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PSYC 211 (Behavioural Neuroscience) > Introduction Part 1 > Flashcards

Introduction Part 1 Flashcards

1
Q

Where are motor neurons located?

A

In the CNS, controls the contraction of a muscle or the secretion of a gland

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2
Q

Where are most interneurons located?

A

Within the CNS and connect neurons to each other, all sensory neurons are connected by interneurons

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3
Q

What is a major substrate of brain plasticity?

A

Dendrites, and the small membranous protrusions which dictate dendritic spine density

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4
Q

The thicker the axon the ____ the action

A

faster, usually thicker because of the myelin sheath

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5
Q

What are the supporting cells of the CNS?

A

Glial cells, which provide nutrients for the neurons

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6
Q

What do astrocytes do?

A

Digest debris and participate in phagocytosis, the most numerous glia in the brain

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7
Q

What do oligodendrocytes do?

A

Help produce myelin sheath

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8
Q

What do microglia do?

A

Smallest immune cells of the CNS, help destroy pathogens and migrate to the site of infection and injury

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9
Q

What are ependymal cells?

A

Line brain ventricles and produce the CSF - protection of the brain & means of removing metabolic waste

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10
Q

What are mylenating glia?

A

Includes oligodendrocytes and shwann cels

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11
Q

(T/F) Schwann cells insultate the PNS

A

T, and Oligo cells insulate the CNS

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12
Q

What is the BBB lined by?

A

Astrocytes, and helps keep tight junctions and substances require active transport. Area postrema is less conservative

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13
Q

What is MS?

A

An attack on the oligodendrocytes in the CNS, breaks down the myelin and makes communication thry these circuits less reliable

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14
Q

Dicsuss the role of inhibition in a reflex arc

A

The excitatory synapses can be overriden by inhibitory synapses if our brain wants to. An interneuron will inhibit the motor neuron preventing a muscular contraction

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15
Q

Which cell type has the smallest (most negative) RMP?

A

Skeletal muscle (-95 mV)

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16
Q

What are three ways of measuring electrical potentials of axons?

A

1) Electrode (apply electrical stimulation or record electrical stimulation)
2) Microelectrode (record activity of individual neurons)
3) Membrane potential ( the electrical charge across a cell membrane)

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17
Q

What are the three main players necessary for maintaining RP?

A
  • The neuronal membrane
  • Fluid
  • Ion channels (proteins) in the neuronal membrane q
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18
Q

What are the two key factors at play when it comes to RMP?

A
  • Diffusional force

- Electrostatic force

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19
Q

What is electrostatic force determined by?

A
  • Electric potential (voltage) - reflects the difference in charge between anode and cathode
  • Electrical conductance - refers to the relative ability or inability (resistance)of an electrical charge to migrate
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20
Q

Which force initially rules?

A

-Diffusion, and then electrical potential difference across the membrane

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21
Q

How is an equilibrium achieved?

A

When the electrical force of the ion is equal in the diffusion force of the ion (for example, K+)

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22
Q

(T/F) there is a higher water concentration inside the cell

A

F, more outside as there is a higher concentration of salt outside the cell, more K+ inside the cell
-Adding more sodium on the outside helps achieve greater osmotic balance

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23
Q

What causes Na+ to “leak” inside the cell?

A

Due to the concentration gradient (more Na+ outside vs inside), however is offset by the electrical force (As the +Na ions enter, space inside is less negative and therefore Na+ is less pulled inside)

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24
Q

What causes K+ to leak outside the cell?

A

Due to the concentration gradient, however K+ leaving the cell makes it more polarized, therefore there is a stronger electrical pull to bring the K+ back into the cell

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25
Q

What is RMP more skewed towards? Why?

A

k+, as the membrane is much more permeable to K+, there are 40x more channles

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26
Q

(T/F) the membrane is maintained at it’s equilibrium potentail

A

False, as membranes are always leaky, K+ is leaking out, and Na+ is leaking in

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27
Q

What is the solution for the leaks?

A

The sodium potassium pump, energy drives 3 K+ into the cell and 2 Na+ out of the cell

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28
Q

How do astrocytes regulate potassium?

A

Will take up K+ when extracellular levels are high, this is important because if more K+ is outside the cell then the cell is more negative, and therefore will be harder to depolarize

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29
Q

What is an action potential caused by?

A

A brief increase in membrane permeability to Na+, then a brief increase in permeability of membrane to K+

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30
Q

(T/F) the AP is of fixed size and duration

A

T

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31
Q

What are the two laws for the principles of generation of an AP?

A

1) All or none law

2) rate law

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32
Q

What is the all or none law?

A

The AP will be generated entirely across the length of the axon, or not at all

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33
Q

What is the rate law?

A

The magnitude, or size of each AP is constant, but what changes is how often it fired and the frequencies when we consider a weak stimulus compared to a strong stimulus

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34
Q

In an AP, what is the current?

A

Net movement of K+ across a membrane

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35
Q

In an AP, what is the potassium channel number proportional to?

A

Electrical conductance (i.e. more or less resistance)

36
Q

What is the flow and driving force of an AP?

A

The membrane potassium current

37
Q

(T/F) K+ will not leave the cell until Na+ channel cloes

A

F, starts to leave prior to the apex of the AP, and right after the Na+ channles have opened up and before the Na+ channels become refractory

38
Q

What causes the slight period of hyperpolaization

A

Extra K+ will diffuse out of the cell, still permeable to K+
-Not the voltage gated channels, but the K+ channels are open, therefore as we know that K+ is greater on the inside, more diffusion will push K+ out than needed

39
Q

What are the 4 properties of Na+ channels?

A
  • These channels are closed at normal RMP, and will only open when less negative
  • When depolarized, the individual channles will open qucikly
  • They will be inactivated (stay open) for 1 ms
  • They will not open again until they repolarize (becomes negative)
  • Must be de-inactivated
40
Q

What serves to rectify or reset membrane potential?

A

Potassium conductance

41
Q

What are the two ways depolarization can occur? What is this known as?

A

Thru both chemical and electrical signals

-Collectively known as generator potentials

42
Q

When are voltage gates K+ channles closed?

A

At rest and during the rising phase, only have one gate

43
Q

What is the refractory period?

A

The time after the Ap when no other AP can occur

44
Q

What is an absolute RP?

A

When Na+ channels are inactivated (must be de-inactivated by more -charge) and no AP is possible

45
Q

What is a relative RP?

A

Some, but not all Na+ channels are de-inactivated (or activated)

  • K+ channels are open
  • AP can occur, but requires a stronger depolarization because inside of cell is still very negative (K+ flowing out still)
46
Q

What does orthodromic conduction mean?

A

APs travel in one direction, and goes from soma down the axon terminal

47
Q

What does antidromic conduction mean?

A

Backwards propogation of nerve impulse, from axon terminal to soma

48
Q

What is the typical conduction velocity of an AP?

A

10m/sec

49
Q

What are the four factors which influence conduction velocity?** (PAMS)

A
  • Path of positive charge
  • Axonal excitability
  • Myelin
  • Spread of AP across the membrane
50
Q

Discuss the path of the positive charge

A
  • If the path across a wide axon with few open membrane pores (inside axon), the conduction will be faster
  • If the path is a narrow axon with many open pores, it will be slower (across the axonal membrane)
51
Q

Discuss Axonal excitability

A

Depends on the axonal diameter (where bigger = faster) and the number of voltage-gated channels

52
Q

Discuss myelination

A
  • larger axon=faster conduction
  • Insulate the axon
  • Creates saltatory conduction where there are Na+ channels concentrated at the nodes of ranvier
53
Q

Discus the spread of AP along a membrane

A

Speed of the AP depends on how far the depolarization is ahead of the AP spread, and depends on the axon structure –> garden hose analogy: If there are holes in a garden hoe, the larger the diameter the less AP charge is lost

54
Q

When there are less voltage gates channels on a membrane, what happens?

A

-require greater depolarization, and more sensitive to anesthetics (channel blockers)

55
Q

What is synaptic transmission?

A

The primary means of communication between neurons

56
Q

What is postsynaptic potentials?

A

Brief periods of depolarization or hyperpolarizations

57
Q

Where can a postsynaptic potential be terminate on?

A

The dendrite or the soma

58
Q

Most of the synaptic transmission in the nervous system is ___

A

chemica

59
Q

Discuss axodendritic arrangement

A

Axon –> dendrite

60
Q

Discuss axosomatic arrangement

A

Axon –> cell body

61
Q

discuss axoaxonic arangement

A

Axon –> axon

62
Q

Discuss dendrodendritic arrangement

A

Dendrites –> dendrites

63
Q

How does the arrival of AP trigger NP release?

A

Depolarization of terminal membrane causes the opening of voltage Ca+ gated channelsWhat (Ca+ pulls outwards, but has an inward driving force as the inside of the cell becomes much more negative)

64
Q

What are the two types of NP receptor?

A

1) Transmitter-gated (Amines, AA) Ionotropic –> Allows for fast synaptic transmission
2) GPCR Metobotropic receptors –> slower and more diverse actions, where ANY type of NT can bind. Most autoreceptors are G-protein-coupled.

65
Q

What is an example of an Ionotropic receptor?

A
  • ACh

- Will bind to alpha subunit, channel opens and Na+ now enters the postsynaptic cell

66
Q

_____ are less specific than voltage gated ion channels

A

NT channels - Ach channles are pearmeable to both Na+ and K+

67
Q

As a rule of thumb, when the membrane is permeable to ___ it is excitatory, and when permeable to ___ it is inhibitory

A

Na+ (EPSP)
Cl- (IPSP)

both are found in higher concentration outside the cell

68
Q

How do GPC receptors function?

A

Thru effector proteins, where the downstream proteins will effectuate the opening of a G-protein-gated ion channel
-Can also synthesize secondary messengers which alter cellular metabolism

69
Q

Influx of Na+ causes ___

A

depolarization, EPSP

70
Q

Efflux of K+ causes ____

A

Hyperpolarization, IPSP

71
Q

Influx of CL- causes ____

A

Hyperpolarization, IPSP

72
Q

Influx of Ca+ causes ___

A

Activation of enzymes/contractions of ions

73
Q

Why must Nts be cleared from the synaptic cleft?

A

-Because the signals must terminate, and there is a risk for desensitization

74
Q

How are NTs removed from the synaptic cleft?

A
  • Diffusion
  • Re-uptake into the presynaptic axon terminal
  • Enzymatic degradation
75
Q

What is neural intergration?

A

When potentials summate to have a greater effect within a synaptic neuron, depends on whether summation is EPSP or IPSP

76
Q

What are the two types of EPSP summation?

A
  • Spatial summation

- Temporal summation

77
Q

What is spatial summation?

A

-Adding of EPSPs generated at different synapses in the same dendrite

78
Q

What is temporal summation?

A

-Adding EPSPs to generate the SAME synapse in rapid succession

79
Q

What are autoreceptors?

A
  • Found ont he presynaptic axon terminal, usually controlled by GPCRS
  • Are often inhibitory and turn off the release of APs
  • Can be though of as a “safety valve”
80
Q

What can axoaxonic synapses produce?

A
  • Presynaptic inhibition

- Presynaptci facilitation

81
Q

How do axoaxonic synapses produce presynaptic inhibition?

A

By reducing the amount of NT released by the terminal button, as in the terminal button it is effectuating its action on

82
Q

How do axoaxonic synapses produce presynaptic facilitation?

A

By increasing the amount of NT released by the terminal button

83
Q

How can IPSPS function?

A

-Can bind to different transmitter, an allow different ions to pass thru channels, causing hyperpolarization

84
Q

What are two types of nonsynaptic chemical communication?

A

1) neuromodulators

2) hormones

85
Q

How do neuromodulators work?

A

Chemicals released by neurons which will travel further and be dispersed further than NTs

86
Q

How do hormones work?

A

-Secreted by endocrine glands, where there are target cells which contain receptors for particular hormones

PSYC 211 (Behavioural Neuroscience) (4 decks)

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