Ligand-Gated Channels

How do Ligand-Gated Channels Function?

Receptors open and shut ion channels directly, binding of transmitter makes the channel open.

Give examples of Ligand-Gated Channels

Nictotinic Cholinergic Receptors (nACHR)

Gamma-aminobutyric acid (GABA)

Name the location, function, structure of the nACHR

• Skeletal muscle

• Contraction of muscle

• Pentamer crosses lipid bilayer

Explain how the muscle contracts from the nACHR

Once Acetylcholine binds to receptors, an internal pore opens.

Na* ions flow down their electrochemical gradient into the cell.

The membrane becomes depolarised and the muscle contracts

Name the location, function, structure of GABA

Central Nervous System

Decreases Neuronal Excitability

Carboxilic Acid and Amine group

Explain how GABA act as inhibitory neurotransmitter

Once GABA binds to receptors on the post-synaptic neuron, internal pores open.

Flow of CI* ions flow into the post-synaptic neuron making it Hyperpolarised.

This lowers neuronal excitation.

What does Epilepsy cause?

Too much neuronal excitation, however GABA neurotransmitters calm this down

How does Treatment for GABA disorders work?

Drugs, like Benzodiazepines, allosterically modulate the GABA receptor.

This increases CI* entry making the post-synaptic neuron more hyper-polarised.