Voltage-gated ion channels	Ligand-gated ion channels
Respond to changes in membrane potential of the cell	Binding of the neurotransmitter  ligand directly opens the channel
Transmits signals from cell body to nerve terminal	Responsible for fast synaptic transmission typical of hierarchical pathways
Examples includes Na+, K+ and Ca2+ channels	Activation of these channels typically results in brief opening of the channels

Compare ionotropic and metabotropic receptors.

• Ionotropic receptors  consist of multiple subunits and are responsible for opening ion channels, binding of the neurotransmitter ligand directly opens the channel. Activation results in brief opening of the channel (a few milliseconds to ten milliseconds).
• Metabotropic receptors are seven-transmembrane G protein-coupled receptors responsible for metabolic changes, binding of the neurotransmitter engages a  G protein which results in the production of second messengers that mediate intracellular signaling cascades. Activation lasts longer (even minutes).

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

• Ionotropic receptors are GABA, Nicotinic, EAA and 5-HT₃
• Metabotropic receptors consists of two transduction systems the adenylyl cyclase system and the phospholipase system with  the following receptors each:

Adenyl cyclase system

Positevely linked receptors	Negatively linked receptors
β1+2, D1	D2, α2, 5-HT1A+B, M2

Phospholipase C system

All positively linked α₁, 5-HT₂, M₁, H₁

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

• An excitatory postsynaptic potential (EPSP) occurs when an excitatory pathway is stimulated, a small depolarization or excitatory postsynaptic potential is recorded. e.g when EAA binds to Na⁺ ion channels depolarization occurs, resulting in an EPSP.
• An inhibitory postsynaptic potential (IPSP) occurs when an inhibitory pathway is stimulated e.g when GABA binds to Chloride channels, hyperpolarization occurs resulting in an IPSP.

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

• Calcium ions trigger the release of neurotransmitter from synaptic vesicles into the synaptic cleft