The Hair Strand Defined
Cortical cells constitute the bulk of a hair, and it is the cortex that gives a hair fiber its eventual shape, resilience, elasticity and curl. Within each cortical cell are bundles of hair protein called fibrils, running parallel to the fiber axis, and between the fibrils is a softer material called the matrix. The cortex may contain cortical fusi, pigment granules, and/or large oval-to-round-shaped structures called ovoid bodies. Cortical fusi in are irregular-shaped airspaces of varying sizes. They are commonly found near the root of a mature human hair, although they may be present throughout the length of the hair. In the living portion of the hair root the fusi are filled with fluid; as the hair grows and dries out, air replaces the fluid.
Macro Synthetic Fibers are the new generation of synthetic fibers. Currently all of the Macro Synthetic Fibers being marketed are classified as polyolefins. A Polyolefin is an umbrella name for a number of ‘polys’ like polypeptide. The defining physical properties of Macro Synthetic Fibers are length (1 ½”-2 ½”), configuration (thicker strands) and dosage (3-9 lbs/yd3).
Scaly, protective layers to shield the inner parts of each hair strand. Hair cuticle is hard and transparent. Each individual cuticle overlaps another like shingles, stretching toward the end lengths of each piece of hair. Dead cells, which form scales, form the cuticle. Aside from protecting the inner layers of the hair, the cuticle also controls how much water can enter the hair. The shiny luster found on the hair of many people can be attributed to their hair cuticle cells.
A chain of amino acids joined together through peptide bonds. There are three main side bonds, two of which are physical in nature – meaning that they are broken and reformed through physical changes in the state of the hair. The two physical side bonds are salt bonds and hydrogen bonds. Both of these physical bonds can be broken using an application of heat and/or moisture, and reform with cooling and drying. This is what allows the hair to styled to add curl or straighten the hair from its natural state. The physical side bonds account for 2/3rds of the hair’s strength and elasticity in spite of the fact that they are the weakest bonds found in the hair. This is due to the sheer number of salt and hydrogen bonds in the hair.
The other main side bond is a chemical side bond – so named because it requires a chemical reaction to break or reform – and it is called the disulfide bond because it links two polypeptide chains via cysteine sulfur atoms forming cystine (an oxidized form of cysteine). The disulfide bonds are the strongest of the side bonds although they are weaker than the peptide and polypeptide bonds.
Hair is a filamentous biomaterial that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types and hair care, but hair is also an important biomaterial primarily composed of protein, notably keratin. Attitudes towards hair, such as hairstyles and hair removal, vary widely across different cultures and historical periods, but it is often used to indicate a person's personal beliefs or social position, such as their age, gender, or religion.
A hair follicle is a part of the skin, which grows a hair by packing old cells together. Attached inside the top of the follicle are sebaceous glands, which are tiny sebum-producing glands in almost all skin except on the palms, lips and soles of the feet. The thicker the hair, the more the number of sebaceous glands there are.
Also attached to the follicle is a tiny bundle of muscle fiber, called the arrector pili, which is responsible for causing the follicle lissis to become more perpendicular (upright) to the surface of the skin. The muscle area can also cause the follicle to stick up slightly above the nearby skin (piloerection) with a pore incased with skin oil. This process results in goose bumps (or goose flesh). Stem cells are at the junction of the arrector and the follicle, and are principally responsible for the ongoing hair production during a process known as the Anagen stage.
The average growth rate of healthy hair follicles on the scalp is nearly 0.5 inches (13 mm) per month.
- the condition of your scalp meaning that your scalp may be dry, oily, or flaky
- the characteristic of your hair meaning if it is fine, frizzy, coarse, curly, wavy, straight, or chemically treated.
- your environment such as your city or country, your air conditioned home or work office, and whether your climate is hot or humid, wet and windy, or hot and dry.