Neurotranmission Flashcards
What is dendritic aborization and why is it important for neuronal function?
Dendritic aborization is the branching out of dendrites. It is important as it allows for dendrites to make new synaptic connects.
What is the Neuromuscular Junction?
It is a specialised synapse between an α-motor neuron and a muscle fibre at the motor end plate.
What is muscle atrophy and how does it come about?
It is the decrease in the mass of the muscle (as seen in motoneuron diseases) and is cause by denervation.
What are Excitatory Post-Synaptic potentials (EPSPs)?
They are potentials that cause the depolarisation of the post-synaptic membrane.
What are Inhibitory Post-Synaptic Potentials (IPSPs)?
They are potentials that hyperpolarize the post-synaptic membrane.
What causes the generation of EPSPs and IPSPs?
EPSPs = An increase in Na+ or Ca2+ permeability.
IPSPs = An increase in Cl- or K+ permeability.
What determines the final post-synaptic cellular response of the EPSPs and IPSPs?
Synaptic integration and Summation.
What are the 4 criteria that a molecule needs to meet in order to be considered a neurotransmitter?
1) It should be synthesised in the neuron.
2) It should be present in the presynaptic terminal.
3) There should be a specific mechanisms for removing it the synaptic cleft.
4) When applied exogenously it should mimic exactly the action of the endogenously released transmitter.
Which 3 amino acids act as neurotransmitters?
Glutamate, GABA (gamma-aminobutyric acid) and glycine.
What other molecules aside from biogenic amines and amino acids can act as neurotransmitters?
ATP and adenosine, and nitric oxide (NO-)
Which 6 biogenic amines act as neurotransmitters?
Acetylcholine, Noradrenaline, Adrenaline, Dopamine, Serotonin (5-HT), Histamine.
What is acetylcholine synthesised from and Where?
It is synthesized from Choline and acetyl CoA in the pre-synaptic terminal.
Which two receptor types for Acetylcholine act on?
It acts on Nicotinic (ligand-gated ion channels) and Muscarinic (G-protein coupled) receptors.
What is noradrenaline synthesised from and where?
It is synthesised from tyrosine in the post-synaptic membrane.
What are the two receptor types that Noradrenaline acts on?
α-adrenergic receptors and β-adrenergic receptors.
What are α-adrenergic receptors and what does the activation of the two subtypes result in?
They are G-protein coupled receptors.
α1 activation results in Ca2+ release.
α2 activation results in inhibition of adenylate cyclase.
What are β-adrenergic receptors and what their activation result in?
They are G-protein coupled receptors.
They activation results in activation of adenyl cyclase, and thus an increase in cAMP
How does the drug Amphetamine work in Noradrenergic synpases?
it works by blocking the re-uptake of Noradrenaline from the synaptic cleft so that the effect of NA is prolonged.
What are the effects of Muscarine and Atropine on the heart?
Muscarine slows the heart rate.
Atropine blocks the actions of muscarine and the vagus nerve, preventing the lowering of the heart rate.
What are the effects of Nicotine and Curare on the skeletal muscles?
Nicotine stimulates contraction of skeletal muscle.
Curare blocks the action of nicotine at the NMJ and prevents the contraction of the skeletal muscle.
How does stimulation of the vagus nerve cause the heart rate to slow down?
Stimulation of the vagus nerve causes the release of the substance Vagusstoff, which slows the heart rate down.
What is the effect of a bacterial infection that leads to the release of the Tetanus toxin on the muscle?
It causes an increase in muscle contraction as it works on inhibitory neurons to prevent the fusion of vesicles with the pre-synaptic membrane.
What is the effect of the nerve gas ‘Sarin’ on the muscle?
It causes uncontrolled muscle contraction by inhibiting the action of acetylcholinesterase.
What is the effect of the Toxin ‘Tetrodotoxin’ on the muscle?
It prevents muscle contraction by binding to sodium-channels. , which thus prevents the formation of action potentials.
Where are the 5 muscarinic receptors sub-types primarily found?
M1 = found in Neural cells.
M2 = found in Cardiac cells.
M3 = found in Glandular/smooth muscle cells.
M4 and M5 = found in the CNS.
What are drugs that stimulate and inhibit muscarinic receptors called?
Drugs that stimulate muscarine receptors are called parasympathomimetics.
Drugs that inhibit these receptors are called parasympatholytics.
