Bio 1-L10-Signalling via Ligand Gated Ion Channels

what causes action potential depolarisation?

1. ligand gated na channels

2. voltage gated na channels

types of neurotransmitter receptors

1. ionotropic- ligand gated ion channels

2. metabotropic- indirect gating of ion flux- causes cascades etc due to signalling changes- ion G proteins and tyrosine kinase

2 receptor classes

1. nicotinic- ionotropic- depolarisation etc

2. muscarinic- metabotropic- excretory or inhibitory

nicotinic receptors- example

• acetylcholine receptors

• pentamer- 4 alpha helices

• when it binds it changes confirmation of protein- m2 twists and allows ions in

• m2 is hydrophilic

example of Act binding to 2 different receptors

1. nicotinic- causes depolarization, excitatory effect.

2. muscarinic- leads to inhibitory responses or modulation of other signals such as heart rate

what is important to remember about receptors and neurotransmitters?

it doesn’t always depend on the neurotransmitters but the type of receptor they bind to

explain action potential propagation down the neurons

1. dendrites- ligand gated Na channels and K channels

2. axon hillcok- voltage gated Na channels and Cl- channels

3. axon- voltage gated Na to allow to go down and K+ to avoid backpropogation

4. presynaptic terminal- voltage gated Na and calcium channels

difference between glutamate and GABA

• Glutamate is excitatory- depolarisation- can cause epilepsy

• GABA is inhibitory- hyperpolarizes neurons- reducing the likelihood of action potential generation. - alcohol, benzes