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Nervous System Of Gastropods
The nervous system of gastropods consists of a series of paired ganglia connected by major nerve cords, and a number of smaller branching nerves. It is sometimes called ganglionic. Description The brain of a gastropod consists of three pairs of ganglia, all located close to the oesophagus and forming a nerve ring around it. In some primitive forms, these ganglia are relatively discrete, but in most species they have become so closely bound together as to effectively form separate lobes of a single structure. The cerebral ganglia are located above the oesophagus and supply nerves to the eyes, tentacles, and other sensory organs in the head. Beneath the oesophagus, at the forward part of the foot, lie the pedal ganglia. As their name implies, these supply nerves to the foot muscles. The third pair of ganglia within the brain lie slightly behind and below the cerebral ganglia. These are the pleural ganglia, and supply nerves to the mantle cavity. Bundles of nerves connect the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymnaea Stagnalis Central Ring Ganglia
''Lymnaea'' is a genus of small to large-sized air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the subfamily Lymnaeinae ( of the family Lymnaeidae, the pond snails.Bouchet, P.; Rosenberg, G. (2013). Lymnaea Lamarck, 1799. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=160345 on 2013-06-06 Some species are used in aquaculture under the name Melantho snails. Numerous ''Lymnaea'' species serve as intermediate hosts for trematodes. ''Lymnaea'' is the type genus of the family Lymnaeidae. Species Species within the genus ''Lymnaea'' include: * † ''Lymnaea acuminata'' Brongniart, 1810 * † '' Lymnaea acuta'' Repelin, 1902 * † ''Lymnaea aequalis'' Serres, 1818 * † '' Lymnaea alamosensis'' Arnold, 1908 * † ''Lymnaea antiqua'' Brongniart, 1810 * † ''Lymnaea aptensis'' Matheron, 1861 * † '' Lymnaea ativuncula'' White, 1886 * † '' Lymnaea bertschingeri'' Maillard, 1892 * † ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torsion (gastropod)
Torsion is a gastropod synapomorphy which occurs in all gastropods during larval development. Torsion is the rotation of the visceral mass, mantle, and shell 180˚ with respect to the head and foot of the gastropod. This rotation brings the mantle cavity and the anus to an anterior position above the head. In some groups of gastropods ( Opisthobranchia) there is a degree of secondary detorsion or rotation towards the original position; this may be only partial detorsion or full detorsion. The torsion or twisting of the visceral mass of larval gastropods is not the same thing as the spiral coiling of the shell, which is also present in many shelled gastropods. Development There are two different developmental stages which cause torsion. The first stage is caused by the development of the asymmetrical velar/foot muscle which has one end attached to the left side of the shell and the other end has fibres attached to the left side of the foot and head. At a certain point in larva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epileptogenesis
Epileptogenesis is the gradual process by which a typical brain develops epilepsy. Epilepsy is a chronic condition in which seizures occur. These changes to the brain occasionally cause neurons to fire in an abnormal, hypersynchronous manner, known as a ''seizure''. Epileptogenesis is a chronic disorder. Genetic factors are the most triggering factor. The treatment is difficult to find. There is almost no therapy available for epileptogenesis patients. In epileptogenesis, a normal brain is transformed into an epileptic brain and generates spontaneous seizures. Epileptogenesis is the process by which brain injury leads to chronic epilepsy. Epileptogenesis can be triggered by both acquired as well as genetic factors. Previously, epileptogenesis was considered to be represented by the latent period, but recently, based on clinical observations, epileptogenesis is now considered to extend beyond the latent period. The procedure of epileptogenesis typically happens in three phases: fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix Aspersa
''Cornu aspersum'' (syn. ''Cryptomphalus aspersus''), known by the common name garden snail, is a species of land snail in the family Helicidae, which includes some of the most familiar land snails. Of all terrestrial molluscs, this species may well be the most widely known. It was classified under the name ''Helix aspersa'' for over two centuries, but the prevailing classification now places it in the genus ''Cornu''. The snail is relished as a food item in some areas, but it is also widely regarded as a pest in gardens and in agriculture, especially in regions where it has been introduced accidentally, and where snails are not usually considered to be a menu item. Description The adult bears a hard, thin calcareous shell in diameter and high, with four or five whorls. The shell is variable in coloring and shade of color, but generally it has a reticulated pattern of dark brown, brownish-golden, or chestnut with yellow stripes, flecks, or streaks (characteristically inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix (gastropod)
''Helix'' is a genus of large, air-breathing land snails native to Europe and the Mediterranean region. They are the type genus of the family Helicidae, and are among the first animal genera described by Carl Linnaeus.Rosenberg, G.; Bouchet, P. (2014). ''Helix'' Linnaeus, 1758. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=153970 on 2015-02-24 Members of the genus first appeared during the Oligocene. Like most land snails, ''Helix'' species are hermaphroditic, and like other helicids, a courting pair will impale each other with hormone-rich love darts prior to exchanging sperm. Well-known species include ''Helix pomatia'' (Roman snail, Burgundy snail, or edible snail) and '' Helix lucorum'' (Turkish snail). ''Cornu aspersum'' (garden snail) – another well-known helicid – was originally described as a member of ''Helix'' (as "''Helix aspersa''"), but the prevailing classification places it as the sole member of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Action Potential
An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and in some plant cells. Certain endocrine cells such as pancreatic beta cells, and certain cells of the anterior pituitary gland are also excitable cells. In neurons, action potentials play a central role in cell-cell communication by providing for—or with regard to saltatory conduction, assisting—the propagation of signals along the neuron's axon toward synaptic boutons situated at the ends of an axon; these signals can then connect with other neurons at synapses, or to motor cells or glands. In other types of cells, their main function is to activate intracellular processes. In muscle cells, for example, an action potential is the first step in the chain of events l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. Non-animals like plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. When multiple neurons are connected together, they form what is called a neural circuit. A typical neuron consists of a cell body (soma), dendrites, and a single axon. The soma is a compact structure, and the axon and dend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymnaea
''Lymnaea'' is a genus of small to large-sized air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the subfamily Lymnaeinae ( of the family Lymnaeidae, the pond snails.Bouchet, P.; Rosenberg, G. (2013). Lymnaea Lamarck, 1799. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=160345 on 2013-06-06 Some species are used in aquaculture under the name Melantho snails. Numerous ''Lymnaea'' species serve as intermediate hosts for trematodes. ''Lymnaea'' is the type genus of the family Lymnaeidae. Species Species within the genus ''Lymnaea'' include: * † ''Lymnaea acuminata'' Brongniart, 1810 * † '' Lymnaea acuta'' Repelin, 1902 * † ''Lymnaea aequalis'' Serres, 1818 * † '' Lymnaea alamosensis'' Arnold, 1908 * † ''Lymnaea antiqua'' Brongniart, 1810 * † ''Lymnaea aptensis'' Matheron, 1861 * † '' Lymnaea ativuncula'' White, 1886 * † '' Lymnaea bertschingeri'' Maillard, 1892 * † ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osphradium
The osphradium is a pigmented chemosensory epithelium patch in the mantle cavity present in six of the eight extant classes of molluscs (it is absent in the scaphopoda and monoplacophora; among cephalopoda, only the nautilus has what appears to be a set of osphradia), on or adjacent to the ctenidia (gills). The main function of this organ is disputed but it is believed to be used to test incoming water for silt and possible food particles or, in some species, for sensing the presence of light. It is a popular idea among malacologists that the presence of an osphradium should be a molluscan synapomorphy. However, an osphradium is absent in monoplacophorans and scaphopods. Moreover, the differences in enervation of these patches suggest that the osphradium (as a patch enervated from the ctenidial nerve) may be different from another organ sometimes called the posterior sensory organ (PSO) with separate enervation from the lateral nerve cords. Both types of sensory organs are foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. Branchia (pl. branchiae) is the zoologists' name for gills (from Ancient Greek ). With the exception of some aquatic insects, the filaments and lamellae (folds) contain blood or coelomic fluid, from which gases are exchanged through the thin walls. The blood carries oxygen to other parts of the body. Carbon dioxide passes from the blood through the thin gill tissue into the water. Gills or gill-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians. Semiterrestrial marine animals such as crabs and mudskippers have gill cham ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscera
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system. An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that makes the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Nervous System
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. It is a structure composed of nervous tissue positioned along the rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain (precursor structures exist in onychophorans, gastropods and lancelets). The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals. Overview In vertebrates, the brain and spinal cord are both enclosed in the meninges. The meninges provide a barrier to chemicals dissolv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
