Neurotransmitter 3D Animation
on Tuesday, December 21, 2010




Neurotransmitters are endogenous chemicals which transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side of the synapse. Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow graded electrical potentials. Low level "baseline" release also occurs without electrical stimulation. Neurotransmitters are synthesized from plentiful and simple precursors, such as amino acids, which are readily available from the diet and which require only a small number of biosynthetic steps to convert. The chemical identity of neurotransmitters is often difficult to determine experimentally. For example, it is easy using an electron microscope to recognize vesicles on the presynaptic side of a synapse, but it may not be easy to determine directly what chemical is packed into them. The difficulties led to many historical controversies over whether a given chemical was or was not clearly established as a transmitter. In an effort to give some structure to the arguments, neurochemists worked out a set of experimentally tractable rules. According to the prevailing beliefs of the 1960s, a chemical can be classified as a neurotransmitter if it meets the following conditions: * There are precursors and/or synthesis enzymes located in the presynaptic side of the synapse. * The chemical is present in the presynaptic element. * It is available in sufficient quantity in the presynaptic neuron to affect the postsynaptic neuron; * There are postsynaptic receptors and the chemical is able to bind to them. * A biochemical mechanism for inactivation is present. There are many different ways to classify neurotransmitters. Dividing them into amino acids, peptides, and monoamines is sufficient for some classification purposes. Major neurotransmitters: * Amino acids: glutamate, aspartate, D-serine, γ-aminobutyric acid (GABA), glycine * Monoamines and other biogenic amines: dopamine (DA), norepinephrine (noradrenaline; NE, NA), epinephrine (adrenaline), histamine, serotonin (SE, 5-HT), melatonin * Others: acetylcholine (ACh), adenosine, anandamide, nitric oxide, etc. In addition, over 50 neuroactive peptides have been found, and new ones are discovered regularly. Many of these are "co-released" along with a small-molecule transmitter, but in some cases a peptide is the primary transmitter at a synapse. β-endorphin is a relatively well known example of a peptide neurotransmitter; it engages in highly specific interactions with opioid receptors in the central nervous system. Single ions, such as synaptically released zinc, are also considered neurotransmitters by some[by whom?], as are some gaseous molecules such as nitric oxide (NO) and carbon monoxide (CO). These are not classical neurotransmitters by the strictest definition, however, because although they have all been shown experimentally to be released by presynaptic terminals in an activity-dependent way, they are not packaged into vesicles. By far the most prevalent transmitter is glutamate, which is excitatory at well over 90% of the synapses in the human brain. The next most prevalent is GABA, which is inhibitory at more than 90% of the synapses that do not use glutamate. Even though other transmitters are used in far fewer synapses, they may be very important functionally—the great majority of psychoactive drugs exert their effects by altering the actions of some neurotransmitter systems, often acting through transmitters other than glutamate or GABA. Addictive drugs such as cocaine and amphetamine exert their effects primarily on the dop

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Closed Reduction of Distal Radius Fractures - Discussion: (distal radius fracture menu) - closed reduction & immobilization in plaster cast remains accepted method of treatment for majority of stable distal radius frx; - unstable fractures will often lose reduction in the cast and will slip back to the pre-reduction position; - patients should be examined for carpal tunnel symptoms before and after reduction; - carpal tunnel symptoms that do not resolve following reduction will require carpal tunnel release; - cautions: - The efficacy of closed reduction in displaced distal radius fractures. - Technique: - anesthesia: (see: anesthesia menu) - hematoma block w/ lidocaine; - w/ hematoma block surgeon should look for "flash back" of blood from hematoma, prior to injection; - references: - Regional anesthesia preferable for Colles' fracture. Controlled comparison with local anesthesia. - Neurological complications of dynamic reduction of Colles' fractures without anesthesia compared with traditional manipulation after local infiltration anesthesia. - methods of reduction: - Jones method: involves increasing deformity, applying traction, and immobilizing hand & wrist in reduced position; - placing hand & wrist in too much flexion (Cotton-Loder position) leads to median nerve compression & stiff fingers; - Bohler advocated longitudinal traction followed by extension and realignment; - consider hyper-extending the distal fragment, and then translating it distally (while in extended position) until it can be "hooked over" proximal fragment; - subsequently, the distal fragment can be flexed (or hinged) over the proximal shaft fragment; - closed reduction of distal radius fractures is facilitated by having an assistant provide counter traction (above the elbow) while the surgeon controls the distal fragment w/ both hands (both thumbs over the dorsal surface of the distal fragment); - flouroscopy: - it allows a quick, gentle, and complete reduction; - prepare are by prewrapping the arm w/ sheet cotton and have the plaster or fibroglass ready; - if flouroscopy is not available, then do not pre-wrap the extremity w/ cotton; - it will be necessary to palpate the landmarks (outer shaped of radius, radial styloid, and Lister's tubercle, in order to judge success of reduction; - casting: - generally, the surgeon will use a pre-measured double sugar sugar tong splint, which is 6-8 layers in thickness; - more than 8 layers of plaster can cause full thickness burns: - reference: Setting temperatures of synthetic casts. - position of immobilization - follow up: - radiographs: - repeat radiographs are required weekly for 2-3 weeks to ensure that there is maintenance of the reduction; - a fracture reduction that slips should be considered to be unstable and probably require fixation with (pins, or ex fix ect.) - there is some evidence that remanipulation following fracture displacement in cast is not effective for these fractures; - ultimately, whether or not a patient is satisfied with the results of non operative treatment depends heavily on th

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This condition is seen in imperforate hymen or transverse vaginal septum. Pt presents with primary amenorrhea. Dr Hemant Damle Prof Dept of OBGYN SKNMC Pune India

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Symptoms of liver failure include vomiting, diarrhea and fatigue as well as the symptoms from stage 3. While the progression from cirrhosis to failure can take years, the damage is irreversible and leads to eventual death. The key to treating liver disease is to diagnose the condition as early as possible.

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A uterine fibroid (also uterine leiomyoma, myoma, fibromyoma, leiofibromyoma, fibroleiomyoma, and fibroma) (plural of ... myoma is ...myomas or ...myomata) is a benign (non-cancerous) tumor that originates from the smooth muscle layer (myometrium) and the accompanying connective tissue of the uterus. Fibroids are the most common benign tumors in females and typically found during the middle and later reproductive years. While most fibroids are asymptomatic, they can grow and cause heavy and painful menstruation, painful sexual intercourse, and urinary frequency and urgency. Uterine fibroids is the major indication for hysterectomy in the US.[2] Fibroids are often multiple and if the uterus contains too many leiomyomatas to count, it is referred to as uterine leiomyomatosis. The malignant version of a fibroid is uncommon and termed a leiomyosarcoma.

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Sleep apnea is a potentially serious sleep disorder in which breathing repeatedly stops and starts. You may have sleep apnea if you snore loudly, and you feel tired even after a full night's sleep. The main types of sleep apnea are: Obstructive sleep apnea, the more common form that occurs when throat muscles relax. Central sleep apnea, which occurs when your brain doesn't send proper signals to the muscles that control breathing. Complex sleep apnea syndrome, also known as treatment-emergent central sleep apnea, occurs when someone has both obstructive sleep apnea and central sleep apnea. If you think you might have any form of sleep apnea, see your doctor. Treatment can ease your symptoms and may help prevent heart problems and other complications.

Otto Placik MD. a board certified Chicago Illinois based plastic surgeon presents instructional video on post genital surgery (labia minora reduction aka labiaplasty or labioplasty or clitoral hood reduction) massage exercises for treatment of labum minora psot surgical fibrosis or hypersensitivity. Photos pictures and video of anatomic models are reviewed . Great for patients thinking about or planning labiaplasty or vaginal cosmetic surgery

Bacterial meningitis is very serious and can be deadly. Death can occur in as little as a few hours. While most people with meningitis recover, permanent disabilities such as brain damage, hearing loss, and learning disabilities can result from the infection. There are several types of bacteria that can cause meningitis. Some of the leading causes of bacterial meningitis in the United States include Streptococcus pneumoniae, group B Streptococcus, Neisseria meningitidis, Haemophilus influenzae, and Listeria monocytogenes.