Unit 1 Flashcards
1
Q
Neuron Doctrine
A
Brain is composed of individual, highly specialized neurons. Not connected like wire, but separated by functional space
2
Q
Soma
A
Cell body. Receives information and decides whether to release further information
3
Q
Neurite
A
Cellular fibers extending from soma
4
Q
Pre-synaptic terminal
A
End of soma which contains synaptic vesicles of neurochemical signals for neurotransmitters
5
Q
Synapse
A
Connection between one cells pre-synaptic terminal and another’s post-synaptic area
6
Q
Neurontransmitter Receptors
A
Specialized (specific NT) proteins in post-synaptic membrane that bind neurotransmitters and form comm. link
7
Q
Law of Dynamic Polarization
A
By Ramon Cajal. Dendrites and axons are specialized neurites that receive and relay (respectively) chem. info. in the form of NT
8
Q
Axodentritic Synapses
A
Synapses between one cell’s axon and another’s dendrite.
9
Q
Axosomatic Synapses
A
Synapses between one cell’s axon and another’s soma.
10
Q
Axoaxonic Synapses
A
Synapses between one cell’s axon and another’s axon.
11
Q
Axosynaptic Synapses
A
Synapses between one cell’s axon and another’s synapse.
12
Q
Neuronal Action at Synapse
A
NT release from pre-synaptic terminal onto NT Receptors in post-synaptic membrane of neighboring neuron.
13
Q
Reuptake Pump
A
Specialized proteins in pre-synaptic terminal membrane that transport NT back into pre-synaptic terminal for re-use/breakdown
14
Q
SSRIs
A
Selective Serotonin Reuptake Inhibitors. Drugs that block reuptake pumps, thus forcing higher levels of NT in synaptic cleft, thus higher post-synaptic uptake.
15
Q
Types of Neurons
A
Bipolar, Unipolar, Multipolar. Depends on how many neurites from soma
16
Q
Sensory Neurons
A
Bring info from body to CNS
17
Q
Motor Neurons
A
Transmit info out of CNS to muscles
18
Q
Interneurons
A
Lie between sensory and motor neurons
19
Q
Neuronal Membrane
A
Phospholipid bilayer. Amphipathic (hydrophobic + philic region)
20
Q
Glutamate
A
Neuronal Excitor
21
Q
Aspartate
A
Neuronal Excitor
22
Q
Glycine
A
Neuronal Inhibitor
23
Q
Tyrosine + Tryptophan
A
Precursors for dopamine, serotonin, etc
24
Q
Peptide hormones
A
Small proteins released from nerve cell that act as neurochemical signals between cells or go into body organs
25
Structural Proteins
Help determine nerve cell shape and structure (actin, tubulin, elastin)
26
Anterograde Transport
Transport of material away from cell body to neurites with Kinesin
27
Retrograde Transport
Transport of material towards cell body from neurites using Dynein
28
Exocytosis
Process of dumping vesicle contents into extracellular space by bonding vesicle membrane with pre-synaptic membrane. Calcium breaks up bonds on synapsin on vesicles which wrap around proteins on membrane and pull.
29
Endocytosis
Process of recollecting materials from synaptic cleft by pinching pre-synaptic membrane into vesicle. Clathrin pulls membrane back to make new vesicle.
30
Chemoaffinity Hypothesis
Chemical signals (trophic factors) that allow for contact between neurons to find one another and make synapses.
31
Receptor Down-Regulation
If presynaptic cell increases its trophic factors being released, the postsynaptic cell decreases its receptor numbers to stabilize NT info reception. Desensitized. See: drug addiction
32
Receptor Up-Regulation
If presynaptic cell decreases its trophic factors being released, the postsynaptic cell increases its receptor numbers to stabilize NT info reception. Supersensitive. See: Phantom limb pain.
33
Schwann Cell
Glial cells that mylinate neurons in the peripheral nervous system. Each cell is associated with single neuronal axon, thus when axon is damaged, they form guidance tube to guide regeneration.
34
Oligodendrocytes
Cells that mylinate neurons in CNS. Because of so may neurons in CNS, oligodendrocytes supply multiple axons, thus cannot allow for regeneration.
35
Cation
Positive ion
36
Anion
Negative ion
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Chemical Quantity
Molar concentration (number of particles in 1liter of solution)
38
Intracellular Concentration (In cell)
High concentration of K+; Low of Na+, Cl-, Ca++
39
Extracellular Concentration (Outside cell)
Low concentration of K+; High concentration of Na+, Cl-, Ca++
40
Ion Pores
Proteins in membrane that form channel from inside to outside. Monomer (single protein) or polymer (mult. proteins)
41
Entropy
Process of disorder in a system. Evens out highly organized concentration gradients towards equilibrium by diffusion. Counters enthalpy. Diffusion principle
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Enthalpy
Process of maintaining concentration gradients by electrostatic force. Counters entropy. Electrical principle
43
Electrostatic Force
Development of charges within/without cell to retain the opposite charged ions
44
Equilibrium Potential (Em)
Determines necessary electrical charge (enthalpy) to balance out natural process of diffusion (entropy) for a given ion. Determined by Nernst Equation.
45
K+
Potassium ion. Em: -92mV
46
Membrane Potential (Vm)
Actual charge within a cell. Resting potential for a neuron: -70mV
47
Depolarization
Movement of ions that results in a more positive internal charge of a neuron.
48
Hyperpolarization
Movement of ions that results in a more negative internal charge of a neuron
49
Na+
Sodium ion. ENa: +56mV. Depolarizing effect on Vm when leaked in.
50
Cl-
Cloride ion. ECL: -66mV. Depolarizing effect on Vm when leaked in.
51
Relative Permeabilities of Ions
K:Cl:Na :: 1: 0.45: 0.04. Seeing as potassium leaks most, resting potential of neuron (-70mV) is closest to K+'s Em (-93mV)
52
Goldman Equation
Solves for value of Vm (membrane potential) by considering concentration and permeability of ions. Gives Em as -67mV = 3mV less negative than actual Em because it does not take into account the Sodium/Potassium Pump.
53
Sodium/Potassium Pump
Energy consuming process that makes up missing 3mV hyperpolarizing influence from Goldman Equation. Moves 3 Na+ out, 2 K+ in = net -3mV charge. Predominant energy-consuming process in brain.
54
Axon
Electrically excitable domain. Neurite that contains synapse.
55
Action Potential
Region of instability in voltage relationship. After cell hits -60mV (all or nothing threshold), abrupt depolarization to 50mV (Na+ enters axon) then rapid hyperpolarization to -80mV (K+ exits axon .5 msecs after Na+) overshooting resting potential before returning to resting potential. Takes 5 msecs. Based on conductance (movement) of ions, not gross concentration within/outside cell.
56
Na+ and K+ Conductance (g) in Action Potential
gNa is voltage and time dependent on turning self on/off (respectively). gK is voltage dependent.
57
Sodium Channel
Coiled amino acid chain on membrane that allows Na+ into cell. 1st gate: depolarization uncoils amino acids to unblock channel while timer allows gate open for one msec. 2nd gate: time basd and makes gate closed regardless of state of 1st gate.
58
Potassium Channel
Coiled amino acid chain on membrane that allows K+ out of cell. Larger, less sensitive than Na+ channel. 1 gate: voltage based opening w/o inactivation mechanism and remains opens until almost EK. Has delay mechanism that delays opening for 1msec after depolarization
59
Action Potential Propagation
Blocking channels allows next gate to detect pos charge and open -> move charge down axon.
60
Pre-synaptic Calcium Channels
Exist only in terminal. Ca++ enters cell -> depolarizes presynaptic terminal. Activates kinase which adds phosphate (phosphorylation) to synapsin on vesicle which allows it to go to terminal end, unfold vesicle proteins, and coil with membrane proteins.
61
Post-synaptic region
Chemically exciteable (signal that opens gates is chemical, not electrical signal as conductance is determined by presence of neurotransmitter. Results in Post-Synaptic Potentials (NOT Action potential)
62
Post-synaptic Potential
Small, variable changes in cell charge (membrane potential), produced by NT activated ion channels. Classified based on effect on axon hillock region.
63
Axon Hillock Region
Interface between cell body and axon.
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Excitatory Post Synaptic Potentials
EPSPs. Help hillock reach threshold (depolarizing dendrites and soma). Postsynaptic increase in Na+ / Ca++ conductance or decrease in K+ conductance. Increase positive charge = excitatory
65
Inhibitory Post Synaptic Potentials
IPSPs. Prevent hillock from reaching threshold (hyperpolarizing/block depolarization) Increase K+ or Cl- conductance. Decrease positive charge in cell = inhibitory. Often occur in absence of excitation, much more occuring than EPSPs
66
Integration
Dedritic reduction of all synaptic influences into single action potential. Takes into account spatial and temporal summation
67
Spatial summation
Adding together of EPSPs / IPSPs over space. Combined sum of inhib/exc influences. Synapses clses to axon hillock are more influential.
68
Temporal Summation
Sum of EPSPs / IPSPs over time. Repetive activation affects synaptic influence (additive). Bidirectional (Strong IPSP and Strong EPSP will cancel each other out)
69
Neurotransmitter Receptors as Neurotransmitter Channels
Possess a ligand (NT) binding site and gate that opens/closes when site is occupied. Excitation and inhibition properties of receptor, NOT NT
70
Affinity
How fast a ligand binds to receptor
71
Potency
How biologically effective a ligand is once bound to receptor
72
Agonist
Ligand that binds to receptor and activates it, producing post synaptic potential in target neuron. Can be exogenous or endogenous
73
Antagonist
Ligand that binds to receptor and prevents activation, blocking post synaptic potential in target neuron. High affinity. Never endogenous.
74
Exogenous
From outside body / artificial
75
Endogenous
From inside body / natural
76
Allosteric Modifiers
Bind to a receptor at allosteric site (not agonist/antagonist site) and increases affinity to binding to ligand.
77
Acetylcholine (ACh)
Synthesized by cholineacetyltransferase (ChAT) which fuses Acetate and Choline together. Interfaces between muscles and nerves.
78
Gamma-Aminobutyric Acid (GABA)
Inhibitory NT. Most common NT in brain. Most produce gCl. Synthesized from amino acid glutamate. Produces presynaptic inhibition in terminal
79
GABA Receptors
Cl- ion channel. Has at least two allosteric binding sites, one for Benzodiazepines, one for Barbituates: act as allosteric modifiers for GABA
80
Presynaptic Inhibition
GABA blocks synaptic terminal from incoming action potential by flooding terminal with Cl- (cloride shunting) which brings mV to -66, blocks Na+ which keeps Ca++ from coming in -> no release
81
GABA Antagonists
Produce unblock excitation and leads to epilepsy. Epilepsy also product of loss of GABA producing neurons. Includes Strychnine poison.
82
Glutamate
Chemically similar to GABA, mediates most excitation in brain.
83
Excitotoxicity
Glutamate causes cell death. Too much glutamate -> breaks down membrane -> release of too much glutamate -> ...
84
Glycine
Inhibitor in spinal cord, where it is used instead of GABA.
85
Biogenic Amines
Family of NTs synthesized from tyrosine (Catecholamines) or tryptophan (indolamines). Include dopamine, norepinephrine, adrenaline, serotonin, and melatonin
86
Peptide Transmitters
Short chain of amino acids. Can be used as peptide neurotransmitters (signal between neurons) or as peptide hormones (released into bloodstream to act as signal btw brain and body). Synthesized as large proteins in soma but broken down into active peptides. Metabolically expensive, so they work at low concentrations for long period of time (neuromodulators).
87
Endorphins/Enkephalins
Peptides that act as natural pain killers (morphines). Antagonized by naloxone.
88
Vasopressin and Oxytocin
Peptides involved in social recognition, aggression, nurturing, affiliation, water retention, milk letdown, and other CNS functions (contractile)
89
Catecholamines
Tyrosine -(tyrosine hydroxylase)-> L-Dopa -(AAA decarboxylase)-> Dopamine -(dopamine B-hydroxylase)-> Norepinephrine -> Epinephrine
90
Indolamines
Tryptophan -(Tryptophan-5-hydroxylase)-> 5-Hydroxytryptophan -(5 HTP-decarboxylase)-> Serotonin
91
Neuromodulation
Neuromodulator: substance that acts by modifying the affinity of a receptor for another NT. Large number of NTs present possibility of great complexity in chem signaling. Peptides often co-transmitters, released with other NTs.
