Neurotransmitters and Receptors Flashcards
What is ACh?
A neurotransmitter
Where is ACh used?
- Only neurotransmitter used in motor division of somatic nervous system (sensory neurones used glutamate and various peptides at synapses)
- One of many neurotransmitters in ANS
What is effect of ACh in cardiac tissue?
Inhibitory effect, lowers heartrate
What is effect of ACh in skeletal muscle?
Excitatory
What is the cholinergic system?
Cholinergic refers to ACH, usually used to describe neurones, receptors or synapses that use ACh
E.g. a neurone that releases ACh is cholinergic
What are cholinergic agents?
Mimic the action of ACh
What happens when ACh binds to ACh receptors on skeletal muscle fibres?
Opens ligand-gated sodium channels in cell membrane
Sodium ions then enter cell (see previous)
Muscle contraction
In the ANS, where is ACh released?
- All pre and post ganglionic parasympathetic neurones
- All pre-ganglionic sympathetic neurones
- Some post-ganglionic sympathetic fibre
- In the pseudomotor neurones to the sweat glands
How does ACh act in the CNS?
Has a variety of effects as a neuromodulator for plasticity, arousal, and reward. ACh has an important role in the enhancement of sensory perceptions when we wake up and in sustaining attention.
How is ACh synthesised?
In certain neurones by the enzyme choline acetyltransferase from the compounds choline and acetyl-CoA
What breaks down ACh?
Acetylcholinesterase
What can neurotoxins inhibiting acetylcholinesterase lead to?
Paralysis of muscles needed for breathing and beating of heart
What are adrenergic receptors (adrenoceptors)?
G protein-coupled receptors that bind catecholamines
What are catecholamines?
Include dopamine, adrenaline, noradrenaline
What do catecholamines lead to?
Overall stimulatory responses (associated with stress)
