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

Most intact aortic aneurysms do not produce symptoms. As they enlarge, symptoms such as abdominal pain and back pain may develop. Compression of nerve roots may cause leg pain or numbness. Untreated, aneurysms tend to become progressively larger, although the rate of enlargement is unpredictable for any individual. Rarely, clotted blood which lines most aortic aneurysms can break off and result in an embolus. They may be found on physical examination. Medical imaging is necessary to confirm the diagnosis. Symptoms may include: anxiety or feeling of stress; nausea and vomiting; clammy skin; rapid heart rate. In patients presenting with aneurysm of the arch of the aorta, a common symptom is a hoarse voice as the left recurrent laryngeal nerve (a branch of the vagus nerve) is stretched. This is due to the recurrent laryngeal nerve winding around the arch of the aorta. If an aneurysm occurs in this location, the arch of the aorta will swell, hence stretching the left recurrent laryngeal nerve. The patient therefore has a hoarse voice as the recurrent laryngeal nerve allows function and sensation in the voicebox. Abdominal aortic aneurysms, hereafter referred to as AAAs, are the most common type of aortic aneurysm. One reason for this is that elastin, the principal load-bearing protein present in the wall of the aorta, is reduced in the abdominal aorta as compared to the thoracic aorta (nearer the heart). Another is that the abdominal aorta does not possess vasa vasorum, hindering repair. Most are true aneurysms that involve all three layers (tunica intima, tunica media and tunica adventitia), and are generally asymptomatic before rupture. The most common sign for the aortic aneuysm is the Erythema nodosum also known as leg lesions typically found near the ankle area. The prevalence of AAAs increases with age, with an average age of 65–70 at the time of diagnosis. AAAs have been attributed to atherosclerosis, though other factors are involved in their formation. An AAA may remain asymptomatic indefinitely. There is a large risk of rupture once the size has reached 5 cm, though some AAAs may swell to over 15 cm in diameter before rupturing. Before rupture, an AAA may present as a large, pulsatile mass above the umbilicus. A bruit may be heard from the turbulent flow in a severe atherosclerotic aneurysm or if thrombosis occurs. Unfortunately, however, rupture is usually the first hint of AAA. Once an aneurysm has ruptured, it presents with a classic pain-hypotension-mass triad. The pain is classically reported in the abdomen, back or flank. It is usually acute, severe and constant, and may radiate through the abdomen to the back. The diagnosis of an abdominal aortic aneurysm can be confirmed at the bedside by the use of ultrasound. Rupture could be indicated by the presence of free fluid in potential abdominal spaces, such as Morison's pouch, the splenorenal space (between the spleen and left kidney), subdiaphragmatic spaces (underneath the diaphragm) and peri-vesical spaces. A contrast-enhanced abdominal CT scan is needed for confirmation. Only 10–25% of patients survive rupture due to large pre- and post-operative mortality. Annual mortality from ruptured abdominal aneurysms in the United States alone is about 15,000. Another important complication of AAA is formation of a thrombus in the aneurysm.

Formerly called toxemia, preeclampsia is a condition that pregnant women develop. It is marked by high blood pressure in women who have previously not experienced high blood pressure before. Preeclamptic women will have a high level of protein in their urine and often also have swelling in the feet, legs, and hands.

With keratoconus, the clear, dome-shaped tissue that covers the eye (cornea) thins and bulges outward into a cone shape. Its cause is unknown. Symptoms first appear during puberty or the late teens and include blurred vision and sensitivity to light and glare. Vision can be corrected with glasses or contact lenses early on. Advanced cases may require a cornea transplant.

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Body Restoration Physiotherapy has successfully been serving the area of St. Albert and Edmonton for over 23 years. They offer services such as; vestibular rehabilitation, physiotherapy, registered massage therapy, acupuncture, radial shockwave therapy, and IMS therapy. Many individuals come to Body Restoration when in need of any physical therapy services.

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The human brain is the command center for the human nervous system. It receives input from the sensory organs and sends output to the muscles. The human brain has the same basic structure as other mammal brains, but is larger in relation to body size than any other brains.

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