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Exploring Neuroscience > Unit 1 Exam (Ch 2,3,4) > Flashcards

Unit 1 Exam (Ch 2,3,4) Flashcards

Resting Potential, Action Potential, Intro info

1
Q

Glia

A

-Contribute to brain fxn by insulating, supporting, or nourishing neighboring neurons

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2
Q

Neuron

A
  • Brain cell
  • Basic unit of brain fxning
  • Sense changes in environment
  • Communicate changes to other neurons
  • Command body’s response to these sensations
  • Cell body, dentrites, axon, neuronal membrane (separates inside from outside)
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3
Q

Histology

A

-The microscopic study of the structure of tissues

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4
Q

Cajal

A
  • Worked out circuitry of brain using golgi stain

* *Communicate through CONTACT not Continuity

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5
Q

Soma/Cell body

A
  • Cystol: watery fluid inside cell, K+ rich, separated from outside by neuronal membrane
  • Contains organelles
  • Cytoplasm: Everything inside cell membrane, including organelles but excluding nucleus’
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6
Q

Nucleus

A
  • Spherical
  • double membrane
  • Location of chromosomes/transciption
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7
Q

Gene expression

A
  • Reading of DNA
  • Final product= proteins
    • Give neurons unique characteristics
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8
Q

Protein synthesis

A
  • Creation of proteins (translation)
  • Location= cytoplasm
  • Done by mRNA (4 diff nucleic acids in chain, sequence represents genes)
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9
Q

Transcription

A

-Assembling of mRNA that contains info of a gene
-Result= transcript
@ One end of gene= promoter, where RNA polymerase binds to initiate
-Other end= terminator, RNA recognizes as end of transcription
-RNA splicing
-mRNA leaves nucleus through pores
***Transcription of a single gene gives rise to several diff mRNAs and protein products

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10
Q

RNA splicing

A
  • In middle of gene= introns and exons
  • introns removed and exons fused together
  • Altetnatively spliced mRNA–> specific exons removed w/ introns
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11
Q

Amino Acids

A
  • Building blocks of proteins

- 20 kinds

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12
Q

Translation

A

-Assembling of proteins from amino acids using mRNA

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13
Q

Molecular Biology

A

-Study of DNA in the nucleus and synthesis of protein molecules in cell

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14
Q

Genome

A

-Entire length of DNA that comprises the genetic info in our chromosomes

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15
Q

Gene copy # variations

A
  • Genes are missing or duplicated

- Potential cause of schizophrenia and autism

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16
Q

Mutations

A
  • Errors in gene
  • Small mutations= single nulceotide polymorphisms
    • Misspelling of word due to single letter
  • Can affect protein/neuron fxn
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17
Q

Genetic Engineering

A

-Ways to change organisms by design w/ gene mutations or insertions

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18
Q

Knockout mice

A

-Mice w/ deleted gene

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19
Q

Transgenic mice

A

-Genes introduced and overexpressed

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20
Q

Knockin mice

A

-Negative gene replaced w/ modification

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21
Q

Rough ER

A
  • Membrane w/ ribosomes attached

- Stained by Nissl Stain

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22
Q

Ribosomes

A
  • Location of protein synthesis on rough ER

- Use the blueprint provided by mRNA to manufacture proteins from raw material to create amino acids

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23
Q

Free Ribosomes

A
  • Freefloating ribosomes
  • Attached by strand of mRNA
  • Create proteins in cytosol
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24
Q

Smooth ER

A
  • Membraneous organelle
  • Proteins jut out of membrane, are folded
  • Play no role in processing proteins, regulate calcium
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25
Q

Golgi Apparatus

A
  • Membrane enclosed discs in soma

- Sort proteins and deliver them to diff parts of neuron

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26
Q

Mitochondria

A
  • Site of cellular respiration
  • Folds= cristae
  • Brings pyruvic avid and oxygen into cystol
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27
Q

The Neuronal Membrane

A
  • Barrier to enclose cytoplasm inside the neuron
  • Excludes certain substances that float in fluid that bathes neuron
  • Protein comp. depends on whether soma, dendrites, or axon
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28
Q

Cytoskeleton

A
  • Gives neuron shape

- Made up of microtubules, microfilaments, and neurofilaments

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29
Q

Microtubules

A
  • Largest
  • Located at neurites (run longitudinally)
  • Straight, thin, hallow pipe
  • Small strands= tubulin
  • Anchor microtubules to each other and parts of neuron
  • Actin guides axons onto dendritic spines
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30
Q

Microfilaments

A
  • Smallest
  • Concentrated at synapses
  • Run longitudinally along neurites (dendrites and axons)
  • As thick as cell embrane
  • Made up of two thin strands of actin (changes size of cell)
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31
Q

Neurofilaments

A
  • Middle size
  • Structural support of axon
  • Intermediate filaments in other cells, neurofilaments in neurons
  • Multiple subunits wound together in ropelike structure
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32
Q

Axon

A
  • Specialized for transfering info over distances
  • Axon hillock: beggining of axon connected to soma
  • Thicker the axon, faster impulse travels
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33
Q

Axon distinctions

A

(1) no rough ER
(2) diff protein comp than soma
(3) no protein synthesis

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34
Q

Axon collaterals

A

-Branches from axon
-Travel long distances to comm. w/ diff parts of NS
Ex: Recurrent collaterals: axon collateral returns to comm with same cell that gives rise to axon/ dendrites of neighbors

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35
Q

Axon Terminal

A
  • End of an axon
  • Comes in contact w/ other neurons at synapse
  • Terminal arbor- short branches at end of axon that forms synapse
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36
Q

Innervation

A

-When a neuron makes synaptic contact with another cell

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37
Q

Cytoplasm in axon terminal differences from axon

A

(1) Microtubules do not extend into the terminal
(2) terminal contains synaptic vessicles
(3) inside surface of membrane that faces the synapse has a particularly dense covering of proteins
(4) Axon terminal cytoplasm has mitochondria (high energy demand)
(5) not myelinated

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38
Q

Synapse

A
  • side: presynaptic (axon terminal) and postsynaptic (recieving dendrites/soma)
  • Space btwn= synaptic celft
  • Transfer of info= synaptic transmission
    • electrical at axon, chemical at synapse, electrical at dendrites
  • *Located at dendritic spines
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39
Q

Neurotransmitters

A

-Chem signal released at presynaptic end into synaptic cleft

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40
Q

Axoplasmic Transport

A
  • Movement of materials down an axon
  • Material is enclosed w/in vessicles, walk down microtubules of axon using protein
    • Soma to terminal= anterograde transport w/ Kinesin
    • Terminal to soma= retrograde transport w/ dynein
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41
Q

Dendrites

A
  • Dendritic tree= dendrites of single neuron
    • branch= dendritic branch
  • Has RECEPTORS that detect the neurotransmitters in the synaptic cleft
  • Dendritic spines- isolate various chem reactions triggered by synaptic activation
  • Cytoplasm similar to axons
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42
Q

Ways to classify neurons

A
  • Structure: # of neurites, types of dendrites, connections, axon length
  • Classification based on gene expression
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43
Q

Number of Neurites

A
  • Unipolar= 1 neurite
  • Bipolar= 2 neurites
  • Multipolar= 3 or more neurites (most pop in brain)
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44
Q

Dendrites as way of classifying neurons

A
  • Stellate cells= star shaped
    • Either spiny or aspinous
  • Pyramidal cells
    • Always spiny
  • Spiny or aspinous (nonspiny)
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45
Q

Connections as way of classifying neurons

A
  • Primary sensory neurons- @ sensory surfaces of body such as skin
  • Motor neurons- muscles and command movements
  • Interneurons- Connect to other neurons, brain and spinal cord
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46
Q

Axon length as way of classifying neurons

A
  • Golgi type I neurons/ projection neurons
    • One part of brain to another
  • Golgi type II neurons/local circuit neurons
    • short axons that do not extend beyond cell body
47
Q

Neuron classifications based on gene expression

A
  • Diff in gene expression causes physical differences
    • Ex: pyramidal v stellate
  • Which neurotransmitter used
    • Due to diff in expression of proteins
    • Ex: motor neuron= acetylchonline
48
Q

Astrocytes

A
  • Glia
  • Abundant at synapses and nodes of ranvier
  • Influence whether a neurite can grow or retract
  • Regulates chemical content in extracellular space
  • Restrict spread of neurotransmitters released at synpase/ remove neurotransmitters
  • Control concentration of substances
49
Q

Myelinating Glia

A
  • Oligodendroglial (CNS, several axons) and Schwann cells (PNS, one axon)
  • Insulate axons w/ myelin
    • Uninsulated part of axon= Node of Ranvier (saltatory conduction)
      • Speeds up impulses
      • Highly enriched w/ ion channels
50
Q

Microglia

A
  • Glia
  • Phagocytes
  • Remove debris left by dead or decaying neurons and glia
51
Q

Neuron Doctrine

A
  1. Neuron is the basic unit of NS

2. Neurons in contact through synapse, not continuity

52
Q

How is a neuron unique?

A

-Specialization for sending info rapidly along great distances

53
Q

Action Potential

A
  • A brief fluctuation in membrane potential caused by the rapid opening and closing of voltage-gated ion channels
  • Spike, nerve impulse, discharge
  • Fixed in size and duration
  • Info encoded in the pattern of electrical impulses
  • Positive inside, neg outside
54
Q

Excitable Membrane

A
  • Cells capable of generating and conducting action potential
    • Nerve and muscle cells
55
Q

Resting Membrane Potential

A

-Positive outside, neg inside
-Difference in electrical charge across membrane
Vm= -65 mV
-Calculated using Goldman equation
*K+ higher inside, Na+ and Ca2+ higher outside
*Membrane permeable to K+ at rest because potassium leak channels

56
Q

Ions

A
  • Atoms ot molecules that have a net electrical charge

- Ex: Na- or Cl+

57
Q

Neuronal Phospholipid Membrane

A
  • Sheet of phospholipids 2 molecules deep
  • Hydrophobic heads face inner and outer watery environment
  • Hydrophilic tails face each other
58
Q

Hydrophilic

A

-Polar Molecules/water loving

59
Q

Hydrophobic

A

-Nonpolar molecules/water fearing

60
Q

Lipid

A
  • A class of water-insoluble molecules
  • important to structure of all membranes
  • Form barrier btwn water-soluble ions and water during RP and AP
61
Q

Channel Proteins

A

-Rod-shaped proteins w/ polar groups exposed at either end by only hydrophobic groups showing on their middle surfaces

62
Q

Ion channels

A
  • Ion selectivity
  • Specified by diameter of the pore
  • Nature of lining R-group
  • Gating= channels can open and close due to changes in microenvironment
63
Q

Ion Pumps

A

-Enzymes that use energy to transport certain ions across membrane against concentration gradient

64
Q

Influences on Movement of Ions

A

-Influenced by diffusion and electricity

65
Q

Diffusion

A
  • Net movement of ions from regions of high concentraton to regions of low concentration (Moving w/ conc gradient)
  • Causes ions to be pushed through channels of the membrane
  • Ions move this way when
    (1) Membrane has channels permeable to ions
    (2) Concentration gradient across the membrane
66
Q

Concentration Gradient

A
  • Differences in concentration from one region to another

- Ions flow down their concentration gradient

67
Q

Ohms Law

A

V=IR

  • Relationship btwn conductance, potential, and ammount of current that will flow
  • If no current, no voltage possible
68
Q

What requirements are there to drive ions across a membrane?

A
  1. Membrane that posesses channels permeable to that ion (provides conductance)
  2. Electrical potential difference across the membrane
69
Q

Membrane Potential

A
  • The voltage across the neuronal membrane at any moment
  • Close to Ek at RP
  • Symbol= Vm
    1. Larger changes in membrane potential caused by small changes in ionic concentration
    2. Net diff in electrical charge occurs at the inside and outside surfaces of the membrane
    3. Ions driven across membrane at rate equal to diff btwm membrane potential and equilibrium potential
    4. Conc. diff across membrane is known for that ion, equilibrium potentials can be calculated for that ion
70
Q

Voltometer

A

-Measures the electrical potential diff btwn tip of microelectrode and wire outside cell

71
Q

Equilibrium state

A

-Diffusional and electrical forces are opposite and equal

72
Q

Ionic equilibrium potential

A
  • Electrical potential differences that exactly balances an ionic concentration gradient
  • Eion
  • Membrane potential that would result if a membrane were selectively permeable
73
Q

Ionic Driving Force

A
  • The diff between real membrane potential and equilibrium potential (Vm-Eion)
  • Biggest absolute value
  • Tells us which way and how powerfully an ion would flow if we opened a channel selective to that ion
74
Q

Distribution of Ions across a membrane

A
  • K+ more concentrated on inside
  • Na+ and Ca2+ outside
  • Ionic concentration gradients established by the actions of ionic pumps in the neuronal membrane
    • Sodium-potassium pump & calcium pump
75
Q

Sodium-Potassium Pump

A
  • Uses ATP to drive Na+ and K+ against their. concentration gradients
  • Na+ out, K+ in
  • Maintains resting potential
76
Q

Calcium Pump

A

-Active transport of Ca2+ out of cytosol across membrane

77
Q

Goldman Equation

A

-A mathematical relationship used to predict membrane potential from the concentrations and membrane permeabilities of ions
Vm=RT/F ln (sum of Pinion conc. at equilibrium)

***ACCOUNTS FOR ALL IONS

78
Q

Depolarization

A

-The change in membrane potential from the normal resting value (-65mV) to a less neg value

79
Q

Charge

A
  • Colombs
  • Positive or neg based on valence e-
  • Ex: Na+ or Cl-
80
Q

Energy

A
  • Joules

- Force x distance applied

81
Q

Selective Permeability

A
  • Cells leak K+ at rest
  • K+ higher intercellularly, conc. gradient pushes the ion out of the cell–> inside more neg
  • THE MORE PERMABLE A CELL IS TO AN ION, THE CLOSER THE CELLS POTENTIAL WILL BE TO THAT EQULIBRIUM POTENTIAL
82
Q

How do we change membrane potential?

A
  • Permeability
    • Ion channels–> ligand gated channels, voltage gated channels, mechanically gated channels
  • Concentration Gradients
    • Electronic ion pumps regulate internal ion concentration
83
Q

Pumps

A

-Membrane proteins that slowly move ions against their concentration gradient

84
Q

Channels

A
  • Allow ions to flown w/ concentration/ electrochemical gradient
  • Selective to specific ions
85
Q

Receptors

A

-Embedded within ion channels such as ligand’s binding triggers to opening the channel

86
Q

Action Potential Steps/ Info

A
  • A positive voltage shift that activates voltage gated sodium channels
  • Travels down axon to depolarize axon terminal
  • Terminal depolarization initiates transmitter release
  • Frequency and pattern used to transfer info
  • Length: 2 mseconds
  • ALL OR NONE
87
Q

What would happen if a neuron where deprived of ATP?

A
  • The cell would die of excitotoxicity (too many action potentials)
  • Loss of ATP–> Ion pumps cease to fxn–>intracellular K+ drops, Intracellular Na+ rises, Intracellular Ca2+ rises–> cell depolarizes and spikes uncontrollably–>all no longer polarized–> dead
88
Q

Voltage Gated Sodium Channels

A
  • Activated by voltage, inactivates itself
  • Highly selective to sodium
  • Closed at RP, twists open w/ depolarization
  • S4=voltage sensor (activates pore opening through depolarization)
  • Ball and chain
  • Resting closed, activated open, inactivated closed
89
Q

Voltage Gated Potassium Channels

A

-Activated by depolarized voltage

90
Q

Voltage-gated Ca2+ channels

A

-Trigger burst firing

91
Q

Ligand Gated excitatory channels

A
  • Both bind to neurotransmitter glutamate
  • AMPA: allows Na+ into cell
  • NMDA: Allows Na+ and Ca2+ into cell
  • Creates post synaptic potential (PSP) that could trigger AP
92
Q

Ligand Gated Inhibitory Channels

A

-GABA-A: Binds to neurotransmitter GABA to allow the flow of Cl- ions into the cell

93
Q

Mechanically Gated Touch Receptors

A
  • Meissner’s Corpuscles and Merkel’s Discs

- Concentrated near surface of skin

94
Q

Mechanically Gated Pain Receptors

A
  • Free nerve endings (heat) and Pacinian Corpuscus (deep pressure)
  • Have a higher threshold activation
  • Travel to brain via different routes than light touch
95
Q

What causes post-synaptic potential?

A

-Caused by the activation of ligand gated channels and mechanically gated channels

96
Q

Capacitance

A
  • The ability to “store” charge
  • Measured in Farads
  • dependent on distance of separation of charge
  • Neurons deal with this through myelination
    • Decreases capacitance (AP travels faster)
97
Q

Rising Phase

A
  • Rapid depolarization of membrane
  • About 40 mV
  • Membrane sodium channels open, Na+ go into cell
  • Inside membrane has neg membrane potential= driving force for Na+
98
Q

Overshoot

A
  • Membrane potential goes to value closer to Ena, greater than 0mV
  • Due to relative permeability favoring Na+
99
Q

Falling Phase

A
  • Rapid repolarization until neuron is more neg inside than before
  • Na+ inactivates
  • K+ channels open–> outward
  • Causes membrane potential to be neg again
100
Q

Undershoot

A
  • Hyperpolarization
  • Gradual restoration of RP
  • VG k+ channels add to resting K+ permeability
  • Membrane potential goes towards Ek
101
Q

How does Depolarization occur?

A
  1. Caused by specialized Na+ ion channels sensitive to membrane stretching
  2. Interneurons-> Na+ entry through channels sensitive to neurotransmitter
  3. Injecting current through microelectrode
102
Q

Generation of Multiple APs

A

-Firing frequency of AP reflects magnitude of the depolarizing current

103
Q

Relative Refractory Period

A
  • Amount of current required to depolarize a neuron to AP threshold is elevated above normal
  • Difficult to initiate another AP
104
Q

Optogenetics

A
  • Controlling neural activity w/ light

- Introduces neurons to foreign genes that express membrane ion channels that open in response to light

105
Q

Hodgkins and Huxley

A
  • Voltage clamp
  • Proved rising phase= influx of Na+, falling= outflux K+
  • Gates opened by depolarization, inactivated by + membrane potential, open again after membrane returns to neg value
  • K+= delayed recifier, opens after Na+ channels
106
Q

Patch Clamp

A
  • *Allows you to control for current or voltage to find out the other in V=IR
  • Used to study ionic currents passing through individual ion channels
  • Sealing tip of electrode to small patch of neuronal membrane
  • Patch torn away, measures membrane potential
  • Enabled fxnal properties of VG sodium channels
107
Q

Threshold

A

-Membrane potential at which enough voltage-gated Na+ channels open so relative ionic permeability of membrane favors Na+ over K+

108
Q

Absolute Refractory Period

A
  • Na+ channels inactivate when membrane becomes strongly depolarized
  • Cannot be activated again, AP cannot be generated again till membrane potential is neg
109
Q

Factors Influencing Conduction Velocity

A
  • Velocity increases w/ increased axon diameter
  • Presence or absence of myelin
  • Axonal size and # of voltage gated chanels in membrane
110
Q

Spike Initiation Zone

A
  • The part of the neuron where axon originates from the soma

- Axon hillock

111
Q

Why does sodium go into the cell instead of out?

A
  • Higher conc outside than in

- Ena= +60mV

112
Q

Why does potassium go out of the cell instead of in?

A
  • Higher conc. inside than out

- Ek=-90mV

113
Q

Characteristics of Action Potential

A
  • All or none, either reaches threshold or doesn’t
  • Same magnitude and duration
  • Membrane briefly more positive inside than out
  • Regenerated over distance
    • Wave motion

Exploring Neuroscience (6 decks)

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