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6

Check the parameters that go into the Goldman equation... it shows that permeability of ions is as important as their concentrations. If the permeability is zero, there is no potential. Because other conductances are mostly closed at rest, the leak channels are almost entirely responsible for the resting membrane potential (there is a minor component, a ...


6

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. ...


4

There are two ways to think about the "charge" of a cell. One way is by looking at all the chemical species inside the cell and calculating their sum charge. If you do this, you're going to get a neutral solution up to many decimal points of rounding error. Therefore, we don't really care or bother to do this. You'll get the same for the ...


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Post-synaptic vs pre-synaptic inhibition Yes, inhibitory post-synaptic potentials (IPSPs) are always in the context of post-synaptic inhibition, because they are post-synaptic potentials. They occur because of inhibitory neurotransmitters (for example, GABA) are released and bind to post-synaptic receptors, particularly ligand-gated chloride channels. We ...


3

"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 ...


3

Sodium channels are primarily voltage-gated - these are the channels responsible for action potentials. Many other receptors are ligand-gated, and these are typically the signal that causes the initial voltage change that opens the voltage-gated sodium channels; however, these channels are less selective cation channels and are permeable to ions like ...


3

This is a bit of a strange way to plot out these data, I think Figure 3.2 is easier to understand, but basically these are data plotted from early voltage-clamp experiments trying to walk you through how the Hodgkin-Huxley model was developed. They step the voltage to a particular point and look at the current. There are two phases to this current: an early ...


2

By "cerebrum" I assume you really mean the cerebral neocortex, since the cerebrum includes other subcortical structures that themselves are quite distinct (e.g., the basal ganglia). Simply, the neocortex and cerebellum have completely different functions. The cerebellum performs a particular class of computations that are very different from the variety of ...


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Apparently, olfactory axons and GnRH producing neurons are among the first neurons that migrate from neural crest at around 39th day of gestation in humans (Cassoni et al., 2016). In rodents, early GnRH neurons migrate together with a heterogeneous coalescence of placode-derived and neural crest-derived migratory cells (Forni et al., 2011) and ...


2

Synapses are pretty much one-to-one Here's some EM pictures of synapses, from Wikimedia commons: You should gather from these images that these are super organized structures. There's a dense, dense gathering of cellular machinery at the synapse that creates a dark electron-dense region shown by the arrows. There's no room for more than one cell to be ...


2

Not really. There really is little difference in neurons in mammal and indeed not much change across vertebrates. You have to go back all the way to jellyfish before you find major differences in neurons. https://pubmed.ncbi.nlm.nih.gov/30826503/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159607/


2

Sensory receptors and neurons get their selectivity from physical processes and their position in space. For example, photoreceptor cells in the retina respond to light in a specific position in space because the lens and structure of the eye directs light incoming in a particular angle to a specific spot on the retina. Sensory receptors in the skin can ...


1

Yes, this is a very basic neuroscience question, something that would probably come up in the first week of a neurophysiology class or unit. The polarization of the membrane at rest is due to cells being primarily permeable to potassium at rest, and due to a concentration difference of potassium inside vs. outside the membrane. Inside, potassium is high, ...


1

No, they change conformation in response to voltage. Wikipedia has some general discussion of the gating process, as would any basic neuroscience textbook. The primary energy (ATP) cost of neurotransmission is in establishing ion concentration gradients, via the sodium/potassium ATPase. You can think of this as a special case of secondary active transport, ...


1

As you mentioned yourself, there are differences in brain size, form and structure. This difference also affects the size and shape of cells, i.e. you won't find meter-long neurons in mice, but rather in bigger animals. However, the types of cells are overall the same among the mentioned species. It was found that the ratio of glia cells to neurons greatly ...


1

The brain is massively parallel. There are a lot of recurrent connections and feedback loops that are important for setting expectations, building a model of the world, and learning, but the pathway for stimulus to response is quite simple (see the diagrams in Grossberg & Pilly, and the latency profile in Schmolesky et al). It has to be, because if you ...


1

Axonal boutons are named as such due to their shape. Dendro-dendritic synapses do not resemble this shape and are never referred to as boutons. It does not appear that synaptophysin is expressed on dendrites (Fletcher et al. 1991), but I am unaware of a study that targeted dendro-dendritic synapses specifically. References Fletcher, TL, P Cameron, P De ...


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PSD-95 is a protein located in the post-synaptic region inside a cell. In fact it's named for this, "post synaptic density-95" referring to the dense appearance of the post synaptic area on an EM microscope and this protein's presence there. "Synaptic targeting" in this context refers to how that protein gets to where it belongs (the ...


1

I don't know if this directly answers your questions, but I think some confusion may stem from an underlying misconception of receptor vs receptor cell. In most contexts (though not this one), 'receptors' do not refer to cells. Receptors are proteins on the cell membrane that transduct some signal/stimulus to the cell. Sometimes a "normal" ...


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Short answer Nociceptors are different from mechanoreceptors. Background Mechanoreceptors in the skin have specialized dendritic regions that facilitate their specific role in sensing different types of mechanical force, e.g., pressure receptors (Merkel’s disks) versus vibration receptors (Pacinian corpuscles and Meissner's corpuscles). See Fig. 1 for ...


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The answer is right in the second half of the sentence: running from the orbital frontal cortex to the cingulate gyrus, striatum (cuadate nucleus and putamen), globus pallidus, thalamus and back to the frontal cortex Orbital frontal cortex, cingulate gyrus, striatum, globus pallidus, thalamus, and back to (orbital) frontal cortex: these are all different ...


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Short answer Neurotransmitter release is triggered by an influx of calcium ions from the extracellular space into the cytosol through voltage-gated calcium channels in the plasma membrane. Long answer Typical synaptic vesicle release is triggered by calcium influx through T-type calcium channels. These are voltage-sensitive channels in the plasma membrane;...


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