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C ERASMUS
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LE 1.1

23 Feb 2021, 23:42 Publicly Viewable
  1. Which types of ion channels are found on the nerve cell membranes?

Voltage-gated channels and ligand-gated channels

  1. Name 3 differences between voltage-gated and ligand-gated ion channels.

  • Voltage-gated channels respond to changes in membrane potential of the cell, while ligand-gated channels respond to the binding of a neurotransmitter to the ion channels.
  • Voltage-gated ion channels are sodium, potassium and calcium channels whilst ligand-gated channels have GABA-A, ACh, Glutamate and serotonin transmitters.
  • Voltage-gated channels have metabotropic receptors where ligand-gated channels have ionotropic receptors.

  1. Compare ionotropic and metabotropic receptors.

Ionotropic

Metabotropic

Transmembrane ion channels that open or close due to binding of neurotransmitters.

Ion channels are regulated by a ligand.

Only four known receptors: GABAA, Nicotinic, **EAA and 5-HT3

Receptor stimulation is faster and doesn’t have prolonged effects.

Signal transduction is used for metabolic changes.

2nd Messengers modulate the ion channels

Seven transmembrane G-protein coupled receptors

Metabotropic receptor activation causes longer lasting effects.

  1. Classify the CNS receptors into ionotropic and metabotropic and know the transduction mechanism of each receptor.

Ionotropic

  • GABA-A, Nicotinic, EAA, 5-HT3

Metabotropic

  • Adenylyl cyclase system: Beta 1+2, D1, D2, Alpha2, 5-HT1a+b, M2
  • Phospholipase C system: Alpha1, 5-HT2, M1, H1

  1. Explain the difference between an EPSP and an IPSP and give examples of each

EPSP- Excitatory post synaptic potential when depolarization takes place. E.g. Glutamate

IPSP- Inhibitory post synaptic potential when hyperpolarization takes place. E.g. GABA-A

  1. What is the role of calcium in the development of a synaptic potential?

The influx of calcium ions causes neurotransmitters to be released from vesicles into the synaptic cleft. By means of exocytosis these neurotransmitters can bind to receptors to initiate a signal.  

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