Blocks 1-4
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| Neuron doctrine= | brain composed of individual, highly specialized cells (neurons) separated by functional space (synapses), not connected continuously as previously believed
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| 2 other names for "cell body" | soma, parikaryon
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| cellular fibers emerging from soma (2 types) unique to neurons | dendrites (multiple), axon (one)
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| if a neuron is "active," what is it doing? | releasing neurotransmitters
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| neurotransmitters are housed in ___ found in ___, located where on neuron? | synaptic vesicles, pre-synaptic terminals/boutons, tip of axon
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| Purpose/function of dendrites | input area- where neuronal information is received
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| neurotransmitters are released from __ and received onto specialized __ embedded in post-synaptic membrane of next cell | pre-synaptic terminal, NT receptors
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| What % of NTs actually naturally bind to receptors? | 10-15%
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| name specialized proteins embedded in membrane of pre-synaptic terminal that collects, binds, and transports unbound NTs back into pre-syn terminal for breakdown or re-use | re-uptake pumps
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| Prozac is an example of what and what is it's function and why is it useful? | SSRI (Selective Seratonin Re-uptake Inhibitor) which blocks re-uptake pumps so as to increase pool of available NTs by locking them in synapse
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| NEurons are characterized by how many neurites originate from soma- list different types (4) | bipolar, unipolar (sensory), multipolar (majority), pyrimidal (motor skills)
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| Which early neuroscientist developed Law of Dynamic Polarization, deducing neuronal function from neuron structure? | Ramon Cajal
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| When info flows from dendrite -> soma -> axon -> dendrite, this is passed through what sort of connection? | axodendritic synapse
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| info passed from axon -> soma through what connection? | axosomatic synapse
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| info passed from axon -> axon through what connection? | axoaxonic synapse
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| info passed form axon -> synaptic terminal through what connection? | axosynaptic synapse
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| T/F: cells can only be pre- or post- synaptic, but not both | False, all are both and can send/rcv info
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| What is the purpose of the neuronal membrane? | to separate intra- and extra- cellular environments
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| what do polar molecules (water for example) have, which organic, non-polar molecules (ex: carbon) do not? | electrical charge
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| opposite charges __, while like charges __. | attract, repel
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| organic/nonpolar molecules are "water-fearing" aka: | hydrophobicity (vs hydrophilicity)
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| Phospholipid= | phosphate (polar) head attached to lipid hydrocarbon (nonpolar tail: major component of nerve cell membranes)
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| Hydrophobic + hydrophilic regions= | amphipathic
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| 2 functions of proteins in neuronal membrane? | form hydrophilic channels/pumps, float (fluid mosaic)
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| DNA is to alphabet as protein is to ___ | words
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| Process of DNA -> RNA (production of an RNA copy of gene) is: | transcription
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| Process of RNA -> assembly of amino acids in specific order to make proteins: | Translation
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| Codes for specific amino acid sequence: | m(essenger)RNA
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| 2 roles of amino acids: | make up bigger proteins, act as NTs
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| 5 ways proteins are important for cell function | peptide hormones, NT transporters and receptors, NT channels and pumps, structural proteins, enzymes
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| In what way are peptide hormones different from NTs? | Released to blood stream as well as brain
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| Explain whether NT channels and pumps are active/passive | Channels are passive (allow movement of cell-moving salts), pumps are active (forces them in or out)
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| A protein is an enzyme if.. | it is a catalyst causing chemical reactions to create products from building blocks
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| PRocess of moving proteins and syn vesicles (NTs) from soma to pre-syn terminal is called (2 names) | Orthograde/Anterograde Axoplasmic transport
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| process of moving proteins and syn vesicles toward soma | Retrograde axoplasmic transport
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| Name of motor protein involved in anterograde transport | kinesin (very fast/efficient)
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| Name of motor protein involved in retrograde transport | dynein-dynactic
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| Goal of exocytosis | Release contents of loaded syn vesicles into syn
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| List 3 steps of exocytosis | 1. fusion of syn vesicle w/ plasma membrane
2. syn vesicle contents (hormonal signals/NTs) dumped into extracellular space
3. secretion
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| Explain process of endocytosis | piece of membrane pinches back to form new vesicle
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| when is exocytosis > endocytosis? purpose of this? | During neuronal growth, allows growth of axonic membrane in certain direction to connect with another neuron and form synapses
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| when is exocytosis < endocytosis? purpose of this? | during neuronal pruning, bad match with another neuron so withdraws to allow re-direction
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| when is exocytosis = endocytosis (functional balance)? | at a mature synapse/stable association between neurons
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| name the hypothesis which explains how neurites find their way during development? | chemoaffinity hypothesis
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| according to chemoaffinity hypothesis, what are the chemical signals used and what is their role in neuronal development? | trophic factors are released from neuron, if receptor is in vicinity, will feel gradient and put out own chemicals to guide growing neuron
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| name 2 trophic factors | NGF (nerve growth factor), BDNF (brain derived neurotrophic factor)
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| name the tip of a growing neuronal axon and explain how it changes | growth cone, sends out filopedia which flatten IF correct partner. Pre-/post- syn densities then appear (NT receptors/reuptake pumps)
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| explain neural plasticity in normal vs 2 abnormal forms | normal= signal:protein receptors= 1:1
down-regn= pre-syn cell inc trophic influence -> dec protein to protect from over-stim of post-syn cell
up-reg= pre-syn cell dec trophic influence -> inc protein to have better chance of catching signal
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| what is prob w/ down reg? | post-syn cell = less sensitive to NT presence (ex. drug addiction- when off drug, dec in protein appears to be inability of function)
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| what is prob w/ up reg? | post-syn cell = supersensitive to any remaining NT presence (ex. phantom limb pain)
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| name regeneration cells in PNS and describe role: | Schwann cells- responsible for 1 axon, attach to neuron at site of injury -> sensitive scar tissue
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| name regeneration cells in CNS and describe role: | oligodendrocyte- can respond to damage but can't get to all -> damage to CNS neurons = permanent. Responsible for many axons.
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| molecules are formed by __, which differ by structure of pos charged __ and neg charged __ | atoms, nucleus, electrons
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| what is an ion? | atom that has either lost or gained a charge
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| describe chemical composition of intracellular environment of neuron | rich in potassium K+ like freshwater
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| describe chem composition of extracellular environment of neuron | rich in sodium Na+ like sea water, Cl- and Ca++
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| Ion pore= __ in membranes which serve what purpose? | proteins, channel from out to inside so cells can function
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| name of 1 protein and name of many proteins together | monomer, polymer
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| name the 4 ions prevalent in intra/extra cellular env and abbrev | Sodium Na+, Potassium K+, Chloride Cl-, Calcium Ca++
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| ___ describes the process of disorder/chaos in system, making it less organized (aka Diffusion) | Entropy
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| ___= principle of opposites attracting (developing -charge stops flow of +charge leaving) | Enthalpy
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| define equilibrium | point where enthalpy (electrostatic force) balances entropy (diffusion force) for any charged ion
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| nernst equation determines balance potential (aka ___ w/ abbrev) | Equilibrium Potential (Em)
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| Equilibrium potential= __ necessary to balance process of __ | Electrical charge (mV), diffusion
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| Ek (Equilibrium potential for Potassium)= ? (w/ interpretation) | -93mV -> inside of neuron must be 93mV more neg than outside for electrostatic force to balance diffusion force
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| an electrode measures __ (w/ abbrev) (aka resting potential) of a neuron, which is __ | membrane potential (Vm)= -70mV
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| a neuron can either __ or __ electrical charge | gain or lose
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| gaining pos charge -> upward deflection on oscilloscope= | depolarization
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| gaining neg charge -> downward deflection on oscilloscope= | hyperpolarization
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| define "force" of 3 ions on a neuron | "passive leak" across membrane= charge leaking in or out (K, Na, Cl)
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| T/F: If an ion leaks the most (high permeability), it has the most influence on charge? | True (resting potential (Vm) closer to Eq potential (Em) of K & Cl)
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| Order of permeability of 3 ions? | K, Cl, Na
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| what is the predominant energy-consuming process in brain and how it works? | sodium/potassium membrane pumps. Moves 3 sodium out and 2 potassium in to maintain ion gradient
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| name the electrically excitable domain | axon
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| what effect does neg elec signal have on axon | none, hyperpolarization equal to input
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| what effect does pos elec signal have on axon | depolarization into region of instability in current/voltage relationship -> action potential (AP)
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| Describe what AP looks like: | 1. reaches threshold (-60mV)
2. rapid depol -> almost reaches ENa (30-50mV= 'overshoot's 0)
3. rapid hyperpol -> almost reaches EK (-80mV= undershoots Vm)
4. gradual return of membrane potential to resting value (-70mV)
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| T/F: large amount of ions need to move for charge to change | False
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| define conductance of an ion and give abbrev | ability to move across membrane (gNa or gK etc)
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| describe AP in terms of ions and charge: | 1. gain 10mV charge
2. inward pos current (Na rushes in)
3. outward pos current (K rushes out)
4. excess K diffuses away
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| describe AP in terms of conductance: | 1. +10mV charge
2. -> inc gNa (voltage dependent)
-> gNa turns self off (time dependent)
3. -> inc charge (more pos) -> inc gK (voltage dependent, less sensitive)
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| what happens to Na channels during AP? (gates) | 1. at rest, 2 gates closed
2. AP: depol -> physical re-shaping to unblock channel for only millisec (spring action timer)
3. inactivation gate closes and stays closed (refractory period) regardless of state of other gate/timer until K channels close
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| what are the differences between Na & K channels (how is K diff?) | 1. K has no inactivation gate, stays open until around Ek (-80mV)
2. Timer delays opening for 1 msec after depol
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| where on axon and in what direction does AP occur? | at nodes of ranvier, away from soma
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| how does Na & K return to original intra/extra cellular sites? | sodium/potassium pump (3 Na out, 2 K in)
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| name the other electrically excitable domain | pre-syn terminal (elect. signal triggers NT release)
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| what type of channel exists only at pre-syn term? | Ca
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| why is calcium an important piece of neuronal activity? | Entry to terminal facilitates NT release:
-activates fusion of vesicle proteins and membranes proteins -> bind and release (exocytosis)
-frees bound reserve vesicles to free pool
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| what calcium-dependent enzyme is present in terminal which aids in release of bound vesicles? | Kinase
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| what signals the postsyn potential | NTs binding to receptors
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| what is the chemically excitable domain | post syn region
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| what regulates ion conductance in chemically excitable domain? | presence of NTs -> chemical signal
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| postsyn potential= small and variable changes in __ produced by __-activated ion channels | membrane potential (Vm), transmitter
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| junction between soma and axon | axon hillock
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| EPSP function/role | conducive to AP (depol -> closer to threshold for AP)
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| IPSP function/role | prevents hillock from reaching threshold (hyperpol/block depol)
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| 2 ways to get excitatory effects (EPSP) | Increase gNa or gCa/ Decrease gK
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| how to get inhibitory effect (IPSP) | Increase gK or gCl
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| what happens when gCl is activated? | slightly depol (ECl= -66mV) but holds Vm near ECl and blocks depol influence
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