Ion channels found on nerve cell membranes.

Voltage-gated and Ligand-gated channels.

 

3 Differences between ligand-gated and voltage-gated channels.

1. Voltage gated channels are ion specific while ligand gated channels are non specific.

2.  Voltage gated channels are activated by changes in membrane potential while ligand channels await the binding of a ligand (Neurotransmitter) to the channel.

3.  Examples of voltage gated channels are sodium, potassium and calcium channels and examples of ligand channels are Ach, nicotinic cholinergic, and GABA receptors.

 

Ionotropic vs metabotropic receptors.

Ionotropic: 1. Binding of a neurotransmitter directly opens the channel

2. Results in brief opening of the channel

3. responsible for fast synaptic transmission in CNS

Metabotropic: 1. Binding of the neurotransmitter results in release of 2de messengers 

2. Can last minutes

3. Inhibit or facilitate neurotransmitter release.

 

CNS receptors 

Ionotropic: GABAa, Nicotinic, EAA and seratonin

Metabotropic: Adenylyl cyclase system, Phospholipase C system

 

EPSP and IPSP

EPSP: Activation of additional action potential as a result of depolarization eg Ach channels

IPSP: Suppression of additional action potential as a result of hyperpolarization eg Chloride channels open causing hyperpolarization

 

Role of calcium in development of synaptic potential

Calcium results in fusion between synaptic vesicles and the pre synaptic membrane which causes neurotransmitters to be released.