Notes in 1- How Nerves Work

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Published	02/10/2024	The nervous system is divided into:{{c1::Central Nervous System (CNS)}} → Brain & Spinal cord{{c1::Peripheral Nervous System (PNS)}} → P…
Published	02/10/2024	{{c1::Sulci (sing. sulucus)}} → grooves/valleys in the brain {{c1::Gyri (sing. gyrus)}} → dividing convolutions/hills in the brainThe degree…
Published	02/10/2024	Anatomy of the CNS:[A] {{c1::Cerebrum}}, largest part of the brain, two hemispheres connected at corpus callosum, made up of four lobes:[1] {{c2::Fron…
Published	02/10/2024	What are Meninges?
Published	02/10/2024	There are {{c1::12}} pairs of cranial nerves in the brain, each of them relate to a specific function e.g. optic, olfactory.. etc.There are …
Published	02/10/2024	There are three types of neurons:{{c1::Posterior (dorsal) root}} is a PNS nerve root that consists of sensory (afferent) fibers that conveys neural im…
Published	02/10/2024	Gray matter vs White matterWhat's the difference?Compare brain and spinal cord white/gray matter distribution
Published	02/10/2024	Spinal tracts are groups of nerve fibers, divided into:{{c1::Ascending Spinal Tracts (sensory)}} → sensory receptors to CNS{{c1::Descending Spinal Tra…
Published	02/10/2024	Spinal cord pathway:{{c1::Afferent/Sensory/Dorsal (Ascending Tract)}}PNS impulses taken from receptors into dorsal root ganglion (cell bodies)Dor…
Published	02/10/2024	Structure of a neuron:{{c1::Dendrites}} (receives information){{c1::Soma}} (contains nucleus){{c1::Initial segment}} (trigger and generation of action…
Published	02/10/2024	{{c1::Glia/Neuroglia}} are non-neuronal cells in the CNS and PNS, they make up 90% of cells in the CNS.There are 4 types in the CNS:[1] {{c2::Astrocyt…
Published	02/10/2024	There are three types of membrane potentials:[1] {{c1::Action potentials (AP)}} - transmit signals over long distances[2] {{c1::Graded potentials (GP)…
Published	02/10/2024	How is resting membrane potential (Vm) i.e. potential difference approx -70mV maintained/generated?
Published	02/10/2024	An equation that describes the membrane potential that would result if the membrane was permeable to only one ion is known as the {{c1::Nern…
Published	02/10/2024	The {{c1::equilibrium potential of an ion (Eion)}} is the membrane potential at which the {{c2::electrical}} and {{c2::chemical/concentration}} f…
Published	02/10/2024	Why doesn't half of the K+ move out of the cell to equilibrate as it goes down its concentration gradient?
Published	02/10/2024	According to Nernst's equation of K+, the equilibrium potential/RMP for neurons should be approx -90mV, but that isn't the case in reality. Why i…
Published	02/10/2024	Why is K+ considered the major contributing ion to the RMP?
Published	02/10/2024	The {{c1::Goldman-Hodgkin-Katz (GHK)}} equation calculates the membrane potential that results from the contribution of all ions that can cross the me…
Published	02/10/2024	How does the Na+ / K+ pump contribute to the resting membrane potential?
Published	02/10/2024	What happens to the RMP if you poison the Na+ / K+ pump?
Published	02/10/2024	How is the K+ maintained in the brain when you have a high [K+] in the blood?
Published	02/10/2024	How does hyperkalaemia cause ventricular fibrillation in the heart?
Published	02/10/2024	Graded potentials generate action potentials when they depolarise the cell to reach the threshold (from -70 mV to -55mV).e.g. of graded potential…
Published	02/10/2024	Properties of graded potentials[1] {{c1::Graded}} (small stimulus = small response & vice versa)[2] {{c1::Decremental}} (they diminish o…
Published	02/10/2024	How do neurons generate graded potentials?
Published	02/10/2024	What makes fast IPSPs/EPSPs fast and slow IPSPs/EPSPs slow?
Published	02/10/2024	Fast IPSPs/EPSPs are fast because they are mediated by {{c1::ion channels}}.Fast → begins quickly and the effect lasts millisecondsIonotropic rec…
Published	02/10/2024	Compare ion channels opening/closing and their effects on membrane potential whether its IPSP (hyperpolarization) or EPSP (depolarization)
Published	02/10/2024	{{c1::GABA}} is the principle fast inhibitory neurotransmitter in the brain.{{c1::Glutamate}} is the principle fast excitatory neurotransmit…
Published	02/10/2024	What are the properties that allow graded potentials to perform synaptic integration?
Published	02/10/2024	A synapse that is closer to the initial segment (axon hillock) will generate a graded potential that is greater than a synapse that is farther away fr…
Published	02/10/2024	{{c1::Synaptic integration}} is the process of summing all inputs from presynaptic neurons, whether inhibitory or excitatory, at the axon hillock, it …
Published	02/10/2024	Synapses can be excited/inhibited post- or pre-synapse:b → post-synaptic excitation of the somac → post-synaptic inhibition of the soma Integrati…
Published	02/10/2024	There are three types of synaptic connections:[1] {{c1::Axo-dendritic}} synapse → a (usually excitatory synapses e.g. Glutamate)[2] {{c1::Axo-somatic}…
Published	02/10/2024	Action potential propagation:Graded potential reaches threshold (-55 mV) this causes:[1] {{c1::Depolarization}}opening of Na+ voltage gated …
Published	02/10/2024	At the start of an action potential propagation the excitability of the cell is high, but once the action potential fires it drops to zero, and no act…
Published	02/10/2024	Why can't an action potential be generated both ways as it propagates through the cell?
Published	02/10/2024	Why does the cell permeability to Na+ increase more than usual as voltage gated Na+ channels open?
Published	02/10/2024	Properties of an action potential:[1] They have a threshold at {{c1::-55 mV}}[2] {{c1::All-or-none}} - you never get a half action potential![3] Encod…
Published	02/10/2024	What are the properties of an action potential?
Published	02/10/2024	Action potential vs Graded potential.What's the difference?
Published	02/10/2024	How can action potentials be delivered across long distances without decaying?
Published	02/10/2024	There are two ways to speed up action potential conduction velocity:[1] {{c1::Large axons}}→ {{c2::Axial resistance}} is lower in larger axons th…
Published	02/10/2024	What are the consequences of demyelination?
Published	02/10/2024	Multiple sclerosis in the CNS and Gullain-Barre syndrome in the PNS are both examples of {{c1::demyelinating}} diseases.
Published	02/10/2024	Subthreshold vs Suprathreshold graded potential What's the difference?
Published	02/10/2024	In the human body there are five different classifications of axons based on their {{c1::conduction velocity}}, which correlates with its varying anat…
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Published	02/10/2024	The {{c1::neuromuscular junction}} is a synapse between a motor neuron and a skeletal muscle.The motor neurone stimulates contraction in skeletal musc…
Published	02/10/2024	Neuromuscular junction action potential propagation:- Arrival of action potential from {{c1::motor neuron}} to presynaptic terminal.- Opening of {{c1:…
Published	02/10/2024	Why does the neuromuscular junction contain no synaptic integration?i.e. how does a healthy NMJ have a high safety factor?
Published	02/10/2024	Why would administration of a drug that inhibits acetylcholinesterase improve muscle function in patients with a deficiency of ACh receptors on their …
Published	02/10/2024	All of these are orthodox transmitters i.e. released through Ca2+ dependent exocytosis except {{c1::nitric oxide (NO)}} can diffuse across t…
Published	02/10/2024	What are nonspecific monovalent cation channels?
Published	02/10/2024	The end plate graded potential at the end of a neuromusuclar junction is always big enough to reach the {{c1::threshold}} and fire an action potential…
Published	02/10/2024	Types of synaptic connectivity: - {{c1::Convergence}}- {{c1::Divergence}}- {{c1::Feedback inhibition}} - stimulus causes a response that countera…
Published	02/10/2024	A {{c1::divergent pathway}} is a type of synaptic connectivity where one presynaptic neuron branches to affect a larger number of postsynaptic neurons
Published	02/10/2024	A {{c1::convergent pathway}} is a type of synaptic connectivity where many presynaptic neurons provide input to influence a smaller number of postsyna…
Published	02/10/2024	{{c1::Synaptic plasticity}} is the ability of the nervous system to change activity at synapses.Occurs primarily in the CNSe.g. enhancing activity → p…
Published	02/10/2024	As graded potential increase in strength (amplitude), they trigger more {{c1::frequent}} action potentials, releasing more neurotransmitter.
Published	02/10/2024	NMJ vs CNS neuron synaptic transmission.What are the similarities/differences?
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