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Cuticle
A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structure, function, and chemical composition. Human anatomy In human anatomy, "cuticle" can refer to several structures, but it is used in general parlance, and even by medical professionals, to refer to the thickened layer of skin surrounding fingernails and toenails (the eponychium), and to refer to the superficial layer of overlapping cells covering the hair shaft ( cuticula pili), consisting of dead cells, that locks the hair into its follicle. It can also be used as a synonym for the epidermis, the outer layer of skin. Cuticle of invertebrates In zoology, the invertebrate cuticle or cuticula is a multi-layered structure outside the epidermis of many invertebrates, notably arthropods and roundworms, in which it forms an exoskeleton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod Exoskeleton
Arthropods are covered with a tough, resilient integument, cuticle or exoskeleton of chitin. Generally the exoskeleton will have thickened areas in which the chitin is reinforced or stiffened by materials such as minerals or hardened proteins. This happens in parts of the body where there is a need for rigidity or elasticity. Typically the mineral crystals, mainly calcium carbonate, are deposited among the chitin and protein molecules in a process called biomineralization. The crystals and fibres interpenetrate and reinforce each other, the minerals supplying the hardness and resistance to compression, while the chitin supplies the tensile strength. Biomineralization occurs mainly in crustaceans. In insects and arachnids, the main reinforcing materials are various proteins hardened by linking the fibres in processes called sclerotisation and the hardened proteins are called sclerotin. The dorsal tergum, ventral sternum, and the lateral pleura form the hardened plates or sclerit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropods
Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metamerism (biology), metameric) Segmentation (biology), segments, and paired jointed appendages. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. They form an extremely diverse group of up to ten million species. Haemolymph is the analogue of blood for most arthropods. An arthropod has an open circulatory system, with a body cavity called a haemocoel through which haemolymph circulates to the interior Organ (anatomy), organs. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. They have ladder-like nervous systems, with paired Anatomical terms of location#Dorsal and ventral, ventral Ventral nerve cord, nerve cord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Cuticle
A plant cuticle is a protecting film covering the outermost skin layer (epidermis) of leaves, young shoots and other aerial plant organs (aerial here meaning all plant parts not embedded in soil or other substrate) that have no '' periderm''. The film consists of lipid and hydrocarbon polymers infused with wax, and is synthesized exclusively by the epidermal cells. Kolattukudy, PE (1996) Biosynthetic pathways of cutin and waxes, and their sensitivity to environmental stresses. In: Plant Cuticles. Ed. by G. Kerstiens, BIOS Scientific publishers Ltd., Oxford, pp 83-108 Description The plant cuticle is a layer of lipid polymers impregnated with waxes that is present on the outer surfaces of the primary organs of all vascular land plants. It is also present in the sporophyte generation of hornworts, and in both sporophyte and gametophyte generations of mosses. The plant cuticle forms a coherent outer covering of the plant that can be isolated intact by treating plant tissue with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutan (polymer)
Cutan is one of two waxy biopolymers which occur in the cuticle of some plants. The other and better-known polymer is cutin. Cutan is believed to be a hydrocarbon polymer, whereas cutin is a polyester, but the structure and synthesis of cutan are not yet fully understood. Cutan is not present in as many plants as once thought; for instance it is absent in ''Ginkgo''. Cutan was first detected as a non- saponifiable component, resistant to de-esterification by alkaline hydrolysis, that increases in amount in cuticles of some species such as ''Clivia miniata'' as they reach maturity, apparently replacing the cutin secreted in the early stages of cuticle development. Evidence that cutan is a hydrocarbon polymer comes from the fact that its flash pyrolysis products are a characteristic homologous series of paired alkanes and alkene In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematode
The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (helminths) are the cause of soil-transmitted helminthiases. They are classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the flatworms, nematodes have a tubular digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity suggested there are over 25,000. Estimates of the total number of extant species are su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair
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 afte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutin
Cutin is one of two waxy polymers that are the main components of the plant cuticle, which covers all aerial surfaces of plants, the other being cutan. It is an insoluble substance with waterproof quality. Cutin also harbors cuticular waxes, which assist in cuticle structure. Cutan, the other major cuticle polymer, is much more readily preserved in fossil records. Cutin consists of omega hydroxy acids and their derivatives, which are interlinked via ester bonds, forming a polyester polymer of indeterminate size. There are two major monomer families of cutin, the C16 and C18 families. The C16 family consists mainly of 16-hydroxy palmitic acid and 9,16- or 10,16-dihydroxypalmitic acid. The C18 family consists mainly of 18-hydroxy oleic acid Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic ... [...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] |
Mealworm
Mealworms are the larval form of the yellow mealworm beetle, ''Tenebrio molitor'', a species of darkling beetle. The yellow mealworm beetle prefers a warmer climate and higher humidity. Male mealworm beetles release a sex pheromone to attract females to mate. ''Tenebrio molitor'' has been used in biomedical research. Mealworms can be a dietary source for animals and humans. They are also considered pests, especially to food storage. Description Like all holometabolic insects, ''T. molitor'' goes through four life stages: egg, larva, pupa, and adult. Larvae typically measure about or more. Adults are generally in length. ''T. molitor'' is dark brown or black as an adult, with larvae up to long and adults up to long. The yellow mealworm beetle can be differentiated from other beetles, due to the linear grooves that are evenly divided and run along the abdomen. The beetle has only four tarsal segments on its hind legs. Most ground beetles, which are similar in size to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Botany
Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who specialises in this field. "Plant" and "botany" may be defined more narrowly to include only land plants and their study, which is also known as phytology. Phytologists or botanists (in the strict sense) study approximately 410,000 species of Embryophyte, land plants, including some 391,000 species of vascular plants (of which approximately 369,000 are flowering plants) and approximately 20,000 bryophytes. Botany originated as history of herbalism#Prehistory, prehistoric herbalism to identify and later cultivate plants that were edible, poisonous, and medicinal, making it one of the first endeavours of human investigation. Medieval physic gardens, often attached to Monastery, monasteries, contained plants possibly having medicinal benefit. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eponychium
In human anatomy, the eponychium is the thickened layer of skin at the base of the fingernails and toenails. It can also be called the medial or proximal nail fold. Its function is to protect the area between the nail and epidermis from exposure to bacteria. The vascularization pattern is similar to that of perionychium. The eponychium differs from the cuticle – the eponychium is made up of live skin cells whilst the cuticle is dead skin cells. In hoofed animals, the eponychium is the deciduous hoof capsule in fetuses and newborn foal A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt (horse), colt for a male foal and filly for a female foal, and are used until the horse is three or four. Whe ...s, and is a part of the permanent hoof in older animals. The word ''eponychium'' comes . See also * Hyponychium * Lunula References Nail anatomy {{anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
