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Cerumen
Earwax, also known by the medical term cerumen, is a brown, orange, red, yellowish or gray waxy substance secreted in the ear canal of humans and other mammals. It protects the skin of the human ear canal, assists in cleaning and lubrication, and provides protection against bacteria, fungi, and water. Earwax consists of dead skin cells, hair, and the secretions of cerumen by the ceruminous and sebaceous glands of the outer ear canal. Major components of earwax are long chain fatty acids, both saturated and unsaturated, alcohols, squalene, and cholesterol. Excess or compacted cerumen is the buildup of ear wax causing a blockage in the ear canal and it can press against the eardrum or block the outside ear canal or hearing aids, potentially causing hearing loss. Physiology Cerumen is produced in the cartilaginous portion which is the outer third portion of the ear canal. It is a mixture of viscous secretions from sebaceous glands and less-viscous ones from modified apocri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceruminous Gland
Ceruminous glands are specialized sudoriferous glands (sweat glands) located subcutaneously in the external auditory canal, in the outer 1/3. Ceruminous glands are simple, coiled, tubular glands made up of an inner secretory layer of cells and an outer myoepithelial layer of cells. They are classed as apocrine glands. The glands drain into larger ducts, which then drain into the guard hairs that reside in the external auditory canal. Here they produce cerumen, or earwax, by mixing their secretion with sebum and dead epidermal cells. Cerumen keeps the eardrum pliable, lubricates and cleans the external auditory canal, waterproofs the canal, kills bacteria, and serves as a barrier to trap foreign particles (dust, fungal spores, etc.) by coating the guard hairs of the ear, making them sticky. These glands are capable of developing both benign and malignant tumors. The benign tumors include ceruminous adenoma, ceruminous pleomorphic adenoma, and ceruminous syringocystadenoma papilliferu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ear Canal
The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Structure The human ear canal is divided into two parts. The elastic cartilage part forms the outer third of the canal; its anterior and lower wall are cartilaginous, whereas its superior and back wall are fibrous. The cartilage is the continuation of the cartilage framework of pinna. The cartilaginous portion of the ear canal contains small hairs and specialized sweat glands, called apocrine glands, which produce cerumen ( ear wax). The bony part forms the inner two thirds. The bony part is much shorter in children and is only a ring (''annulus tympanicus'') in the newborn. The layer of epithelium encompassing the bony portion of the ear canal is much thinner and therefore, more sensitive in comparison to the cartilaginous portion. Size and sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otorhinolaryngology
Otorhinolaryngology ( , abbreviated ORL and also known as otolaryngology, otolaryngology–head and neck surgery (ORL–H&N or OHNS), or ear, nose, and throat (ENT)) is a surgical subspeciality within medicine that deals with the surgical and medical management of conditions of the head and neck. Doctors who specialize in this area are called otorhinolaryngologists, otolaryngologists, head and neck surgeons, or ENT surgeons or physicians. Patients seek treatment from an otorhinolaryngologist for diseases of the ear, nose, throat, base of the skull, head, and neck. These commonly include functional diseases that affect the senses and activities of eating, drinking, speaking, breathing, swallowing, and hearing. In addition, ENT surgery encompasses the surgical management of cancers and benign tumors and reconstruction of the head and neck as well as plastic surgery of the face and neck. Etymology The term is a combination of New Latin combining forms ('' oto-'' + ''rhino-'' + ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Asia
South Asia is the southern subregion of Asia, which is defined in both geographical and ethno-cultural terms. The region consists of the countries of Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.;;;;;;;; Topographically, it is dominated by the Indian subcontinent and defined largely by the Indian Ocean on the south, and the Himalayas, Karakoram, and Pamir mountains on the north. The Amu Darya, which rises north of the Hindu Kush, forms part of the northwestern border. On land (clockwise), South Asia is bounded by Western Asia, Central Asia, East Asia, and Southeast Asia. The South Asian Association for Regional Cooperation (SAARC) is an economic cooperation organization in the region which was established in 1985 and includes all eight nations comprising South Asia. South Asia covers about , which is 11.71% of the Asian continent or 3.5% of the world's land surface area. The population of South Asia is about 1.9 billion or about one- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White People
White is a racialized classification of people and a skin color specifier, generally used for people of European origin, although the definition can vary depending on context, nationality, and point of view. Description of populations as "White" in reference to their skin color predates this notion and is occasionally found in Greco-Roman ethnography and other ancient or medieval sources, but these societies did not have any notion of a White or pan-European race. The term "White race" or "White people", defined by their light skin among other physical characteristics, entered the major European languages in the later seventeenth century, when the concept of a "unified White" achieve universal acceptance in Europe, in the context of racialized slavery and unequal social status in the European colonies. Scholarship on race distinguishes the modern concept from pre-modern descriptions, which focused on physical complexion rather than race. Prior to the modern era, no Europe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black People
Black is a racialized classification of people, usually a political and skin color-based category for specific populations with a mid to dark brown complexion. Not all people considered "black" have dark skin; in certain countries, often in socially based systems of racial classification in the Western world, the term "black" is used to describe persons who are perceived as dark-skinned compared to other populations. It is most commonly used for people of sub-Saharan African ancestry and the indigenous peoples of Oceania, though it has been applied in many contexts to other groups, and is no indicator of any close ancestral relationship whatsoever. Indigenous African societies do not use the term ''black'' as a racial identity outside of influences brought by Western cultures. The term "black" may or may not be capitalized. The '' AP Stylebook'' changed its guide to capitalize the "b" in ''black'' in 2020. The '' ASA Style Guide'' says that the "b" should not be capitalized. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indigenous Peoples Of The Americas
The Indigenous peoples of the Americas are the inhabitants of the Americas before the arrival of the European settlers in the 15th century, and the ethnic groups who now identify themselves with those peoples. Many Indigenous peoples of the Americas were traditionally hunter-gatherers and many, especially in the Amazon basin, still are, but many groups practiced aquaculture and agriculture. While some societies depended heavily on agriculture, others practiced a mix of farming, hunting, and gathering. In some regions, the Indigenous peoples created monumental architecture, large-scale organized cities, city-states, chiefdoms, states, kingdoms, republics, confederacies, and empires. Some had varying degrees of knowledge of engineering, architecture, mathematics, astronomy, writing, physics, medicine, planting and irrigation, geology, mining, metallurgy, sculpture, and gold smithing. Many parts of the Americas are still populated by Indigenous peoples; some countries have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Asian People
East Asian people (East Asians) are the people from East Asia, which consists of China, Taiwan, Japan, Mongolia, North Korea, and South Korea. The total population of all countries within this region is estimated to be 1.677 billion and 21% of the world's population in 2020. However, large East Asian diasporas, such as the Chinese, Japanese, Korean, and Mongolian diasporas, as well as diasporas of other East Asian ethnic groups, mean that the 1.677 billion does not necessarily represent an accurate figure for the numbers of East Asian people worldwide. The major ethnic groups that form the core of East Asia are the Chinese, Koreans, and Japanese. Other ethnic groups of East Asia include the Ainu, Bai, Manchus, Mongols and other Mongolic peoples, Nivkh, Qiang, Ryukyuans, Tibetans, and Yakuts. Culture The major East Asian language families are the Sinitic, Japonic, and Koreanic families. Other language families include the Tibeto-Burman, Ainu languages, Mongolic, Tungusic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recessive Gene
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as incomplete d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominant Gene
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as incomplete d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, horns, claws, hooves, and the outer layer of skin among vertebrates. Keratin also protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. Excessive keratinization participate in fortification of certain tissues such as in horns of cattle and rhinos, and armadillos' osteoderm. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin comes in two types, the primitive, softer forms found in all vertebrates and harder, derived forms found only amon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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