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Synapses are held together by adhesion molecules, like cadherins and neuroligins/neurexins, so they aren't just loose adjacent membrane, they are securely anchored in place. The adhesion molecules serve both a structural and regulatory role, being important for synapse formation and plasticity. Missler, M., Südhof, T. C., & Biederer, T. (2012). ...


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In biology, functional unit of a system refers to the smallest structural element that is capable of performing the tasks typical for that system (MP Hlastala, Physiology of Respiration). In the nervous system, a neuron is usually considered a functional unit, because it is capable of performing the basic task of this system, that is transmitting signals. ...


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This is an interesting question with good comments. I did medical school, and I am here on unix.se, so let me give some thoughts: The central nervous system consists of "gray" and "white" matter. In the spinal chord you have this gray butterfly shape, in the neocortex it is "gray matter" (neuron's cell body) and "white matter" (neuron's myelinated axons). ...


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"Functional unit" doesn't have a very specific meaning. It's mostly a term used to help biology students imagine organs as collections of parts. The entities named functional units in a textbook don't typically perform every single function of a whole organ. A cardiomyocyte, for example, is a functional unit of the heart. It can perform really important ...


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First about the terms: The outer side of the cranial bones is covered by a single layer of periosteum that is specifically called pericranium. The inner side of the cranial bones is covered by dura mater that has 2 layers: the periosteal (or sometimes called endosteal) layer that is attached to the inner side of the bones the meningeal layer that covers ...


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Olfactory receptor neurons (ORNs) in the olfactory epithelium in the nasal cavity project to the olfactory bulb; this projection is Cranial Nerve 1 and it's more of a collection of fibers rather than a highly organized nerve. Your surprise or confusion is probably based on this: My understanding is that the projections that emanate from the olfactory ...


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Aside from autapses and pacemaking cells, there are also some kinds of sensory neurons that exhibit a spontaneous resting (constantly depolarizing) activity that helps with encoding stimuli. The benefit of having constant activity is that stimuli can further excite or inhibit this activity, and this can be valuable information. Sensory neurons such as ...


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The hippocampus is considered archicortex rather than neocortex. Sometimes hippocampus is considered "sub-cortical" but I think this is only really fair if you really mean "sub-neocortical"; it's common for "cortical" to be used as a shorthand for neocortex in human neurobiology. Writers will be more specific when necessary. The piriform cortex and related ...


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The heart of course does have Alpha 2 pre synaptic receptors , the definition states that alpha 2 receptors are present on sympathetic postganglionic endings , so I don't see why heart should be an exception . I will explain to you how reflex tachycardia occurs . When you give non selective blockers , presynaptic Alpha 2 are blocked , therefore the pre ...


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Could anyone offer an explanation as to why these structures are distinctly NOT continuous at this point? The crista galli physically separates the straight gyrus. Click to zoom Click to zoom ... that would, presumably, permit grey matter from the left hemisphere to be directly continuous with grey matter from the right hemisphere. However, no such ...


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Expanding on @Frieke's answer, evolution often adapts old functions for new processes. So, just as how membrane polarization is useful in unicellular organisms (Irazoqui and Lew, 2004) but can be exploited for neuronal depolarization, vesicular release also has unicellular prototypes (Oliveira et al., 2010) that preface eukaryotic neurotransmitter release. ...


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