair.
- Medical Content
- 29 min
- Fashion Statement
- What Is hair?
- Structure of Hair
- Characteristics of Hair
- Functions of Hair
- Hair in Human Evolution
- Social and Cultural Significance of Hair
This colourful hairstyle makes quite a fashion statement. Many people spend a lot of time and money on their hair, even if they don’t have an exceptional hairstyle like this one. Besides its display value, hair actually has important physiological functions.
is a filament that grows from a in the of the skin. It consists mainly of tightly packed, keratin-filled cells called . The human body is covered with hair follicles, with the exception of a few areas, including the mucous membranes, lips, palms of the hands, and soles of the feet.
The part of the hair located within the follicle is called the .The root is the only living part of the hair. The part of the hair that is visible above the surface of the skin is the hair shaft. The shaft of the hair has no biochemical activity and is considered dead.
Two visible characteristics of hair are its colour and texture. In adult males, the extent of balding is another visible characteristic. All three characteristics are genetically controlled.
In humans, one function of head hair is to provide insulation and help the head retain heat. Head hair also protects the skin on the head from damage by . The function of hair in other locations on the body is debated. One idea is that body hair helps keep us warm in cold weather. When the body is too cold, muscles contract and cause hairs to stand...
Among mammals, humans are nearly unique in having undergone significant loss of body hair during their evolution. Humans are also unlike most other mammals in having curly hair as one variation in hair texture. Even non-human primates (see Figure 10.5.7) all have straight hair. This suggests that curly hair evolved at some point during human evolut...
Hair has great social significance for human beings. Body hair is an indicator of biological sex, because hair distribution is . Adult males are generally hairier than adult females, and facial hair in particular is a notable secondary male sex characteristic. Hair may also be an indicator of age. White hair is a sign of older age in both males and...
- Christine Miller
- 2020
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Jan 17, 2023 · The shaft is the part of the hair projecting from the surface of our skin. A round shaft results in straight and coarse hair. An oval hair shaft is responsible for wavy hair. A flat shaft causes curly hair. Each hair can also be broken into three main parts. They are, from the most superficial to the deepest: Cuticle, the outermost portion.
Figure 13.4.1 13.4. 1: dyed hair. Hair is a filament that grows from a hair follicle in the dermis of the skin. It consists mainly of tightly packed, keratin-filled cells called keratinocytes. The human body is covered with hair follicles except for a few areas, including the mucous membranes, lips, palms of the hands, and soles of the feet.
Jan 11, 2022 · The medulla is the innermost part of the hair shaft, can be continuous, discontinuous, segmented along the shaft, or even absent, depending on the type, caliber, and age of the fiber, and it is part of the excretory system of the human body. The main component of hair (65–95%) is made up of protein (keratin) and consists of low-molecular ...
Jun 29, 2022 · The average rate of hair growth is 0.5 inches (1.25 cm) per month. This means that the average person’s hair can grow about six inches a year! There are three phases of hair growth. The first is the anagen, or active growing, phase. Cell division in the hair’s root is in full swing, fed by blood vessels in the papilla at the bottom of the ...
Oct 28, 2020 · These cells keratinize as they differentiate and move upward to form the centrally located hair shaft. Melanocytes interspersed among the matrix cells produce pigment for the hair shaft [ 4 ]. The hair shaft consists of three layers. From deep to superficial, they are the medulla, the cortex, and the cuticle.
