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Neuroscience > Chapter 5 > Flashcards

Chapter 5 Flashcards

1
Q

What is the purpose of synaptic transmission?

A
  • Synaptic transmission is information transfer at the synapse
  • Plays a role in all the operations of the nervous system
  • 1987:Charles Sherrington
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2
Q

How does information flow through the synapse?

A
  • Generally in one direction: neuron to target cell
  • First neuron: presynaptic neuron
  • Target cell: postsynaptic neuron
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3
Q

What are the two types of synapses?

A
  1. Electrical synapses (later 1950s, Furshpan and Potter)
  2. Chemical synapses (1921, Otto Loewi)
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4
Q

What is the structure of the electrical synapse?

A

Electrical synapse consists of a gap junction: a channel formed by Connexin proteins

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5
Q

What does it mean for cells to be electrically coupled?

A

Ions from the cytoplasm of one cell flow to the cytoplasm of another cell

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6
Q

What is the difference between electrical and chemical synapses?

A
  • Electrical synapses are bidirectional
  • Very fast transmission (postsynaptic potentials PSPs)
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7
Q

What is synaptic integration?

A

When several postsynaptic potentials (PSPs) occur simultaneously to excite a neuron, causing action potential

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8
Q

What is axdendritic synapse?

A

Axon to dendrite

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9
Q

What is axsomatic synpase?

A

Axon to cell body

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10
Q

What is axoaxonic synapse?

A

Axon to axon

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11
Q

What is axospinous synapse?

A

Axon to dendritic spine

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12
Q

What are the two types of categories of CNS synaptic membrane differentiations?

A

Gray’s Type I morphology and Gray’s Type II morphology

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13
Q

What is Gray’s Type I Morphology?

A

Asymmetrical morphing, usually excitatory synapses
-Glutamate transmitter

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14
Q

What is Gray’s Type II Morphology?

A

Symmetrical morphing, usually inhibitory synapses
- GABA or glycine neurotransmitter
- In addition to being on dendrites, they’re also clustered on soma or near axon hillock

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15
Q

What is the role and function of the neuromuscular junction (NMJ)?

A
  • Studies of NMJ established the principles of synaptic transmission
  • The postsynaptic membrane (motor end plate) contains junctional folds with numerous neurotransmitter receptors
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16
Q

What is the basis for neurological and psychiatric disorders?

A

Defective synaptic transmission

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17
Q

What is the sequence for chemical synaptic transmission?

A
  • Neurotransmitter synthesis
  • Load neurotransmitter into synaptic vesicles
  • Vesicles fuse to presynaptic terminal
  • Neurotransmitter spills into synaptic cleft
  • Binds to postsynaptic receptors
  • Biochemical/electrical response elicited into postsynaptic cell
  • Removal of neurotransmitter from synaptic cleft
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18
Q

What are amino acids and their role?

A

Small organic molecules that act as vesicles
- Glutamate (Glu)
- GABA
- Glycine (Gly)

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19
Q

What are amines and their role?

A

Small organic molecules that also act as vesicles
- Acetylcholine (Ach)
- Dopamine
- Histamine

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20
Q

What are peptides and their role?

A

Short amino acid chains (proteins) that act as secretory granules
- Substance P
- Dynorphin
- Enkephalins

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21
Q

What is the pathway for secretory granules?

A
  1. They are packaged with peptide neurotransmitters at the soma VIA the rough ER
  2. Enter the Golgi Apparatus pathway
  3. Transported to presynaptic sites via microtubule transport
22
Q

Synaptic vesicles require the local presence of….

A
  1. Neurotransmitter synthesizing enzyme
  2. Vesicular neurotransmitter transport protein
    * Are largely used and recycled locally at presynaptic sites
23
Q

What is shown in the image?

A

Release of neurotransmitter by exocytosis

24
Q

What is the purpose of SNARE proteins?

A

SNARE proteins dock the synaptic vesicle at the synaptic membrane

25
Q

What stimulates the process of exocytosis?

A

Exocytosis is stimulated by an increase in intracellular Calcium

26
Q

What is the sequence for Calcium stimulating exocytosis?

A
  1. Calcium binds to calcium sensor protein (Synaptotagmin)
  2. Alters conformation of SNARE complexes, triggering vesicle membrane incorporation intro presynaptic membrane
27
Q

What is the end result of exocytosis?

A

Neurotransmitter is released into the cleft and the vesicle membrane is recovered by endocytosis

28
Q

What are the neurotransmitter receptors?

A
  • Metabotropic receptors
  • G-protein coupled receptors
  • Transmitter-gated ion channels (ionotropic receptors)
29
Q

What is excitatory post-synaptic potential (EPSP)?

A

Transient postsynaptic membrane depolarization caused by presynaptic release of neurotransmitter

30
Q

What is the purpose of EPSP integration?

A
  • EPSP integration is when EPSPs are added together to produce significant postsynaptic depolarization
  • With sufficient EPSP integration, threshold can be reached to fire an action potential
31
Q

What is inhibitory post-synaptic potential (IPSP)?

A

Transient hyperpolarization of postsynaptic membrane potential caused by presynaptic release of neurotransmitter

32
Q

What is the function of inhibitory synapses?

A

They take membrane potential away from the action potential threshold
- They exert powerful control over neuron output

33
Q

What generates an EPSP?

A
  • A neurotransmitter, commonly glutamate
  • Glutamate ion channels = AMPA, NMDA
34
Q

What are synaptic vesicles?

A

Elementary units of synaptic transmission

35
Q

What is the purpose quantal analysis?

A

It’s used to determine the number of vesicles that release during neurotransmission

36
Q

Membrane depolarization falls off ____

A

Exponentially with increasing distance along a dendrite

37
Q

What are the purpose of dendrites?

A
  • They contribute to more complex integrative properties
  • Excitable dendrites boost the transmission of an excitatory synaptic event to the soma
38
Q

What ion channels are present in most dendrites?

A

Na+, K+, Ca2+

39
Q

What is the summary of synaptic integration?

A

It’s the process by which multiple synaptic potentials combine within one postsynaptic neuron

40
Q

What is the summary of EPSP?

A

-EPSP allows for neurons to peroform sophisticated computations
- Integration: EPSPs added together to produce significant postsynaptic depolarization
- Spatial summation: EPSPs generated simultaneously at different sites
- Temporal summation: EPSPs generated at the same synapse in rapid succession

41
Q

What generates an IPSP?

A
  1. A neurotransmitter, commonly GABA
  2. Gaba ion channels = GABAR
42
Q

What is the difference between excitatory and inhibitory synapses?

A

They bind different neurotransmitters and allow different ions to pass through channels
- Inhibitory synapses exert powerful control over neuron output

43
Q

What happens if the membrane potential is less negative than -65 mV IPSP?

A

IPSP will have hyperpolarizing effect

44
Q

What is shunting inhibition?

A

The synapse inhibits current flow from soma to axon hillock

45
Q

What is synaptic transmission modulation?

A

It’s the signaling of events that modifies the strength of synaptic transmission
Ex: activating G-protein coupled norepinephrine B-receptor

46
Q

Where are receptors commonly found?

A

In the membrane of presynaptic axon terminal

47
Q

What are autoreceptors?

A

Presynaptic receptors sensitive to the neurotransmitter released by the presynaptic terminal
- Appear to function as a sort of safety valve

48
Q

What is a common effect of activating autoreceptors?

A

Inhibition of neurotransmitter release

49
Q

What are the possible outcomes of a synaptic released neurotransmitter?

A
  • Diffusion of transmitter molecules away from synapse
    1. Reuptake: neurotransmitter re-enters presynaptic axon terminal
  • Requires plasma membrane transport proteins
    2. Uptake by nearby glia cells (astrocytes)
  • Requires plasma membrane transport proteins
    3. Enzymatic degradation
  • Ex: AChE cleaves Ach to render it inactive
50
Q

How do receptors react to drugs in the nervous system (neuropharmacology)?

A
  1. Receptor antagonists: inhibitors of neurotransmitter receptors
    - Curare (nicotinic acetylcholine receptor blocker)
  2. Receptor agonists: mimic actions of naturally occurring neurotransmitters
    - Nicotine (nicotinic acetylcholine receptor activator)
51
Q

Essentially, what is the molecular basis for drug addiction?

A

Hijacking brain reward circuits

Neuroscience (8 decks)

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