Which types of ion channels are found on the nerve cell membranes?

• Voltage-gated ion channels
• Ligand-gated ion channels

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

• Voltage-gated ion channels react to changes in the membrane potential of the cell while ligand-gated ion channels are not ion-specific.
• Voltage-gated ion channels transmit signals from cell to nerve terminal while ligand-gated ion channels bind neurotransmitter to an ion channel.
• Voltage-gated ion channels contain Sodium, Potassium and Calcium channels while ligand-gated ion channels are ionotropic and consist of nicotine and acetylcholine channels.

Compare ionotropic and metabotropic receptors.

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

Ionotropic receptors

Ionotropic receptors in the CNS include GABAA, Nicotinic receptors, Excitatory Amino Acid (EAA) and 5-HT3 receptors

Metabotropic receptors

• Adenylyl Cyclase

This system contains positively (b_1+2, D₁) and negatively (D_2, a_2, 5-HT_1A, M₂) bound receptors. When the positively bound receptors get stimulated, they lead to the formation of second messengers that leads to the conversion of ATP to c-AMP. But when the negatively bound receptors get stimulated it does not lead to the formation of second messengers, thus the formation of c-AMP is inhibited.

2. Phospholipase C

This system only consists of positively bound receptors (a₁, 5-HT₂, M₁, H₁) and result in the formation when stimulated to the conversion of PIP₂ to DAG and IP₃

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

• EPSP

(Excitatory Postsynaptic Potential refers to the activation of the additional action potential as a result of depolarization. This is an example of Nicotinic receptors when Acetylcholine binds, the Sodium channels then open resulting in depolarization due to Sodium flowing in. 

• IPSP

Inhibitory Postsynaptic Potential forms a graded potential which makes a Postsynaptic neuron less likely to cause an action potential as a result of hyperpolarization. This is an example of GABA_A  receptor when gamma-butyric amino acid binds therefore Chloride channels open resulting in hyperpolarization as Chloride flows in. 

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

Calcium possesses the ability to directly depolarize the membrane and it can act as a second messenger. It is found on the axon terminal and when it is released it stimulates calcium influx, which causes vesicles to leave the cell. Calcium is essential for the release of neurotransmitters.