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Harderian Gland
The Harderian gland is a gland found within the eye's orbit that occurs in tetrapods (reptiles, amphibians, birds and mammals) that possess a nictitating membrane. The gland can be compound tubular or compound tubuloalveolar, and the fluid it secretes ( mucous, serous or lipid) varies between different groups of animals. In some animals, it acts as an accessory to the lacrimal gland, secreting fluid that eases movement of the nictitating membrane. Research has proposed that the gland has several other functions, including that of a photoprotective organ, a location of immune response, a source of thermoregulatory lipids, a source of pheromones, and a site of osmoregulation. In mammals, the gland secretes an oily substance used to preen the fur. The presence or absence of this gland is one of the cues used by palaeontologists to determine when fur evolved in the ancestors of mammals. The Harderian gland was first described in 1694 by Swiss anatomist Anatomy () is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cave Vertebrates Of America; A Study In Degenerative Evolution (1909) (20577823892)
Caves or caverns are natural voids under the Earth's surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock shelters). Caves which extend further underground than the opening is wide are called endogene caves. Speleology is the science of exploration and study of all aspects of caves and the cave environment. Visiting or exploring caves for recreation may be called ''caving'', ''potholing'', or ''spelunking''. Formation types The formation and development of caves is known as ''speleogenesis''; it can occur over the course of millions of years. Caves can range widely in size, and are formed by various geological processes. These may involve a combination of chemical processes, erosion by water, tectonic forces, microorganisms, pressure, and atmospheric influences. Isotopic dating techniques can be applied to cave sediments, to determine the time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoprotection
Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight. Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stress caused by excess or fluctuating light conditions. Humans and other animals have also developed photoprotective mechanisms to avoid UV photodamage to the skin, prevent DNA damage, and minimize the downstream effects of oxidative stress. In photosynthetic organisms In organisms that perform oxygenic photosynthesis, excess light may lead to photoinhibition, or photoinactivation of the reaction centers, a process that does not necessarily involve chemical damage. When photosynthetic antenna pigments such as chlorophyll are excited by light absorption, unproductive reactions may occur by charge transfer to molecules with unpaired electrons. Because oxygenic phototrophs generate O2 as a byproduct from the photocatalyzed splitting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomist
Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology, which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine, and is often studied alongside physiology. Anatomy is a complex and dynamic field that is constantly evolving as discoveries are made. In recent years, there has been a significant increase in the use of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes ( salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution, the more water tends to move into it. Pressure must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water by osmosis from the side containing pure water. Although there may be hourly and daily variations in osmotic balance, an animal is generally in an osmotic steady state over the long term. Organisms in aquatic and terrestrial environments must maintain the right concentration of solutes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pheromone
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavior of the receiving individuals. There are ''alarm signal, alarm pheromones'', ''food trail pheromones'', ''sex pheromones'', and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology. Background The portmanteau word "pheromone" was coined by Peter Karlson and Martin Lüscher in 1959, based on the Greek language, Greek () and (). Pheromones are also sometimes classified as ec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation. The internal thermoregulation process is one aspect of homeostasis: a state of dynamic stability in an organism's internal conditions, maintained far from thermal equilibrium with its environment (the study of such processes in zoology has been called physiological ecology). If the body is unable to maintain a normal human body temperature, normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs. Humans may also experience lethal hyperthermia when the wet bulb temperature is sustained above for six hours. Work in 2022 established by experiment that a wet-bulb temperature exceeding 30.55°C caused uncompensab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immune Response
An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellular bacteria, protozoa, Parasitic worm, helminths, and Fungus, fungi which could cause serious problems to the health of the host organism if not cleared from the body. In addition, there are other forms of immune response. For example, harmless exogenous factors (such as pollen and food components) can trigger allergy; latex and metals are also known allergens. A transplanted tissue (for example, blood) or organ can cause graft-versus-host disease. A type of immune reactivity known as Rh disease can be observed in pregnant women. These special forms of immune response are classified as hypersensitivity. Another special form of immune response is CD4+ T cells and antitumor immunity, antitumor immunity. In general, there are two branches of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Gland
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called dacryoadenitis. The lacrimal gland produces tears which are secreted by the lacrimal ducts, and flow over the ocular surface, and then into canals that connect to the lacrimal sac. From that sac, the tears drain through the lacrimal duct into the nose. Anatomists divide the gland into two sections, a palpebral lobe, or portion, and an orbital lobe or portion. The smaller ''palpebral lobe'' lies close to the eye, along the inner surface of the eyelid; if the upper eyelid is everted, the palpebral portion can be seen. The orbital lobe of the gland, contains fine interlobular ducts that connect the orbital lobe and the palpe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit (anatomy)
In anatomy Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ..., the orbit is the Body cavity, cavity or socket/hole of the skull in which the eye and Accessory visual structures, its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is about , of which the eye occupies . The orbital contents comprise the eye, the Orbital fascia, orbital and retrobulbar fascia, extraocular muscles, cranial nerves optic nerve, II, oculomotor nerve, III, trochlear nerve, IV, trigeminal nerve, V, and abducens nerve, VI, blood vessels, fat, the lacrimal gland with its Lacrimal sac, sac and nasolacrimal duct, duct, the eyelids, Medial palpebral ligament, medial and Lateral palpebral raphe, lateral palpebr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology. Lipids are broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/ unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serous
In physiology, serous fluid or serosal fluid (originating from the Medieval Latin word ''serosus'', from Latin ''serum'') is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The fluid fills the inside of body cavities. Serous fluid originates from serous glands, with secretions enriched with proteins and water. Serous fluid may also originate from mixed glands, which contain both mucous and serous cells. A common trait of serous fluids is their role in assisting digestion, excretion, and respiration. In medical fields, especially cytopathology, serous fluid is a synonym for effusion fluids from various body cavities. Examples of effusion fluid are pleural effusion and pericardial effusion. There are many causes of effusions which include involvement of the cavity by cancer. Cancer in a serous cavity is called a serous carcinoma. Cytopathology evaluation is recommended to evaluate the causes of effusions in thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
