|
Flaccidity
Flaccid paralysis is a neurological condition characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma). This abnormal condition may be caused by disease or by trauma affecting the nerves associated with the involved muscles. For example, if the somatic nerves to a skeletal muscle are severed, then the muscle will exhibit flaccid paralysis. When muscles enter this state, they become limp and cannot contract. This condition can become fatal if it affects the respiratory muscles, posing the threat of suffocation. It also occurs in the spinal shock stage in complete transection of the spinal cord occurring in injuries such as gunshot wounds.Saladin, Kenneth S. Anatomy & Physiology: The Unity of Form and Function. McGraw-Hill. 6th Edition. 2012. Causes Polio and other viruses The term ''acute flaccid paralysis'' (AFP) is often used to describe an instance with a sudden onset, as might be found with polio. AFP is the most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscle Tone
In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sullivan, S. B. (2007). Examination of motor function: Motor control and motor learning. In S. B. O’Sullivan, & T. J. Schmitz (Eds), Physical rehabilitation (5th ed.) (pp. 233-234). Philadelphia, Pennsylvania: F. A. Davis Company. It helps to maintain posture and declines during REM sleep. Muscle tone is regulated by the activity of the motor neurons and can be affected by various factors, including age, disease, and nerve damage. Purpose If a sudden pull or stretch occurs, the body responds by automatically increasing the muscle's tension, a reflex which helps guard against danger as well as helping maintain balance. Such near-continuous innervation can be thought of as a "default" or "steady state" condition for muscles. Both the extensor and flexo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weakness
Weakness is a symptom of many different medical conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, including muscular dystrophy and inflammatory myopathy. It occurs in neuromuscular junction disorders, such as myasthenia gravis. Pathophysiology Muscle cells work by detecting a flow of electrical impulses from the brain, which signals them to contract through the release of calcium by the sarcoplasmic reticulum. Fatigue (reduced ability to generate force) may occur due to the nerve, or within the muscle cells themselves. New research from scientists at Columbia University suggests that muscle fatigue is caused by calcium leaking out of the muscle cell. This makes less calcium available for the muscle cell. In addition, the Columbia researchers propose that an enzyme activated by this released calcium eats away at muscle fibers. Su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenovirus
Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from their initial isolation from human adenoids in 1953. They have a broad range of vertebrate hosts; in humans, more than 50 distinct adenoviral serotypes have been found to cause a wide range of illnesses, from mild respiratory infections in young children (the common cold) to life-threatening multi-organ disease in people with a weakened immune system. Virology Classification This family contains the following genera: * '' Aviadenovirus'' * '' Barthadenovirus'' * '' Ichtadenovirus'' * ''Mastadenovirus'' (including all human adenoviruses) * '' Siadenovirus'' * '' Testadenovirus'' Diversity In humans, currently there are 88 human adenoviruses (HAdVs) in seven species (Human adenovirus A to G): * A: 12, 18, 31 * B: 3, 7, 11, 14, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Motor Neuron Lesion
An upper motor neuron lesion (also known as pyramidal insufficiency) Is an injury or abnormality that occurs in the neural pathway above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves. Conversely, a lower motor neuron lesion affects nerve fibers traveling from the anterior horn of the spinal cord or the cranial motor nuclei to the relevant muscle(s). Upper motor neuron lesions occur in the brain or the spinal cord as the result of stroke, multiple sclerosis, traumatic brain injury, cerebral palsy, atypical parkinsonisms, multiple system atrophy, and amyotrophic lateral sclerosis. Symptoms Changes in muscle performance can be broadly described as the upper motor neuron syndrome. These changes vary depending on the site and the extent of the lesion, and may include: * Muscle weakness. known as 'pyramidal weakness' *Sloth sign. Decreased control of active movement, particularly slowness * Spasticity, a velocity-dependent change in muscle tone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Motor Neuron Lesion
A lower motor neuron lesion is a lesion which affects nerve fibers traveling from the lower motor neuron(s) in the anterior horn/anterior grey column of the spinal cord, or in the motor nuclei of the cranial nerves, to the relevant muscle(s). One major characteristic used to identify a lower motor neuron lesion is flaccid paralysis – paralysis accompanied by loss of muscle tone. This is in contrast to an upper motor neuron lesion, which often presents with spastic paralysis – paralysis accompanied by severe hypertonia. Signs and symptoms * Muscle paresis or paralysis * Fibrillations * Fasciculations – caused by increased receptor concentration on muscles to compensate for lack of innervation. * Hypotonia or atonia – Tone is not velocity dependent. * Hyporeflexia - Along with deep reflexes even cutaneous reflexes are also decreased or absent. * Strength – weakness is limited to segmental or focal pattern, Root innervated pattern The extensor plantar reflex ( Babin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blowgun
A blowgun (also called a blowpipe or blow tube) is a simple ranged weapon consisting of a long narrow tube for shooting light projectiles such as darts. It operates by having the projectile placed inside the pipe and using the force created by forced exhalation ("blow") to pneumatically propel the projectile. The propulsive power is limited by the strength of the user's respiratory muscles and the vital capacity of their lungs. History Many cultures have used such a weapon, but various indigenous and aboriginal peoples of East Asia, Southeast Asia, Western Europe, North America, Central America (the Huehuetenango region of Guatemala), and South America (the Amazon Basin and the Guianas) are best known for its historical usage. Projectiles include seeds, clay pellets, and darts. Some cultures dip the tip of the darts in curare or other arrow poisons in order to paralyze the target. Blowguns were very rarely used by these tribes as anti-personnel weapons, but primarily to h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macushi
The Macushi (''Makuusi'', ) are an Indigenous people living in the borderlands of southern Guyana, northern Brazil in the state of Roraima, and in an eastern part of Venezuela. Identification The Macushi are also known as the Macusi, Macussi, Makushi, Makusi, Makuxi, Teueia, and Teweya people. Macushi, as well as the Arecuna, Kamarakoto, and Taurepan are considered sub-groups of Pemon. Language Macushi people speak the Macushi language, a Macushi-Kapon language, which is part of the Carib language family. Some in Brazil also speak Portuguese, while some in Venezuela speak Spanish, and some in Guyana speak English. The Macushi language is written in the Latin script, and the New Testament was translated into the language in 1996. Macushi were hesitant to teach their language to outsiders, thus the language was threatened in the 1950s, as it was considered "slang" compared to the official Portuguese. Housing and lifestyle They live in villages linked together by tracks an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strychnos
''Strychnos'' is a genus of flowering plants, belonging to the family Loganiaceae (sometimes Strychnaceae). The genus includes about 200 accepted species of trees and lianas. The genus is widely distributed around the world's tropics and is noted for the presence of poisonous indole alkaloids in the roots, stems and leaves of various species. Among these alkaloids are the well-known and virulent poisons strychnine and curare. Etymology The name ''strychnos'' was applied by Pliny the Elder in his ''Natural History'' to ''Solanum nigrum''. The word is derived from the Ancient Greek στρύχνον (''strúkhnon'') – "acrid", "bitter". The meaning of the word ''strychnos'' was not fixed in Ancient Greece, where it could designate a variety of different plants having in common the property of toxicity. Distribution The genus has a pantropical distribution. Taxonomy The genus is divided into 12 sections, though it is conceded that the sections do not reflect evolution of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrodendron Tomentosum
''Chondrodendron tomentosum'' is one of six accepted species in the small genus Chondrodendron, belonging to the Moonseed family Menispermaceae. It is a large tropical liana native to Central and South America. It contains highly toxic alkaloids and is one of the sources of the arrow poison curare – specifically 'tube curare', the name of which is derived from the name of the medicinally valuable alkaloid tubocurarine Tubocurarine (also known as ''d''-tubocurarine or DTC) is a toxic benzylisoquinoline alkaloid historically known for its use as an arrow poison. In the mid-1900s, it was used in conjunction with an anesthetic to provide skeletal muscle relaxat .... __TOC__ Derivation of scientific name The generic name is a compound of Greek χόνδρος ( chondros ) 'cartilage' / 'lump' / 'grain' and δένδρον ( dendron ) 'tree' – hence 'lumpy / gristly tree', while the specific name consists of the Latin adjectival form ''tomentosum'' 'covered in matted hairs'. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curare
Curare ( or ; or ) is a common name for various alkaloid arrow poisons originating from plant extracts. Used as a paralyzing agent by indigenous peoples in Central and South America for hunting and for therapeutic purposes, curare only becomes active when it contaminates a wound or is introduced directly to the bloodstream; it is not active when ingested orally. Curare is prepared by boiling the bark of one of the dozens of plant sources, leaving a dark, heavy paste that can be applied to arrow or dart heads. These poisons cause weakness of the skeletal muscles and, when administered in a sufficient dose, eventual death by asphyxiation due to paralysis of the diaphragm. In medicine, curare has been used as a treatment for tetanus and strychnine poisoning and as a paralyzing agent for surgical procedures. History The word 'curare' is derived from , from the Carib language of the Macusi of Guyana. It has its origins in the Carib phrase "mawa cure" meaning of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxin
Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2000 that can adversely affect function in both developing and mature nervous tissue.Olney 2002 The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate,Choi 1987 nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin,Simpson 1986 and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations. Neurotoxins inhibit neuron control over ion concentrations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetylcholine
Acetylcholine (ACh) is an organic compound that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Parts in the body that use or are affected by acetylcholine are referred to as cholinergic. Acetylcholine is the neurotransmitter used at the neuromuscular junction. In other words, it is the chemical that motor neurons of the nervous system release in order to activate muscles. This property means that drugs that affect cholinergic systems can have very dangerous effects ranging from paralysis to convulsions. Acetylcholine is also a neurotransmitter in the autonomic nervous system, both as an internal transmitter for both the sympathetic nervous system, sympathetic and the parasympathetic nervous system, and as the final product released by the parasympathetic nervous system. Acetylcholine is the primary neurotransmitter of the parasympathet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
