Topic 99 - Axonal transport and synaptic transmission, sensors, types of ion channels   Flashcards

1
Q

Words to include in axonal transport and synaptic transmission

A
  • Axonal transport
    • Neuropeptide
    • Vesicles
    • Presynaptic nerve ending
    • Neuro peptides (binding)
    • Modulated peptides (binding)
    • Carrier proteins
  • Action potential
  • Axon
  • Synaptic nerve ending
  • Neurotransmitters
    • Norepinephrine / noradrenaline
    • Acetylcholine
    • Glicin
    • Larger peptides
  • Synthesis
    • Peptides
    • Vesicles
    • Soma
    • Neuron
  • Motor proteins / transporter
    • ATP
    • Microtubular system
  • Anterograde transport
    • Soma → nerve ending
    • Kinesin
  • Retrograde transport
    • Nerve ending → soma
    • Dynein
  • Synaptic cleft
  • Postsynaptic membrane
  • Hyperpolarization
    • Resting membrane potential ↑
  • Depolarization
    • Resting membrane potential ↓

Neural network

  • Neural network
  • Synapse
    • Neuron
      • Axon
    • Soma
    • dendrite
  • CNS
  • Neurons
  • Electrical synapse
    • Presynaptic neurons
    • Postsynaptic neurons
    • Gap junction
    • Fast response
      • Defensive reflexes
    • Bidirectional
  • Gap junction
    • Synapse
    • Free diffusion of charges
    • Connexin
      • Hexamer
      • 6 connexin peptide
      • Hydrophilic channel
    • Fast communication
    • Bidirectional
      • Rectification
    • CNS
      • Fast reflex arches
      • Cardiac cells
  • Chemical synapse
    • Junctions
    • Non-neuronal cells
    • Vesicles
    • Exocytosis
    • Postsynaptic cell side
    • Threshold action potential
    • Presynaptic terminal
    • Post-synaptic density
    • Voltage gated Ca2+ channel
    • Synaptic vesicle
    • Axon terminal
      • Neurotransmitters
      • Neurotransmitter re-uptake pump
      • Neurotransmitter receptors
    • Synaptic cleft
    • Dendritic spine
  • Metabotropic effect
    • Neurotransmitter
    • Receptor
    • Postsynaptic neuron
    • Short term change
    • Long term change
  • EPSP (Excitatory Postsynaptic Potential)
    • Postsynaptic neuron (↑)
  • IPSP (Inhibitory Postsynaptic Potential)
    • Postsynaptic neuron (↓)
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2
Q

Words to include in sensors, types of ion channels

A
  • Na+
  • K+
  • Cl-
  • Leaking Na+, K+ and Cl- channels
    • Membrane potential
  • Voltage dependent Na+ and K+ channels
    • Action potential
  • Ligand dependent non-selective Na+, K+ and Cl- channels
  • Mechanoreceptive
    • Mechanical stimuli
  • Energy sensor
    • K+ channe
    • ATP
    • Depolarization
    • ATP concentration
  • Voltage dependent Na+ channel
    • Protein
    • IC part
    • Transmembrane part
    • EC part
    • 6-6 transmembrane segments
    • Tetrodotoxin (TIX)
  • Ligand dependent ion channel
    • Nicotinic acetylcholine (n-ACh)
      • Nicotine
      • Curare
      • Neuro-muscular junction
      • CNS
      • Skeletal muscle
        • Pentamer
          • 2 α subunit
          • 2 β subunit
          • 1 Δ subunit
            • D-tubocurarine
      • Nervous system
        • 2 α subunit
        • 3 β subunit
    • Glutamate
      • Excitatory system
      • CNS
      • Permable
        • Na+
        • K+
        • Ca2+
      • AMPA
      • NMDA
      • Kainate
    • Anion channels
      • Hyperpolarization
      • Mediators
        • GABA
        • Glycine
    • G-protein mediated
  • Mechanoreceptive channels (Ca2+-ion channels)
    • Ryanodine and DHP
      • Voltage sensors
      • T-tubules
      • Triad
      • Dihydropyridine (DPH)
      • Ca2+-channels
        • Ryanodine
        • Sarcoplasmic reticulum (SR)
    • IP3-receptor
      • IC Ca2+ stores
    • Voltage-dependent
      • P-type calcium channel
      • T-type calcium channel
      • N-type calcium channel
  • Energy sensor ion channel
    • ATP
    • Regulator subunit
    • Pore-forming subunit
    • Conformational change
    • K+ efflux
      • Depolarization
    • Ca2+ influx
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3
Q

Topics to include in the essay

A
  1. Axonal transport
  2. Neural network
    • Synapse
      • Electrical synapse
      • Gap junction
      • Chemical synapse
      • Metabotropic effect
  3. Sensors, types of ion channels
    • Voltage dependent Na+ channel
    • Ligand-dependent ion channel
      • n-ACh
      • Glutamate
      • Anion channels
      • G-protein mediated
    • Mechanoreceptive channels (Ca2+ ion channels)
      • Ryanodine & DHP
      • IP3-receptor
      • Voltage-dependent
    • Energy sensor ion channel
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4
Q

Axonal transport

A
  • The action potential - conducted through the axon in the synaptic nerve ending produces the release of neurotransmitters
  • The synthesis of peptides and vesicles is only possible in the soma of the neuron
    • ​Axonal transport: The produced neuropeptides and vesicles must be transported to the presynaptic nerve ending
  • Molecular base of the transport: the binding of the neuro- and modulator peptides to carrier proteins in the soma
    • These transporter or motor proteins uses ATP on the microtubular system along the axis of the axon
    • Soma → nerve ending: Anterograde transport by kinesin
    • Nerve ending → soma: Retrograde transport by dynein
    • Vesicles stored in nerve endings are released to the synaptic cleft as a result of an action potential
    • The neurotransmitter can bind to their specific receptors on the postsynaptic membrane
    • The result of receptor-binding can be:
      • Hyperpolarization: Resting membrane potential ↑
      • Depolarization: Resting membrane potential ↓
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5
Q

Axonal transport

What are neurotransmitters composed of?

A
  • Small molecular weight substances, eg.:
    • Norepinephrine
    • Acetylcholine
    • Glicin
  • Large peptides
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6
Q

Neural network

Define synapse

A
  • Synapse:
    • Contact between the axon of one neuron and a dendrite or soma of another
    • Allows neurons to from circuits within the CNS
    • Allow the nervous system to connect to and control other systems of the body
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7
Q

Neural network

Name the different type of synapse

A
  1. Electrical synapse
  2. Gap junction
  3. Chemical synapse
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8
Q

Neural network

Synapse: Electrical synapse

A
  • A mechanical and electrically conductive link between two neurons that is formed at a narrow gap between the pre- and postsynaptic neurons known as a gap junction
  • Compared to chemical synapses:
    • Electrical synapses conduct nerve impulses faster
    • Unlike chemical synapses, they lack gain - the signal in the postsynaptic neuron is the same or smaller than that of the originating neuron
  • Location: In neural systems that require the fastest possible response
    • Eg. defensive reflexes
  • Bidirectional (most of the time)
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9
Q

Neural network

Synapse: Gap junction

A
  • Allows free diffusion of charges between cells
  • Connexin:
    • ​Hexamer
    • Built up by six connexin peptide
  • The shortest information transduction which allows the fastest communication between cells
  • Bidirectional
    • ​Rectification: In some junctions one of the directions is dominant
  • Location: fast reflex arches in the CNS
    • Eg. between cardiac cells
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10
Q

Neural network

Synapse: Chemical synapse

A
  • Signal between:
    • Between neurons
    • Between neuron and non-neuronal cells
  • One neuron releases neurotransmitter molecules into the synaptic cleft
    • Triggered by a nerve impulse/AP
  • The neurotransmitters are kept within vesicles and are released into the synaptic cleft by exocytosis. These molecules then bind to receptors on the postsynaptic cell’s side of the synaptic cleft
  • In response to a threshold action potential, a neurotransmitter is released at the presynaptic terminal
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11
Q

Metabotropic effect

A
  • Metabotropic effect: The binding of neurotransmitters to receptors in the postsynaptic neuron can trigger either short term changes or long term changes
  • Long term effects are based on the the fact that neurotransmitters cause intramembrane or IC changes leading to long term depolarization or hyperpolarization
    • ​Metabolic changes evokes the alteration of K+ and Ca2+ conductance, which is the primary reasons of long term depolarization or hyperpolarization
  • Gap junction procces leads either to:
    • EPSP (Excitatory Postsynaptic Potential)
      • Man discharge frequency of the postsynaptic neuron ↑
    • IPSP (Inhibitory Postsynaptic Potential)
      • Man discharge frequency of the postsynaptic neuron ↓
  • Transmitters involved: Metabotropic transmitters
    • Response to them: metabotropic response
  1. Binding of ligand to receptor
  2. IC 2nd messenger
  3. IC metabolic (metabotropic) effect
  4. Long lasting depolarization or hyperpolarization
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12
Q

Types of ion channels

Role

A
  • They are proteins molecules that span across the cell membrane allowing the passage of ions from one side of the membrane to the other side
  • They are selective - they only allow certain ions to pass
  • They are involved in the transmission of signals in the nervous system
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13
Q

Type of ion channels

Name the different types of ion channels

A
  • Leaking sodium, potassium and chloride channels
    • Maintenance of the membrane potential
  • Voltage-dependent sodium and potassium channels
    • Generation of action potential
  • Ligand-dependent non-selective sodium, potassium and chloride channels
    • Multiple
  • Mechanoreceptive
    • Uptake of tactile and other mechanical stimuli
  • Energy sensor
    • Potassium channel sensitive to ATP causes depolarization according to the ATP concentration of cell
  • More info about these channels on the next cards:
    • Voltage dependent Na+ channel
    • Ligand dependent ion channels
      • ​Nicotinic acetylcholine dependent non-selective Na+/K+ channel
      • Glutamate dependent cation channel
      • Anion channels
      • G-protein mediated signal transduction
    • Mechanoreceptive channels (Ca2+ ion channels)
      • ​Ryanodine and DHP
      • IP3-receptor
      • Voltage-dependent
    • Energy sensor ion channel
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14
Q

Types of ion channels

Voltage dependent Na channel

A
  • This protein contains IC, transmembrane and EC parts
  • Four main domains with 6-6 transmembrane segments (1-6) each
  • Specific inhibitor: tetrodotoxin (TIX, a poison)
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15
Q

Types of ion channels

Name the different types of ligand dependent ion channels

A
  • Nicotinic acetylcholine dependent non-selective Na+/K+ channel
  • Glutamate dependent cation channels
  • Anion channels
  • G-protein mediated signal transduction
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16
Q

Types of ion channels

Ligand dependent ion channels: Nicotinic acetylcholine dependent non-selective Na+/K+ channel

A
  • Stimulated by nicotine
  • Inhibited by curare
  • Receptor of the neuro-muscular junction and the CNS
  • In skeletal muscle:
    • Pentamer containing:
      • 2 α-subunits
      • 2 β-subunits
      • 1 Δ-subunit
        • Binds d-tubocurarine
  • In nervous system:
    • Contains:
      • 2 α-subunits
      • 3 β-subunits
17
Q

Types of ion channels

Ligand dependent ion channels: Glutamate dependent cation channels

A
  • Important excitatory system of the CNS
  • Permeable for Na+, K+ and Ca2+
  • Three different types are known:
    • AMPA
    • NMDA
    • Kainate
18
Q

Types of ion channels

Ligand dependent ion channels: A__nion channels

A
  • Opening of anion channels causes hyperpolarization
  • Two main mediators are known:
    • GABA
    • Glycine
19
Q

Types of ion channels

Name the different types of mechanoreceptive channels (Ca2+ ion channels)

A
  • Ryanodine and DHP (Dihydropyridine) receptor
  • IP3-receptor
  • Voltage dependent
20
Q

Types of ion channels

Mechanoreceptive channels: Ryanodine and DHP (Dihydropyridine) receptor

A
  • Voltage sensors in T-tubules or in triad
    • Blocked by dihydropyridine (DPH)
  • Mechanically activates the calcium channels (sensitive to ryanodine) located in sarcoplasmic reticulum
21
Q

Types of ion channels

Mechanoreceptive channels: IP3-receptor

A

Mobilizes Ca2+ from the IC calcium stores

22
Q

Types of ion channels

Mechanoreceptive channels: Voltage-dependent Ca2+-channels

A
  • Activated by membrane potential change
  • Most well known types:
    • P-type calcium channel
    • T-type calcium channel
    • N-type calcium channel
23
Q

Types of ion channels

Energy sensor ion channel

A
  • Low level of ATP: the channel is open
  • ATP levels increase:
    • Regulator subunit shows conformational change
    • Pore-forming subunit shows conformational change
    • K+ efflux terminates, IC + increases, this leads to depolarization
    • Ca2+ influx: different metabolic effects