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Cortex (hair)
The cortex of the hair shaft is located between the hair cuticle and medulla and is the thickest hair layer. It contains most of the hair's pigment, giving the hair its color. The major pigment in the cortex is melanin, which is also found in skin. The distribution of this pigment varies from animal to animal and person to person. In humans, the melanin is primarily denser nearer the cuticle whereas in animals, melanin is primarily denser nearer the medulla.James, William; Berger, Timothy; Elston, Dirk (2005) ''Andrews' Diseases of the Skin: Clinical Dermatology'' (10th ed.). Saunders. Page 8. . See also * List of distinct cell types in the adult human body The list of human cell types provides an enumeration and description of the various specialized cells found within the human body, highlighting their distinct functions, characteristics, and contributions to overall physiological processes. Cell ... References Hair anatomy {{Dermatology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair Shaft Diagram
Hair is a protein filament 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 alpha-keratin. Attitudes towards different forms of 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. Overview Meaning The word "hair" usually refers to two distinct structures: #the part beneath the skin, called the hair follicle, or, when pulled from the skin, the bulb or root. This organ is located in the dermis and maintains stem cells, which not only re-grow the hair after it falls o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair Cuticle
Comparison of sheep (top) and human (bottom) hairs with different cuticle textures The hair cuticle is the outermost part of the hair shaft.James, William; Berger, Timothy; Elston, Dirk (2005) ''Andrews' Diseases of the Skin: Clinical Dermatology'' (10th ed.). Saunders. Page 8. . It is formed from dead cells, overlapping in layers, which form scales that strengthen and protect the hair shaft. These layers are formed of keratin proteins. The hair cuticle is also known to contain anteiso-18-methyleicosanoic acid which contribute to the hydrophobic properties of hair. Diagram of the hair shaft, indicating medulla (innermost), cortex, and cuticle (exterior) While the cuticle is the outermost layer, it is not responsible for the color of the hair. Melanin is the pigment that gives hair its color and is found in the cortex. See also *List of distinct cell types in the adult human body The list of human cell types provides an enumeration and description of the various speciali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medulla (hair)
The medulla is the innermost layer of the hair shaft. This nearly invisible layer is the most soft and fragile, and serves as the pith or marrow of the hair. Some mammals don't have a medulla in their hair. The presence or absence of this layer and the characteristics of the medulla can aid taxonomists in identifying what taxa a hair comes from. Characteristics include whether the medulla contains air pockets as well as the histology of the medulla. Scientists are still uncertain about the exact role of the medulla, but they speculate that it is primarily an extension that is more prominent in depigmented (grey or white) hair .James, William; Berger, Timothy; Elston, Dirk (2005) ''Andrews' Diseases of the Skin: Clinical Dermatology'' (10th ed.). Saunders. Page 8. . See also List of distinct cell types in the adult human body The list of human cell types provides an enumeration and description of the various specialized cells found within the human body, highlighting thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanin
Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. Pheomelanin is a cysteinated form containing poly benzothiazine portions that are largely responsible for the red or yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research has been undertaken to investigate its efficacy in treating neurodegenerative disorders such as Parkinson's. Allomelanin and pyomelanin are two types of nitrogen-free melanin. The phenotypic color variation observed in the epidermis and hair of mammals is primarily determi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuticle (hair)
Comparison of sheep (top) and human (bottom) hairs with different cuticle textures The hair cuticle is the outermost part of the hair shaft.James, William; Berger, Timothy; Elston, Dirk (2005) ''Andrews' Diseases of the Skin: Clinical Dermatology'' (10th ed.). Saunders. Page 8. . It is formed from dead cells, overlapping in layers, which form scales that strengthen and protect the hair shaft. These layers are formed of keratin proteins. The hair cuticle is also known to contain anteiso-18-methyleicosanoic acid which contribute to the hydrophobic properties of hair. Diagram of the hair shaft, indicating medulla (innermost), cortex, and cuticle (exterior) While the cuticle is the outermost layer, it is not responsible for the color of the hair. Melanin is the pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Distinct Cell Types In The Adult Human Body
The list of human cell types provides an enumeration and description of the various specialized cells found within the human body, highlighting their distinct functions, characteristics, and contributions to overall physiological processes. Cells may be classified by their physiological function, histology (microscopic anatomy), lineage, or gene expression. Total number of cells The adult human body is estimated to contain about 30 trillion (3×1013) human cells, with the number varying between 20 and 100 trillion depending on factors such as sex, age, and weight. Additionally, there are approximately an equal number of bacterial cells. The exact count of human cells has not yet been empirically measured in its entirety and is estimated using different approaches based on smaller samples of empirical observation. It is generally assumed that these cells share features with each other and thus may be organized as belonging to a smaller number of types. Classification ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
